Oviposition Preference, Larval Survival, Flight Trends, and Control Measures for Western Bean Cutworm (Lepidoptera: Noctuidae) in Dry Bean

Lindsey Anne Goudis

A Thesis presented to The University of Guelph

In partial fulfilment of requirements for the degree of Master of Science In Environmental Biology

Guelph, Ontario, Canada

©Lindsey Anne Goudis, October, 2014

ABSTRACT

OVIPOSITION PREFERENCE, LARVAL SURVIVAL, FLIGHT TRENDS, AND CONTROL MEASURES FOR WESTERN BEAN CUTWORM (LEPIDOPTERA: NOCTUIDAE) IN DRY BEAN

Lindsey Anne Goudis Advisory Committee: University of Guelph, 2014 Chris L. Gillard Rebecca H. Hallett Tracey S. Baute

Western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae) is a pest of corn and dry beans in the midwestern United States, but its pest status in Ontario dry beans is poorly understood. Studies were conducted to examine oviposition preference and larval survival, moth captures, and insecticide efficacy and timing. No preference was found between market classes for oviposition, however larval survival was greatest on light red kidney and lowest on adzuki bean. Moth captures were highest on coarse and fine textured soil, and within

20 km of the Lake Huron shoreline. Thiamethoxam, spinetoram, methoxyfenozide, lambda- cyhalothrin, and chlorantraniliprole were all effective at reducing feeding damage, and application 4 – 18 days after 50% egg hatch was optimal. At current population levels however, insecticide applications provided no economic benefit, though continual monitoring of this pest in dry bean fields is recommended.

Acknowledgements

There are many people I would like to say a very large thank you to for their help and support throughout my research. First and foremost I would like to thank my two co-advisors,

Mr. Chris Gillard and Dr. Rebecca Hallett. Chris was always available to answer any questions or concerns, and was insistent on beginning the writing process early, which I now understand why. Rebecca’s words of advice and experience were invaluable in terms of setting up trials, manuscript writing, and any entomological questions I had. I would also like to thank my third advisory committee member Tracey Baute from the Ontario Ministry of Agriculture, Food and

Rural Affairs, for her guidance and support throughout the thesis writing process.

I would also like to thank Cara McCreary, technician in the edible beans lab, for all of her help planting, maintaining, and harvesting trials, in addition to the hours she spent patiently explaining various aspects of statistics. A thank you also goes out to Jocelyn Smith, for allowing me to use moths from her western bean cutworm colony as well as laboratory space to run my experiments, and to Cheryl Trueman for her support with the snap bean trial. I would also like to thank Gerard Pynenburg, Greg Wilson, and Harold Wright at Syngenta Crop Protection for use of their land as well as for their help maintaining my Plattsville trials, and Dan Wilson at Hensall

District Co-operative for recording WBC damage in commercial dry bean loads and relaying the information to me. I would also like to thank my current employer BASF, which has allowed me time to complete my thesis while working.

I would also like to thank technicians Don Depuydt, Cara McCreary, Phyllis May, and

Kris McNaughton for their technical support, as well as my fellow graduate students Ally

iii

Friesen, Erin LeClair, and Xinyu Zhang who helped with ratings and egg collection despite being busy themselves.

I would also like to thank the many students who helped with the ratings in the field, moth counting, larval measuring, egg mass collecting, harvesting, and the many samples that were analyzed in the fall. This includes Jocelyn Hayes, Megan Vyn, Kelsey Flanagan, Julie

Moore, Cynthia Zhou, Saman Pathirana, Tonya MacLukiewicz, Mitchell Bloomestyn, Nikki

Galbraith, and Jesse Kankula.

My parents Debbie and Jim, and my sister Paige, have always been there for me and I would like to thank them from the bottom of my heart for all of their love and support through the years. I would also like to thank Dan Mepham, for the many weekends he helped me check plants for egg masses, and who always brought a smile to my face and made me laugh no matter how stressed out I was.

I would like to thank the many producers who allowed me to place pheromone traps in their dry bean fields, as well as those that let me conduct trials on their land. Lastly, I would like to thank my funding agencies the Ontario Bean Producers, the Agriculture Adaptation Council

F.I.P Program, the OMAFRA – University of Guelph Sustainable Production Program, and the

Ontario Processing Vegetable Growers; without their generous financial support, this research never would have come to fruition.

Table of Contents Acknowledgements ...... iii Table of Contents ...... v List of Tables ...... vii List of Figures ...... x Table of Acronyms ...... xii

CHAPTER ONE: Literature Review and Research Objectives 1.1 Dry Beans, Phaseolus vulgaris L...... 1 1.1.1 History...... 1 1.1.2 Dry Bean Development...... 1 1.1.3 Market Classes ...... 3 1.1.4 Dry Bean Production...... 3 1.1.5 General Introduction to Insect Pests of Dry Bean ...... 4 1.2 Western Bean Cutworm...... 5 1.2.1 Introduction ...... 5 1.2.2 Morphology and Development ...... 6 1.2.3 Lifecycle and Development on Dry Beans ...... 7 1.2.4 Host Plants ...... 8 1.2.5 Pest Status ...... 9 1.2.6 Impact in Dry Bean ...... 11 1.3 Western Bean Cutworm Monitoring Techniques ...... 11 1.3.1 Common Trap Types for Lepidopterans ...... 11 1.3.2 Correlations between Trap Captures and Field Damage ...... 13 1.4 Foliar Insecticides for the Control of Western Bean Cutworm and Other Lepidopteran Pests ...... 14 1.5 Research Objectives...... 17 CHAPTER TWO: Western Bean Cutworm (Lepidoptera: Noctuidae) Oviposition Preference and Larval Survival on Dry Beans 2.1 Abstract...... 20 2.2 Introduction...... 21 2.3 Materials and Methods...... 22 2.3.1 Dry Bean Oviposition Field Trial ...... 22 2.3.2 Alternate Host Oviposition Field Trial ...... 25 2.3.3 Dry Bean Oviposition Preference Laboratory Trial ...... 27 2.3.4 Larval Survival Trial ...... 28 2.3.5 Data Analysis ...... 29 2.4 Results and Discussion ...... 31 2.4.1 Oviposition Field Trials ...... 31 2.4.2 Dry Bean Oviposition Preference Laboratory Trial ...... 34 2.4.3 Larval Survival Trial ...... 34 2.5 Conclusion ...... 44

CHAPTER THREE: Insecticide Efficacy and Timing for the Control of Western Bean Cutworm (Lepidoptera: Noctuidae) in Dry and Snap Beans 3.1 Abstract...... 45 3.2 Introduction...... 46 3.3 Materials and Methods...... 49 3.3.1 Dry Bean Insecticide Timing and Efficacy Trials ...... 49 3.3.2 Snap Bean Insecticide Timing Trial ...... 54 3.3.3 Data Analysis ...... 56 3.4 Results and Discussion ...... 58 3.4.1 Dry Bean Insecticide Timing Trial ...... 58 3.4.2 Dry Bean Insecticide Efficacy Trial ...... 69 3.4.3 Snap Bean Insecticide Timing Trial ...... 76 3.5 Conclusion ...... 82

CHAPTER FOUR: Western Bean Cutworm (Lepidoptera: Noctuidae) Pheromone Trap Monitoring and Damage Assessment in Dry Beans 4.1 Abstract...... 84 4.2 Introduction...... 85 4.3 Materials and Methods...... 88 4.3.1 Population Monitoring in Grower Fields ...... 88 4.3.2 Field Damage in Grower Fields ...... 92 4.3.3 Data Analysis ...... 92 4.4 Results and Discussion ...... 93 4.4.1 Population Monitoring in Grower Fields ...... 93 4.4.2 Field Damage in Grower Fields ...... 103 4.5 Conclusion ...... 103

CHAPTER FIVE: General Discussion 5.1 Oviposition Preference and Larval Survival ...... 106 5.2 Insecticide Timing and Efficacy ...... 108 5.3 Pheromone Trap Monitoring and Damage Assessment ...... 108 5.4 Recommendations and Conclusions ...... 110

References ...... 111

List of Tables

Table 2.1. Market classes and cultivars of dry bean (Phaseolus vulgaris and adzuki bean, Vigna angularis) used in western bean cutworm oviposition field trials at Bothwell, ON, 2012-2013 ..24

Table 2.2. Plant species used in the alternate host oviposition field trials at Bothwell, ON, 2012- 2013...... 26

Table 2.3. Mean (± 95% CI) number of western bean cutworm eggs laid per plant on seven dry bean market classes for each of the three developmental stages examined in laboratory experiments conducted at Ridgetown, ON, 2013...... 35

Table 2.4. Survival of newly eclosed western bean cutworm larvae fed three tissue types and three dry bean market classes for twenty-eight days, expressed as a percentage (± 95% Cl) of the control diet, in laboratory experiments conducted at Ridgetown, ON, 2013 ...... 36

Table 2.5. Developmental parameters (± S.E) of newly eclosed western bean cutworm larvae fed three dry bean market classes or a diet control for twenty-eight days in laboratory experiments conducted at Ridgetown, ON, 2013 ...... 38

Table 2.6. Head capsule width (± S.E) of western bean cutworm larvae fed three dry bean market classes or a diet control for 28 days in laboratory experiments conducted at Ridgetown, ON, 2013...... 39

Table 2.7. Developmental parameters (± S.E) of newly eclosed western bean cutworm larvae fed three dry bean tissue types or a diet control for 28 days in laboratory experiments conducted at Ridgetown, ON, 2013 ...... 41

Table 2.8. Head capsule width (± S.E) of western bean cutworm larvae fed three dry bean tissue types or a diet control for 28 days in laboratory experiments conducted at Ridgetown, ON, 2013 ...... 42

Table 3.1. Dates for dry bean planting, western bean cutworm egg mass inoculation, 50% egg mass hatch, and insecticide applications at Ridgetown, Plattsville, and Exeter Ontario trials in 2012-2013 ...... 51

Table 3.2. Analysis of variance of the different fixed effects examining the percentage of damaged dry bean pods by western bean cutworm at 3-6 weeks after 50% egg mass hatch at Ridgetown, Ontario, 2012 ...... 60

Table 3.3. Effect of active ingredient on the percentage of dry bean pods (±95% CI) with feeding damage from western bean cutworm at 3-6 weeks after 50% hatch of egg masses at Ridgetown, ON, 2012 ...... 61

vii

Table 3.4. Analysis of variance of the different fixed effects examining the percentage of damaged dry bean pods by western bean cutworm at 1-7 weeks after 50% egg hatch in insecticide timing trials at Ridgetown and Exeter, Ontario, 2013 ...... 62

Table 3.5. Effect of active ingredient on the percentage of dry bean pods (± 95% CI) with feeding damage from western bean cutworm at 1-7 weeks after 50% hatch of egg masses at Ridgetown and Exeter, ON, 2013 ...... 63

Table 3.6. Effect of application timing on the percentage of dry bean pods (±95% CI) with feeding damage from western bean cutworm at 1-7 weeks after 50% hatch of egg masses at Ridgetown and Exeter, ON, 2013 ...... 64

Table 3.7. Effect of active ingredient on damage to plant sample dry bean pods (± 95% Cl) from western bean cutworm feeding at Ridgetown and Exeter, ON, 2012-2013...... 65

Table 3.8. Effect of time of insecticide application on damage to dry bean pods (±95% Cl) at Ridgetown and Exeter, ON, 2012-2013 ...... 67

Table 3.9. Effect of active ingredient on the percentage of dry bean seeds with western bean cutworm feeding damage (±95% Cl) in a 200 seed at Ridgetown and Exeter, ON, 2012-2013 ...68

Table 3.10. Insecticide efficacy treatment list for reducing western bean cutworm feeding damage in dry beans at Ridgetown, Plattsville, and Exeter, ON, 2012 – 2013 ...... 70

Table 3.11. Analysis of variance of the fixed effect (insecticide product) examining the percentage of damaged dry bean pods by western bean cutworm at 2-8 weeks after 50% egg hatch in insecticide efficacy trials at Ridgetown and Exeter, ON, 2013 ...... 71

Table 3.12. Analysis of variance of the different fixed effects examining the percentage of western bean cutworm egg mass hatch, and the number of hatched eggs in insecticide timing trials in snap beans at Ridgetown, ON, 2011 – 2013 ...... 77

Table 3.13. Percentage of hatched western bean cutworm egg masses and the number of hatched eggs by insecticide active ingredient before treatment applications in insecticide timing trials in snap beans at Ridgetown, ON, 2011 – 2013 ...... 79

Table 3.14. Effect of active ingredient on the number (± 95% CI) of western bean cutworm damaged snap bean leaves at Ridgetown, ON 2011-2013 ...... 80

Table 3.15. Effect of active ingredient on pod yield (kg/ha), percentage of undamaged, and percentage of western bean cutworm damaged snap bean pods (± 95 % CI) at Ridgetown, ON 2011-2013 ...... 81

Table 4.1. Growing degree day (GDD) accumulations (Base 50°F) corresponding to predicted moth emergence (Seymour et al. 2004), and mean values for three sites near Goderich, ON, 2011 – 2013...... 97

viii

Table 4.2. Weekly captures (± S.E) of male western bean cutworm moths grouped by distance from the shoreline of Lake Huron, ON in 2011 – 2013 ...... 99

Table 4.3. Weekly captures (± S.E) of male western bean cutworm moths in 2011-2013 by site soil texture class ...... 102

Table 4.4. Percentage of seed samples (± 95% Cl) with western bean cutworm feeding damage, and damage severity grouped by dry bean market class in 2010 – 2012 ...... 104

List of Figures

Figure 2.1. Weekly western bean cutworm moth captures at oviposition field trial sites in 2012 and 2013 near Bothwell, ON. Dates (± 1 day) were: Week 3 = 17 – 23 June, Week 4 = 24 – 30 June, Week 5 = 1 – 7 July, Week 6 = 8 –15 July; Week 7 = 16 – 22 July; Week 8 = 23 – 29 July; Week 9 = 30 July – 5 Aug; Week 10 = 6 – 12 Aug; Week 11 = 13 – 19 Aug; Week 12 = 20 – 26 Aug...... 32

Figure 3.1. Effect of active ingredient on the percentage of damaged dry bean pods (± 95% CI) by western bean cutworm measured during the season at 2-8 weeks after insecticide application at Ridgetown and Exeter, ON, 2013. Treatments are listed in table 3.10. Damaged pod ratings were square-root (x + 0.5) transformed (R: weeks 4 and 6, E: weeks 2 and 6) and arcsine square- root (R: weeks 2 and 8, E: weeks 4 and 7) transformed for analysis to satisfy the assumptions of normality, and back-transformed data are presented. Means within the same week and location followed by the same letter are not significantly different (P ≥ 0.05) according to Fisher’s Protected LSD test...... 72

Figure 3.2. Effect of active ingredient on the percentage of damaged dry bean pods in plant samples (± 95% Cl) from western bean cutworm at Ridgetown, Plattsville, and Exeter, ON, 2012-2013. Damage severity 1=superficial feeding damage ≤ 0.25 cm in diameter; damage severity 2=superficial feeding damage > 0.25 cm in diameter; damage severity 3=deep feeding damage entering the pod. Treatments are listed in table 3.10. Total percent damage ratings were arcsine-square root transformed and damage severity 1-3 categories were logarithmic (x + 1) transformed for data analysis to satisfy the assumptions of normality. Back-transformed data are presented. Means in the same damage severity category followed by the same letter are not significantly different (P ≥ 0.05) according to Fisher’s Protected LSD test ...... 74

Figure 3.3. Effect of active ingredient on the percentage of dry bean seed in plant and harvest samples (± 95% Cl) damaged by western bean cutworm at Ridgetown, Plattsville, and Exeter, ON, 2012-2013. Treatments are listed in table 3.10. Plant sample seed was collected from the eight plants that were removed from plots before harvest; Harvest sample seed was collected from the yield samples when plots were combined or threshed. Plant sample percentages were logarithmic (x +1) transformed, and harvest sample percentages were arcsine square-root transformed to satisfy the assumptions of normality. Back-transformed data are presented. Means in the same sample category that share the same letter are not significantly different (P ≥ 0.05) according to Fisher’s Protected LSD test...... 75

Figure 4.1. Google Earth (Google Inc., Mountain View, CA) map of pheromone trap placement in 2013 in relation to Lake Huron for western bean cutworm moth captures ...... 89

Figure 4.2. Average weekly trap captures of western bean cutworm in Southern Ontario 2011- 2013. Dates (± 1 day) were: Week 6 = 8 –15 July; Week 7 = 15 – 22 July; Week 8 = 22 – 29 July; Week 9 = 29 July – 5 Aug; Week 10 = 5 – 12 Aug; Week 11 = 12 – 19 Aug; Week 12 = 19 – 26 Aug ...... 94

Figure 4.3. Cumulative pheromone trap captures by year of western bean cutworm moths based on the number of growing degree days (base 50°F) accumulated as of May 1st (left column) and January 1st (right column) in 2011 – 2013. Vertical black, grey, and dotted lines = 25, 50, and 75% of total moth captures respectively ...... 96

Figure 4.4. Seasonal captures (± S.E) of western bean cutworm moths in 2011-2013 at differing distances from the shoreline of Lake Huron, ON. Means that share the same letter are not significantly different (P ≥ 0.05) according to Fisher’s Protected LSD test ...... 100

Table of Acronyms

BBCH – Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie scale

DAH50 – Days after 50% egg mass hatch

DAI – Days after inoculation

GDD – Growing degree days

OMAFRA – Ontario Ministry of Agriculture, Food and Rural Affairs

ROI – Return on investment

WBC – Western bean cutworm

xii

CHAPTER ONE

Literature Review and Research Objectives

1.1 Dry Beans, Phaseolus vulgaris L. 1.1.1 History

The dry bean or common bean, Phaseolus vulgaris L. (Fabaceae), is a leguminous warm season crop grown throughout much of the world. Its origin can be traced back as far as eight millennia to wild relatives in South and Central America (Gepts and Debouck 1991), though records show its first appearance in Ontario was in the last thousand years (Hart et al. 2001).

Once in North America, this crop grew in importance to become one of the three staple foods of indigenous peoples, and along with corn and squash were known as the ‘three sisters’ (Hart

2008).

Dry beans are divided into groups known as market classes. These groups are composed of many cultivars sharing similar seed attributes (Myers and Baggett 1999). Current dry bean market classes arise from two main genetic ancestral lines: Andean and Mesoamerican (Mamidi et al. 2011). The Andean line originated along the southwestern edge of South America, while the Mesomerican line comes from Mexico and Central America (Mamidi et al. 2011).

Mesoamerican beans include market classes such as black and navy, which have characteristically smaller seeds than their Andean counterparts such as kidney and cranberry

(Mamidi et al. 2011; Ibarra-Perez et al. 1997).

1.1.2 Dry Bean Development

Dry beans are a dicotyledonous crop which reproduce primarily by self-pollination. Cross pollination can occur in bean populations; however its frequency varies widely from 0 – 85%

1 and is influenced by factors such as growth habit, seed size, and environmental conditions

(Ibarra-Perez et al. 1997).

Four different growth habits (Types I-IV) occur in dry beans, though only three are found in commercial production (Voysest and Dessert 1991). Type I plants have a determinate bush style structure, making them desirable for commercial production as they can be direct combined at maturity. These plants are upright in growth habit, have a short flowering period, and possess an extremely limited ability to vine. Type II plants are indeterminate with slight vining possible, but also have a bush-style structure like Type I. Type III plants are indeterminate in their growth habit, and can be found with either a bush style of growth, or a climbing style. The bush-style plants create vines, though they are still manageable under an agricultural setting. Type IV plants are indeterminate in their growth habit and possess a strong ability to vine and climb (Kelly

2000). Consequently, Type IV plants are difficult to harvest with machinery and are impractical for most large commercial operations. Indeterminate plants, such as Type II, III, and IV, possess a vegetative meristem at the terminal end of the plant which allows for continued production of branches under favorable environmental conditions. These types also have a longer flowering period than Type I plants (Debouck 1991).

The many stages of dry bean growth can be documented with the use of the Biologische

Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale designed for monocotyledonous and dicotyledenous weed species (Hess et al. 1997) This scale assigns each developmental period a numerical value between one and ninety-nine, with each value corresponding to a specific milestone. The vegetative growth of the plant is classified between zero and twenty-nine, while reproductive growth is classified with values above fifty-one; ninety-nine corresponds to the fully mature plant (Hess et al. 1997). Regardless of growth habit

2 or market class, the number of days to initial flowering in dry bean plants is approximately 40-

50% of the estimated time to maturity (Cerna and Beaver 1990).

1.1.3 Market Classes

There are many different market classes of dry bean grown internationally. Production in

Canada focuses on navy, otebo, and black bean, which are of Mesoamerican origin, in addition to kidney, cranberry, and pinto, which are of Andean origin. An additional market class produced in Ontario is adzuki bean (Stewart et al. 2010). This market class differs in its genus and species when compared to traditional dry beans, P. vulgaris, as it belongs to Vigna angularis (Willd.)

Ohwi & H. Ohashi.

Dry bean varieties are also grouped by the colour of their seed coat. The white bean category consists of navy bean, while the coloured bean category consists of black, pinto, cranberry, and kidney bean market classes. A third category known as Japanese beans exists and is composed of the otebo and adzuki bean market classes, which are shipped primarily to Asian markets.

1.1.4 Dry Bean Production

Dry beans contain between 15 and 25% protein on a dry weight basis, and contain ≥ 27% carbohydrates (Nichols et al. 2011). This high nutrient content makes them a beneficial source of protein for populations that cannot afford, or choose not to consume, a meat-based diet.

Asia is the continent responsible for the majority of dry bean production in the world, and contributed 47.7% of the 22,923,401 tonnes produced in 2010 (FAOSTAT 2012). Brazil is the largest producing individual country (13.8% of total production), with South America as a whole responsible for 17.2% of worldwide production (FAOSTAT 2012). Myanmar, India, USA, and

China are the four additional top producing countries aside from Brazil for the 2010 cropping

3 season (FAOSTAT 2012). Production of dry beans in Ontario, and Canada in general, is relatively small in comparison to other crops, such as corn and soybeans. On average, 116,100 ha were planted to dry beans in Canada in the 2008-2011 cropping seasons, resulting in the production of 226,600 metric tonnes (Statistics Canada 2013). Pinto, cranberry and navy beans are the three primary market classes produced in the Canadian Prairie Provinces, with Manitoba growing pinto beans as their main market class. Production in Alberta also focuses on Andean market classes, however Mesoamerican market classes are grown as well (Blackshaw and

Saindon 1996). In Ontario in 2010, 82,600 tonnes of white beans and 46,700 tonnes of coloured beans were produced (OMAFRA 2011). Ontario produces the majority (>50%) of the navy beans in the country (Statistics Canada 2013), however additional market classes such as cranberry, kidney, and black are also grown (Soltani et al. 2008).

Canada is the fifth largest exporter of dry beans in the world, responsible for the export of

$240 million worth of product in 2010 (FAOSTAT 2012). Historically, navy bean makes up approximately 35% of Canadian dry bean exports (AAFC 2010). In 2010, over 3 million tonnes of dry bean were traded throughout the world, worth approximately USD $2.89 billion

(FAOSTAT 2012). The top two exporting countries in 2010 were China and Myanmar, with

950,424 and 496,533 tonnes respectively (FAOSTAT 2012).The top two dry bean importing countries in the world were India and Brazil, purchasing 495,368 and 181,162 tonnes in 2010

(FAOSTAT 2012).

1.1.5 General Introduction to Insect Pests of Dry Bean

There are four main dry bean pests of importance in Ontario, which include the bean leaf beetle, Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), the potato leaf hopper,

Empoasca fabae (Harris) (Homoptera: Cicadellidae), Mexican bean beetle, Epilachna varivestis

Mulsant (Coleoptera: Coccinellidae), and tarnished plant bug, Lygus lineolaris (Palisot de

Beauvois) (Hemiptera: Miridae).

Defoliation of dry bean plants is often caused by E. varivestis or C. trifurcata (OMAFRA

2009; Klass and Muka 2012). Both adults and larvae of E. varivestis cause damage to bean plants by feeding on flowers, leaves, and pods, and this insect is considered the main defoliator of dry beans in the midwestern United States (Barigossi et al 2003). The host crop for C. trifurcata is soybean, Glycine max, but adults can also surface feed on dry bean leaves and pods, increasing the risk for secondary infection (OMAFRA 2009). Damage from these two insects can be found as small circles on the surface of the pods, which typically do not enter into the deeper tissue.

Piercing damage to the plant is primarily caused by two insects, L. lineolaris and E. fabae. L. lineolaris adults and older nymphs pierce plant tissue with their proboscis and remove nutrients from the plant. This direct feeding can increase the risk for fungal and bacterial infection at the puncture wound, and can also result in pitting of the bean seed making it esthetically undesirable (OMAFRA 2009). E. fabae not only pierces the foliage of dry bean plants to feed, but also injects saliva to digest parts of the plant (Nault et al. 2004). Feeding results in yellowing of the outer leaf margins (OMAFRA 2009; Nault et al. 2004). E. fabae are common pests in Ontario dry bean fields (Schaafsma et al. 1998), though populations are often controlled with neonicotinoid seed treatments (Nault et al. 2004).

1.2 Western Bean Cutworm

1.2.1 Introduction

The western bean cutworm (WBC), Striacosta albicosta (Smith) (Lepidoptera:

Noctuidae) has only recently been detected in Ontario (Michel et al 2010), and is thought to be a

5 pest of corn, dry and snap beans, as it is in areas of the midwestern United States (Hoerner 1948;

Douglass et al. 1957). This climbing cutworm was initially identified in Arizona, and classified in the Agrotis genus in 1887 (Smith 1887). This insect went through two additional classifications into the Loxagrotis genus (McDunnough 1928), and later the Richia genus. The most recent re-classification occurred in 2004 where it was placed in, still remains, and is the only member of the Striacosta genus (LaFontaine 2004).

1.2.2 Morphology and Development

Eggs of WBC are laid in masses, with the number of eggs per mass varying greatly from

5 - 200 (Seymour et al. 2004). Each egg is circular in shape, and has lines emanating out from a central point at the top. The eggs take 5 – 7 days to hatch (Seymour et al. 2004) and are white in colour when first laid. Eggs then turn tan in colour, and finally turn dark purple or black prior to hatch (Seymour et al. 2004; Michel et al. 2010).

First and second instars of WBC are light brown in colour with a black head capsule.

Once they reach the third (Rice 2007) or fourth (Michel et al. 2010) instar characteristic markings develop on the pronotum, and can be seen as two thick dark brown stripes. Their larval life cycle consists of 6 instars and is approximately 55.9 days in length (Antonelli 1974; Dorhout and Rice 2010). Larvae then overwinter underground in a pre-pupal stage, pupate in the late spring, and emerge as adult moths in the mid-late summer (Seymour et al. 2004).

Adult WBC moths are ~2 cm in length with a wingspan of ~3.8 cm (Cook 2004;

Seymour et al. 2004; Michel et al. 2010). Moths can be identified by the tan stripe running along the outer edge of each forewing (Seymour et al. 2004). Other characteristic features include the presence of two dark brown markings surrounded by a tan border on each wing: one marking is circular, and the other is kidney-bean in shape. Both markings are in the middle of each

6 forewing, with the circular marking more medial when the wings are extended (Purdue

University 2009; Michel et al. 2010).

1.2.3 Lifecycle and Development on Dry Beans

WBC goes through five main developmental stages in its lifetime: egg, larva, prepupa, pupa, and adult moth (Hagen and Roselle 1966). It has one generation per year (univoltine) and undergoes complete metamorphosis (Cullen and Jyotika 2008). This insect overwinters as a prepupate, and emerges as a moth in early summer (Seymour et al. 2004). Once emerged from the soil, moths mate and lay eggs. Pre-tassel corn is preferred for oviposition early in the season, with egg masses also being found on tasseled corn and dry beans as the season progresses; the developmental stage which damages the plants is the larval stage.

Very little is known about the reproductive habits of WBC. It is also unknown whether females have a pre-ovipositioning period directly after emergence from the soil, though other noctuids have been shown to possess this trait. For example the pre-ovipositioning period of the hypocala moth, Hypocala andremona (Stoll) (Lepidoptera: Noctuidae), is approximately 1.2-4.0 days (Hohmann et al. 2011), for fall armyworm, Spodoptera frugiperda (J.E. Smith)

(Lepidoptera: Noctuidae), it is 2.3-7.4 days (Murúa et al. 2008), and approximately four days for the soybean looper, Pseudoplusia includens (Walker) (Lepidoptera: Noctuidae) (Jost and Pitre

2002). Based on the trend exhibited by other noctuid moths, it is likely that WBC does possess a pre-oviposition period. This non-reproductive period would allow females time to disperse from their overwintering sites prior to egg laying.

Currently it is not known whether there is a preferred market class or developmental stage of dry bean by WBC for oviposition. Once egg laying does commence, eggs are laid on the underside of dry bean leaves and hatch after approximately seven days (Hoerner 1948). Once

7 hatched, first instar larvae feed on plant foliage after consuming their egg shell, or chorion, and larvae feed for an average of 55.9 days (Antonelli 1974; Dorhout and Rice 2010). Feeding occurs primarily at night, with larvae often seeking shelter in the soil or bean foliage during the day.

Larvae can also be found feeding on all types of tissue on the dry bean plant, with younger larvae initially feeding on leaf and flower tissue, and older larvae feeding on dry bean pods (Michel et al. 2010). It is currently unknown if larvae are able to survive solely on dry bean leaf tissue, as eggs are typically deposited on plants later in the growing season when flower buds and pods are present.

In the fall, larvae move into the soil and create a chamber where they overwinter in the pre-pupal stage (Blickenstaff et al. 1975). Pupation is thought to begin the next spring when soil temperatures rise above 50°F (10°C) (Volenberg 2011). In Nebraska, Seymour et al. (2004) found that 25% moth emergence occurred at 1319 growing degree days (GDDs) (base 50°F),

50% at 1422 GDDs, and 75% at 1536 GDDs when accumulations began as of 1 May. This model also appears to be used for explaining emergence counts in Wisconsin (Cullen and Jyotika

2008; Volenberg 2011); though GDD estimates for 25% emergence do differ by 1 GDD. It is not yet known whether GDD accumulations accurately explain moth emergence and flight in

Ontario.

1.2.4 Host Plants

The main host crops for WBC are corn, snap and dry beans. Previous larval survival studies have shown that it is unlikely other crops will act as suitable secondary hosts for the latter larval stages (Blickenstaff and Jolley 1982). Larvae were shown to survive in small numbers on soybeans (Glycine max), tomato (Solanum esculentum), ground cherry (Physalis subglabrata), and nightshade (Solanum nigrum) (Blickenstaff and Jolley 1982). These plants however, were

8 not considered suitable hosts due to the low weight larvae attained (Blickenstaff and Jolley

1982). A laboratory study performed in 2010 (J. L. Smith, personal correspondence1), showed that larval survival is possible on leaf tissue from plants other than corn and bean; however it is unknown if moths will oviposit on these crops or if larvae will survive on these crops in a field setting.

1.2.5 Pest Status

After its initial discovery, WBC presence was reported in Colorado (Hoerner 1948). By

1956 its range expanded to include Idaho, Kansas, Nebraska, Iowa, Utah, New Mexico, Texas, and Alberta, Canada (Crumb 1956). After 1999, the range of this pest expanded further, with migration occurring into Minnesota, Illinois, Missouri, Wisconsin, Indiana, Michigan, Ohio,

Pennsylvania, New York, as well as the Canadian provinces of Ontario and Quebec (Michel et al. 2010). WBC has now expanded its habitable range across the major corn and bean producing areas of both the United States, and Canada. Miller et al. (2009) determined that WBC populations did not undergo a reduction in genetic variability throughout the expansion period, showing that expansion was accessible to a large number of moths, rather than a select few.

There does appear to be a large variation between the time moths are initially found in a new location and the time it takes for economic damage to occur. Areas such as Nebraska, where

WBC was found in 1935, did not see damage of economic importance until 15 years later

(Hagen 1963). Iowa did not see economic damage in corn until 2000, thirty years after moths were first found (Rice et al. 2004). In Colorado, WBC was not recognized as a pest of corn until

1966, even though the first dry bean damage was found in 1915 (Blickenstaff and Jolley 1982). It

1 J. L. Smith, Research Associate, Field Crop Pest Management, University of Guelph, Ridgetown Campus, Ridgetown, Ontario, Canada 9 is not known however, whether economic damage was lacking in fields, or whether it simply was not reported.

In Ontario to date, finding egg masses and larvae of this late season pest in dry bean fields is very difficult. As of 2013 no economic damage by WBC to dry beans had been reported, though in 2014 damage has been identified (T. S. Baute, personal communication2). The financial impact of damage in the 2014 samples however, is not currently known. In corn, Paula-

Moraes (2013) found that a loss of 945.52 kg/ha resulted with an infestation density of one larvae per ear.

Though WBC has been a pest in North America for some time, factors potentially allowing it to expand its geographical range are summarized in Hutchison et al. (2011).

Transgenic corn hybrids are currently used to control populations of the European corn borer,

Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae) (Fernandez-Cornejo and Caswell 2006).

Since WBC is not affected by the Cry1Ab toxin in hybrids (Cantangui and Berg 2006) competition with O. nubilalis may have been reduced, potentially allowing WBC populations to increase. Reduced tillage is another factor that may have contributed to the increase in habitable range of WBC. With fewer passes over the field with tillage equipment, fewer pre-pupates may be killed from coming into contact with equipment. Climate change is another factor mentioned, possibly allowing moths to overwinter in areas that were previously too cold (Hutchison et al.

2011). Miller et al. (2009) point out physical barriers may also have limited the spread of WBC, with the Missouri River appearing to pose a barrier to dispersal until approximately forty years ago. Prior to this time, larvae had only been found west of this waterway (Miller et al. 2009).

2 T. S. Baute, Field Crop Entomologist – Program Lead, Ontario Ministry of Agriculture, Food and Rural Affairs, Ridgetown, Ontario, Canada. 10

Soil type may impact the success of emergence on WBC populations as well, as Hoerner (1948) noted that more moths emerged from sandy soils than clay. Since larvae can burrow deeper in sandy soils, this may allow greater survivability as they are better protected from winter elements and tillage equipment (Blickenstaff et al. 1975).

1.2.6 Impact in Dry Bean

This insect has been documented as a pest of dry beans as far back as the 1940s although the damage seen was variable (Hoerner 1948). In Michigan, 4 larvae in one foot of bean row (0.3 m) resulted in significantly more damage than the rows that were uninfested (Michel et al 2010).

The first instances of WBC damage in dry bean in Ontario were found in 2014, though the economic impact to the producer is not currently known (T.S. Baute, personal communication3).

Though no economic damage has yet been reported, OMAFRA (2009) recommends spraying dry bean fields if accumulated WBC pheromone trap moth captures exceed 1000 by peak flight, to prevent economic damage. It is currently unknown however, how well trap counts correlate to field damage in Ontario.

1.3 Western Bean Cutworm Monitoring Techniques

1.3.1 Common Trap Types for Lepidopterans

Two main trapping methods are commonly used to capture and monitor lepidopteran pests in agriculture; black light traps and pheromone-baited traps. Both are used to estimate peak lepidopteran flight and ultimately predict peak egg laying in a variety of crops.

Black light traps rely on attracting insects with the use of light, rather than pheromone lures. A disadvantage of black light traps is that they are not species-specific and attract many

3 T. S. Baute, Field Crop Entomologist – Program Lead, Ontario Ministry of Agriculture, Food and Rural Affairs, Ridgetown, Ontario, Canada. 11 other nocturnal flying insects, requiring extensive sorting of the catch to isolate WBC (Toda and

Kitching 2002). Pheromone traps attract male moths with the use of a synthetic female pheromone specifically formulated for the lepidopteran species of interest. Once the moths arrive, they are either captured or killed (Seymour et al. 2004). Uni-traps are a commonly used pheromone traps for monitoring lepidopteran pests (Gross and Carpenter 1991; Reardon et al.

2006). These traps are low maintenance, and sample collection is relatively simple. They are also available in solid green, yellow, and white; colour is chosen based on the desired pest species.

The upper part of this trap houses the pheromone lure, has a hole in the middle to allow for moth entry, and has a rain guard over the top to prevent samples from becoming saturated. The lower portion of the trap houses the killing agent and the captured insects. There are a variety of additional attractant, or active traps, that perform the same function as the Uni-trap, including sticky-wing, delta (Knodel and Agnello 1990), and milk jug traps (Dorhout and Rice 2008). The sticky-wing and delta traps use glue to capture the moths once they are attracted by the pheromone, while milk jug traps use an antifreeze solution.

The optimum location of the trap in the field for capture of lepidopteran insects appears to vary by species and throughout the season. Ngollo et al. (2000) found that in corn, O. nubilalis trap captures early in the season were highest at the field edge, but were highest when placed in the middle of the field around peak moth flight. No differences in WBC catch were found between various pheromone trap types in either beans and corn (Mahrt et al. 1987; Dorhout and

Rice 2008). Trap height appears to be important, with traps placed at either 0.6 m or 1.2 m above the ground capturing the highest number of WBC moths on a daily basis in bean fields (Mahrt et al. 1987). Examining traps placed in corn fields however, traps at a height of 0.6 m resulted in the lowest catch over the season, compared to traps at 1.2 and 1.8 m (Dorhout and Rice 2008).

Peak flight period can be identified up to two weeks earlier with black-light traps than with pheromone traps (Laurent and Frérot 2007), though these traps do capture both sexes unlike the pheromone traps which capture primarily male moths. Peak with pheromone trap captures occurs later, most likely due to competition between the synthetic pheromone lures and the pheromones released by virgin females (Palaniswamy et al. 1990), and also due to a reduction in virgin females, making the synthetic pheromones of greater attraction than previously.

1.3.2 Correlations between Trap Captures and Field Damage

Pheromone trap captures up to peak flight of WBC have shown to increase with increasing dry bean damage in the field in Idaho (Mahrt et al. 1987), though it is not known whether a similar pattern exists in Ontario. Black light traps, compared to pheromone traps, more accurately estimated potential damage from WBC over large areas, but cannot be relied upon to estimate damage on a per field basis (Mahrt et al. 1987). Moth captures from black-light traps monitoring other lepidopterans, such as O. nubilalis, have shown positive correlations with egg mass numbers in the field (Palaniswamy et al. 1990; Laurent and Frérot 2007), however no such correlations have been examined with WBC.

Actual WBC populations in the field are difficult to determine as egg masses, larvae, and adult moths can often go undetected due to the dense canopy in bean fields. Pheromone trap captures are often used as a guide for insecticide applications in dry beans, as WBC are difficult to find in the dense foliage of dry bean fields. Examination of the crop for damage is suggested if trap captures leading up to peak flight exceed 700, and spraying is recommended if counts surpass 1000 (OMAFRA 2009) or if adjacent corn fields have reached threshold; though it is unknown if applications based on trap counts are as accurate in the Great Lakes region as they are in the midwestern United States (Michel et al. 2010).

1.4 Foliar Insecticides for the Control of Western Bean Cutworm and other Lepidopteran Pests

An action threshold of 3.64 larvae per square metre is recommended for dry beans in

Nebraska, but determining larval density is very difficult due to small larval size and extensive plant foliage (Hagen 1963). Thus the utility of these thresholds is unclear as larvae are often difficult to locate in dry bean fields due to their nocturnal behavior (Michel et al. 2010). Even if larvae were visible, it is unknown if this threshold would be accurate in Ontario.

Only two insecticide active ingredients, lambda-cyhalothrin and chlorantraniliprole, are registered for use in dry beans to control WBC in Ontario. Lambda-cyhalothrin (Matador®

120EC, Syngenta Crop Protection Canada, Guelph, ON) is a pyrethroid insecticide, which has a broad range of insect control and low toxicity to both mammalian and aquatic organisms

(Spurlock and Lee 2008). Pyrethroid insecticides are commonly used, and 40% of the insecticides registered in the United States belong to this class (Spurlock and Lee 2008).

Pyrethroids are Group 3 insecticides known for delaying the closing of sodium channels during nerve impulse transmission, altering the functioning of the nervous system (Vijverberg et al.

1982), and resulting in insect death.

Since feeding by WBC on dry beans occurs primarily at night, it is also the most effective time to spray, as larvae will likely be on the plant (Michel et al. 2010). In Michigan, lambda- cyhalothrin appeared to significantly reduce the percentage of damaged pods during the season, as well as the percent of damage found at harvest (Jewett et al. 2009). This product also proved to be 100% efficacious in corn when sprayed 13 days after egg mass inoculation (Davidson et al.

2006).

Chlorantraniliprole (Coragen®, E.I. DuPont Canada Co., Mississauga, ON) is a member of a new class of chemicals, the anthranilic diamides. This product is registered for control of a

14 variety of lepidopteran pests in dry beans, and other crops in Canada. Anthranilic diamide insecticides belong to Group 28, and act on the ryanodine receptor (Cordova et al. 2006). This active ingredient, unlike pyrethroids, impacts the muscle rather than the nervous system. By binding to the ryanodine receptor, release of calcium is caused within the cell, affecting muscle contraction in the insect (Cordova et al. 2006). The potential toxicity of chlorantraniliprole was examined with other noctuid species, such as the fall armyworm, S. frugiperda, where laboratory studies found the oral LD50 to be 0.1-0.4ppm (Cordova et al. 2006). This low concentration, coupled with the long length of time this product is active for, would allow good pest control for an extended period of time during the cropping season.

A premixed formulation of lambda-cyhalothrin and chlorantraniliprole (Voliam

Xpress™, Syngenta Crop Protection Canada, Guelph, ON) is registered for WBC control in corn.

This product uses two modes of action to control larvae, however it is not yet registered for use in dry bean in the premixed formulation.

There are a variety of other active ingredients that may be efficacious against WBC, including: thiamethoxam, methoxyfenozide, and spinetoram. Thiamethoxam is a second generation neonicotinoid insecticide, which offers good control of lepidopteran pests (Nauen et al. 2003). It is registered for foliar application to dry beans in a premixed formulation with lambda-cyhalothrin, however not for control of WBC. Thiamethoxam belongs to Group 4A, which acts by binding to the nicotinic acetylcholine receptors and antagonizing acetylcholine

(Maienfisch et al. 2001). This results in disruption of nerve impulse transmission in the body of the insect. It had a high oral LD50 (1.94-2.41 ppm) when examined for its control of the Oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), however when applied in

15 combination with chlorantraniliprole, the oral LD50 (0.12-0.14ppm) was lowered (Jones et al.

2012).

Methoxyfenozide, Group 18A, is a diacylhydrazine insecticide whose activity is aimed specifically at lepidopteran larvae (Moulton et al. 2002). This insecticide functions by binding to the ecdysteroid receptor, resulting in premature moulting and death of the insect (Hardke et al.

2011; Moulton et al. 2002). This insecticide does not result in rapid insect death however, and can take 7-11 days before larval populations are reduced (Murray et al. 2005). This product may not be practical for controlling WBC larval populations, as the delay in death may result in continued feeding on the harvestable portion of the crop, further reducing quality. Currently this product is only registered for use on apple, peach and cranberry crops in Canada, and not against

WBC. This active ingredient is however, registered for WBC control in corn in the United States.

Spinetoram is a spinosyn insecticide, and belongs to Group 5. This chemical affects the

GABA receptors and the nicotinic acetylcholine receptors, resulting in altered neurotransmission

(Hardke et al. 2011). It is registered for the control of lepidopteran pests in a variety of crops, though not for WBC in corn or in dry beans. In cotton, it was found to sufficiently control populations of the cotton bollworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) (Brickle et al. 2001). Spinetoram also exhibited a low LD50 level when controlling S. frugiperda (Hardke et al. 2011). It has not however, been examined for its efficacy against WBC.

Dimethoate is an organophosphate insecticide and is registered for use in dry beans.

Organophosphates, Group 1B, can be used on a wide variety of pests from different insect orders, however currently this product is not registered for the control of any lepidopteran pests.

Products from this group prevent the breakdown of acetylcholine, allowing continual nerve excitation and paralysis of the insect (Fukuto 1990). When examined for control other noctuid

16 populations, such as H. zea, this product actually increased larval numbers to a level above the economic threshold (Knight et al. 2007); possibly due to a reduction in predator populations.

Though many of the previously mentioned chemicals are not registered for WBC control, their efficacy on other lepidopteran pests may yield insight into their potential use against this pest.

1.5 Research Objectives

The overall objective of this research is to identify phenological preferences, efficacious insecticides, and determine patterns affecting pheromone trap captures.

1. Identify whether oviposition preference exists for certain dry bean market classes or

additional crops.

There is currently no information in the literature examining whether certain dry bean market classes, or alternate crops, are at greater risk for oviposition by WBC. Identifying at-risk market classes should encourage producers to monitor those crops closely to prevent damage.

Identifying additional crops that could serve as oviposition hosts for WBC would allow the development of monitoring programs in these crops before WBC becomes a significant problem.

It is hypothesized that no additional crops will provide suitable oviposition hosts for WBC as there has been no evidence of this in the literature.

2. Determine larval survival and development of newly hatched larvae on different tissue

from dry bean market classes.

When examining larval survival, determining which tissue results in the highest survival will be useful to determine the plant stages, in addition to the market classes, at greatest risk for damage.

Information does exist in the literature on larval survival (Blickenstaff and Jolley 1982), however it examines survival on a variety of plants with multiple tissue types present, rather than

17 individual tissue types. It is hypothesized that leaf and flower tissue of dry beans will provide survival and development of larvae similar to the control diet, as young larvae have been found feeding on these plant parts (Michel et al. 2010). Pod tissue however will result in significantly lower survival. The reduced survival is expected as older larvae generally feed on pod tissue, while newly hatched larvae do not (Seymour et al. 2004).

3. Identify the most efficacious application timing for currently registered insecticide

products.

It is currently thought that insecticide applications for control of WBC should be based on trap captures. If trap thresholds are reached, product application should occur within 10-21 days after peak moth flight (Michel et al. 2010). It is not currently known however, how applications at different periods after peak egg laying will affect yield or quality. Determining this will allow producers to develop more effective management strategies.

4. Determine additional active ingredients that are efficacious at controlling WBC

populations.

Currently there are only two active ingredients registered for the control of WBC in dry beans.

Identifying additional products will be useful for producers when there is more than one insect pest that requires control. This would also allow them to determine the best option available, and help to implement resistance management strategies. It is hypothesized that methoxyfenozide, thiamethoxam and spinetoram will all be efficacious against WBC, as they are all registered for the control of other lepidopteran pests. It is also hypothesized that dimethoate will not be effective, since it is not currently registered for the control of any lepidopteran pests.

5. Monitor pheromone trap counts in Ontario, with a focus on Huron county, and identify

factors affecting catch numbers.

It is currently not known if there are external factors, such as soil type or distance from the shoreline of Lake Huron that are impacting captures in Uni-traps in Ontario; Huron county was focussed on as a large amount of dry beans are grown in this area. It is hypothesized that soil type will impact captures early in the season when moths are emerging from the soil, as will distance from the shoreline

6. Examine dry bean seed samples possessing lepidopteran feeding damage at a dry bean

elevator and identify patterns.

Little information exists in the literature about post-harvest dry bean seed damage at the elevator.

It is not known if there is a higher presence of damage in certain market classes, but it is hypothesized that visual damage will be greater in large seeded market classes, since seed from smaller market classes with significant damage would be light, and would be removed by harvest equipment.

Overall it is important to determine what factors influence WBC behavior so that the most effective monitoring and management strategies can be determined for dry beans in

Ontario.

CHAPTER TWO

Western bean cutworm (Lepidoptera: Noctuidae) oviposition preference and

larval survival on dry beans

2.1 Abstract

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a new pest in the Great Lakes region, and its potential impact to dry beans is not well understood.

A two year field study was conducted to examine oviposition preference for eight dry bean market classes, as well as other crop and weed species. Oviposition preference and larval survival were also examined in laboratory experiments. Very little oviposition occurred in dry bean field trials, despite 2013 having an 8-10% density of WBC egg masses in nearby corn fields; exceeding the current action threshold for pre-tassel corn. In the laboratory oviposition study, no differences in preference were found among market classes. Significant differences in larval survival were observed, with the lowest survival rates occurring on adzuki pod tissue and the highest on kidney bean pod tissue. Smaller head capsule widths were also observed in larvae developing on adzuki beans than on other market classes. Based on larval survival, kidney beans appear to be at the greatest risk for economic damage, whereas adzuki beans appear to be a less suitable host.

Key Words Striacosta albicosta, Phaseolus vulgaris, Vigna angularis

2.2 Introduction

The western bean cutworm (WBC), Striacosta albicosta (Smith) (Lepidoptera:

Noctuidae), is native to North America (Smith 1887) and has been previously documented as a pest of corn (Douglass et al. 1957) and dry beans (Hoerner 1948). WBC was first documented in

Arizona (Smith 1887), but in recent years has expanded its range northward and eastward across the United States and into the Great Lakes region of the United States and Canada (O’Rourke and Hutchison 2000; DiFonzo and Hammond 2008; Tooker and Fleischer 2010). It was briefly mentioned in Alberta, Canada (Crumb 1956) though its presence has not been mentioned in this area since. The first Eastern Canadian record of WBC however, occurred in Ontario in 2008 and in Quebec in 2009 (Michel et al. 2010). The potential risk this pest poses to the dry bean industry in the Great Lakes region is not fully understood.

Dry beans are a unique grain crop as they reach the consumer market in relatively unprocessed states (i.e. dried or canned whole beans), making visual appearance an important criteria of marketability. The four main market classes of Phaseolus vulgaris L. grown in Ontario are navy, black, kidney, and cranberry beans (Soltani et al. 2010). Adzuki beans, Vigna angularis

(Willd.) Ohwi and Ohashi, are also grown and are an important export product (Stewart et al.

2010).

For the dry bean industry in the Great Lakes region, it is important to determine the market classes and developmental stages at greatest risk of damage by WBC. It is also important to identify potential new WBC host plants, as this region supports the production of a number of niche field and vegetable crops. Oviposition preferences of WBC for crops other than dry beans and corn have not been reported previously in the literature. Larval feeding studies have indicated that larvae are able to feed on tomato, Solanum lycopersicum L., ground cherry,

Physalis subglabrata Mack. & Bush, and nightshade, Solanum nigrum L. (Blickenstaff 1979).

Later research concluded however, that none of these crops were acceptable hosts for WBC development (Blickenstaff and Jolley 1982). Since the latter research was performed in a laboratory and did not investigate oviposition preferences, it is not known whether WBC would choose to oviposit on these species or other crops in a field setting. Furthermore, determining larval survival and development on dry bean tissues will help to elucidate the risk posed by WBC to commercial dry bean production, and provide a basis for future research and pest management recommendations.

2.3 Materials and Methods

2.3.1 Dry Bean Oviposition Field Trial

This study was conducted near Bothwell, ON in 2012 and 2013, utilizing a split-plot design to examine the main effect of three planting dates, and the secondary effect of eight dry bean market classes (Table 2.1) on the number of eggs laid by WBC females under natural field conditions.

A field was selected in both 2012 and 2013 near Bothwell, Ontario, that had a high density of WBC the previous year. Both fields were on sandy soil, and had corn as the previous crop. The trial was located on the edge of the field in both years.

Three replicates were setup in the 16 m by 23 m trial area, with each replicate being 3 m deep by 16 m wide. A space of 1 m occurred between replicates, with a 2.5 m spacing occurring between the outer replicates and the trial border. Each replicate was composed of three plots. The main plot effect in the trial was planting date (early, mid, or late), which was randomized within each replicate. The sub-plot effect was market class, which was randomized within each plot.

Each plot was composed of eight sub-plots. Each sub-plot was one row of dry beans, one for each market class (Table 2.1), planted 3 m in length. Sub-plots were spaced 0.76 m apart, and sown using a hand planter (EarthWay Products, Inc., Bristol, IN). Planting occurred on 4, 19, and

26 June 2012, and 4, 17, and 25 June 2013, for the early, mid, and late plantings, respectively.

These timings were selected so that plants in the vegetative, flowering, and early pod-set growth stages would be present at the same time during the period of peak moth flight. Seed was obtained from Hensall District Co-operative (Hensall, ON), and rates were selected to achieve a final planting density of approximately forty plants per metre of row.

The presence of male moths was monitored at the trial location in each year using a single green Uni-trap (International Pheromone Systems, Cheshire, UK) equipped with a WBC synthetic pheromone lure (Scentry Biologicals, Inc., Billings, MT). One 4 cm long piece of

Ortho Home Defense Max No-Pest Insecticide Strip (Scotts Miracle-Gro Co., Marysville, OH) was placed in the bottom of the trap to kill arriving moths. Traps were placed in the middle of the trial area, which was near the edge of the field, at a height of approximately 1.2 m. Moth captures were monitored weekly from the beginning of June to the end of August, and lures were changed at three week intervals. Once moth presence was observed, four randomly selected plants per plot were destructively sampled each week for six weeks and all leaves were examined for the presence of egg masses. Egg masses were identified as WBC based on visual examination with a hand lens. Only two plants from the early planted plots were sampled in 2012, due to a low plant density. Growth stage was recorded for each plant using the Biologische

Bundersanstalt Bundessortenamt and Chemical Industry (BBCH) scale (Hess et al. 1997).

Vegetative plants scored between 10-29, flowering plants between 51-65, and pod-set plants between 69-89. Egg mass data recorded included location on the plant (top, middle or bottom

Table 2.1. Market classes and cultivars of dry bean (Phaseolus vulgaris and adzuki bean, Vigna angularis) used in western bean cutworm oviposition field trials at Bothwell, ON, 2012-2013.

Market Class Cultivar Navy T9905 Cranberry Hooter Pinto La Paz Light Red Kidney Inferno Dark Red Kidney Majesty Black Zorro Otebo Fuji Adzuki Erimo

24 third), leaf surface (upper or lower), the number of eggs per mass, and a visual rating of larval feeding as the percentage of leaf area consumed.

2.3.2 Alternate Host Oviposition Field Trial

A split-plot design experiment examined the main effect of two different planting times

(early and late), and the secondary effect of ten crop and two weed species (Table 2.2) on the number of eggs laid by WBC females under natural field conditions.

Seed was obtained from Ontario Seed Co. Limited (Waterloo, ON), and from both the horticultural and weed research programs at University of Guelph Ridgetown Campus

(Ridgetown, ON). Three replicates were setup in the 14 m by 22 m trial area, with each replicate being 5 m deep by 14 m wide. A spacing of 1 m occurred between replicates, with a 3.5 m spacing occurring between the outer replicates and the trial border. Each replicate was composed of two plots. The main plot effect in the trial was planting date (early, or late), and was randomized within each replicate. The sub-plot effect was plant type (Table 2.2), which was randomized within each plot. Sub-plots each consisted of a single plant, and were arranged so that each plot was four sub-plots deep and three sub-plots wide. A spacing of 1 m occurred between sub-plots. Early planting dates were selected to match the typical planting date for each species in the region, with late plantings made two weeks after early plantings. Weed species were direct seeded in 2012 with the earliest seeded crop. Due to establishment difficulties in

2012, in 2013 weed species were transplanted with the earliest transplanted crop in order to improve establishment (Table 2.2). The number of egg masses, their location on the plant (top, middle, or bottom third), and on the leaf surface (upper or lower) was recorded once a week for 6 weeks after first detection of moths in the Uni-trap.

Table 2.2. Plant species used in the alternate host oviposition field trials at Bothwell, ON, 2012-2013.

Planting Date

Common Name Scientific Name Family Cultivar Seeding Method 2012 2013 Pepper Capsicum Solanaceae Bell Boy Transplant 1 and 15 June 4 and 18 June annuum L.

Squash Cucurbita Cucurbitaceae Butternut Transplant 1 and 15 June 4 and 18 June moschata Duchesne ex Poir

Dry Bean Phaseolus Fabaceae T9905 Direct 5 and 19 June 4 and 18 June vulgaris L. Snap Bean Phaseolus Fabaceae Matador Direct 5 and 19 June 4 and 18 June vulgaris L. Clammy Ground Cherry Physalis Solanaceae - Direct (2012), 15 and 28 May 21 May and 4 June heterophylla Transplant (2013) Nees Peas Pisum sativum Fabaceae Sugar Snap Direct 9 and 22 May 15 and 29 May L. Tomato Solanum Solanaceae Big boy (2012); Transplant 28 May and 12 June 4 and 18 June lycopersicum L. H2653 (2013)

Egg Plant Solanum Solanaceae Black Beauty Transplant 1 and 15 June 4 and 18 June melongena L. Eastern Black Nightshade Solanum Solanaceae - Direct (2012), 15 and 28 May 21 May and 4 June ptychanthum Transplant (2013) Dunal Potato Solanum Solanaceae Superior Direct 9 and 22 May 15 and 29 May tuberosum L.

Field Corn Zea mays L. Poaceae HL B49R Direct 9 and 22 May 15 and 29 May

Sweet Corn Zea mays L. Poaceae Peaches and Cream Direct 5 and 19 June 4 and 18 June

2.3.3 Dry Bean Oviposition Preference Laboratory Trial

A randomized complete block design experiment examined oviposition preference among seven different market classes (Table 2.1, excluding adzuki beans) at three developmental stages: vegetative, flowering, and early pod-set. Vegetative plants corresponded to BBCH values between 13-29, flowering plants between 51-65, and pod-set plants between 69-72 (Hess et al.

1997). The experiment was conducted at University of Guelph Ridgetown Campus in 2013.

An experimental unit consisted of a 1m3 cage containing one plant of each of the seven market classes of the same developmental stage, spaced 25 cm equidistant from each other. Five replicates were completed for the vegetative developmental stage, and six for the flowering, and early pod-set stages. Plants were grown in a greenhouse under natural light conditions at 20-

25°C to ensure availability when newly emerged moths were available from the University of

Guelph Ridgetown Campus WBC colony.

For each replicate, three male and two female moths (< 24 h old) were isolated from the lab colony for 48 h after eclosion in a wooden-framed mating cage (15 cm x 15 cm x 40 cm) with fine plastic mesh on all sides. After the 48 h period, moths were placed into the cage containing test plants for 72 h. The experiment initially took place in a laboratory at 24-26°C day temperature, 14-16°C night temperature, with a 16:8 h light: dark ratio and a relative humidity of

70-80%. In April 2013, the trial was relocated to a greenhouse however to avoid contamination of the laboratory with white flies (Bemisia spp.), after four vegetative and one flowering replicate had been completed. Environmental conditions in the greenhouse ranged from 20 – 30°C during the day and 10 – 20°C during the night.

The number of egg masses per plant was recorded at 24, 48, and 72 h after moths were introduced into the cage. Plant height and the number of trifoliate leaves, flowers and pods were

27 also recorded at 24, 48 and 72 h. Egg mass observations were categorized into 6 levels based on the number of eggs present: 0-5, 6-15, 16-25, 26-50, 51-100, >100. No plants or moths were used more than once during the trial.

2.3.4 Larval Survival Trial

A laboratory study was conducted to examine larval survival and development. Larval survival and development were compared among three tissue types (leaf, flower, and pod), and secondarily among three dry bean market classes (navy, light red kidney, and adzuki) relative to a control diet. The experiment was arranged in a split-plot with three replicates for each tissue type by market class combination along with a diet control. Each replicate consisted of four bioassay trays (C-D International Inc., Pitman, NJ) containing 32 individual cells; one for each market class plus a control. All replicates for each tissue type were run concurrently.

Plant tissues were collected as needed from field-grown bean plants at the University of

Guelph Ridgetown Campus, and washed with tap water to remove undesired insects and debris.

Washed tissue was then air dried and placed intact into each of the cells in the 32 cell bioassay tray. A small square of filter paper (Fisherbrand, Fisher Scientific, Pittsburgh, PA) cut to approx.

3 cm x 3 cm, was placed in the bottom of each cell, and distilled water was added to the point of saturation, but not to pooling. Diet control was prepared as described by Dyer et al. (2013), and

15 mL was placed into each cell after preparation. Tissue for leaf and pod treatments was changed every 3-4 d and flower tissue every 2-3 d, to ensure sufficient fresh tissue was available to larvae at all times. The amount of control diet used was sufficient for the duration of the experiment and was not changed.

Egg masses were collected as needed from a commercial corn field near Bothwell, ON.

Small squares of leaf tissue were cut out leaving a 3 cm margin of leaf tissue around each side of

28 the egg mass. Masses were then placed on moistened filter paper in a Petri dish, and kept at 26°C until hatch. Within 24 h of eclosion, larvae were individually transferred to a bioassay tray cell using a camel hair brush. Rearing covers were placed over all cells to allow air exchange but prevent larval escape. Larvae were maintained for 28 d at a 16:8 h light:dark period, with a 26°C day and 18°C night temperature at 60% RH.

Larval survival, weight, and body width and length were recorded at 7 day intervals.

Body length was determined from the anterior portion of the head capsule, to the anal prolegs using a digital caliper (Marathon Watch Company Ltd., Richmond Hill, ON). Body width was determined at the widest point. At 28 days, larvae were weighed, drowned, and then immediately placed in a red-topped test tube ( BD Vacutainer™, Becton, Dickinson and Company Canada,

Mississauga, ON) filled with 70% ethanol for preservation. Final body measurements were taken immediately after death, and head capsule widths were determined with the use of a dissecting microscope and an ocular micrometer.

2.3.5 Data Analysis

Statistical analyses were performed using SAS version 9.2 (SAS Institute Inc., Cary,

NC). All data was first tested for normality using the Shapiro-Wilk’s Normality Test. Data not normally distributed were transformed with the use of logarithmic, square-root, or arcsine square-root transformations to obtain the highest Shapiro Wilk’s statistic. Mean separations were performed using Fisher’s Protected LSD, α=0.05. Means were then back-transformed, as required, for presentation of results.

For the dry bean and alternate host oviposition field trials, a two-way ANOVA was performed using PROC MIXED with market class, planting date, and factor interaction as fixed effects, and replicate and year as random effects. A mixed model was used so that impact of

29 random effects could be examined in addition to the impact of the fixed effects (Littell et al.

2006).

For the oviposition preference laboratory trial, data for each egg mass category were converted to the total number of eggs laid on each market class within each developmental stage.

This was done so that the total number of egg masses laid on each plant could be determined.

The median for each egg number category was taken and multiplied by the number of egg masses laid on a plant; for the >100 category, a median of 150 was used. The number of eggs were log (x + 1) transformed and a one way ANOVA was performed using PROC MIXED for each developmental stage, where market class was the fixed effect and replication was the random effect.

In the larval survival study, survival at each weekly interval was examined with a two- way ANOVA using PROC MIXED. Survival was compared to the control diet, whose values were set at 100%. Market class, tissue type, and factor interaction were fixed effects and replicate was the random effect. Survival at 7, 14, and 21 days were square-root (x + 0.5) transformed for analysis; while survival at 28 days was log (x + 1) transformed. Larval weight, length and width at 7, 14, 21, and 28 days, and head capsule width at 28 days, were also subjected to a two-way ANOVA with market class and tissue type being the fixed effects and replicate being the random effect. Prior to examining the impact of tissue type alone, a one-way

ANOVA was performed to determine whether differences existed among the controls for each of the three tissue types. If no differences were found, an average value for the control at each tissue type was used and a one-way ANOVA using PROC MIXED was performed to examine larval weight, length, width, and head capsule width, compared to the control diet for each

30 parameter measured. If differences were found, a pair-wise comparison was performed between the tissue type and its corresponding control.

2.4 Results and Discussion

2.4.1 Oviposition Field Trials

Despite over 1500 dry bean plants examined each year, only 4 WBC egg masses were found. No statistical analyses were conducted, due to a lack of treatment response. No eggs were found on any plant samples collected in 2012, while surrounding corn fields had egg masses on approx. 1-2% of plants. In 2013, four egg masses were found on dry bean plants; two on navy, one on dark red kidney, and one on otebo. In 2013, egg mass numbers were low compared to the surrounding corn field, which had eggs present on approx. 8-10% of plants based on visual examination. Moths appeared to prefer to oviposit on pre-tassel corn plants, which agrees with previous research (Seymour et al. 2004), and in 2013 this stage was present for a longer period, due to the presence of re-planted corn. In dry beans, young WBC larvae can be found feeding on both leaf and flower tissue (Hoerner 1948; Michel et al 2010), though it is not currently known if moths are seeking out dry bean plants at a certain developmental stage to oviposit on. WBC moth captures at the trial site in 2012 totaled 656, with peak flight occurring between 23 and 29

July (Fig. 2.1). In 2013 moth captures totaled 1082, and peak flight occurred between 30 July and 5 August. Though moths were present at the trial location, it was evident from the lack of egg masses in the trial that female moths were not attracted to dry bean plants for oviposition.

No larval feeding was observed in 2012. In 2013, WBC feeding could not be identified due to high levels of feeding by Japanese beetle (Popillia japonica Newman) in the trial. In

500

450

400

350

300

250 2012 2013 200

Number of Captured Moths Captured of Number 150

100

0 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 Week 12

2013, a large amount of re-planted corn (due to frost kill) was present in the surrounding field.

The resulting extended presence of pre-tassel corn, which is a preferable plant stage for oviposition (Eichenseer et al. 2008), may have contributed to the low egg mass numbers found on dry bean plants.

The number of eggs observed in the alternate host field trial was similarly low. Four egg masses were found in 2012, with three on field corn, and one on tomato. The egg masses found on corn hatched, while the egg mass found on tomato did not, despite having the purple colour typical of fertilized eggs near eclosion (Eichenseer 2008). The eggs on the tomato plant may therefore have experienced parasitism, desiccation, or some antagonistic effect by the plant. Egg masses, based on visual examination, were black in appearance, and occasionally had small pinholes characteristic of possible parasitoid infestation. In 2013, no egg masses were found on any treatments, even though WBC pressure in the surrounding corn reached threshold for control. Foliar feeding damage in 2012 could not be conclusively identified as WBC, due to a lack of observed WBC egg masses and larvae. In 2013, WBC feeding could not be determined due to feeding from Japanese beetle and tobacco hornworm (Manduca sexta L.). Factors that may have affected oviposition include late planted corn in 2013 as described previously, and the use of single plant sub-plots. Single plants may have been less desirable for oviposition due to the lack of dense foliage present.

WBC will oviposit on dry beans and field corn, and larvae have been found feeding on other crops, such as tomato Solanum lycospersicum Mill (Blickenstaff 1979). Based on the high density of WBC egg masses found in the re-planted corn that surrounded both 2013 trials, it appears that pre-tassel corn may be more desirable for oviposition than other potential hosts.

This was not always the case however, as Hoerner (1948) initially considered WBC to be a pest of dry beans, with a secondary host being ground cherry.

2.4.2 Dry Bean Oviposition Preference Laboratory Trial

There were no differences in the number of eggs laid per plant among the seven dry bean market classes examined at vegetative (F = 1.50, df = 6, 24, P = 0.2190), flowering (F = 0.69 df

= 6, 30, P = 0.6558), and early pod-set (F = 1.18, df = 6, 30, P = 0.3452) growth stages (Table

2.3). There were however, only 64 egg masses laid in the trial in total. Therefore, it appears that preference does not exist among market classes within a developmental stage for WBC oviposition; however this is a tentative conclusion given that relatively few egg masses were laid.

All moths were 2 days old at the beginning of the experiment; however Capinera (2001) found that the pre-oviposition period for this pest was ~4 days. This may have been a major factor in the low oviposition rates; thus the use of older moths is advisable in the future.

Increasing the number of females in each cage may have also resulted in more egg masses, however due to colony restrictions and difficulties in obtaining a large number of moths that eclosed on the same day, a limitation of two females per cage existed. It is also possible that low egg laying was a result of insect biotype. The moths obtained from the colony developed from eggs collected from corn fields, not dry bean fields. If a biotype did exist with this insect, this could also explain the low egg mass numbers on dry bean plants.

2.4.3 Larval Survival Trial

Differences in larval survival were observed among market classes and tissue types

(Table 2.4). Survival on leaf tissue from kidney bean was significantly lower than on the diet control at 21 (F = 5.14, df = 6, 24, P = 0.0016) and 28 days (F = 9.11, df = 6, 24, P < 0.0001).

Developmental Stagea Market Class Vegetative Flowering Early Pod-Set Navy 7 (-6.1, 10.7)a 0 (-1.3, 7.0)a 1 (-0.4, 13.1)a Cranberry 1 (-1.7, 6.3)a 6 (-6.2, 14.5)a 12 (-11.6, 25.1)a Pinto 0 (-0.1, 4.4)a 8 (-7.6, 15.8)a 0 (-2.2, 11.3)a Light Red Kidney 0 (-0.1, 4.4)a 1 (-0.2, 8.5)a 10 (-9.9, 23.4)a Dark Red Kidney 0 (-0.1, 4.4)a 5 (-5.3, 13.6)a 0 (-3.1, 10.4)a Black 0 (-5.0, 9.6)a 3 (-3.7, 12.0)a 0 (-3.1, 10.4)a Otebo 4 (-4.2, 8.8)a 6 (-6.6, 14.9)a 12 (-11.7, 25.2)a Means followed by the same letter within each developmental stage are not significantly different, Fisher’s Protected LSD, P ≥ 0.05. aNumber of egg masses were square root (x + 0.5) transformed for data analysis to satisfy assumptions of normality; back-transformed data are presented.

Tissue Type Market Leaf Flower Pod Class Survival (%) at 7 Days (± 95% Cl)a Control 100 (-23.2, 26.2)a A 100 (-23.2, 26.2)a A 100 (-23.2, 26.2)a A Adzuki 85 (-21.3, 24.3)a A 56 (-17.0, 20.0)b A 3 (-2.8, 5.8)d B Kidney 80 (-20.5, 23.6)a A 100 (-23.2, 26.2)a A 41 (-14.3, 17.4)b B Navy 91 (-22.1, 25.2)a A 99 (-23.1, 26.1)a A 15 (-8.1, 11.1)c B Survival (%) at 14 Days (± 95% Cl)a Control 100 (-31.0, 36.6)a A 100 (-31.0, 36.6)a A 100 (-31.0, 36.6)a A Adzuki 68 (-25.1, 30.8)a A 49 (-21.0, 26.6)b A 2 (-3.1, 8.8)c B Kidney 74 (-26.2, 31.8)a AB 94 (-30.0, 35.6)a A 43 (-19.3, 25.0)b B Navy 86 (-28.5, 34.2)a A 87 (-28.7, 34.4)ab A 14 (-10.0, 15.7)c B Survival (%) at 21 Days (± 95% Cl)a Control 100 (-29.3, 34.3)a A 100 (-29.3, 34.3)a A 100 (-29.3, 34.3)a A Adzuki 64 (-22.9, 28.0)ab A 40 (-17.8, 22.8)b A 1(-1.1, 6.2)d B Kidney 53 (-20.7, 25.8)b AB 80 (-25.9, 30.9)a A 36 (-16.5, 21.6)b B Navy 65 (-23.2, 28.2)ab A 83 (-26.4, 31.4)a A 12 (-8.9, 13.9)c B Survival (%) at 28 Days (± 95% Cl)b Control 100 (-45.2, 81.7)a A 100 (-45.2, 81.7)a A 100 (-45.2, 81.7)a A Adzuki 55 (-24.9, 45.0)ab A 17 (-7.9, 14.3)c B 1 (-0.7, 1.4)d C Kidney 33 (-15.0, 27.2)b A 23 (-10.5, 19.0)bc A 30 (-10.1, 25.4)b A Navy 52 (-23.8, 43.1)ab A 53 (-24.1, 43.5)ab A 13 (-6.1, 11.0)c B For each time period, means within a column (lower case) and row (upper case) followed by the same letter are not significantly different (P ≥ 0.05) according to Fisher’s Protected LSD test. aSurvival percentages were square-root (x + 0.5) transformed for data analysis to satisfy assumptions of normality; back-transformed data are presented. bSurvival percentages were log (x + 1) transformed for data analysis to satisfy assumptions of normality; back- transformed data are presented.

With flower tissue, survival on adzuki was lower than on the control and on most other market classes at 7 (F = 9.52, df = 6, 22, P < 0.0001), 14 (F = 4.20, df = 6, 22, P = 0.0058), and 21 (F =

5.14, df = 6, 24, P = 0.0016) days. At 28 days (F = 9.11, df = 6, 24, P < 0.0001), larval survival was lowest on flower tissue from adzuki and kidney bean; however survival on flower tissue from kidney bean was not different than that on flower tissue from navy bean. For pod tissue, survival on all market classes was lower than the control at all dates; survival was lowest on adzuki, followed by navy and kidney at 28 days.

No factor interaction effect was seen with developmental parameters (data not shown), though each factor individually was found to have a significant effect. Examining solely the impact of dry bean market class and the diet control on larval development, at 7 days (F = 3.47, df = 3, 21, P = 0.0345), the weight of larvae fed adzuki tissue was lower than those fed the control diet and kidney bean tissue (Table 2.5). At 14 (F = 13.61, df = 3, 21, P <0.0001), 21 (F =

11.47, df = 3, 20, P = 0.0001), and 28 days (F = 15.40, df = 3, 20, P < 0.0001) all market classes had lower larval weights than the control. At 14 days (F = 4.09, df = 3, 21, P = 0.0197), larvae fed adzuki tissue were shorter than those fed the control diet, and navy tissue. At 21 (F = 3.48, df

= 3, 20, P = 0.0350) and 28 days (F = 4.55, df = 3, 20, P = 0.0138), larvae fed adzuki or kidney tissue were shorter than those fed the control diet. Larvae fed adzuki tissue were thinner at 7 (F =

8.18, df = 3, 23, P = 0.0007), 14 (F = 3.14, df = 3, 21, P = 0.0468), and 21 days (F = 1.20, df =

3, 21, P = 0.0098) than those fed the control diet, but by 28 days (F = 1.47, df = 3, 20, P =

0.2527) no differences were observed.

Larvae fed adzuki tissue had narrower head capsules at 28 days (F = 4.45, df = 3, 20, P =

0.0149) than larvae fed the control diet, kidney, or navy tissue (Table 2.6). Based on the measurements by Antonelli (1974), it appears that all larvae in this study had reached the 6th

Market 7 Day 14 Day 21 Day 28 Day Class Larval Weight (mg) Control 8.4 ± 1.03a 110.3 ± 7.10a 452.2 ± 37.45a 713.2 ± 56.00a Adzuki 5.0 ± 1.09b 58.7 ± 7.50b 169.8 ± 46.39b 398.1 ± 63.42b Kidney 8.2 ± 1.03a 73.9 ± 7.10b 258.2 ± 37.45b 414.9 ± 56.00b Navy 6.2 ± 1.03ab 74.0 ± 7.10b 254.7 ± 37.45b 514.3 ± 56.00b Larval Length (mm) Control 7.6 ± 0.28a 16.5 ± 0.67a 25.9 ± 1.27a 29.4 ± 1.43a Adzuki 6.6 ± 0.30a 14.3 ± 0.69b 21.0 ± 1.50b 26.2 ± 1.61b Kidney 6.9 ± 0.28a 15.5 ± 0.67ab 23.0 ± 1.27b 25.0 ± 1.43b Navy 7.0 ± 0.28a 16.1 ± 0.67a 23.8 ± 1.27ab 27.0 ± 1.43ab Larval Width (mm) Control 1.1 ± 0.04a 2.6 ± 0.17a 4.2 ± 0.19a 4.8 ± 0.23a Adzuki 0.8 ± 0.04b 2.1 ± 0.18b 3.0 ± 0.24b 4.3 ± 0.29a Kidney 1.0 ± 0.04a 2.4 ± 0.17ab 3.7 ± 0.19a 4.3 ± 0.23a Navy 1.0 ± 0.04a 2.4 ± 0.17ab 3.9 ± 0.19a 4.5 ± 0.23a Means in a column within each developmental parameter followed by the same letter are not significantly different (P ≥ 0.05) according to Fisher’s Protected LSD test.

Table 2.6. Head capsule width (± S.E) of western bean cutworm larvae fed three dry bean market classes or a diet control for 28 days in laboratory experiments conducted at Ridgetown, ON, 2013.

Head Capsule Market Class Width (mm) Control 3.6 ± 0.17a Adzuki 3.3 ± 0.18b Kidney 3.7 ± 0.17a Navy 3.7 ± 0.17a Means followed by the same letter are not significantly different (P ≥ 0.05) according to Fisher’s Protected LSD test.

39 instar by 28 days. This is also supported by the measurements of Dyer et al. (2013). Though all larvae reached the 6th instar, larvae fed adzuki tissue did not develop as quickly as larvae fed kidney or navy bean tissue, or the control diet, based on the significantly smaller head capsule width observed.

Larval weights were lower with all tissue types compared to the control diet at 14 (F =

3.77, df = 3, 23, P = 0.0244), 21 (F = 4.88, df = 3, 22, P = 0.0095), and 28 days (F = 5.53, df = 3,

22, P = 0.0055) (Table 2.7). No differences were found at 7 days (F = 2.33, df = 3, 23, P =

0.1009). No differences were found among larval lengths at 7 (F = F = 0.57, df = 3, 23, P =

0.6433), 14 (F = 0.88, df = 3, 23, P =0.4641), 21 (F = 1.11, df = 3, 22, P =0.3669), or 28 days (F

= 1.77, df = 3, 22, P = 0.1824). No differences in larval width were found at 7 (F = 1.97, df = 3,

25, P = 0.1436) or 21 days (F = 0.92, df = 3, 22, P = 0.4461). However, at 14 days (F = 3.22, df

= 3, 23, P = 0.0415) larvae were wider when fed the control or flower tissue, than those fed pod tissue, and at 28 days (F = 9.26, df = 3, 22, P = 0.0004), larvae fed the control, flower, or pod tissues were wider than larvae fed leaf tissue. No differences were found in larval head capsule width at 28 days between tissue types when compared to the diet control (F = 0.10, df = 3, 22, P

= 0.9585) (Table 2.8).

Adzuki was the only market class included in these studies not belonging to P. vulgaris, and lower survival and slower development on this species suggests that WBC collected from

Ontario are not well adapted to this potential host. Adzuki beans are therefore likely to be the market class at least risk of infestation and economic damage by WBC. The centre of origin for adzuki beans is eastern Asia, which is different from the other market classes, which originate in either Central or South America (Pratap and Kumar 2011). The adzuki market class also belongs

Tissue 7 Days 14 Days 21 Days 28 Days Type Larval Weight (mg) Control 8.4 ± 1.87a 10.3 ± 13.52a 452.2 ± 58.89a 713.2 ± 78.14a Leaf 8.3 ± 1.20a 75.2 ± 8.10b 251.5 ± 37.80b 453.8 ± 55.80b Flower 6.4 ± 1.20a 72.3 ± 8.10b 246.6 ± 37.80b 402.0 ± 55.80b Pod 4.7 ± 1.25a 58.2 ± 8.55b 204.7 ± 41.56b 487.7 ± 59.63b Larval Length (mm) Control 7.6 ± 0.56a 16.5 ± 1.08a 25.9 ± 2.00a 29.4 ± 1.90a Leaf 6.8 ± 0.33a 15.8 ± 0.75a 22.4 ± 1.42a 26.7 ± 1.39a Flower 6.8 ± 0.33a 15.1 ± 0.75a 22.8 ± 1.42a 25.4 ± 1.39a Pod 6.8 ± 0.35a 14.0 ± 0.77a 23.2 ± 1.52a 25.9 ± 1.48a Larval Width (mm) Control 1.1 ± 0.08a 2.6 ± 0.25a 4.2 ± 0.35a 4.8 ± 0.27a Leaf 1.0 ± 0.05a 2.3 ± 0.17ab 3.6 ± 0.22a 3.7 ± 0.16b Flower 1.0 ± 0.05a 2.5 ± 0.17a 3.5 ± 0.22a 4.6 ± 0.16a Pod 0.9± 0.05a 2.0 ± 0.18b 3.8 ± 0.25a 4.7 ± 0.18a Means in a column within each developmental parameter followed by the same letter are not significantly different, Fisher’s Protected LSD, P ≥ 0.05.

Table 2.8. Head capsule width (± S.E) of western bean cutworm larvae fed three dry bean tissue types or a diet control for 28 days in laboratory experiments conducted at Ridgetown, ON, 2013 ..

Head Capsule Tissue Type Width (mm) Control 3.6 ± 0.25a Leaf 3.6 ± 0.18a Flower 3.5 ± 0.18a Pod 3.6 ± 0.19a Means followed by the same letter are not significantly different, Fisher’s Protected LSD, P ≥ 0.05.

42 to a different genus and species, Vigna angularis, than other dry beans, Phaseolus vulgaris, and has not been mentioned as a possible host crop of WBC in the past. Blickenstaff and Jolley

(1982) also found that larval weights on Vigna were significantly lower than those on Phaseolus, showing its limited suitability as a WBC host crop.

It is not currently known why pre-tassel corn is more attractive than dry beans at any developmental stage. One possibility could be the development of different biotypes of WBC for corn and dry beans. This may help to explain why damage has been seen in corn over a number of years, but damage to dry beans was only first identified this year.

Lower larval survival was found on pod tissue than on leaf and flower tissue for all market classes except kidney bean at all dates. Survival on the kidney bean market class did not differ between leaf and pod tissue at 14, 21, and 28 days (Table 2.4). Based on high pod tissue survival after 28 days, the kidney market class appears to be at a greater risk for damage compared to the adzuki and navy bean market classes. Overall it appears that survival on pod tissue is low when compared to the other tissues examined.

Since WBC has not been reported to be a major defoliator, it is unlikely that leaf tissue comprises the majority of their diet at any developmental stage. Feeding on flower tissue is unlikely to have a significant effect on bean production, as plants often produce more flowers than pods (Nakamura 1986). Survival of larvae on pod tissue in our study could have been affected by larval age. Larvae do not typically feed on pod tissue until the 3rd instar (Michel et al.

2010) and this experiment used only newly eclosed larvae. The trial was conducted with neonate larvae on all tissue types however, so that comparison between the three tissue types could occur.

Additional studies examining survival and development of third instars on pod tissue are recommended to further understand the impact this pest can have to dry beans. Since egg masses

43 were collected from a corn field, including corn tissue in the studies would also allow survival to be compared between the two host crops. This may either support or refute the possibility of

WBC biotypes.

2.5 Conclusion

Of the three market classes examined in laboratory studies, kidney beans appear to be at the greatest risk of WBC damage, while adzuki beans appear to be a poor host for WBC.

However, the very low oviposition rates observed in field trials suggest that dry beans are generally at a low risk of economic damage by WBC. Corn appears to be a more suitable host than beans for WBC, as there were egg masses on 8-10% of corn plants in the surrounding field which is above the recommended action threshold for pre-tassel corn in Ontario. WBC larvae can survive on leaf and flower tissue of dry beans; however their feeding on leaf tissue is not thought to impact the crop economically (Michel et al. 2010). Damage to pod tissue is most important in assessing economic impact. Based on laboratory survival rates on pod tissue, kidney bean appears to be at the greatest risk for WBC damage.

Additional laboratory studies are recommended to examine oviposition preference and larval performance on other market classes of beans, and the effect of feeding by more mature instars. Since larvae appear to either change their feeding preference to pod tissue around the 3rd instar, or are only capable of feeding on pod tissue from this instar and beyond, feeding studies examining the impact of the latter instars on pod tissue would be useful in order to more completely assess the risk posed by WBC to the dry bean industry.

CHAPTER THREE

Insecticide Efficacy and Timing for the Control of Western Bean

Cutworm (Lepidoptera: Noctuidae) in Dry and Snap Beans

3.1 Abstract

The western bean cutworm, Striacosta albicosta (Smith) (Lepidoptera: Noctuidae), is a recent pest of corn, dry, and snap beans, in the Great Lakes region, but best practices for its management are not well studied. Insecticide efficacy and timing application studies determined lambda-cyhalothrin and chlorantraniliprole were capable of reducing feeding damage in both dry and snap bean trials by as much as 4 and 6% respectively. The best application timing was determined to be 4 to 18 days after 50% egg hatch, though no economic benefit was found when products were applied to dry beans. Additionally, thiamethoxam, methoxyfenozide and spinetoram were also found to be efficacious at reducing western bean cutworm damage when compared to an untreated control.

Key Words Striacosta albicosta, Phaseolus vulgaris, feeding damage, larvae

3.2 Introduction

Common bean (Phaseolus vulgaris L.) is commonly grown as snap or dry beans in the

Great Lakes region of North America. Snap beans are harvested while pods are still green and prior to the development of mature seeds, while dry beans are harvested once the crop has fully matured (Gepts 1998). Canada is the fifth largest exporter of dry beans in the world, exporting

217,909 tonnes of product worth $214 million USD in 2011 (FAOSTAT 2013). Exports of snap beans are small in comparison to dry beans, with only 1,193 tonnes worth $1.59 million USD exported in 2011 (FAOSTAT 2013). The majority of snap beans are consumed domestically, and are aimed at either the fresh or the processing market. Though little of the crop is exported, in

Ontario in 2011 31,155 tonnes worth $14.4 million were produced (OMAFRA 2014). For consumer acceptance, visual quality is of utmost importance for both crops.

The western bean cutworm (WBC), Striacosta albicosta (Smith) (Lepidoptera:

Noctuidae), is native to North America and is a pest of corn (Zea mays L.), as well as snap and dry beans. Since the initial documentation of this pest in Arizona (Smith 1887), it has gradually spread across the major corn and bean production areas of the United States (Crumb 1956; Appel et al. 1993; O’Rourke and Hutchison 2000; Dorhout and Rice 2008; DiFonzo and Hammond

2008; Tooker and Fleischer 2010), reaching Ontario and Quebec, Canada in 2008 and 2009 respectively (Baute 2009; Michel et al. 2010). Factors such as climate change, transgenic corn introduction, and reduced tillage regimes, have been suggested as potential reasons for the range expansion of this insect, but none have been definitively identified as a cause (Hutchison et al.

2011).

WBC is a univoltine insect that overwinters as a prepupate (Douglass et al. 1957).

Pupation occurs in the early spring, with moths emerging from the soil between late June and

46 mid-August. Once emergence occurs, female moths mate and look for egg laying sites. Moths appear to prefer pre-tassel corn (Hagen 1962; Holtzer 1983), but will also lay eggs in dry and snap beans (Blickenstaff 1983). In beans, eggs are deposited on the leaves of plants between late

July and mid-August, taking five to seven days to hatch (Douglass et al. 1957). At this point, flowers will be evident on dry bean plants, with some pin pods visible in mid-August. Feeding initially occurs on leaf and flower tissue of the plant (Hoerner 1948; Paula-Moraes et al. 2012), with larval movement being greater within than across bean rows (Blickenstaff 1983). However, the most noticeable feeding damage is caused by older larvae (3rd to 6th instars) feeding on pods and seeds.

The current recommendation for WBC control in the Great Lakes region is to scout fields

10-20 days after peak moth flight, identified with the use of pheromone traps, and if pod feeding is easily found, insecticide application is necessary (Michel et al. 2010). In addition, an insecticide is recommended if pheromone traps in the immediate vicinity of dry bean fields capture 1000 or more moths by field by peak moth flight (OMAFRA 2009). There are however, no recommendations for insecticide application based on larval numbers or egg counts in dry beans. An economic threshold of 6.5 larvae per metre of row exists for irrigated dry beans in

Nebraska (Seymour et al. 2004), but it is unknown whether this threshold is appropriate in the

Great Lakes region, due to differing environmental conditions. Since larvae feed primarily at night and often hide in the soil or in the bean canopy during the day, thresholds based on larval numbers are difficult to determine.

The first cases of WBC damage in Ontario bean fields were found in 2014 (T. S. Baute, personal communication4), however it is not currently known to what degree economic return

4 T. S. Baute, Field Crop Entomologist – Program Lead, Ontario Ministry of Agriculture, Food and Rural Affairs, Ridgetown, Ontario, Canada. 47 was affected. Damage to dry beans has been reported in Michigan, however it is unknown if it caused economic losses (Chludzinski 2013). There are currently two active ingredients registered in Canada for insecticidal control of WBC in beans: lambda-cyhalothrin and chlorantraniliprole.

Lambda-cyhalothrin is a Group 3A neurotoxic pyrethroid insecticide which causes paralysis of the nervous system (Davies et al. 2007). Chlorantraniliprole is a Group 28 insecticide, belonging to the anthranilic diamide class, and causes death by impairing muscle contractions (Cordova et al. 2006). Other active ingredients that were examined were: thiamethoxam, methoxyfenozide, spinetoram, and dimethoate. Thiamethoxam is a neonicotinoid insecticide, and is registered for use as both a seed treatment and a foliar product in dry beans, however not for control of WBC.

It results in death of the insect by binding to the nicotinic acetylcholine receptors and antagonizing acetylcholine (Maienfisch et al. 2001). Methoxyfenozide binds to the ecdysteroid receptor of lepidopteran larvae, resulting in premature moulting and death of the insect (Hardke et al. 2011; Moulton et al. 2002). This active ingredient is registered for use in dry bean, however not for control of WBC. Spinetoram impacts nerve transmission in the insect by affecting the

GABA and the nicotinic acetylcholine receptors (Hardke et al. 2011); it is not currently registered for use in dry beans, or for control of WBC. Dimethoate is an organophosphate insecticide, which prevents the breakdown of acetylcholine in the insect. This active ingredient is not registered for control of any lepidopteran pests, although it is registered for use in dry bean.

Past research examining WBC control focused on insecticide efficacy rather than application timing, and involved older chemistries (Hoerner 1948; Hagen 1963). Though identifying which active ingredients are efficacious for WBC control in beans is important, application timing is equally as important since larvae can move into bean pods by the third instar, making control with contact insecticides difficult (Michel et al. 2010). Application too

48 early may result in control products being applied before peak egg laying. This would result in either having to spray the field more than once, or result in damage from larvae that hatched after the insecticide application. Whereas application too late increases the risk that larvae will have reached an instar capable of burrowing into the bean pods (Michel et al. 2010) and will be out of range of the insecticides. Because there is very low tolerance for feeding damage to dry and snap beans in the Great Lakes region by WBC, determining efficacy and proper application timing of insecticides is of utmost importance for controlling this insect. It will also contribute to the development of pest management recommendations for this pest in dry and snap beans.

3.3 Materials and Methods

3.3.1 Dry Bean Insecticide Timing and Efficacy Trials

Insecticide timing and efficacy trials were each conducted in artificially infested plots in

Ridgetown, Ontario, in 2012, and in Ridgetown and Exeter, Ontario, in 2013. An insecticide efficacy study was also conducted in Plattsville, Ontario, in 2012. The insecticide timing trials had a randomized complete block design with 16 treatments and four replicates. Treatments were two insecticide active ingredients, applied alone or in combination, at five application time intervals, in addition to an untreated control. Insecticide treatments were lambda-cyhalothrin at

9.96 g a.i/ha (Matador® 120EC, Syngenta Crop Protection Canada, Guelph, ON), chlorantraniliprole at 50 g a.i/ha (Coragen®, E.I. DuPont Canada Co., Mississauga, ON), and lambda-cyhalothrin + chlorantraniliprole at 25 g + 50 g a.i/ha respectively (Voliam Xpress™,

Syngenta Crop Protection Inc., Guelph, ON). Application timing treatments were 4, 11, 18, 25, and 4 + 11 + 18 + 25 days after 50% egg hatch (DAH50). Egg hatch was determined based on visual observation of masses every two days until at least 50% of eggs in each plot had hatched.

All treatments were applied with a hand-held CO2 spray boom with TT11002 nozzles (TeeJet®

Technologies, Springfield, IL) at 30 psi in 200L/ha of water. Application with this nozzle at this pressure resulted in medium sized droplets and uniform coverage.

The insecticide efficacy trials were designed as a randomized complete blocks with eight treatments and four replicates. Treatments were lambda-cyhalothrin at 9.96 g a.i/ha (Matador®

120EC, Syngenta Crop Protection Canada, Guelph, ON), chlorantraniliprole at 50 g a.i/ha

(Coragen®, E.I. DuPont Canada Co., Mississauga, ON), lambda-cyhalothrin + chlorantraniliprole at 25 + 50 g a.i/ha (Voliam Xpress™, Syngenta Crop Protection Inc., Guelph,

ON), lambda-cyhalothrin + thiamethoxam at 19.08 + 25.38 g a.i./ha (Endigo™, Syngenta Crop

Protection Inc., Guelph, ON), dimethoate at 480 g a.i/ha (Cygon™ 480-AG, Cheminova Canada

Inc., Kilworth, ON), methoxyfenozide at 72 g a.i/ha (Intrepid™ 240F, Dow AgroSciences

Canada Inc, Calgary, AB), spinetoram at 30 g a.i/ha (Delegate™ WG, Dow AgroSciences

Canada Inc., Calgary, AB), and an untreated control. All treatments were applied at 8 DAH50.

Dimethoate, though not registered for control of lepidopteran pests, was included in the study to see if application would result in an increase in WBC larval feeding damage over the untreated control due to a reduction in susceptible predator populations.

In all trials, navy beans (cv. T9905) without insecticide or fungicide seed treatments were planted using a conventional field planter. Planting dates for insecticide timing and efficacy trials differed among locations (Table 3.1) in response to environmental conditions. Each plot was composed of 4 rows of dry beans, 6 m in length, and planted 76 cm apart at a density of 20 seeds per metre. Plots were isolated from each other by a 2 m buffer on all sides of oats, Avena sativa

L., to discourage movement of larvae between plots. A 5 m harvest area in each plot row was

Table 3.1. Dates for dry bean planting, western bean cutworm egg mass inoculation, 50% egg mass hatch, and insecticide applications at Ridgetown, Plattsville, and Exeter Ontario trials in 2012-2013.

Egg Mass Egg Masses Year Location Planting Date Inoculation per Plot 50% Hatch Insecticide Applications Insecticide Timing Trial 2012 Ridgetown 23 May 20 July 16 21 July 25 July, 1,8,15 Aug

2013 Ridgetown 4 June 15 July 16 19 July 23, 30 July, 6,13 Aug Exeter 6 June 17 July 16 21 July 25 July, 1,8,15 Aug Insecticide Efficacy Trial 2012 Ridgetown 23 May 20 July 16 21 July 29 July Plattsville 15 June 28 July 12 28 July 5 Aug

2013 Ridgetown 4 June 15 July 16 19 July 26 July Exeter 6 June 17 July 16 21 July 30 July

51 marked with stakes, and within these 5 m sections four flags were placed at 1 m intervals in each row to identify egg mass placement locations.

WBC egg masses were collected from a corn field located near Bothwell, ON. A section of the corn leaf approximately 5 cm by 5 cm was cut out around the mass. Masses were placed on dry bean foliage in both trials the same day as collected, or kept in a walk-in cooler overnight and placed out the next morning. Dry bean plants were flowering at the time of egg mass placement. Masses were stapled to the underside of dry bean leaves, with the eggs facing out. A density of 16 egg masses per plot was achieved for all trials except Plattsville in 2012, where 12 masses per plot were used (Table 3.1).

Lambda-cyhalothrin at a rate of 9.96 g a.i/ha was applied 22 June 2012 to control an outbreak of potato leaf hopper, Empoasca fabae (Harris) in both trials at Ridgetown in 2012.

This application occurred 3-4 weeks prior to WBC egg mass inoculation, and lambda- cyhalothrin was chosen for its lack of residual control (Hardke et al. 2011). Application of fluazinam (Allegro 500F, Syngenta Crop Protection Inc., Guelph, ON) at 300 g a.i/ha occurred on 21 Aug in order to control white mold, Sclerotinia sclerotiorum (Lib.) in Ridgetown in 2013.

Pod damage ratings were performed at weekly intervals after treatment application in the field in 2012 and every two weeks in 2013. For each rating, two random flags in each of the middle two rows were chosen as evaluation sites. Pods on two plants nearest each flag were examined for feeding damage incidence (%), and damage severity using a 0-3 scale, with 0=no damage, 1=surface damage ≤ 0.25 cm diameter, 2=surface damage > 0.25 cm diameter, and

3=damage entering the pod. Damage in category 1 and 2 samples may also have been from C. trifurcata, as this insect was found occasionally in the trial. Category 3 damage was characteristic of WBC.

Prior to harvest, two plants were removed from each of the two central inoculation points in each of the two middle rows. Total pods per plant were recorded, and damage severity was rated for all pods, as described above. Pods were then threshed using an Agriculex single plant thresher (Agriculex Inc., Guelph, ON) and seeds were weighed, counted, and visually inspected for percent blemished and insect damaged seed. Any seed damage was considered to be from

WBC, as C. trifurcata primarily feed on pod surfaces (OMAFRA 2009). WBC damaged seed from the plant samples was placed into one of four categories based on visual examination of the percentage of the seed consumed: 1=1-25%, 2=26-50%, 3=51-75%, and 4=76-99%; and, the total number of seeds in each category determined. Due to the small size of seed samples from the eight collected plants, samples were combined for each replicate and moisture was determined with a Motomco 919 moisture meter (Dickey-John Corp., Patterson, NJ).

At harvest, all remaining plants between the 5 m stakes in the 2 middle rows of each plot were cut at soil level and, at Ridgetown, were placed in a stationary thresher (Almaco, Nevada,

IA) in 2012, and a Wintersteiger combine (Wintersteiger, Wintersteiger, Austria) in 2013. The two middle rows were direct-harvested at Plattsville (2012) with a Wintersteiger plot combine and at Exeter (2013) with a Hege plot combine (Hege Maschinen, Niederlassung, DK). The collected seed was weighed, and gross yield (kg/ha) was determined at the standard moisture of

18%. Gross yield included all seeds, whether whole or split, that were harvested. 200 seeds were removed from each harvest sample and the percentage of blemished seed and WBC damaged seed was recorded.

The return on investment (ROI) formula from Gillard et al. (2012) was modified to determine ROI for total gross yield. Total gross yield rather than marketable yield was used so

53 that a greater understanding of the damage WBC is causing to dry bean seeds could be determined. The equation used was:

ROI = (Yield – 2(Pick))*$0.86 – Insecticide Cost – Insecticide Application Cost [1]

Where Pick= the total percentage of blemished and WBC damaged seed by weight. For the market price of dry beans, the 2012 navy bean insurance claim price of $0.86/kg (Agricorp

2012) was used. Insecticide costs, using the 2012 manufacturer’s suggested retail price for each product were: lambda-cyhalothrin $15.75/ha, chlorantraniliprole $47.51/ha, lambda-cyhalothrin

+ chlorantraniliprole $48.87/ha, dimethoate $30.75/ha, lambda-cyhalothrin + thiamethoxam

$31.89/ha, methoxyfenozide $30.79/ha, and spinetoram $41.45/ha, and Insecticide Application

Cost = $24.70/ha based on 2012 insecticide custom application costs (OMAFRA 2013).

3.3.2 Snap Bean Insecticide Timing Trial

An insecticide timing trial in snap bean was conducted in 2011, 2012, and 2013 at

Ridgetown, Ontario, utilizing a randomized complete block design with 9 treatments and four replicates. Two chemical treatments (lambda-cyhalothrin at 9.96 g a.i/ha, and chlorantraniliprole at 50 g a.i/ha) were applied at four time intervals (4, 10, 14, 4 + 10 + 14 days after inoculation

(DAI) with egg masses), in addition to an untreated control. Insecticide treatments were applied using the same method described for the dry bean trials.

Snap bean seed (cv. Matador) was planted 13 June 2011, 31 May 2012, and 6 June 2013 with the use of a Monosem air planter (Monesem, Edwardsville, KS). Each plot was composed of six rows of snap beans, 7 m long with 76 cm row spacing. Plots were separated by 1.5 m of bare ground and replicates were separated by 2 m of bare ground.

Egg mass inoculation occurred between 18-19 July in all years when bean plants were flowering. Collection and preparation of egg masses were similar to those mentioned for the dry

54 bean trials previously. Two masses were attached to bean plants in the middle two rows by pinning (2011) or stapling (2012 and 2013) them to the underside of leaves with eggs facing outwards. Flags were placed at each inoculation point so they could be found easily throughout the season. Masses were placed 1.52 m apart within rows in 2011 and 2012, and were placed 5 m apart in 2013. Hatch was confirmed prior to the earliest insecticide application. Insecticide treatments were applied to the middle two rows of snap beans 22 and 29 July, and 2 Aug 2011,

22, 28 July, and 1 Aug 2012, and 23 and 29 July, and 2 Aug 2013, in 200L/ha of water with a hand-held CO2 spray boom at 30 psi.

WBC leaf feeding damage was examined 1-3 weeks prior to harvest in each year, and the number of leaves with evidence of WBC feeding were counted for the entire length of each of the two middle rows. Feeding by WBC on the foliage was not extensive in any year, but was identified as small holes in the leaves, in addition to small areas of skeletonization or window- paneing. The damage was identical to that seen in the laboratory on leaf tissue fed on by neonates, though no larvae were visually observed feeding. This was not surprising however as larvae generally hide in the foliage or burrow into the soil during the day (Michel et al. 2010).

Harvest occurred on 15 Aug 2011, 7 Aug 2012, and 13 Aug 2013. A 1 m section containing an egg mass inoculation site from each of the two middle rows was hand harvested. Pods longer than 5 cm in length were removed from plants and weighed. In 2011 and 2013, pods were placed into one of 4 categories: clean, surface feeding, deep tissue feeding (i.e. into pod), or surface and deep tissue feeding. In 2012, pods were placed into one of 5 categories: clean, surface feeding, deep tissue feeding, sting damage, or sting damage in addition to feeding. ‘Sting damage’ was characterized by a visual scar typically caused by a proboscis entering the pod tissue, possibly due to the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), the green stink bug,

Acrosternum hilare (Say), or the brown stink bug Euschistus servus (Say). ‘Sting damage’ was excluded from analysis as it was not the focus of the study. Each damage category was then weighed and expressed as a percentage of the total yield (kg/ha). As the ‘sting damage in addition to feeding’ did not differentiate between surface feeding and deep tissue feeding, the

2012 data were analyzed separately.

3.3.3 Data Analysis

All data were analyzed using PROC MIXED (SAS Version 9.2, SAS Institute Inc., Cary,

NC) unless otherwise indicated. For the initial analysis of the data, each location by year was considered a separate environment. Environments were combined for analysis if the highest order interaction was not significant (P ≥ 0.05). PROC UNIVARIATE was used to test data for normality and homogeneity of variance based on the Shapiro-Wilk statistic. To satisfy the assumptions of ANOVA, data were transformed as needed using the square-root (x + 0.5), logarithmic (x + 1), or arcsine square-root transformation as appropriate. Data were back- transformed for presentation of the results. Fisher’s protected LSD, α = 0.05, was used to perform means separation if significant sources of variation were found. If significance was found with application timing, an additional one-way ANOVA using PROC MIXED was performed to examine the sole impact of application timing on the various factors.

The dry bean insecticide timing trial was analyzed using a two-way ANOVA. Variances were divided into fixed (insecticide product, application timing, and insecticide product by application timing) and random effects (replicate and environment). Field pod ratings examining

WBC damage incidence were logarithmic (x + 1) transformed for all locations and weeks except for Exeter 2013 data at week 7, which was arcsine square-root transformed. Field ratings examining WBC damage severity were categorical and a Wilcoxon rank sum test with PROC

NPAR1WAY was used to examine each fixed factor individually. PROC CORRESP was used to create a contingency table to test treatment differences. For plant samples collected prior to harvest, total pod numbers, the total percentage of insect damaged pods, as well as the percentage belonging to each damage severity category were examined. Total pod number data were logarithmic (x + 1) transformed. Data were also logarithmic (x + 1) transformed for all damage severity categories, and were arcsine square-root transformed for total percentage of insect damaged pods. Seed from these samples were also examined for the percentage of seed with evidence of WBC feeding, and data were logarithmic (x + 1) transformed for analysis.

In harvest samples, the percentage of WBC damaged seed in a 200 seed sample and return on investment (ROI) were examined. WBC damaged seed values were logarithmic (x + 1) transformed for analysis. ROI was analyzed using a one-way ANOVA, as this method allowed comparison within and among insecticide products, as well as the untreated control.

The dry bean insecticide efficacy trials were analyzed using a one-way ANOVA.

Variance was divided into fixed (insecticide product) and random effects (replicate and environment). Field pod ratings examining damage incidence at Plattsville 2012 week 2,

Ridgetown 2012 weeks 4, 5, and 6, Exeter 2013 weeks 2 and 6, and Ridgetown 2013 weeks 4 and 6 were square-root (x + 0.5) transformed for analysis. Incidence ratings at Plattsville 2012 week 4 were logarithmic (x + 1) transformed, and ratings at Plattsville 2012 weeks 3 and 5,

Ridgetown 2012 week 6, Exeter 2013 weeks 4 and 7, and Ridgetown 2013 weeks 2 and 8 were arcsine square-root transformed. Field damage severity ratings were categorical, and a Wilcoxon rank sum test using PROC NPAR1WAY was used to examine the impact of insecticide product.

PROC CORRESP was then used to create a contingency table to examine treatment differences.

For plant samples collected prior to harvest, total pod damage percentages were arcsine square-root transformed, and all damage severity categories were logarithmic (x + 1) transformed. With the seed from plant samples, the percentage of WBC damaged seed was examined; values were logarithmic (x + 1) transformed for analysis. In harvest samples, ROI, and the percentage of WBC damaged seed in a 200 seed sample were examined. ROI values were logarithmic (x + 1) transformed, and WBC damage percentages were logarithmic (x + 1) transformed for their respective analyses.

The snap bean insecticide timing trial was analyzed using a two-way ANOVA. Variances were divided into fixed (insecticide product, application timing, and insecticide product by application timing) and random effects (replicate and year). Egg hatch percentages were determined for each of 2011 – 2013 individually, and data was transformed using an arcsine square-root transformation. The number of hatched eggs was also determined for each year.

Field leaf ratings examining the number of leaves fed on by WBC larvae were square-root (x +

0.5) transformed in 2011 at 15 DAI and in 2013 at 18 DAI; logarithmic (x + 1) transformations were used in 2011 and 2013 at 24 DAI, and for 2012 at 13 DAI. With harvest samples, yield and

2012 WBC damage data were square root (x + 0.5) transformed. The percentage of undamaged pods, and 2011 and 2013 WBC damaged pods were arcsine square-root transformed.

3.4 Results and Discussion

3.4.1 Dry Bean Insecticide Timing Trial

Two insecticide active ingredients, alone and in combination, and five application time intervals were examined for their ability to reduce WBC damage in beans in comparison to an untreated control. No differences were found in egg hatch prior to the first insecticide

58 application, indicating that larval populations among treatments were similar (data not shown).

At Ridgetown in 2012, differences in pod damage incidence were only observed with insecticide active ingredient at week 6 (Table 3.2), with both lambda-cyhalothrin and chlorantraniliprole having a lower percentage of damaged pods than the untreated control (Table 3.3). At both locations in 2013, all insecticide products at weeks 3, 5, and 7 (Table 3.4) had a lower percentage of pods with feeding damage than the untreated control (Table 3.5). With application timing, differences were found at week 7 at both locations (Table 3.4). At Ridgetown lower damage levels were found with all timings except 25 DAH50 when compared to the untreated control.

Lower damage levels were also found with the 4 DAH50 and multiple DAH50 timing, than at 25

DAH50 (Table 3.6). Damage severity ratings were not reported due to the low incidence of feeding damage in the field. Based on estimates of 3% survival from egg to adult (Appel et al.

1993), 2 – 13 % survival 20 days after egg hatch (Paula-Moraes et al. 2013), and that approximately 1600 eggs were placed in each plot, greater damage incidence was expected in these trials.

There were no differences found in the number of pods per plant for the plant samples collected from each plot (data not shown), showing that though young WBC do feed on flower tissue, they do not appear to impact the number of pods at harvest. The total percentage of damaged pods however was impacted by insecticide product, with both lambda-cyhalothrin and chlorantraniliprole individually having less total pod damage than the untreated control, and the combination treatment having lower damage than all other treatments (F = 18.27, df = 3, 218, P

< 0.0001) (Table 3.7). The combination treatment had the lowest total pod damage (F = 5.99, df

= 3,218, P = 0.0006), however this was primarily due to lower superficial ≤ 0.25 cm feeding levels, which were predominantly from bean leaf beetle. No differences were found among

Week 3 Week 4 Week 5 Week 6 Source dfa F-value df F-value df F-value df F-value Insecticide 3, 57 1.37 3, 57 1.54 3, 57 0.37 3, 60 3.06* Timing 4, 57 1.75 4, 57 0.80 4, 57 0.65 4, 60 0.84 Insecticide x Timing 12, 57 0.81 12, 57 0.43 12, 57 0.51 12, 60 1.36 * P < 0.05 anumerator degrees of freedom, denominator degrees of freedom

Table 3.3. Effect of active ingredient on the percentage of dry bean pods (±95% CI) with feeding damage from western bean cutworm at 3-6 weeks after 50% hatch of egg masses at Ridgetown, ON, 2012.

Damaged % of Pods (± 95% CI)a Treatmentb Week 3 Week 4 Week 5 Week 6 1 0.32(-0.26, 0.32)a 0.33(-0.23, 0.27)a 0.06(-0.08, 0.09)a 0.12(-0.05, 0.05)a 2 0.12(-0.22, 0.27)a 0.18(-0.20, 0.24)a 0.10(-0.08, 0.09)a 0.05(-0.04, 0.05)b 3 0.22(-0.24, 0.30)a 0.17(-0.20, 0.24)a 0.09(-0.08, 0.09)a 0.02(-0.04, 0.05)b 4 0.19(-0.23, 0.29)a 0.12(-0.19, 0.23)a 0.09(-0.08, 0.09)a 0.06(-0.04, 0.05)ab Means within each week that share the same letter are not significantly different, Fisher’s Protected LSD, P ≥ 0.05. aDamage incidence percentages were logarithmic (x +1) transformed for data analysis to satisfy assumptions of normality, and back-transformed data are presented. b1=untreated, 2=lambda-cyhalothrin (10 g a.i/ha), 3=chlorantraniliprole (50 g a.i/ha), 4=lambda-cyhalothrin + chlorantraniliprole (25 + 50 g a.i/ha).

Week 1 Week 3 Week 5 Week 7 dfa F-value df F-value df F-value df F-value Source Ridgetown Insecticide 3,57 1.75 3,57 4.21** 3,57 9.13*** 3,57 38.02*** Timing 4,57 0.25 4,57 2.12 4,57 1.28 4,57 2.73* Insecticide x Timing 12,57 0.86 12,57 0.92 12,57 1.54 12,57 0.61 Exeter Insecticide 3,57 2.11 3,57 9.59*** 3,57 50.47*** 3,60 39.49*** Timing 4,57 0.20 4,57 0.05 4,57 1.17 4,60 6.14** Insecticide x Timing 12,57 0.46 12,57 0.52 12,57 0.45 12,60 0.82 * P < 0.05; ** P < 0.01; *** P < 0.0001 anumerator degrees of freedom, denominator degrees of freedom

Damaged % of Pods (± 95% CI)b Treatmenta Week 1 Week 3 Week 5 Week 7c Ridgetown 1 0.06(-0.04, 0.04)a 0.29(-0.18, 0.21)a 2.02(-0.65, 0.83)a 0.74(-0.13, 0.14)a 2 0.01(-0.04, 0.04)a 0.07(-0.15, 0.17)b 0.20(-0.26, 0.33)b 0.11(-0.09, 0.09)b 3 0.01(-0.04, 0.04)a 0.09(-0.15, 0.17)b 0.26(-0.27, 0.35)b 0.12(-0.09, 0.09)b 4 0.01(-0.04, 0.04)a 0.02(-0.14, 0.16)b 0.16(-0.25, 0.32)b 0.07(-0.08, 0.09)b Exeter 1 0.00(-0.06, 0.06)a 0.86(-0.45, 0.59)a 1.57(-0.95, 1.51)a 0.74(-0.16, 0.18)a 2 0.07(-0.06, 0.06)a 0.39(-0.34, 0.44)b 0.26(-0.47, 0.74)b 0.06(-0.04, 0.06)b 3 0.05(-0.06, 0.06)a 0.30(-0.31, 0.41)b 0.39(-0.52, 0.82)b 0.08(-0.04, 0.06)b 4 0.04(-0.06, 0.06)a 0.25(-0.30, 0.40)b 0.47(-0.55, 0.87)b 0.04(-0.03, 0.05)b Means within each week and location that share the same letter are not significantly different, Fisher’s LSD, P ≥ 0.05. a1=untreated, 2=lambda-cyhalothrin (10 g a.i/ha), 3=chlorantraniliprole (50 g a.i/ha), 4=lambda-cyhalothrin + chlorantraniliprole (25 + 50 g a.i/ha). bDamage incidence percentages were logarithmic (x + 1) transformed for data analysis to satisfy assumptions of normality, and back-transformed data are presented. cDamage percentages were arcsine square root transformed at Exeter for data analysis to satisfy assumptions of normality, and back-transformed data are presented

Damaged % of Pods (± 95% CI)b Treatmenta Week 1 Week 3 Week 5 Week 7c Ridgetown Untreated 0.00(-0.09, 0.10)a 0.86(-0.67, 1.04)a 1.57(-1.21, 2.28)a 2.68(-1.57, 2.73)a

4 DAH50 0.05(-0.07, 0.07)a 0.20(-0.31, 0.43)a 0.24(-0.47,0.77)a 0.30(-0.36, 0.49)c 11 DAH50 0.06(-0.06, 0.07)a 0.33(-0.33, 0.44)a 0.59(-0.59, 0.95)a 0.53(-0.37, 0.49)bc 18 DAH50 0.03(-0.06, 0.06)a 0.53(-0.38, 0.51)a 0.53(-0.57, 0.91)a 0.68(-0.41, 0.54)bc 25 DAH50 0.04(-0.06, 0.06)a 0.78(-0.44, 0.59)a 1.03(-0.76, 1.21)a 1.17(-0.53, 0.69)ab Multiple 0.03(-0.06, 0.06)a 0.24(-0.31, 0.41)a 0.46(-0.54, 0.87)a 0.44(-0.35, 0.46)c Exeter Untreated 0.06(-0.07, 0.08)a 0.29(-0.22, 0.27)a 2.02(-1.17, 1.90)a 0.74(-0.48, 0.71)a

4 DAH50 0.00(-0.04, 0.04)a 0.08(-0.15, 0.18)a 0.33(-0.35, 0.48)a 0.29(-0.18, 0.26)ab 11 DAH50 0.01(-0.04, 0.04)a 0.11(-0.15, 0.18)a 0.50(-0.37, 0.49)a 0.10(-0.08, 0.14)b 18 DAH50 0.03(-0.04, 0.04)a 0.11(-0.15, 0.18)a 0.45(-0.36, 0.47)a 0.08(-0.07, 0.13)b 25 DAH50 0.03(-0.04, 0.04)a 0.12(-0.15, 0.18)a 0.65(-0.40, 0.53)a 0.19(-0.12, 0.18)b Multiple 0.03(-0.04, 0.04)a 0.11(-0.15, 0.18)a 0.37(-0.34, 0.45)a 0.10(-0.08, 0.14)b Means within each week and location that share the same letter are not significantly different, Fisher’s LSD, P ≥ 0.05. a Application timings were made at days after 50% egg hatch. Multiple timing applications were made at all four intervals (4+11+18+25 DAH50). bDamage incidence percentages were logarithmic (x + 1) transformed for data analysis to satisfy assumptions of normality, and back-transformed data are presented. cDamage percentages were arcsine square root transformed at Exeter for data analysis to satisfy assumptions of normality, and back-transformed data are presented

Table 3.7. Effect of active ingredient on damage to plant sample dry bean pods (± 95% Cl) from western bean cutworm feeding at Ridgetown and Exeter, ON, 2012-2013.

c,d Combined Damage Pod Damage Severity (%) (± 95% Cl) Treatmenta (%)b One Two Three 1 6.4(-3.63, 7.10)a 2.1(-0.60, 0.75)a 1.2(-1.13, 2.40)a 2.3(-1.20, 1.86)a 2 3.3(-2.08, 4.07)b 1.7(-0.53, 0.66)a 1.0(-1.05, 2.21)a 0.5(-0.54, 0.85)b 3 3.9(-2.37, 4.62)b 2.3(-0.64, 0.79)a 1.0(-1.03, 2.17)a 0.6(-0.57, 0.90)b 4 2.1(-1.53, 3.00)c 1.1(-0.40, 0.50)b 0.7(-0.90, 1.92)a 0.4(-0.51, 0.80)b Means within each column that share the same letter are not significantly different, Fischer’s Protected LSD, P ≥ 0.05. a1=untreated, 2=lambda-cyhalothrin (10 g a.i/ha), 3=chlorantraniliprole (50 g a.i/ha), 4=lambda-cyhalothrin + chlorantraniliprole (25 + 50 g a.i/ha). bDamage percentages were arcsine square-root transformed to satisfy assumptions of normality, and back- transformed data are presented. cDamage percentages were logarithmic (x + 1) transformed to satisfy assumptions of normality, and back- transformed data are presented. dOne=Surface feeding ≤ 0.25 cm in diameter; Two=Surface feeding > 0.25 cm in diameter; Three=Deep tissue feeding.

65 treatments (Table 3.8) with respect to superficial feeding > 0.25 cm (F = 1.86, df = 3, 218, P =

0.1367). Examining deep tissue feeding, all insecticide treatments had damage percentages lower than the untreated control (F = 32.60, df = 3, 218, P < 0.0001). With application timing, between

4 – 18 DAH50 and the multiple DAH50 timing had lower total pod damage levels than the untreated control (F = 5.34, df = 4, 218, P = 0.0004), primarily due to differences in deep tissue feeding (Table 3.8). Though the 25 DAH50 application timing had less deep tissue feeding damage than the control, it had similar total pod damage. Treatment responses were similar for superficial feeding > 0.25 cm in diameter (F = 4.07, df = 4,218, P = 0.0034), and deep tissue feeding (F = 5.14, df = 4,218, P = 0.0006), with 4 and 11 DAH50, in addition to the multiple

DAH50 timing, having lower damage levels than both the untreated control and the 25 DAH50 applications (Table 3.8). Seed from the individual plant samples were also examined; however no differences were found in the amount of damaged seed (data not shown).

In the harvest samples, the percentage of damaged seed in a 200 seed sample was lower with all insecticide treatments (F = 13.87, df = 3, 217, P <0.0001) compared to the untreated control (Table 3.9); no differences were found with application timing (data not shown).

Examining ROI, no differences were found between any of the treatments at Ridgetown in 2012 and 2013, or at Exeter (data not shown). All insecticide products were effective against WBC.

An additive effect was occasionally observed when lambda-cyhalothrin and chlorantraniliprole were applied together, though this additive effect was not seen with the damage severity of 3 category, so cannot be linked to greater control of WBC than each active ingredient offered individually.

Prior insecticide studies in corn confirm the efficacy of lambda-cyhalothrin (Walter et al.

1999) and chlorantraniliprole (Trueman 2013) for control of WBC. The most effective

Table 3.8. Effect of time of insecticide application on damage to dry bean pods (±95% Cl) at Ridgetown and Exeter, ON, 2012-2013.

c,d Combined Damage Pod Damage Severity (%) (± 95% Cl) Treatmenta (%)b One Two Three Untreated 6.9(-4.45, 6.49)a 2.1(-0.58, 0.73)ab 1.1(-1.13, 2.37)ab 2.3(-1.19, 1.86)a

4 DAH50 2.7(-2.31, 4.21)bc 1.3(-0.52, 0.67)bc 0.7(-0.84, 1.67)cd 0.4(-0.46, 0.70)c

11 DAH50 2.5(-2.18, 4.14)bc 1.2(-0.48, 0.61)c 0.7(-0.87, 1.75)bcd 0.3(-0.46, 0.69)c

18 DAH50 3.9(-2.97, 4.86)b 2.0(-0.65, 0.83)abc 1.1(-1.04, 2.08)abc 0.5(-0.50, 0.76)c

25 DAH50 6.6(-4.12, 5.89)a 2.5(-0.76, 0.97)a 1.6(-1.29, 2.60)a 1.3(-0.78, 1.18)b Multiple 2.2(-1.97, 3.95)c 1.3(-0.49, 0.62)c 0.5(-0.75, 1.51)d 0.3(-0.44, 0.66)c Means within each column that share the same letter are not significantly different, Fischer’s Protected LSD, P ≥ 0.05. aApplication timings were made at days after 50% egg hatch. Multiple timing applications were made at all four intervals (4+11+18+25 DAH50). bDamage percentages were arcsine square-root transformed to satisfy the assumptions of normality, and back- transformed data are presented. cDamage percentages were logarithmic (x + 1) transformed to satisfy assumptions of normality, and back- transformed data are presented. dOne=Surface feeding ≤ 0.25 cm in diameter; Two=Surface feeding > 0.25 cm in diameter; Three=Deep tissue

feeding.

Table 3.9. Effect of active ingredient on the percentage of dry bean seeds with western bean cutworm feeding damage (±95% Cl) in a 200 seed at Ridgetown and Exeter, ON, 2012-2013.

Treatmenta % damaged seed (± 95% CI)b 1 0.77(-0.17, 0.19)a 2 0.24(-0.12, 0.13)b 3 0.29(-0.12, 0.14)b 4 0.21(-0.12, 0.13)b Means that share the same letter are not significantly different, Fisher’s Protected LSD, P ≥ 0.05. a1=untreated, 2=lambda-cyhalothrin (10 g a.i/ha), 3=chlorantraniliprole (50 g a.i/ha), 4=lambda-cyhalothrin + chlorantraniliprole (25 + 50 g a.i/ha). bDamage percentages were logarithmic (x + 1) transformed to satisfy assumptions of normality, and back- transformed data are presented.

68 application timing for insecticide treatments was found to be 4 to 18 DAH50, which is consistent with the findings of Chludzinski (2013). The results found are expected as larvae older than 18 days will have reached third instar or greater and have likely burrowed into bean pods (Michel et al. 2010), resulting in the decreased efficacy found at the 25 DAH50 application timing. Though differences in efficacy were found at the different application timings, based on ROI it appears that at the infestation rates used in the trials, insecticide use at any of the application timings was not economically justified.

3.4.2 Dry Bean Insecticide Efficacy Trial

Six insecticide active ingredients (seven insecticide products and an untreated control) (Table

3.10), were compared in field trials for their control of WBC larvae. No differences were found in the percentage of hatched eggs for any of the locations (data not shown), showing that the products were applied at a similar larval density for all treatments. No differences in pod damage incidence were found among treatments in 2012 (data not shown), but differences were evident in 2013 (Table 3.11). Ratings in 2012 were done at earlier weeks (2, 3, 4, and 5), which may have attributed to the lower incidence seen and the lack of significant differences. At Ridgetown in 2013 (Fig. 3.1), no differences were found at week 2, 4 or 6 after product application, however at week 8 all insecticide products had lower damage than the untreated control. At Exeter (Fig.

3.1) at week 2 no differences were found, however at week 4 all insecticide products, with the exception of chlorantraniliprole and dimethoate, had damage levels lower than the untreated control. Week 6 showed similar results to week 4, with the exception of spinetoram, which also showed damage percentages similar to the untreated control. At week 7, all products except dimethoate had lower damage than the untreated control. Due to the low pod damage incidence levels (< 2%) found, damage severity data were not presented.

Table 3.10. Insecticide efficacy treatment list for reducing western bean cutworm feeding damage in dry beans at Ridgetown, Plattsville, and Exeter, ON 2012 – 2013.

Treatment Number Active Ingredient Rate (g a.i/ha) 1 Untreated - 2 Lambda-cyhalothrin 10 3 Chlorantraniliprole 50 4 Lambda-cyhalothrin + chlorantraniliprole 25 + 50 5 Dimethoate 480 6 Lambda-cyhalothrin + thiamethoxam 19 + 25 7 Methoxyfenozide 72 8 Spinetoram 30

Week 2 Week 4 Week 6 Week 7 Week 8 Location df F-value df F-value df F-value df F-value df F-value Ridgetown 7, 24 0.86 7, 24 1.44 7, 23 1.72 - - 7, 24 3.45* Exeter 7, 23 0.96 7, 23 2.72* 7, 24 3.08* 7, 24 3.89** - - * P < 0.05; ** P < 0.01; *** P < 0.0001

Ridgetown a a a a a a a a a

a a b b a a b a a a b a a a b b b a a a a a a

a Exeter a a a a a a a a a a a ab ab b b b b b b b b b b a bc abc c ab bc c c

Figure 3.1. Effect of active ingredient on the percentage of damaged dry bean pods (± 95% CI) by western bean cutworm measured during the season at 2-8 weeks after insecticide application at Ridgetown and Exeter, ON, 2013. Treatments are listed in table 3.10. Damaged pod ratings were square-root (x + 0.5) transformed (R: weeks 4 and 6, E: weeks 2 and 6) and arcsine square-root (R: weeks 2 and 8, E: weeks 4 and 7) transformed for analysis to satisfy the assumptions of normality, and back-transformed data are presented. Means within the same week and location followed by the same letter are not significantly different (P ≥ 0.05) according to Fisher’s Protected LSD test.

For plant samples collected prior to harvest, differences among treatments were found for total pod damage, and for each of the three damage severity categories (Fig. 3.2). All insecticide treatments had lower total pod damage than the untreated control, except for dimethoate (F =

7.53, df = 7, 117, P < 0.0001). For pods with superficial damage ≤ 0.25 cm in diameter, percentages were lower in the lambda-cyhalothrin + thiamethoxam, and methoxyfenozide treatments than in the untreated control and dimethoate treatments (F = 2.16, df = 7, 117, P =

0.0430). With superficial feeding > 0.25 cm in diameter, the lambda-cyhalothrin, and lambda- cyhalothrin + thiamethoxam treatments had a lower percentage of damage than the untreated control, dimethoate, and spinetoram treatments (F = 2.23, df = 7, 117, P = 0.0365). With deep tissue feeding, all treatments except dimethoate, had a lower percentage of damage than the untreated control (F = 8.50, df = 7, 117, P < 0.0001). The efficacy found with lambda- cyhalothrin, chlorantraniliprole, and lambda-cyhalothrin + chlorantraniliprole in this trial appears be similar to the dry bean insecticide timing trial, while thiamethoxam, spinetoram, and methoxyfenozide also appeared effective at reducing pod damage by WBC.

In seed from plant samples, lower damage levels were found with all treatments when compared to the untreated control (F = 15.29, df = 7, 117, P < 0.0001). In addition, all chemical treatments resulted in lower damage than the dimethoate treatment (Fig. 3.3 Plant Samples).

Harvest samples had no differences among treatments for yield or 200 seed sample weight (data not shown). Differences in the percentage of WBC damaged seed in harvest samples were found, with all treatments having lower damage levels than the untreated control (Fig. 3.3 Harvest

Samples), and treatments containing lambda-cyhalothrin, and methoxyfenozide having lower damage levels than dimethoate (F = 5.66, df = 7,117, P < 0.0001). No differences in ROI were

a a

b b b b a b a b a a ab ab ab a a ab b abc a b bc abc abc b b c b b b b

0.7 a Plant Samples 0.6 0.5 0.4 b 0.3 0.2 c c c c c c 0.1

Percentage seed damaged of Percentage 0 1 2 3 4 5 6 7 8 Treatment

1.2 a

Harvest Samples 1

0.8 b 0.6 bc bc 0.4 cd cd cd

0.2 d Percentage seed damaged of Percentage 0 1 2 3 4 5 6 7 8 Treatment

75 seen among the 5 application timings for each of the three insecticides used when compared to the untreated control (data not shown).

All products, with the exception of dimethoate, were effective at controlling WBC damage in dry bean. Dimethoate is not registered for control of lepidopteran pests, so its lack of efficacy was expected. It was included in the experiment because it is recommended for the control of other insects in dry bean in Ontario (OMAF 2014) such as Mexican bean beetle

(Epilachna varivestis), potato leafhopper (Empoasca fabae), and tarnished plant bug (Lygus lineolaris). Lambda-cyhalothrin and chlorantraniliprole showed good control, which supports previous research (Walter et al. 1999; Trueman 2013), as well as the results obtained in the insecticide timing trial. Thiamethoxam, which is often included as a seed treatment component in dry beans, was effective when applied to foliage. This reiterates the efficacy it has exhibited with other noctuid pests (Gehan and Abdalla 2006). Methoxyfenozide and spinetoram are not currently registered for control of WBC, but were found to be effective, which agrees with prior research examining their efficacy against noctuids (Hardke et al. 2011; Belay et al. 2012).

3.4.3 Snap Bean Insecticide Timing Trial

No differences in egg hatch were observed among snap bean treatments when years were combined (data not shown), however differences in hatch percentage and the number of hatched eggs did vary for insecticide product in both 2012 and 2013 (Table 3.12). In 2012, the chlorantraniliprole treatment had a lower egg mass hatch percentage than the untreated control.

Examining the number of hatched eggs for each insecticide treatment however, both lambda- cyhalothrin and chlorantraniliprole had fewer hatched eggs than the untreated control. In 2013 the untreated control had a lower egg mass hatch percentage when compared to both

2011 2012 2013 df F-value df F-value df F-value Source Percentage hatch of egg masses Product 2, 33 0.84 2, 33 3.79* 2, 33 16.97*** Timing 3, 33 0.30 3, 33 0.75 3, 33 0.79 Product x Timing 6, 33 0.37 6, 33 0.95 6, 33 1.41 Number of hatched eggs Product 2, 36 0.82 2, 33 5.96** 2, 33 0.05 Timing 3, 36 1.84 3, 33 0.21 3, 33 0.87 Product x Timing 6, 36 0.73 6, 33 0.95 6, 33 0.28 * P < 0.05; ** P < 0.01; *** P < 0.0001

77 lambda-cyhalothrin and chlorantraniliprole, however no differences were found in the total number of hatched eggs (Table 3.13). Though hatch was lower in two of the treatments in 2012, hatch was still above 80%, and there were over 200 hatched eggs with each insecticide treatment.

Examining foliar feeding in 2011, no differences were observed at either 15 or 24 DAI ratings (Table 3.14). In 2012 only one rating was performed at 13 DAI, and plants treated with lambda-cyhalothrin had fewer damaged leaves than those treated with chlorantraniliprole (F =

3.80, df = 2, 33, P = 00327). In 2013 at the 18 DAI rating, both insecticide products had fewer damaged leaves when compared to the untreated control (F = 3.69, df = 2, 36, P = 0.0348). At 24

DAI, only lambda-cyhalothrin had fewer damaged leaves than the untreated control (F = 7.26, df

= 2, 36, P = 0.0022).

Examining harvest samples, total pod yield (F = 9.27, df = 2, 127, P = 0.0002) and the percentage of undamaged pods (F = 36.12, df = 2, 126, P < 0.0001) were lower in the untreated control than in both insecticide treatments (Table 3.15). The percentage of pods with evidence of

WBC feeding was lower in both insecticide treatments for 2011 + 2013 (F = 82.93, df = 2, 80, P

< 0.0001), and 2012 (F = 18.54, df = 2, 33, P < 0.0001), when compared to the untreated control.

No differences were found with application timing for any of the factors examined (data not shown). Though differences were found in the number of hatched eggs for each of the insecticide treatments in 2012, based on the higher larval densities and low damage levels found in the dry bean trials, it is unlikely that the differences found would have had much impact on the damage levels found in the snap bean trials.

Both insecticide active ingredients were effective at reducing WBC damage in snap beans, which supports the results obtained from the dry bean trials, as well as previous research

(Walter et al. 1999; Trueman 2013). The application timings used in the snap bean trials were

2011b 2012b 2013b Producta Hatch percentage of egg masses (± 95% Cl) 1 58.4(-17.32, 16.31)a 100.0(-12.54, 11.24)a 70.8(-33.80, 24.22)b 2 71.7(-16.68, 14.06)a 92.6(-27.06, 6.80)ab 94.5(-24.84, 4.37)a 3 65.4(-17.15, 15.31)a 82.7(-32.27, 16.71)b 97.1(-21.54, 0.13)a Number of hatched eggs (± S.E) 1 198.4 ± 26.32a 389.8 ± 52.84a 276.8 ± 56.02a 2 210.9 ± 26.32a 263.0 ± 52.84b 276.1 ± 56.02a 3 164.8 ± 26.32a 236.3 ± 52.84b 288.4 ± 56.02a Means within each year and factor that share the same letter are not significantly different, Fisher’s Protected LSD, P ≥ 0.05. a1=untreated, 2 = lambda-cyhalothrin (10 g a.i/ha), 3 = chlorantraniliprole (50 g a.i/ha) bHatch percentages were arcsine square-root transformed for data analysis to satisfy assumptions of normality, and back-transformed data are presented.

Table 3.14. Effect of active ingredient on the number (± 95% CI) of western bean cutworm damaged snap bean leaves at Ridgetown, ON 2011-2013.

2011 2012 2013 Treatmenta 15 DAI (± 95% CI)b 13 DAI (± 95% CI)c 18 DAI (± 95% CI)b 1 25.5(-7.00, 8.06)a 122.8(-53.61, 94.49)ab 9.9 (-2.11, 2.35)a 2 20.2(-6.16, 7.25)a 102.7(-44.88, 79.11)b 6.6 (-1.73, 1.97)b 3 23.4(-6.65, 7.74)a 138.6(-60.39, 106.48)a 6.6 (-1.73, 1.97)b 24 DAI (± 95% CI)c 24 DAI (± 95% CI)c 1 1.5 (-0.83, 1.24a - 22.7(-3.85, 4.60)a 2 2.7(-1.23, 1.84)a - 13.8(-2.40, 2.87)b 3 1.8(-0.93, 1.39)a - 17.8(-3.06, 3.66)ab Means within each rating date for each year that share the same letter are not significantly different, Fisher’s Protected LSD, P ≥ 0.05. DAI = Days after inoculation with egg masses a1=untreated, 2 = lambda-cyhalothrin (10 g a.i/ha), 3 = chlorantraniliprole (50 g a.i/ha) bLeaf ratings were square-root (x + 0.5) transformed to satisfy the assumptions of normality, and back-transformed data are presented. cLeaf ratings were logarithmic (x + 1) transformed to satisfy the assumptions of normality, and back-transformed data are presented.

Table 3.15. Effect of active ingredient on pod yield (kg/ha), percentage of undamaged, and percentage of western bean cutworm damaged snap bean pods (± 95 % CI) at Ridgetown, ON 2011-2013.

d Undamaged WBC Damaged Pods (%) Treatmenta Total Yield (kg/ha)b Pods (%)c 2011 + 2013c 2012b 1 5589(-2825.5, 3810.2)b 90(-20.9, 9.0)b 1.1(-0.42, 0.48)a 4.8(-4.76, 11.42)a 2 7450(-3338.1, 4321.7)a 96(-17.1, 3.8)a 0.3(-0.28, 0.34)b 0.2(-2.16, 5.19)b 3 7368(-3317.2, 4301.2)a 96(-17.2, 4.0)a 0.1(-0.24, 0.30)b 0.1(-2.29, 5.06)b Means within each column that share the same letter are not significantly different, Fischer’s Protected LSD, P ≥ 0.05. a1=untreated, 2 =lambda-cyhalothrin (10 g a.i/ha), 3=chlorantraniliprole (50 g a.i/ha). bMeans were square-root (x + 0.5) transformed for data analysis to satisfy the assumptions of normality, and back- transformed data are presented. cMeans were arcsine square-root transformed for data analysis to satisfy the assumptions of normality, and back- transformed data are presented. d2012 trial presented separately to meet the assumptions of normality

81 applied earlier than products in the dry bean trials as they were based on DAI timings rather than

DAH50 timings. Since hatch took between 0-4 days, the snap bean products were likely applied within 1-2 days after egg hatch. Both products appear to offer good control of young larvae immediately after hatch. In the 2012 snap bean trial pod damage levels may have been high enough to impact economic return, however both insecticide products were able to limit the damage found when compared to an untreated control. Though higher feeding levels were found in the foliar ratings with both insecticide products, these high levels are not evident in the pod ratings. This could be due to larval death, larval movement from the research location, or that larvae remained feeding on leaves though pods were present. WBC is not known to be a major defoliator of snap beans, and pod damage was used as the more accurate way of measuring the efficacy of the insecticides tested. Examination of application timings beyond 14 DAI in snap beans may also not be practical due to the short time between bloom and harvest, whereas this period is much longer in dry beans.

3.5 Conclusion

Based on the studies conducted, the best time for applications of foliar insecticide products for the control of WBC is between 4 and 18 DAH50 in dry bean. Since egg masses were placed on plants at full flower, early pod development was occurring at 11 DAH50, and by 18 and

25 DAH50 pods were almost fully elongated. In snap bean, applications at 4, 10, and 14 DAI proved effective, however no upper limit was found. Therefore additional application timings beyond 14 DAI should be examined so that the upper DAI application limit can be identified.

Other pests whose feeding period on dry bean plants overlap with WBC include the potato leafhopper, Mexican bean beetle, bean leaf beetle, and the tarnished plant bug (OMAFRA 2009).

It is possible when scouting for one of these other dry bean pests that WBC feeding damage 82 could be identified, though it is unlikely that larvae would be seen. Though all products, with the exception of dimethoate, were effective against WBC, the foliar application of thiamethoxam is not recommended. This is due to concerns about the impact of neonicotinoids on pollinators

(Girolami et al. 2009). Though there was low WBC feeding damage in these trials, an egg mass density of one per metre of row was present. Due to the high potential larval density in the trials, it is unlikely that at a commercial level greater WBC pressure would be found; however WBC populations in the trial may have been impacted by other factors such as predation, or low larval vigor. Based on the research conducted and the low damage levels found in dry bean trials, WBC was not found to damage beans beyond a limit that would result in economic losses. In snap beans however, the damage found was slightly greater. It is possible that the levels found in the untreated control in 2012 would result in losses to the producer.

CHAPTER FOUR

Western Bean Cutworm Pheromone Trap Monitoring and Seed

Damage Assessment in Dry Beans

4.1 Abstract

The western bean cutworm is a relatively recent pest to Ontario, and the impact it has on dry bean production in this area is not well understood. Pheromone traps were set up in 2011–

2013 to monitor moth populations, and seed damage in commercial dry bean samples were monitored in 2010 – 2012. Pheromone trap captures of adult male moths indicated that peak flight occurred between 22 July and 29 July in 2012, and between 29 July and 3 Aug in both

2011 and 2013. The highest capture numbers occurred within 20 km of the shoreline of Lake

Huron, and on soils that were classified as either coarse or fine textured. It was also found that the current GDD estimates for 25, 50 and 75% moth emergence from the midwestern United

States do not accurately forecast moth flight in Ontario. In commercial bean samples, a higher percentage of damage was found in the light red kidney and otebo market classes than in dark red kidney, vine cranberry, and cranberry market classes.

Keywords Peak flight, Striacosta albicosta, Phaseolus vulgaris, pheromone trap, soil type

4.2 Introduction

The western bean cutworm (WBC), Striacosta albicosta (Smith) (Lepidoptera:

Noctuidae) is a recent pest of corn (Zea mays L.) and dry bean (Phaseolus vulgaris L.) in the

Great Lakes region. Populations were first found in Ontario in 2008 (Michel et al. 2010), though the species is native to North America (Smith 1887). The geographical distribution of WBC has gradually expanded over time, with more rapid range expansion in recent years (Miller et al.

2009). This insect now occupies much of the northeastern United States, as well as the provinces of Ontario and Quebec, Canada (Michel et al. 2010). These two provinces, in addition to the states of Michigan and New York, are major dry bean production areas, and WBC potentially poses an economic risk to producers. Factors such as climate change, the introduction of genetically modified corn, and reduced tillage have been suggested as possible reasons for range expansion of WBC, but none have been definitively identified as causes (Hutchison et al. 2011).

Damage to dry bean crops has been observed in Michigan, although its economic impact was not determined (Chludzinski 2013). The first case of WBC feeding damage in dry bean fields in Ontario was confirmed in 2014 in Middlesex County near Strathroy (T.S. Baute, personal communication5). No economic damage due to WBC larval feeding in edible bean has been observed in Ontario to date, however the fields where damage was identified in 2014 have not been harvested yet.

In Nebraska, WBC trap captures are used to determine the timing of insecticide applications in dry bean (Seymour et al. 2004), however their reliability in predicting damage in the Great Lakes region has been questioned due to climatic differences between these two regions (Michel et al. 2010). In Nebraska, risk to dry beans is classified as low, moderate and

5 T. S. Baute, Field Crop Entomologist – Program Lead, Ontario Ministry of Agriculture, Food and Rural Affairs, Ridgetown, Ontario, Canada. 85 high based on WBC moths captured up to the point of peak flight, with less than 700, 700 –

1000, and 1000+ moths being the criteria for each of the three categories respectively (Seymour et al. 2004). In corn in Nebraska, scouting is performed to determine whether an insecticide application should occur. If more than 8% of corn plants have egg masses, it is recommended to apply a control product (Seymour et al. 2004).

Using GDD models (base 50°F) to predict moth flight as of May 1st for each year, it has been predicted that 25, 50 and 75% moth emergence occur at 1319 – 1320, 1422 and 1536

GDDs (Seymour et al. 2004; Cullen and Jyotika 2008; Volenberg 2011), respectively. It is unknown whether these GDD accumulations are accurate for the Great Lakes region, which is generally more humid than the midwestern United States in the summer months, and may therefore increase the success of emerging adults.

In commercial dry bean production, little damage to beans is tolerated as this crop typically goes to consumers as a whole dry or processed product, making visual quality important to consumers. Seed with visual blemishes (known as ‘pick’) can result in downgrading of a crop, at a cost to the producer. As little as 2% pick in a crop can result in a lower product grade (Hagen 1963; Canadian Grains 2014). For example, with a market class such as dark red kidney beans, 2% damaged seed in a load results in a discount of $19.84/MT being charged to the producer (D. Wilson, personal communication6), though the grading guidelines and charges often vary by elevator. Based on the 2012 insurance claim price for kidney beans of $1.10/kg

(Agricorp 2012), this would result in a 1.8% reduction in the amount paid to the producer.

Pheromone traps can be used to monitor WBC moth populations in dry bean fields, though it is not currently known if factors such as soil type or dry bean market class have an impact on moth captures. Huron County is the major dry bean growing area of Ontario, and due

6 D. Wilson, Quality Assurance/ Technical Manager, Hensall District Co-operative, Hensall, Ontario, Canada 86 to its proximity to Lake Huron and the prevailing eastward wind direction (Westelaken and

Maun 1985), it is possible that WBC moths arrive in Ontario on wind currents from more westerly locations, such as Michigan. It is not yet known whether WBC prepupae are overwintering in Huron County, and if so, to what extent. To improve understanding of the biology and potential impact of WBC in the Great Lakes region, it is important to identify factors that may affect their movement and abundance, determine the applicability of GDD flight predictions from other regions, determine which bean market classes are at greatest risk of feeding damage, and the amount of feeding damage that occurs. This information will help in determining the risk WBC poses to the dry bean industry in the Great Lakes region, and provide a basis for future research and the development of management recommendations.

Research was conducted to examine whether the distance of pheromone traps from the shore of Lake Huron, or the soil texture at the trap site, had an impact on moth capture numbers.

It is hypothesized that a relationship will exist between trap distance and WBC moth counts, with trap counts being higher closer to the shoreline, as moths were found in Michigan before they were found in Ontario (Michel et al. 2010). It is also hypothesized that greater moth counts will be seen on coarse textured soil, as it is thought that this soil texture allows greater overwintering success (Tooker and Fleisher 2010). It is currently unknown however, the percentage of moths that are arriving from Michigan, or the percentage that are due to overwintering populations in

Ontario.

Commercial damage in dry beans was also examined to determine whether certain market classes have a higher risk for damage among the common dry bean market classes grown in

Ontario. It was hypothesized that the light red kidney class was at greater risk, due to the higher larval survival on this market class seen in the larval survival laboratory study.

4.3 Materials and Methods

4.3.1. Population Monitoring in Grower Fields

Populations of adult male WBC in western Ontario were monitored in 2011-2013 using

Uni-traps (International Pheromone Systems, Cheshire, UK) baited with synthetic female WBC pheromone lures (Scentry Biologicals, Inc., Billings, MT). Traps were placed out in producers’ fields, with each trap being one replicate for a distance or a soil texture category. Traps were suspended at a height of 1.5 m, as this height was previously found to be optimal for WBC

(Dorhout and Rice 2008), and pheromone lures were changed every three weeks throughout the collection period. A single 3 cm x 3 cm piece of Home Defense Maxx Insecticide Strip (Scotts

Canada Ltd., Mississauga, ON), containing the active ingredient Dichlorvous, was placed inside each trap to kill arriving moths. The insecticide strip was not changed for the length of the season, as it was found to remain effective. In 2011, 19 traps were placed in Huron County, six in Perth County, and three in Middlesex County. In 2012, 18 traps were placed in Huron, four in

Middlesex, and one in each of Chatham-Kent, Lambton, and Oxford counties. In 2013, 23 traps were placed in Huron, and two in Chatham-Kent counties. Sites in Huron County were selected along the length of the shoreline of Lake Huron (Fig. 4.1), as well as at varying distances inland to include sites with a range of dry bean market classes and of soil types. All traps were placed in the field between the end of May and mid-June each year and were monitored weekly until the end of August.

To determine whether significance was seen among the seven distance categories from the shoreline of Lake Huron, GPS coordinates for each trap were determined at initial placement using a Garman Nuvi 250W GPS Device (Garmin International Inc., Olathe, KS). Google Earth

(Google Inc., Mountain View, CA) was used to select the point of Lake Huron shoreline at the

Figure 4.1. Google Earth (Google Inc., Mountain View, CA) map of pheromone trap placement in 2013 in relation to Lake Huron for western bean cutworm moth captures.

89 same latitude as the trap, so the shoreline longitude could be determined. Latitude and longitude coordinates for both the trap and shoreline were then converted to decimal degrees format using equation 1 (Shamshiri and Ismail 2012):

Decimal Degree Format = Degrees + (Minutes/60) + (Seconds/3600) [1]

The haversine formula was then used to calculate the earth surface distance between the trap and point of shoreline using equations 2-4 (Cassa et al. 2005) in sequential order:

a = (sin2(∆lat/2) + cos(lat1)*cos(lat2)*sin2(∆long/2) [2]

c = 2*atan2(√a,√(1-a)) [3]

distance = R*c [4]

In equation 2, ∆long = trap longitude – shoreline longitude, ∆lat = trap latitude – shoreline latitude, long1 = trap longitude, long2 = shoreline longitude. In equation 4, R= earth radius of

6,371 km (Han et al. 2005). Equations 3-4 were calculated in radians.

Traps were placed into one of seven categories based on their distance from the Lake

Huron shoreline (0-5.0 km, 5.1-10.0 km, 10.1-20.0 km, 20.1-30.0 km, 30.1-40.0 km, 40.1-50.0 km, and >50.0 km), with 14 replicates in the 0 – 5.0 km category, 18 in the 5.1 – 10.0 km, 11 in the 10.1 – 20.0 km, 19 in the 20.1 – 30.0 km, 6 in the 30.1 – 40.0, 6 in the 40.1 – 50.0, and 4 in the >50 km category over the 2011 – 2013 monitoring period.

Soil type at each site was determined by comparing the trap location as displayed on

Google Earth with county soil maps from soil survey reports (Hoffman et al. 1952; Hoffman and

Richards 1952; Matthews et al. 1957; Wicklund and Richards 1961; Hagerty and Kingston 1992;

Wilson 1994). In situations where more than one soil type occurred at a trap site, the most prevalent soil type was used. Each location was then placed into one of three soil texture categories (coarse, medium, fine) based on the soil texture category determined by county soil

90 maps. Based on the criteria of Brady and Weil (1999), the coarse texture category (including soil classifications in both the coarse and moderately coarse categories) included sands, and loamy sands, the medium textured category included loams, silt loams, and silts, and the fine textured category (included soil classifications in both the fine and the moderately fine categories) included the soil classes of sandy clay loams, silty clay loams, clay loams, sandy clays, silty clays, and clays. In the fine soil texture category there were 43 replicates, in the medium textured soil category there were 20, and in the coarse textured soil texture category there were 15 replicates over the 2011 – 2013 monitoring period.

Yearly GDD accumulations as of January 1st and May 1st (base 50°F) were examined based on historical daily temperature data in Goderich, ON, from the Government of Canada

(2014) to determine whether emergence estimates from the midwestern United States (Seymour et al. 2004) accurately predicted emergence (measured with pheromone traps) in three bean fields in Huron County.

The GDD accumulations from January 1st and May 1st for each of the trap capture weeks were determined using the following formula for degrees Fahrenheit (OMAFRA 2011):

Daily GDD = ((Tmax – Tmin)/2) – Tbase [5]

Cumulative captures of moths from three trap sites in Ontario were determined for each of 2011, 2012, and 2013, and were plotted by GDD accumulation. Trap sites were not identical among the three years, however in all years three sites closest to Goderich, ON were chosen.

Sites in 2011 were from north Blyth, east Benmiller, and south Goderich, in 2012 were from north Bayfield, south Goderich, and northeast Benmiller, and in 2013 were from southwest

Dungannon, southwest Auburn, and east Goderich. GDD for 25, 50 and 75% emergence of

91 moths at each location was determined for both a start date of January 1st and May 1st, and compared to predicted values from Nebraska (Seymour et al. 2004).

4.3.2 Field Damage in Grower Fields

WBC damage to beans was assessed after harvest at the Hensall District Co-operative elevator in Hensall, ON from 2010-2012; damage was examined on an individual market class basis. The field of origin for each of the loads was not known, therefore no examination of the relationship between trap counts and damage levels could be conducted. A 1-2 kg sample from each commercial seed load was taken by elevator staff for quality analysis. From these samples, a 100 seed sample was examined by grading staff and the percentage of seed with visual blemishes and evidence of insect feeding was recorded. All market classes were examined except navy bean, which was excluded due to time constraints. The feeding damage was examined, and determined to be from WBC due to the large feeding holes in the seed, characteristic of feeding damage by this insect. The total number of commercial loads received by the elevator was obtained for each year between 2010 and 2012 and the percentage of samples with WBC damage was determined. The frequency of damage was also determined for each market class.

4.3.3 Data Analysis

All data were analyzed using PROC MIXED (SAS Version 9.2, SAS Institute, Cary, NC) and α = 0.05, unless otherwise stated. Data were combined for analysis if no significant interaction among years was found. PROC UNIVARIATE was used to test data for normality and homogeneity of variance based on the Shapiro-Wilk statistic. If sufficient normality was not found, transformation of data occurred using an arcsine, square-root (x + 0.5), or logarithmic (x

+ 1) transformation to obtain the highest Shapiro-Wilk’s statistic. Data was back-transformed for

92 presentation of the results. A Fisher’s Protected LSD, α=0.05, was used to perform means separation.

A one-way ANOVA using PROC MIXED was used to examine total trap counts, as well as weekly moth counts over seven distance categories and over three soil textures for combined years as well as individual years. Distance or soil texture categories were fixed effects in these analyses, and year was considered a random effect.

Single linear and non-linear regression was also performed using PROC GLM and PROC

NLIN respectively, to determine if there was a linear or exponential relationship between moth counts and distance from the shore.

A one-way ANOVA was performed using PROC MIXED to examine the percentage of the total commercial samples for each market class with evidence of WBC feeding. The frequency of damage within each market class was also examined. In both analyses, market class was the fixed effect and year was the random effect. Seed damage percentage data were arcsine square-root transformed, and damage frequency data were square-root (x+ 0.5) transformed for analysis.

4.4 Results and Discussion

4.4.1 Population Monitoring in Grower Fields

Moth trap captures were examined in 2011 – 2013 to determine whether location or soil texture had an impact on the counts obtained. Peak moth flight in both 2011 and 2013 occurred during week 9 (July 30th – Aug 5th) (Fig. 4.2). In 2012, peak flight occurred during week 8 (July

23rd – July 29th). In 2011 and 2012, peak moth flights in Ontario occurred 1 and 2 weeks later than in Michigan, respectively (Chludzinski 2013); however 2013 Michigan data were unavailable for comparison. 93

350

300

250

200 2011 2012 150 2013 100

Number Captured Moths of Number 50

0 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 Week 12

GDD accumulations were compared to those in Nebraska used for estimating 25, 50, and

75% moth emergence. In Nebraska, 25% emergence occurs at 1319 GDD (base 50°F), 50% at

1422 GDD, and 75% at 1536 GDD (Seymour et al. 2004). These same percentage emergence points appeared to occur earlier in Ontario with both May 1st and January 1st start dates for GDD accumulations (Table 4.1). Examining the average GDD accumulations from three traps as of

May 1st in Goderich, ON (Fig. 4.3), 25% emergence occurred between 146 and 229 GDD earlier than predicted values in Nebraska, and 50% emergence occurred between 112 and 282 GDD earlier. Not only did 75% emergence occur between 116 and 328 GDD earlier than the predicted

1536 GDD estimate in Nebraska, they also occurred earlier than the Nebraska prediction for 50% emergence. Based on the results obtained, it appears that the estimates for 25, 50, and 75% moth emergence in Nebraska based on a May 1st start date for GDD accumulation, do not explain moth emergence in Ontario.

Accumulation of GDD as of January 1st was also performed to see if an earlier start date resulted in a better fit of the Nebraska model for Ontario moth populations. Using this earlier start date, GDD accumulation as of January 1st appears to better explain moth populations based on the values determined in Nebraska (Seymour et al. 2004), however in all instances moth emergence occurred earlier than the predicted number of GDD. Due to this, the estimates used in

Nebraska should not be used as an accurate predictor of moth emergence in Ontario, as it will likely result in an underestimation of the percentage of the moth population that has emerged.

Over the three year period pheromone traps were placed out, no relationship was observed between trap counts and distance from the shoreline of Lake Huron, as regressions examining both linear and exponential decay models had R2 and pseudo R2 values between

May 1st Initialization January 1st Initialization

2000 2000 Location 1 Location 1

Location 2 Location 2

1500 Location 3 1500 Location 3 2011 2011

1000 1000 Number of Moths of Number 500 Moths of Number 500

0 0 500 1000 1500 2000 500 1000 1500 2000 Growing Degree Days Growing Degree Days

2000 2000

1500 1500 2012 2012

1000 1000 Number of Moths of Number Number of Moths of Number 500 500

0 0 500 1000 1500 2000 500 1000 1500 2000 Growing Degree Days Growing Degree Days

2000 2000

1500 1500 2013 2013 1000 1000

500 Number of Moths of Number Number of Moths of Number 500

0 0 500 1000 1500 2000 500 1000 1500 2000 Growing Degree Days Growing Degree Days

Table 4.1. Growing degree day (GDD) accumulations (Base 50°F) corresponding to predicted moth emergence (Seymour et al. 2004), and mean values for three sites near Goderich, ON, 2011 – 2013.

GDD Accumulations for % Moth Captures

Year and Location Start date 25% 50% 75%

Predicted May 1 1319 1422 1536

2011 Average May 1 1170 1310 1420

2012 Average May 1 1173 1253 1383

2013 Average May 1 1090 1140 1208

2011 Average Jan 1 1207 1340 1450

2012 Average Jan 1 1310 1378 1493

2013 Average Jan 1 1128 1190 1250

0.05 – 0.40 (data not shown). The low degree of correlation between trap counts and distance from the shore, suggests that the presence of moths from local populations masked the effect of any influx of moths arriving on prevailing winds from Michigan. This means that it is likely

WBC moths are overwintering in Huron county, as well as coming in from nearby areas such as

Michigan.

When counts were combined for each rating period and examined over the three years, trap captures in the weeks around peak flight were significantly higher closer to the shore than further away. At weeks 7 (F = 4.73, df = 6, 65, P = 0.0005), 8 (F = 5.48, df = 6, 65, P = 0.0001),

9 (F = 3.92, df = 6, 69, P = 0.0020), 11 (F = 2.31, df = 6, 68, P = 0.0432), and 12 (F = 2.63, df =

6, 66, P = 0.0237), the highest trap captures were found within 10 km of the shoreline (Table

4.2). Later in the season, at weeks 9, 11, and 12, higher counts were also found 30 – 40 km from the shoreline. When counts were examined at weekly intervals for each individual year, similar patterns were found (data not shown). The lowest total trap captures occurred at sites between 20 and 50 km from the shoreline, when data was pooled for all three years (F = 4.93, df = 6,69, P =

0.0003) (Fig. 4.4). It has been suggested that coarser soils may offer better overwintering sites

(Tooker and Fleisher 2010), which may explain the increased moth captures found near the shoreline of Lake Huron where sandy soils predominate (Hoffman et al. 1952). The high trap counts >50 km from the shoreline are due to two traps placed in very sandy areas near Bothwell,

ON which are considered ‘hot spots’ for WBC in corn (Baute and Stewart 2011).

Prevailing winds in the Lake Huron area generally come from the westward direction

(Westelaken and Maun 1985). Consequently, it is possible that some captured moths may have arrived in Ontario from other areas, such as north and central Michigan; however the origin of

Table 4.2. Weekly captures (± S.E) of male western bean cutworm moths grouped by distance from the shoreline of Lake Huron, ON in 2011 – 2013.

Number of Weeka Distance (km) traps 6 7 8 9 10 11 12 0-5 14 32 ± 22.4a 86 ± 36.0a 307 ± 51.5ab 328 ± 38.3a 195 ± 43.1a 132 ± 64.0ab 37 ± 17.0a 5-10 18 27 ± 22.3a 58 ± 35.7ab 310 ± 48.5a 306 ± 35.8a 188 ± 42.1a 150 ± 63.3a 39 ± 16.8a 10-20 11 28 ± 22.3a 44 ± 36.8bc 197 ± 57.4bc 276 ± 42.1a 154 ± 44.7a 127 ± 65.2ab 33 ± 17.3ab 20-30 19 29 ± 22.3a 28 ± 35.4c 108 ± 46.8c 174 ± 34.0bc 134 ± 41.2a 71 ± 62.8bc 15 ± 16.6b 30-40 6 8 ± 23.7a 14 ± 38.1c 83 ± 66.0c 210 ± 54.8abc 170 ± 51.1a 76.4 ± 70.0abc 17 ± 18.6ab 40-50 6 20 ± 25.1a 80 ± 38.1ab 135 ± 66.0c 119 ± 54.8c 77 ± 51.1a 29 ± 70.0c 10 ± 19.2b >50 4 18 ± 23.0a 96 ± 40.0a 217 ± 76.8abc 297 ± 65.8ab 155 ± 57.1a 70 ± 74.6bc 9 ± 21.3b Means in the same column followed by the same letter are not significantly different, Fisher’s Protected LSD, P ≥ 0.05. aDates (± 1 day) were: Week 6 = 8 –15 July; Week 7 = 16 – 22 July; Week 8 = 23 – 29 July; Week 9 = 30 July – 5 Aug; Week 10 = 6 – 12 Aug; Week 11 = 13 – 19 Aug; Week 12 = 20 – 26 Aug

1400 a 1200 a ab

1000 ab

800 b b b

600 Total Moths Total 400

200

0 0-5 5-10 10-20 20-30 30-40 40-50 >50 Distance (km)

100 captured moths was not determined. Little information currently exists on the flight behaviour of

WBC and the distances they are capable of traveling, however other noctuids are capable of flying long distances. Mark-recapture data indicated that black cutworm, Agrotis ipsilon

(Hufnagel) (Lepidoptera: Noctuidae) can fly 900-1200 km (Showers et al. 1989). Estimates based on pollen identification, indicate that black cutworm and armyworm, Pseudaletia unipuncta (Haworth) (Lepidoptera: Noctuidae), can fly 1300-1600 km (Hendrix and Showers

1992).

Total moth captures were higher at sites with coarse (917 ± 126.7) and fine (872 ± 89.8) textured soil sites than at sites with medium (597 ± 114.8) textured soils, when pooled over all three years (F = 3.28, df = 2, 73, P = 0.0433). Higher trap captures occurred at sites with coarse textured soil when years were pooled at week 7 (F = 11.39, df = 2, 69, P < 0.0001) (Table 4.3), which was expected based on reports of higher overwintering survival in this soil texture (Tooker and Fleischer 2010). Sites with coarse or fine textured soils had higher WBC captures than those with medium textured soils at weeks 6 (F = 4.30, df = 2, 66, P = 0.0175) and 8 (F = 4.23, df = 2,

70, P = 0.0185), but no differences were found beyond this week. The observed relationship between trap captures and soil type early in the season may be due to the prevalence of locally emerging moths during weeks 6 and 7, while during later weeks both immigrating and local moths are captured. A possible reason for the higher counts on sites with fine textured soil early in the season may be slower plant growth. Depending on planting date, plants may have been less developmentally mature, which may have been desirable to moths looking for oviposition sites.

Moth captures occurred most frequently within 20 km of the Lake Huron shoreline.

Based on the county soil map (Hoffman et al. 1952), it appears visually that the predominant soil

101

Table 4.3 Weekly captures (± S.E) of male western bean cutworm moths in 2011-2013 by site soil texture class.

Number of Weeka Soil Texture traps 6 7 8 9 10 11 12 Fine 43 27 ± 22.5a 49 ± 36.0b 226 ± 40.0a 276 ± 26.5a 164 ± 38.8a 123 ± 59.8a 31 ± 15.7a Medium 20 11 ± 22.9b 31 ± 36.6b 123 ± 46.8b 189 ± 34.7a 143 ± 41.6a 68 ± 61.7a 16 ± 16.3a Coarse 15 37 ± 23.3a 99 ± 37.1a 267 ± 51.7a 261 ± 38.9a 170 ± 43.2a 105 ± 62.8a 30 ± 16.8a Means in the same column followed by the same letter are not significantly different, Fisher’s Protected LSD, P ≥ 0.05. aDates (± 1 day) were: Week 6 = 8 –15 July; Week 7 = 16 – 22 July; Week 8 = 23 – 29 July; Week 9 = 30 July – 5 Aug; Week 10 = 6 – 12 Aug; Week 11 = 13 – 19 Aug; Week 12 = 20 – 26 Aug

102 textures in this area are coarse and fine. It is not possible to determine from this study what soil type individual moths emerged from, nor the distance they traveled before capture. However, both distance from the Lake Huron shoreline and soil texture, appear to affect WBC moth trap captures.

4.4.2 Field Damage in Grower Fields

Differences in damage to commercial samples were found among market classes in the percentage of loads with western bean cutworm feeding damage in 2010-2012 (F = 3.51, df = 6,

12, P = 0.0304) (Table 4.4). No differences were found, however with damage severity within the samples by market class (F = 1.13, df = 6, 12, P = 0.4032) (Table 4.4), though this is likely due to the very low level of damage found in the samples. A higher percentage of damaged loads occurred with light red kidney and otebo beans than dark red kidney, vine cranberry, and cranberry beans, while all market classes except vine cranberry had a higher percentage of damaged loads than cranberry beans. This suggests that WBC may exhibit preferences for different market classes. This is supported by the larval feeding study (Chapter Two), where differences were found in larval survival among the three market classes examined, with light red kidney having the highest. It is contradictory to the dry bean oviposition studies however, as the laboratory study concluded no market class preference. Though differences were found in the commercial seed samples, the exact locations they were taken from, as well as the conditions of the plants, were not known and may have attributed to the differences that were found.

4.5 Conclusion

Western bean cutworm presence based on pheromone trap captures appears greatest in areas with either coarse or fine textured soil, and greatest within 20 km of the shoreline of Lake

103

Table 4.4. Percentage of seed samples (± 95% Cl) with western bean cutworm feeding damage, and damage severity grouped by dry bean market class in 2010 – 2012.

Percentage of Samples Damage Severity (%)b Market Class with Damagea Light Red Kidney 7.7(-7.00, 13.53)a 0.5(-0.34, 0.41)a Otebo 7.1(-6.56, 13.18)a 0.4(-0.31, 0.38)a White Kidney 4.3(-4.27, 11.33)ab 0.6(-0.36, 0.43)a Black 3.9(-3.93, 11.04)ab 0.2(-0.27, 0.34)a Dark Red Kidney 1.6(-1.16, 8.62)b 0.4(-0.32, 0.39)a Vine Cranberry 1.6(-1.14, 8.60)bc 0.3(-0.30, 0.36)a Cranberry 0.5( 1.07, 6.56)c 0.1(-0.26, 0.33)a Means in the same column followed by the same letter are not significantly different, Fisher’s Protected LSD, P ≥ 0.05. aDamage percentages were arcsine square-root transformed to satisfy assumptions of normality, and back- transformed data are presented. bDamage frequencies were square-root (x + 0.5) transformed to satisfy assumptions of normality, and back- transformed data are presented.

104

Huron, ON. However it should be noted that trap locations were focused in Huron County, and examining WBC capture patterns in other counties is recommended. Differences were found with the percentage of seed samples with damage, and light red kidney, otebo, white kidney, and black beans appear at a higher risk for damage than other market classes and should be monitored closely during the season. Research examining larval survival (Chapter Two) showed similar results for the light red kidney market class, as it offered highest larval survival on pod tissue. The GDD accumulations set forth by Seymour et al. (2004) do not appear to accurately explain 25, 50, and 75% moth emergence in Ontario based on both a May 1st and January 1st start date for GDD accumulation (base 50°F). A model for more accurate predictions requires determining the minimum developmental threshold for WBC rather than relying on growing degree days.

The research conducted was a preliminary study to examine WBC activity patterns and the factors affecting pheromone trap captures. Additional studies are recommended to track moths from their overwintering sites and to examine feeding damage throughout the season in dry bean fields in combination with pheromone trap monitoring. Analyzing soil samples taken from each trap location is also recommended to get a more accurate description of the soil texture at each site. Monitoring the flight of emerging moths will allow determination of average flight distances and identify the soil textures or dry bean market classes of greatest attraction.

Monitoring of dry bean damage and pheromone trap captures at one site will allow direct comparison of damage levels with captures to re-examine current spray thresholds. These additional studies are suggested to more completely assess the risk posed by WBC to the dry bean industry in Ontario.

105

CHAPTER FIVE

General Discussion

The western bean cutworm (WBC) is a recently arrived insect in Ontario, and its impact on dry beans is not well understood in this area. Its impact to corn in this same area, is better understood, with economic damage identified as early as 2010 (Baute 2011).The goal of this study was to determine the status of this insect as a pest of dry beans in Ontario. The objectives were to examine oviposition preference, larval survival, insecticide efficacy and timing, trends in moth populations, and damage in commercial dry bean fields.

5.1 Oviposition Preference and Larval Survival

WBC appears to exhibit no oviposition preference among dry bean market classes based on the laboratory studies conducted. However differences in newly eclosed larval survival and development were found between tissue types and market classes in laboratory studies. In the laboratory studies, adzuki bean had the least risk for WBC damage based on the markedly lower survival observed on both flower and pod tissue. Based on pod tissue survival, light red kidney bean appeared to have the greatest risk for damage by WBC, followed by navy bean and adzuki.

Survival on pod tissue was low overall in the trial, which was likely due to larvae being placed on this tissue immediately after hatch. Newly eclosed larvae were used however, so that direct comparison between tissues could occur.

Very low egg laying was observed in both the field dry bean and alternate host oviposition studies, though egg mass densities were high in the surrounding corn field. From this, it appears that corn is preferred for oviposition sites over dry beans, and that bean fields that

106 border corn fields may be at a lower risk for WBC damage. Another possibility, though not examined in these studies, would be the presence of biotypes within this species; one preferring corn, and the other dry beans. This may help to explain why damage is seen in corn in Ontario, but rarely in dry beans.

Due to the lack of oviposition in the field trials, no conclusions could be made with regards to whether WBC moths would oviposit on crops aside from corn and dry beans.

Examining oviposition on dry bean in the laboratory, no preference among market classes were seen, though egg laying in the trial was low.

Limitations to the studies include the use of newly eclosed larvae in the laboratory studies, which may have impacted survival on pod tissue. In addition, only three market classes were used, and the study was not repeated in the field. With the oviposition studies, the main limitations were the low level of oviposition that occurred in the laboratory and field studies, as well as the single plant plots, which may have been less desirable for oviposition.

Additional studies with a higher number of moths are recommended to examine oviposition preference further in the laboratory. Increasing the number of moths in each cage would likely increase the chances for oviposition, and could result in a greater egg mass density.

Caged field oviposition studies with virgin moths are also recommended, as the oviposition field trials that were conducted relied on natural moth populations. Examining larval survival and feeding of third instars on pod tissue from different dry bean market classes is also recommended, as this would give a more realistic representation of the damage that could be caused by WBC in the field.

107

5.2 Insecticide Timing and Efficacy

Lambda-cyhalothrin, chlorantraniliprole, thiamethoxam, methoxyfenozide, and spinetoram were all shown to reduce WBC damage in the dry bean insecticide efficacy trial, while dimethoate was not. Efficacy with this product would have been beneficial, as it is registered for control of a number of dry bean pests and may have allowed control of more than one pest with one application. With the insecticide timing trials in dry and snap beans, pod damage throughout the season was low, although all active ingredients reduced WBC feeding damage, and the best application time with the dry bean trial was found to be 4 – 18 DAH50.

However, based on the return on investment calculated in the dry bean insecticide timing study an insecticide application was not found to have an economic benefit in this study.

The main limitation to the insecticide efficacy and timing trials was the low larval survival that occurred in the field, resulting in limited damage and a lack of economic differences between treatments. An additional limitation was that trials were only conducted on one market class (navy) and need to be examined on multiple market classes, as the larval survival study showed differing survival percentages between the three market classes examined.

Future research should examine the active ingredients used in the insecticide efficacy and timing trials, as well as additional active ingredients, at higher pest densities, on multiple market classes, and, if possible, with naturally infested fields.

5.3 Pheromone Trap Monitoring and Damage Assessment

Male WBC moth populations were monitored in 2011 – 2013, and the highest moth counts were generally experienced within 20 km of the Lake Huron shoreline, and on fine and coarse textured sites. Flight estimates based on GDD accumulations from Nebraska were not

108 found to accurately explain moth flight in Ontario at either a May 1st or January 1st start date for

GDD accumulation. Flight occurred earlier than predicted with 25, 50, and 75% moth emergence, and to accurately predict moth emergence in Ontario, a differing model is needed. In seed samples from commercial fields, several market classes (light red kidney, dark red kidney, otebo, and black bean) had a higher percentage of samples with damage. Based on the results obtained, close monitoring of these market classes should occur, though economic damage is unlikely based on the level of damage found in samples.

One of the limitations of these studies is that traps were placed primarily in Huron

County and monitoring of populations for all of southern Ontario did not occur. Trap site soil textures were also determined from county soil maps, rather than soil samples taken when traps were set up. No relationship can be drawn between soil type and emergence however, as the soil types at the trap sites would have been where the moths were captured in-flight. Though WBC emergence is thought to be higher in coarse textured soils (Tooker and Fleisher 2010), it is unlikely that moths are choosing their egg laying sites based on this criteria. With the commercial bean sample analysis, the main limitations were that monitoring of damage did not include all market classes, and samples were representative of only one elevator.

Future research should examine damage to dry bean fields in the immediate vicinity of each WBC pheromone trap, as it would allow direct comparison between trap counts and field damage to determine the appropriateness of current trap thresholds. Monitoring should also occur over a larger area to better understand the areas at greater risk.

109

5.4 Recommendations and Conclusions

Based on the studies conducted at the current population of WBC in Ontario, insecticide application for control of WBC on dry beans does not have an economic benefit. However dry bean fields should be monitored closely in the coming years, as populations may increase and begin causing economic damage. Should this occur, this study presented multiple active ingredients capable of reducing WBC damage in dry beans, and in the laboratory showed that not all market classes are at an equal risk for damage. Further research is recommended to examine oviposition in the field as well as to compare trap captures to adjacent field damage, so that a more complete understanding of the risk WBC poses to the dry bean industry in Ontario can be determined.

110

References

Agricorp. 2012. Average crop insurance values for dry bean market classes in Ontario.

Agricorp, Guelph, ON.

Agriculture and Agrifood Canada (AAFC). 2010. Overview of the Canadian Pulse Industry

2009. No. 10578E.

Antonelli, A. L. 1974. Resistance of Phaseolus vulgaris cultivars to western bean cutworm,

Loxagrotis albicosta (Smith), with notes on the bionomics and culture of the cutworm.

Ph.D. dissertation, University of Idaho, Idaho.

Appel, L. L., R. J. Wright, and J. B. Campbell. 1993. Economic injury levels for western bean

cutworm Loxagrotis albicosta (Smith) (Lepidoptera: Noctuidae), eggs and larvae in field

corn. J. Kans. Entomol. Soc. 66: 434-438.

Barigossi, J. A. F., G. L. Hein, and L. G. Higley. 2003. Economic injury levels and sequential

sampling plans for Mexican bean beetle (Coleoptera: Coccinellidae) on dry beans. J.

Econ. Entomol. 96: 1106-1167.

Baute, T. 2009. Current distribution of western bean cutworm in the Great Lakes Region.

CropPest Ontario. 14: 7-8.

Baute, T. 2011. Western bean cutworm management strategy for field corn. Available [Online].

www.cornpest.ca/index.cfm/wbc-trap-network/wbc-scouting-and-training-material-a

presentations/western-bean-cutworm-management-strategy-for-corn/

Baute, T., and G. Stewart. 2011. Scout corn ears for western bean cutworm damage. Crop Talk.

11(3): 5-6.

111

Belay, D. K., R. M. Huckaba, and J. E. Foster. 2012. Susceptibility of the fall armyworm

(Spodoptera frugiperda) (Lepidoptera: Noctuidae), at Santa Isabel, Puerto, Rico, to

different insecticides. Fla. Entomol. 95: 476 – 478.

Blackshaw, R. E., and G. Saindon. 1996. Dry bean (Phaseolus vulgaris) tolerance to

imazethapyr. Can. J. Plant Sci. 76:915-919.

Blickenstaff, C. C. 1979. History and biology of the western bean cutworm in southern Idaho,

1942-1977. University of Idaho Agricultural Experiment Station Bulletin 592, Moscow,

Idaho.

Blickenstaff, C. C. 1983. Dispersal of western bean cutworm larvae from egg masses as

measured by damage to beans. J. Environ. Entomol. 12: 902-904.

Blickenstaff, C. C., H. H. Homan, and A. L. Antoneilli. 1975. The western bean cutworm on

beans and corn. Current Information Series No. 302. University of Idaho, College of

Agriculture Cooperative Extension Service.

Blickenstaff, C. C., and P. M. Jolley. 1982. Host plants of the western bean cutworm. Environ.

Entomol. 11:421-425.

Brady, N. C. and R. R. Weil. 1999. The Nature and Properties of Soils, 12th ed. pp. 125-126.

Prentice Hall, Upper Saddle River, NJ.

Brickle, D. S., S. G. Turnipseed, and M. J. Sullivan. 2001. Efficacy of insecticides of different

chemicals against Helicoverpa zea (Lepidoptera: Noctuidae) in transgenic Bacillus

thuringiensis and conventional cotton. J. Econ. Entomol. 94:86-92.

Canadian Grains Commission. 2014. Beans – Chapter 19 official grain grading guide.

Available [Online] http://www.grainscanada.gc.ca/oggg-gocg/19/oggg-gocg-19e-

eng.htm. April 24th, 2014.

112

Cantangui, M. A., and R. K. Berg. 2006. Western bean cutworm, Striacosta albicosta (Smith)

(Lepidoptera: Noctuidae) as a potential pest of transgenic Cry1Ab Bacillus thuringiensis

corn hybrids in South Dakota. J. Environ Entomol. 35: 1439 – 1452.

Capinera, J. L. 2001. Handbook of Vegetable Pests. Academic Press, San Diego, CA.

Cassa, C. A., K. Iancu, K. L. Olson, and K. D. Mandl. 2005. A software tool for creating

simulated outbreaks to benchmark surveillance systems. BMC Med. Inform. Decis. 5: 1 –

Cerna, J. and J. S. Beaver. 1990. Inheritance of early maturity of indeterminate dry bean. Crop

Sci. 30: 1215-1218.

Chludzinski, M. M. 2013. Biology and management of western bean cutworm (Striacosta

albicosta Smith) in Michigan dry beans (Phaseolus vulgaris L.). M.S. thesis, Michigan

State University, Michigan.

Cook, K. A. 2004. Western bean cutworm (Loxagrotis albicosta Smith). Available [Online]

http://ipm.illinois.edu/vegetables/insects/western_bean_cutworm.pdf. September 19th

2013.

Cordova, D., E. A. Benner, M. D. Sacher, J. J. Rauh, J. S. Sopa, G. P. Lahm, T. P. Selby, T.

M. Stevenson, L. Flexner, S. Gutteridge, D. F. Rohades, L. Wu, R. M. Smith, and Y.

Tao. 2006. Anthranilic diamides: a new class of insecticides with a novel mode of action,

ryanodine receptor activation. Pestic. Biochem. Phys. 84:196-214.

Crumb, S. E. 1956. The larvae of Phalaenidae. U.S. Department of Agriculture Technical

Bulletin No. 1135.

113

Cullen, E. and J. Jyotika. 2008. Western bean cutworm: a pest of field and sweet corn (A3856).

University of Wisconsin-System Board of Reagents and University of Wisconsin-

extension, Cooperative Extension.

Davidson, S., T. Randolph, J. Rudolph, and F. Peairs. 2006. 2005 Colorado field crop

management research and demonstration trials. Technical Report Agricultural

Experiment Station. p.12.

Davies, T. G. E., L. M. Field, P. N. R. Usherwood, and M. S. Williamson. 2007. Critical

review of DDT, pyrethrins, pyrethroids and insect sodium channels. IUBMB Life. 59:

151-162.

Debouck, D. 1991. Systematics and morphology, pp. 55-118. In A. van Schoonhoven and O.

Voysest (eds.), Common Beans: Research for Crop Improvement. C.A.B International,

Oxon, UK.

DiFonzo, C. D., and R. Hammond. 2008. Range expansion of the western bean cutworm,

Striacosta albicosta (Noctuidae) into Michigan and Ohio. Crop Management. Online.

doi: 10.1094/CM-2008-0519-01BR.

Dorhout, D. L. and M. E. Rice. 2008. An evaluation of western bean cutworm pheromone

trapping techniques (Lepidoptera: noctuidae) in a corn and soybean agroecosystem. J.

Econ. Entomol. 101:404-408.

Dorhout, D. L., and M. E. Rice. 2010. Intraguild competition and enhanced survival of western

bean cutworm (Lepidoptera: Noctuidae) on transgenic Cry1ab (MON810) Bacillus

thuringiensis corn. J. Econ. Entomol. 103:54-62.

Douglass, J. R., J. W. Ingram, K. E. Gibson, and W. E. Peay. 1957. The western bean

cutworm as a pest of corn in Idaho. J. Econ. Entomol. 50: 543-545.

114

Dyer, J. M., T. W. Sappington, and B. S. Coates. 2013. Evaluation of tolerance to Bacillus

thuringiensis toxins among laboratory-reared western bean cutworm (Lepidoptera:

Noctuidae). J. Econ. Entomol. 100: 2467-2472.

Eichenseer, H., R. Strohbehn, and J. Burks. 2008. Frequency and severity of western bean

cutworm (Lepidoptera: Noctuidae) ear damage in transgenic corn hybrids expressing

different Bacillus thuringiensis cry toxins. J. Econ. Entomol. 101: 555-563.

Fernandez-Cornejo, J., and M. Caswell. 2006. The first decade of genetically engineered crops

in the United States. United States department of Agriculture Economic Information

Bulletin Number 11.

FAOSTAT. 2012. FAOSTAT – Production and Trade. Food and Agriculture Organization of

the United Nations, Rome, Italy.

FAOSTAT. 2013. FAOSTAT - Trade. Food and Agriculture Organization of the United

Nations, Rome, Italy

Fukuto, T. R. 1990. Mechanism of action of organophosphorous and carbamate insecticides.

Environ. Health Persp. 87:245-254.

Gehan, Y. A. and E. F. Abdalla. 2006. Evaluation of some selected pesticides against the two

pod borers Helicoverpa armigera and Etiella zinckenella population infesting cowpea in

the newly reclaimed regions. Res. J. Agric. Biol. Sci. 2: 578 – 583.

Gepts, P. 1998. Origin and evolution of common bean: past events and recent trends.

HortScience. 33: 1124 – 1130.

Gepts, P. and D. Debouck. 1991. Origin, domestication, and evolution of the common bean

(Phaseolus vulgaris L). In van Schoonhoven, A., and O Voysest Common beans:

Research for crop improvement. CAB International, Oxon: UK.

115

Gillard C. L., N. K. Ranatunga, and R. L. Conner. 2012. The control of dry bean anthracnose

through seed treatment and the correct application timing of foliar fungicides. Crop

Protection. 37: 81-90.

Girolami, V., L. Mazzon, A. Squartini, N. Moir, M. Marzaro, A. Di Bernardo, M. Greatti,

C. Giorio, and A. Tapparo. 2009. Translocation of neonicotinoid insecticides from

coated seeds to seedling guttation drops; a novel way of intoxication for bees. J. Econ.

Entomol. 102: 1808 – 1815.

Government of Canada. 2014. Ontario –weather conditions and forecast by locations.

Available [Online]. https://weather.gc.ca/forecast/canada/index_e.html?id=ON.

Gross, H. R., and J. E. Carpenter. 1991. Role of the fall armyworm (Lepidoptera: Noctuidae)

pheromone and other factors in the capture of bumblebees (Hymenoptera: Aphidae) by

universal moth traps. J. Environ. Entomol. 20: 377 – 381.

Hagen, A. F. 1963. Evaluation of populations and control of the western bean cutworm in field

beans in Nebraska. . J. Econ. Entomol. 56:222-224.

Hagen, A. F., and R. E. Roselle. 1966. Entomology – Western bean cutworm in Nebraska and

its control. University of Nebraska Extension Services. 66:1508.

Hagerty, T. P., and M. S. Kingston. 1992. The soils of Middlesex county. Ontario Ministry of

Agriculture and Food.

Han, S. C. C. K. Shum, C. Jekeli, C. Y. Kuo, C. Wilson, and K. W. Seo. 2005. Non-isotropic

filtering of GRACE temporal gravity for geophysical signal enhancement. Geophys. J.

Int. 163: 18 – 25.

116

Hardke, J. T., J. H. Temple, B. R. Leonard, and R. E. Jackson. 2011. Laboratory toxicity and

field efficacy of selected insecticides against fall armyworm (Lepidoptera: Noctuidae).

Fla. Entomol. 94: 272-278.

Hart. J. P. 2008. Evolving the three sisters: the changing story of maize, bean, and squash in

New York and the greater northeast, pp. 87-99. In J.P. Hart (ed.), Current Northeast

Paleoethnobotany II. University of the State of New York, State Education Dept, USA.

Hart, J. P., D. L. Asch, C. M. Scarry, and G. W. Crawford. 2001. The age of the common

bean (Phaseolus vulgaris L.) in the northern eastern woodlands of North America.

Antiquity. 76: 377-385.

Hendrix, W. H., and W. B. Showers. 1992. Tracing black cutworm and armyworm

(Lepidoptera: Noctuidae) northward migration using Pithecellobium and Calliandra

pollen. J. Environ. Entomol. 21: 1092-1096.

Hess, M., G. Barralis, H. Bleiholder, L. Buhrs, T. H. Eggers, H. Hack, and R. Strauss. 1997.

Use of the extended BBCH scale – general for the descriptions of the growth stages of

mono- and dicotyledenous weed species. Weed Res. 37: 433-441.

Hoerner, J. 1948. The cutworm Loxagrotis albicosta on beans. J. Econ. Entomol. 41:631-635.

Hoffman, D. W., and N. R. Richards. 1952. Soil survey of Perth county. No. 15. Experimental

Farms Service, Canada Department of Agriculture and the Ontario Agricultural College.

Hoffman, D. W., N. R. Richards, and F. F. Morwick. 1952. Soil survey of Huron county.

No.13. Experimental Farms Service, Canada Department of Agriculture and the Ontario

Agricultural College.

117

Hohmann, C. L., A. M. Meneguim, and L. Lovato. 2011. Bioecological aspects of Hypocala

andremona (Cramer) (Lepidoptera: Noctuidae) on persimmon cultivars. Acta Sci., Agron.

33: 33-35.

Holtzer, T. O. 1983. Distribution of western bean cutworm eggs among short-, mid-, and long-

season corn hybrids planted on different dates. Environ. Entomol. 12: 1375-1379.

Hutchison, W. D., T. E. Hunt, G. L. Hein, K. L. Steffey, C. D. Pilcher, and M. E. Rice. 2011.

Genetically engineered Bt corn and range expansion of the western bean cutworm

(Lepidoptera: Noctuidae) in the United States: a response to Greenpeace Germany. J.

Integ. Pest Mngmt. 2:1-8.

Ibarra-Perez, F., B. Ehdaie, and J. G. Waines. 1997. Estimation of outcrossing rate in

common bean. Crop Sci. 37: 60-65.

Jewett, M., C. D. DiFonzo, F. Springborn, and G. Varner. 2009. Western bean cutworm in

dry bean-insecticide trial. Available [Online]

http://msuent.com/files/FinalReportWBCInsecticide09.pdf. September 14th, 2013.

Jones, M. M., J. L. Robertson, and R. A. Weinzierl. 2012. Toxicity of thiamethoxam and mixtures of chlorantraniliprole plus acetamiprid, esfenvalerate, or thiamethoxam to neonates of oriental fruit moth (Lepidoptera: Tortricidae). J. Econ. Entomol. 105: 1426-1431.

Jost, D. J., and H. N. Pitre. 2002. Soybean looper (Lepidoptera: Noctuidae) oviposition on

cotton and soybean of different growth stages: Influence of olfactory stimuli. J. Econ.

Entomol. 95: 286-293.

Kelly, J. D. 2000. Remaking bean plant architecture for efficient production. Adv. Agron. 71:

109-143.

118

Klass, C., and A. A Muka. 2012. Mexican Bean Beetle. Available [Online]

http://idl.entomology.cornell.edu/files/2013/11/Mexican-Bean-Beetle-21q0nah.pdf. June

9th 2014.

Knight, K. M. M., H. B. Brier, M. J. Lucy, and R. A. Kopittke. 2007. Impact of mired

(Creontiades spp.) (Hemiptera: Miridae) pest management on Helicoverpa spp.

(Lepidoptera: Noctuidae) outbreaks: the case for conserving natural enemies. Pest Manag.

Sci. 63: 447-452.

Knodel. J. J., and A. M Agnello. 1990. Field comparison of nonsticky and sticky pheromone

traps for monitoring fruit pests in western New York. J. Econ. Entomol. 83: 197 – 204.

Lafontaine, J. D. 2004. The moths of North America including Greenland. Fascicle 27.1

Noctuoidea, Noctuidae (part), Noctuinae (part-Agrotini). E. W. Classey Ltd., London,

United Kingdom. pp. 68-70, 268, 299.

Laurent, P., and B. Frérot. 2007. Monitoring of European corn borer with pheromone-baited

traps: review of trapping system basics and remaining problems. J. Econ. Entomol. 100:

1797-1807.

Littell, R. C. G. A. Milliken, W. W. Stroup, R. D. Wolfinger, and O. Schabenberger. 2006.

SAS® for mixed models, 2nd ed. SAS Institute Inc, Cary, NC

Mahrt, G. G., R. L. Stoltz, C. C. Blickenstaff, and T. O. Holtzer. 1987. Comparisons between

blacklight and pheromone traps for monitoring the western bean cutworm (Lepidoptera:

Noctuidae) in south central Idaho. J. Econ. Entomol. 80: 242-247.

Maienfisch, P., M. Angst, F. Brandl, W. Fischer, D. Hofer, H. Kayser, W. Kobel, A.

Rindlibacher, R. Sann, A. Steinemann, and H. Widmer. 2001. Chemistry and biology

of Thiamethoxam: a second generation neonicotinoid. Pest Manag. Sci. 57:906-913.

119

Mamidi, S., M. Rossi, D. Annam, S. Moghaddam, R. Lee, R. Papa, and P. McClean. 2011.

Investigation of the domestication of common bean (Phaseolus vulgaris) using

multilocus sequence data. Funct. Plant Biol. 38: 953-967.

Matthews, B. C., N. R. Richards, and R. E. Wicklund. 1957. Soil survey of Lambton county.

No. 22. Experimental Farms Service, Canada Department of Agriculture.

McDunnough, J. H. 1928. A generic revision of North American Agrotid moths. National

Museum of Canada, Bulletin 55 (Biological Series 16) pp. 27-28.

Michel, A. P., C. Krupke, T. Baute, and C. Difonzo. 2010. Ecology and Management of the

western Bean Cutworm (Lepidoptera: Noctuidae) in Corn. J. Integ. Pest Mngmt. 1:1-10.

Miller, N. J., D. L. Dorhout, M. E. Rice, and T. W. Sappington. 2009. Mitochondrial DNA

variation and range expansion in the western bean cutworm (Lepidoptera: Noctuidae): No

evidence for a recent population bottleneck. J. Environ. Entomol. 38:274-280.

Moulton, J. K., D. A. Pepper, R. K. Jansson, and T. J. Dennehy. 2002. Pro-active

management of beet armyworm (Lepidoptera: Noctuidae) resistance to tebufenozide and

methoxyfenozide: baseline monitoring, risk assessment, and isolation of resistance. J.

Econ. Entomol. 95: 414-424.

Murray, D. A. H., R. J. Lloyd, and J. E. Hopkinson. 2005. Efficacy of new insecticides for

management of Helicoverpa spp. (Lepidoptera: Noctuidae) in Australian grain crops.

Aust. J. Entomol. 44: 62-67.

Murúa, M. G., M. T. Vera, S. Abraham, M. L. Juaréz, S. Prieto, G. P. Head, and E.

Willink. 2008. Fitness and mating compatibility of Spodoptera frugiperda (Lepidoptera:

Noctuidae) populations from different host plant species and regions in Argentina. Ann.

Entomol. Soc. Am. 101: 639-649.

120

Myers, J. R. and J. R. Baggett. 1999. Improvement of snap bean p. 289-329. In Singh, S.P.

(ed.) Common bean improvement in the twenty-first century, Dordrecht: Kluwer.

Nakamura, R. R. 1986. Maternal investment and fruit abortion in Phaseolus vulgaris. Am. J.

Bot. 73: 1049-1057.

Nauen, R., U. Ebbinghaus-Kintscher, V. Salgado, and M. Kaussmann. 2003. Thiamethoxam

is a neonicotinoid precursor converted to clothianidin in insects and plants. Pest.

Biochem. Phys. 76: 55-69.

Nault, B. A., A. G. Taylor, M. Urwiler, T. Rabaey, and W. D. Hutchison. 2004.

Neonicotinoid seed treatments for managing potato leafhopper infestations in snap bean.

Crop Prot. 23:147-154.

Ngollo, E. D., E. Groden, J. F. Dill, and D. T. Handley. 2000. Monitoring of the European

corn borer (Lepidoptera: Crambidae) in central Maine. J. Econ. Entomol. 93: 256-263.

Nichols, N. N., N. Sutivisedsak, B. S. Dien, A. Biswas, W. C. Lesch, and M. A. Cotta. 2011.

Conversion of starch from dry common beans (Phaseolus vulgaris L.) to ethanol. Ind.

Crop Prod. 33: 644-647.

Ontario Ministry of Agriculture and Food (OMAF). 2014. Publication 812: Field crop

protection guide. Queen’s Printer for Ontario, 2014, Toronto, Canada.

Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA). 2009. OMAFRA

Publication 811: Agronomy guide for field crops. Queen’s Printer for Ontario, 2009,

Toronto, Canada.

Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA). 2011. Estimated area,

yield, production and farm value of specified field crops, Ontario, 2001-2012 (Metric

Units). Available [Online]

121

http://www.omafra.gov.on.ca/english/stats/crops/estimate_metric.htm. February 22nd

2013.

Ontario Ministry of Agriculture Food and Rural Affairs (OMAFRA). 2013. Table 8. Survey

of custom farmwork rates charged in 2012. Available [Online]

http://www.omafra.gov.on.ca/english/busdev/2012customratesa1.htm. March 10th 2014.

Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA). 2014. Beans (green

and wax): Area, production, farm value, price and yield, Ontario 1979 – 2013. Available

[Online] http://www.omafra.gov.on.ca/english/stats/hort/beans.htm. February 23rd 2014.

O’Rourke, P. K., and W. D. Hutchison. 2000. First report of the western bean cutworm, Richia

albicosta (Smith) (Lepidoptera: Noctuidae) in Minnesota corn. J. Agr. Urban Entomol.

17: 213-217.

Palaniswamy, P., B. Galka, and B. Timlick. 1990. Phenology and infestation level of the

European corn borer Ostrinia nubilalis (Hübner) (Lepidoptera: Pyralidae), in southern

Manitoba. Can. Entomol. 122: 1211-1220.

Paula-Moraes, S. V., T. E. Hunt, R. J. Wright, G. L. Hein, and E. E. Blankenship. 2012.

On-plant movement and feeding of western bean cutworm (Lepidoptera: Noctuidae) early

instars on corn. J. Environ. Entomol. 41: 1494-1500.

Paula-Moraes, S., T. E. Hunt, R. J. Wright, G. L. Hein, and E. E. Blankenship. 2013.

Western bean cutworm survival and the development of economic injury levels and

economic thresholds in field corn. J. Econ. Entomol. 106(3): 1274-1285.

Pratap, A., J. Kumar. 2011. Biology and Breeding of Food Legumes. p. 267. CAB

International, Oxfordshire: UK.

122

Purdue University Field Crops IPM. 2009. Western bean cutworm Striacosta albicosta

(Smith). Available [Online]

http://extension.entm.purdue.edu/fieldcropsipm/insects/western-bean-cutworm.php.

March 7th 2013.

Reardon, B. J., D.V. Sumerford, and T. W. Sappington. 2006. Impact of trap design,

windbreaks, and weather on captures of European corn borer (Lepidoptera: Crambidae) in

pheromone-baited traps. J. Econ. Entomol. 99: 2002 – 2006.

Rice, M. E. 2007. Western Bean Cutworm and the Invasion of Illinois Corn: It's Like Deja vu

All Over Again. In Unknown (ed.), Illinois Crop Protection Technology Conference

Proceedings, Illinois, USA, 3J January – 4 January 2007, pp.78-83.

Rice, M. E., D. Dorhout, and R. Pope. 2004. Eastern movement of the western bean cutworm.

In Unknown (ed.). Proceedings of the 2004 Integrated Crop Management Conference,

Iowa State University, Ames, Iowa, 1 December – 2 December 2004, pp.81-84.

Schaafsma, A. W., C. Cardona, J. L. Kornegay, A. M. Wylde, and T. E. Michaels. 1998.

Resistance of common bean lines to the potato leaf hopper (Homoptera: Cicadellidae). J.

Econ. Entomol. 91: 981-986.

Seymour, R. C., G. L. Hein, R. J. Wright, and J. B. Campbell. 2004. Western bean cutworm

in corn and dry beans. Neb. Coop. Ext. Guide G1359. Lincoln, NE.

Shamshiri, R. and W. I. W. Ismail. 2012. Exploring GPS data for operational analysis of farm

machinery. Res. J. Appl. Sci. Eng. Technol. 5(12): 3281-3286.

Showers, W. B., R. B. Smelser, A. J. Keaster, F. Whitford, J. F. Robinson, J. D. Lopez, and

S. E. Taylor. 1989. Recapture of marked black cutworm (Lepidoptera: Noctuidae)

males after long-range transport. Environ. Entomol. 18: 447-458.

123

Smith, J. B. 1887. North American Noctuidae. Proceedings of the United States National

Museum. 10:454.

Soltani, N., C. Shropshire, and P. H. Sikkema. 2010. Tolerance of black, cranberry, kidney,

and white bean to cloransulam-methyl. Weed Biol. Manag. 10: 33-39.

Soltani, N., R. E. Nurse, D. E. Robinson, and P. H. Sikkema. 2008. Response of pinto and

small red Mexican bean to postemergence herbicides. Weed Technol. 22:195-199.

Spurlock, F., and M. Lee. 2008. Synthetic pyrethroids use patterns, and properties and

environmental effects, In J. Gan, F. Spurlock, P. Hendley, and D. Watson (eds.) Synthetic

Pyrethroids Occurrence and Behaviours in Aquatic Environments, American Chemical

Society, Washington: DC. pp. 3-25.

Statistics Canada. 2013. Table 001-0010 - Estimated area, yield, production, average farm price

and total farm value of selected principal field crops: dry beans (white and coloured), in

metric units, annual (table), CANSIM (database) 2008-2011. Available [Online]

www5.statcan.gc.ca/cansim/a26?lang=eng&retrLang=eng&id=0010010&pttern=Dry+be

ans&tabMode=dataTable&srchLan=-1&p1=1&p2=-1. September 27th, 2013.

Stewart, C. L., R. E. Nurse, C. Gillard, and P. H. Sikkema. 2010. Tolerance of adzuki bean to

preplant-incorporated, pre-emergence, and post-emergence herbicides in Ontario,

Canada. Weed Biol. Manag. 10: 40-47.

Toda, M. J., and R. L. Kitching. 2002. Forest ecosystems. In N.E. Stork and T. Nakashizuka

Biodiversity Research Methods IBOY in western Pacific and Asia, Kyoto University

Press, Kyoto Japan, and Trans Pacific Press, Victoria, Australia. pp 27-109.

124

Tooker, J. F., and S. J. Fleischer. 2010. First report of western bean cutworm (Striacosta

albicosta) in Pennsylvania. Crop Management. Online. doi: 10.1094/CM-2010-0616-01-

RS.

Trueman, C. L. 2013. Field evaluation of products for management of European corn borer,

corn earworm, and western bean cutworm in sweet corn, 2013. 2013 Pest Management

Research Report – 2013 Growing Season. Agriculture and Agri-Food Canada – February

2014. Report no. 1. Vol 52: 1-2.

Vijverberg, H. P. M., J. M. van der Zalm, and J. van den Bercken. 1982. Similar mode of

action of pyrethroids and DDT on sodium channel gating in myelinated nerves. Nature.

295:601-603.

Volenberg, D. S. 2011. A multi-tactic approach to managing western bean cutworm. In

Unknown (ed.) Proceedings of the 2011 Wisconsin Crop Management Conference,

Wisconsin, USA, 11 January – 13 January 2011, pp. 152-156.

Voysest, O. and M. Dessert. 1991. Bean cultivars: classes and commercial seed types. In van

schoonhoven, A. and O. Voysest Common beans: research for crop improvement, CAB

International, Oxon: UK.

Walter, S. M., F. B. Peairs, and S. D. Pilcher. 1999. 1998 Colorado field crop insect

management research and demonstration trials. Colorado Agricultural Experiment

Station. Colorado State University Cooperative Extension

Westelaken, I. L., and M. A. Maun. 1985. Spatial pattern and seed dispersal of Lithospermum

caroliniense on Lake Huron sand dunes. Can. J. Bot. 63: 125-132.

Wicklund, R. E., and N. R. Richards. 1961. The soil survey of Oxford county. No. 28.

Research Branch, Canada Department of Agriculture.

125

Wilson, E. A. 1994. Soil maps of Kent County. Resources and Regulations Branch, Ontario

Ministry of Agriculture, Food and Rural Affairs.

126