2011 Beaumont Site Visit: Mexican Rice Borer and Sugarcane Borer

Beaumont Site Visit: Mexican Rice Borer and Sugarcane Borer Sugarcane and Rice Research

Project Investigators: Gene Reagan, LSU AgCenter M.O. Way, Texas A&M AgriLife Research

Post-Doctoral Researcher: Julien Beuzelin

Research Associate: Blake Wilson

Graduate Assistant: Matt VanWeelden

Cooperators: Texas A&M AgriLife Research & Extension Ctr., Beaumont Ted Wilson, Professor and Center Director Lee Tarpley, Associate Professor Yubin Yang, Senior Systems Analyst Fugen Dou, Assistant Professor Mark Nunez and Rebecca Pearson, Research Associates USDA ARS Bill White, Research Scientist (Sugarcane Research Station at Houma, LA) Allan Showler, Research Scientist (Kika de la Garza Research Station at Weslaco, TX) LSU AgCenter Natalie Hummel, Associate Professor, Extension Entomology Louisiana Dept. of Agriculture and Forestry Tad Hardy, State Entomologist American Sugarcane League Rio Grande Valley Sugar Growers, Inc.

28 September, 2011

This work has been supported by grants from the USDA NIFA, Southern Region IPM, Crops at Risk IPM, NRI AFRI Sustainable Bioenergy, and US EPA Strategic Agricultural Initiative programs. We also thank the Texas Rice Research Foundation, the American Sugar Cane League and Rio Grande Valley Sugar Growers Inc, participating Agricultural Chemical Companies, the Texas Department of Agriculture and the Louisiana Department of Agriculture and Forestry for their support. Comparison of Stem Borers Attacking Sugarcane and Rice

(a) Adult female sugarcane borer (b) Sugarcane borer larva

(e) Adult female rice stalk borer (f) Rice stalk borer larva

Photos: (a) B. Castro; (b) J. Saichuk; (c) F. Reay-Jones; (d)(e)(f) A. Mészáros

2 TABLE OF CONTENTS

Comparison of Stem Borers Attacking Sugarcane and Rice ...... 2 Table of Contents ...... 3 Field Research Site Visit Announcement ...... 4 Ten Years of Stem Borer Research Collaboration on Sugarcane and Rice ...... 5 Monitoring Mexican Rice Borer Movement: Range Expansion into Louisiana ...... 7 Evaluation of Commercial and Experimental Sugarcane Cultivars for Resistance to the Mexican Rice Borer, Beaumont, TX, 2010 and 2011 ...... 9 Feeding Behavior and Duration of Exposure of Mexican Rice Borer Larvae on Sugarcane ...... 12 Red Imported Fire Ant Predation on Mexican Rice Borer in Sugarcane at Beaumont, TX in 2011 ...... 13 Pheromone Trap Assisted Scouting and Aerial Insecticidal Control of the Mexican Rice Borer, 2009 and 2010 ...... 14 Comparison of Mexican Rice Borer Pest Pressure in Bioenergy and Conventional Sugarcane ...... 16 Small Plot Assessment of Insecticides Against the Sugarcane Borer, 2011 ...... 18 Field Assessment of Novaluron for Sugarcane Borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), Management in Louisiana Sugarcane ...... 19 Seasonal Infestations of Two Stem Borers (Lepidoptera: Crambidae) in Non-Crop Grasses of Gulf Coast Rice Agroecosystems ...... 28 Harvest Cutting Height and Ratoon Crop Effects on Stem Borer Infestations in Rice ...... 43 Trapping for Mexican Rice Borer in the Texas Rice Belt, 2010 ...... 45 Rice Insecticide Evaluation Studies ...... 46 Beaumont Sugarcane and Energycane Variety Test, 2010 ...... 50 Beaumont Sugarcane and Energycane Variety Test, 2011 ...... 51 Example Data Sheet ...... 52

3 2011 Field Research Site Visit Announcement

To: Louisiana and Texas Sugarcane and Rice Consultants, Agricultural Extension Agents, and Industry Cooperators

From: Gene Reagan and Mo Way LSU AgCenter and Texas A&M Entomologists

Re: Texas AgriLife Research and Extension Center at Beaumont Mexican Rice Borer and Sugarcane Borer Field Research Observations

LOCATION Please do not take any live insects from this location! Texas AgriLife Research andITINERARY Extension Center at Beaumont 1509 Aggie Drive, Beaumont, TX 77713

Tuesday, 27 September – 6:15 pm Meet in lobby of Holiday Inn and Suites to go to dinner probably at Papadeaux’s (optional)

Wednesday, 28 September – 8:00 am Meet in front of Texas AgriLife Research and Extension Center: - Dr. Ted Wilson (Center Director): Welcome and introduction - Dr. Gene Reagan: Overview of planned activities, handouts, and instructions to go to the field

ACTIVITIES 1. Tad Hardy (LA State Entomologist): Review of LA Dept. Ag & Forestry MRB pheromone trap monitoring 2. Dr. Bill White: Variety diversity in the test 3. Dr. Gene Reagan, Dr. Julien Beuzelin, and Mr. Blake Wilson: Hands-on sampling for Mexican rice borer ( MRB) and sugarcane borer (SCB) injury in sugarcane varieties 4. Observe MRB and SCB larvae in replicated test of LA sugarcane varieties (HoCP 08-726, Ho 08-711, L 08-092, HoCP 91-552, L 07-57,Ho 08-706, Ho 08-717, L 79-1002, Ho 02-113, HoCP 04-838, L 08-090, HoL 08-723, Ho 08-709, HoCP 00-950, Ho 07-613, L 08-088, L08-075, HoCP 85-845, Ho 05-961) 5. Mr. Blake Wilson: Use of MRB pheromone traps to help with scouting. 6. Dr. Julien Beuzelin and Mr. Matt VanWeelden: Multi-crop bioenergy research. 7. Dr. Mo Way: Observe MRB and SCB damage and discuss insecticides and cultural practices in rice or visit demonstration of sugarcane stalk splitter machine (Gene Reagan).

Wednesday, 28 September – 11:00 am Sun grant/Chevron/Beaumont energy cane and high biomass sorghum research near main building, Texas AgriLife Research and Center at Beaumont, 1509 Aggie Dr., approx. 9 miles west of Beaumont on Hwy 90.

Wednesday, 28 September – Noon Adjourn and return home

RESERVATION AND HOTEL INFORMATION

For hotel reservations call 409-842-5995 Any time prior to Tuesday, 20 September Reservation Code: LSU Entomology HOTEL ADDRESS: You may reserve rooms with Samantha by email at: Holiday Inn and Suites [email protected] 3950 I-10 South $79.00 + tax reduced rate, Breakfast buffet (6:00 AM) included Beaumont, TX 77705 409-842-7822 (hotel) 409-842-7810 (fax)

DIRECTIONS TO RESEARCH SITE: 9.5 miles west of Beaumont on Hwy 90, ~ 1 mile north on Aggie Drive

4 TEN YEARS OF STEM BORER RESEARCH COLLABORATION ON SUGARCANE AND RICE

Gene Reagan and M.O. Way* LSU AgCenter and Texas A&M AgriLife Research

The Mexican rice borer (MRB), Eoreuma loftini (Dyar), is the most destructive insect pest of sugarcane in North America. This invasive alien species entered the Lower Rio Grande Valley (LRGV) of Texas in 1980, and quickly caused such severe losses that sugarcane farmers were unable to harvest some of their fields. MRB continued to expand its geographical range throughout the Texas Gulf Coast rice producing area and into western Louisiana, now infesting rice in all of Calcasieu Parish (Lake Charles area). Causing as much as 50% yield loss in commercial Texas rice fields, projected economic loss to the Louisiana sugarcane and rice industries may be expected to reach as much as $220 million (sugarcane) and $45 million (rice) annually when MRB becomes fully established. The MRB is also a serious pest of sorghum and corn in Texas. The sugarcane borer (SCB), Diatraea saccharalis (F.), continues to be a serious pest of sugarcane in Louisiana and is also a key pest of rice and non-transgenic corn. MRB was first discovered in the Texas rice belt in 1988 and soon received attention from producer organizations and support industries. At this time, little was known about the biology and ecology of the pest, and even less was known about possible management techniques. After a several million dollar biological control program proved unsuccessful with LRGV sugarcane growers, we knew that control efforts would have to be much more comprehensive. This would require a far greater knowledge of MRB biology and how its life history relates to different host plants. On behalf of the LSU AgCenter and Texas A&M University, we initiated a national competitive grant effort in 2001 starting with $40,000 seed money from the USDA (CSREES) Critical Issues program and a project titled “MRB identification of range and variety resistance assessment.” In addition to three multi-year Strategic Agricultural Initiative grants from the US Environmental Protection Agency, we were successful in obtaining five years of support from two USDA Crops-at-Risk grants. All of these grants have been oriented toward building a system for sugarcane and rice that would not only help to manage stem borer problems, but also reduce area-wide pest populations. This year, our team was expanded to include L.T. Wilson and Yubin Yang (Texas A&M AgriLife), Allan Showler (USDA-ARS), and Jeff Hoy (LSU AgCenter Plant Pathology) for a sustainable biomass energy grant to further mitigate insect and disease pressures on conventional crops in interaction with potentially emerging bioenergy cropping systems.

* Thomas E. (Gene) Reagan, Austin C. Thompson Endowed Professor of Entomology, Louisiana State University Agricultural Center; and M.O. Way, Professor of Entomology, Texas A&M AgriLife Research and Extension Center at Beaumont

5 During the ten years of our collaborative work, we have developed sampling approaches to monitor infestations and quantify pest populations, identified resistant varieties, and evaluated and helped label environmentally friendly insecticides. With colleagues, we have studied numerous plant-insect interactions involving crop and non-crop host preferences, and better defined the role of plant stress impacted by cultural practices, salt, water and nutrients. Techniques reducing scouting efforts and achieving better insecticide application timing were also developed to assist sugarcane consultants. With recently labeled insecticides having four different modes of action (Confirm®, Diamond®, Coragen® / Belt®, Besiege®), the potential for insecticide resistance is also reduced. In rice, a newly developed seed treatment, Dermacor X- 100®, impacts stem borer management in addition to pyrethroid foliar applications. Thank you for participating in the 10th stem borer research site visit training. We welcome you to the 2011 Beaumont Site Visit and hope you depart with good information to help you grow a more profitable crop.

6 MONITORING MEXICAN RICE BORER MOVEMENT: RANGE EXPANSION INTO LOUISIANA

T. Hardy1, T.E. Reagan2, M.O. Way3, R.A. Pearson3, B.E. Wilson2, and J.M. Beuzelin2 1Louisiana Department of Agriculture and Forestry; 2Department of Entomology, LSU AgCenter 3Texas A&M AgriLife Research and Extension Center at Beaumont

Cooperative studies on the Mexican rice borer (MRB), Eoreuma loftini, between the LSU AgCenter, Texas A&M University AgriLife Research Center at Beaumont, the Texas Department of Agriculture, and the Louisiana Department of Agriculture and Forestry have been on-going since 1999 to monitor the movement of this devastating pest of sugarcane towards Louisiana. As previously anticipated, MRB spread into Louisiana by the end of 2008, and was collected in two traps near rice fields northwest of Vinton, LA on December 12. While no MRB specimens were detected in Louisiana in 2009, data from 2010 showed that this invasive pest had expanded its range into Cameron and Calcasieu parishes. Additional MRB moths captured in 2011 indicate the species has expanded its range farther north into southeastern Beauregard Parish. The first specimens trapped since 2008 were collected in non-crop habitat with wild grass hosts 6.8 miles southeast of Vinton, Calcasieu parish, LA, on 22 November 2010. Since that date, numerous specimens have been collected in traps from 36 different locations in Louisiana (Table 1, Fig. 1). Currently, the locations of positive traps have been in rice or wild-host areas; however, the eastern-most location is directly south of Lacassine, and it is anticipated the MRB will soon infest producing sugarcane in that region. More than 200 MRB have been trapped in Calcasieu parish so far in 2011 (Table 1), indicating the species has established a clear presence. Additionally, rice growers in this parish have begun to report MRB larval infestations in their fields. In August, traps were retrieved and/or re-deployed east of their previous locations in an attempt to stay ahead of the eastern MRB movement (Table 2). Continued monitoring of MRB populations will be conducted with additional traps at locations further east and north. Currently, LDAF has a total of 25 MRB pheromone traps in Calcasieu, Cameron and Jefferson Davis parishes, with 3 additional traps in Beauregard and Vermilion parishes. In late September, 12 traps will be added in St. Mary and Iberia parishes near sugarcane processing and off-loading facilities. As the pest’s eastward expansion continues, effective management strategies such as the use of varietal resistance, improved chemical control tactics, and management of non-crop hosts are becoming critical to slow the spread of this devastating insect.

Table 1. 2011 Louisiana MRB Trap Captures Table 2. Monthly Total MRB Captures in LA Parish # Sites # + Sites # MRB Month # MRB Calcasieu 34 24 209 March 36 Cameron 14 11 27 April 59 Beauregard 2 1 3 May 36 Jefferson Davis 12 0 0 June 57 July 19 August 32

Fig. 1. Monitoring MRB movement in Louisiana, 2010 and 2011. Stars designate positive trap locations. Two positive sites in Southwestern Cameron Parish are not shown. References: Hummel, N.A., T. Hardy, T.E. Reagan, D.K. Pollet, C.E. Carlton, M.J. Stout, J.M. Beuzelin, W. Akbar, W.H. White. 2010. Monitoring and first discovery of the Mexican rice borer Eoreuma loftini (Lepidoptera: Crambidae) in Louisiana. Fla. Entomol. 93: 123-124. Hummel, N., G. Reagan, D. Pollet, W. Akbar, J. Beuzelin, C. Carlton, J. Saichuk, T. Hardy, M. Way. 2008. Mexican Rice Borer, Eoreuma loftini (Dyar). LSU AgCenter Pub. 3098. Reay-Jones, F.P.F., L.T. Wilson, M.O. Way, T.E. Reagan, C.E. Carlton. 2007. Movement of the Mexican rice borer (Lepidoptera: Crambidae) through the Texas rice belt. J. Econ. Entomol. 100: 54-60. Reay-Jones, F.P.F., L.T. Wilson, T.E. Reagan, B.L. Legendre, and M.O. Way. 2008. Predicting economic losses from the continued spread of the Mexican rice borer (Lepidoptera: Crambidae). J. Econ. Entomol. 101: 237-250. 8 EVALUATION OF COMMERCIAL AND EXPERIMENTAL SUGARCANE CULTIVARS FOR RESISTANCE TO THE MEXICAN RICE BORER, BEAUMONT, TX, 2010 AND 2011

T.E. Reagan1, B.E. Wilson1, J.M. Beuzelin1, W.H. White2, M.O. Way3, M. VanWeelden1, and A.T. Showler4 1Department of Entomology, LSU AgCenter 2USDA Sugarcane Research Unit at Houma, Louisiana 3Texas A&M AgriLife Research and Extension Center at Beaumont, Texas 4USDA-ARS, Kika de la Garza Agricultural Research Center at Weslaco, Texas

Because of the limitations of chemical and biological control against the Mexican rice borer (MRB), Eoreuma loftini, host plant resistance is an important part of management. As a control tactic, host plant resistance can not only aid in reducing stalk borer injury, but can also reduce area-wide populations and potentially slow the spread of the MRB. The effect of cultivars on reducing area-wide populations is examined by comparing the number of adult emergence holes. In addition, recent research suggests resistant cultivars which impede stalk entry and prolong larval exposure on plant surfaces may enhance the efficacy of insecticide applications. Continued evaluation of stalk borer resistance is necessary as host plant resistance remains a valuable integrated pest management (IPM) tool. A 2-year field study was conducted at the Texas A&M AgriLife Research and Extension Center at Beaumont, TX, to assess resistance to MRB among commercial and experimental sugarcane cultivars. Thirty-eight cultivars were evaluated over both years. The tests included a wide variety of cultivars developed from breeding programs in St. Gabriel, LA; Houma, LA; Canal Point, FL; and Natal, South Africa. In addition, the tests examined resistance in 4 biomass energy cultivars. In both years, the tests had 1-row, 12-foot plots arranged in a randomized block design with 5 replications (See field maps pp. 50-51).

2010 evaluation The 25 varieties evaluated in 2010 include: 5 in commercial use (HoCP 85-845, HoCP 96-540, HoCP 00-950, L 01-299, and L 03-371), 11 experimental clones (HoCP 05-902, HoCP 05-961, HoCP 04-838, Ho 06-563, Ho 07-613, Ho 07-604, Ho 07-617, Ho 07-612, Ho 06-537, L 07-68, and L 07-57), 3 clones bred for high fiber content (Ho 06-9610, US 93-15, and US 01- 40), 2 energy canes (US 08-9001 and US 08-9003), and 4 South African cultivars (N-17, N-21, N-24, N-27). The cultivars from the South African Sugar Research Institute in KwaZulu-Natal (N-cultivars) have potential resistance to MRB because they have demonstrated varying levels of resistance to African stalkborers, especially Eldana spp., which shares many characteristics with MRB. Differences were detected in percentages of bored internodes among cultivars (F=3.56, P<0.001). Results (Table 1) showed infestations ranging from 1.0% bored internodes (N-21 and HoCP 85-845) to 20.4% (Ho 06-563). Of the commercial cultivars, HoCP 85-845 and L 01-299 were the most resistant, while L 03-371 and HoCP 96-540 were the most susceptible. HoCP 96- 540, currently the most widely planted cultivar in Louisiana, experienced nearly 8-fold more injury than the most resistant varieties. All of the South African cultivars showed some level of resistance with N-21 being the most resistant. Adult emergence data followed the same trend as percent bored internodes with moth production ranging from < 0.01 to 0.38 emergence holes/stalk (Table 1); however, differences in emergence among cultivars were not detected (F=1.57, P=0.065).

9 Table 1. MRB injury and moth production in the 2010 Beaumont sugarcane variety test Emergence per Variety % Bored Internodes Stalk

Ho 06-563 20.4 0.38 HoCP 05-902 14.5 0.32 HoCP 04-838 11.0 2.0 Ho 07-612 10.1 0.18 L 03-371 9.6 0.14 HoCP 96-540 7.9 0.08 L 07-57 7.2 0.31 Ho 07-604 6.4 0.04 US 01-40 5.9 0.06 N-27 5.8 0.12 Ho 06-537 5.8 0.18 Ho 07-613 5.5 0.02 N-17 5.4 0.08 HoCP 05-961 5.3 0.12 US 08-9001 5.3 0.04 Ho 06-9610 5.0 0.04 HoCP 00-950 4.6 0.04 L 07-68 4.1 0.12 Ho 07-617 3.9 0.06 US 08-9003 2.7 0.06 N-24 2.4 <0.01 L 01-299 2.3 0.04 US 93-15 1.2 0.011 HoCP 85-845 1.0 <0.01 N-21 1.0 <0.01 *Means which share a line are not significantly different (LSD, α=0.05)

10 2011 evaluation The 2011 test evaluated resistance in 19 cultivars. Cultivars from the 2010 test which were reevaluated include: HoCP 85-845, HoCP 00-950, Ho 07-613, L 07-57, HoCP 05-961, and HoCP 04-838. HoCP 85-845 has been our resistant standard for several years. HoCP 04-838, which appears to have little resistance to the MRB, has recently been released to commercial growers. Experimental cultivars in the early stages of varietal development include: HoCP 08- 726, Ho 08-706, L 08-090, L 08-088, Ho 08-711, Ho 08-717, HoL 08-723, L 08-075, L 08-092, Ho 08-709. Two energy cane varieties, L 79-1002 and Ho 02-113, were also evaluated. Results showed significant differences (F=2.71, P= 0.002) in injury, ranging from 1.9 to 17.2% bored internodes (Table 2). The most resistant cultivars examined were HoCP 85-845 and L 08-075. Experimental cultivar L 08-075 is potentially highly resistant as it demonstrated >8-fold reductions in MRB injury compared to susceptible cultivars. The most susceptible cultivars were HoCP 08-726, L 08-090, and HoCP 04-838. Differences in adult emergence (F= 1.99, P =0.019) followed the same trend as injury data ranging from 0.02 to 0.45 emergence hole per stalk (Table 2). Results from the cultivars which were reevaluated were consistent with findings from 2010. Energy cane varieties showed intermediate levels of resistance.

Table 2. MRB injury and moth production in the 2011 Beaumont sugarcane variety test Variety % Bored Internodes Emergence/stalk HoCP 08-726 17.2 0.45 L 08-090 13.7 0.35 HoCP 04-838 13.4 0.28 HoL 08-723 13.1 0.10 Ho 08-711 13.1 0.46 Ho 08-717 12.4 0.20 Ho 08-706 9.5 0.18 Ho 07-613 9.0 0.27 L 79-1002 8.5 0.21 L 07-57 8.5 0.21 Ho 08-709 8.0 0.07 L 08-088 8.0 0.23 HoCP 00-950 7.9 0.08 Ho 02-113 7.7 0.08 L 08-092 7.7 0.08 Ho 05-961 7.6 0.24 HoCP 91-552 7.6 0.23 HoCP 85-845 3.9 0.10 L 08-075 1.9 0.02 *Means which share a line are not significantly different (LSD α=0.05).

11 FEEDING BEHAVIOR AND DURATION OF EXPOSURE OF MEXICAN RICE BORER LARVAE ON SUGARCANE

Blake E. Wilson1, T.E. Reagan1, J.M. Beuzelin1, and A.T. Showler2 1Department of Entomology, LSU AgCenter 2USDA-ARS Weslaco, Texas

A greenhouse study was conducted at the USDA ARS Kika de La Garza Subtropical Agricultural Research Center (Weslaco, Hidalgo County, TX) to investigate Mexican rice borer (MRB), Eoreuma loftini, larval feeding behavior on immature (6 nodes) and mature (12 nodes) sugarcane stalks of a resistant (HoCP 85-845) and susceptible (HoCP 00-950) cultivar. Plants were arranged in a completely randomized design with each of the four treatments (cultivar by phenological stage) applied to 12 stalks. Strips of freshly laid MRB eggs were attached to the leaves at locations consistent with normal oviposition activity. Egg strips were removed after hatching, and position and feeding behavior of newly emerged larvae were recorded daily. Numerous entry holes into leaf midribs within one day of hatching indicated that many larvae were only briefly exposed on plant surfaces. The number of larvae to enter the midribs, duration of exposure, and larval survival were recorded. Over all treatments ,feeding behavior and establishment of a total of 277 larvae was monitored (Table 1). More than half of newly hatched larvae on immature stalks of HoCP 00- 950 bored into the plant (midrib), where they would be protected from contact insecticides within one day. A greater percentage of larvae became established feeding on the susceptible HoCP 00-950 than on HoCP 85-845. Larval establishment was greater on mature than on immature sugarcane. However, larval survival to stalk entry was greater on immature than mature sugarcane, which may be related to increasing rind hardness as stalks mature. Duration of exposure was shortest on immature HoCP 00-950 (3.4 d) and greatest on mature stalks of HoCP 85-845 (6.4 d). This research demonstrates the short window of exposure of MRB larvae to control tactics. Because of the limited vulnerability of MRB larvae, improved application timing and residual activity of insecticides have potential to enhance efficacy of MRB chemical control. Additionally, resistant cultivars which impede larval establishment and prolong exposure would likely allow increased larval vulnerability to chemical or biological control tactics.

Table 1. MRB larval behavior and exposure on sugarcane, Weslaco, TX, 2010 % of larvae to % of larvae to % of established Duration of establish enter midrib in larvae surviving exposure (day) feeding 1 day to stalk entry HoCP 00-950 6 Nodes 18.2 67.5 3.40 55.0 12 Nodes 31.0 42.5 5.38 41.0 HoCP 85-845 6 Nodes 14.1 24.1 5.95 72.4 12 Nodes 21.9 32.9 6.41 27.4

12 RED IMPORTED FIRE ANT PREDATION ON MEXICAN RICE BORER IN SUGARCANE AT BEAUMONT, TX IN 20111

M.T. VanWeelden1, J.M. Beuzelin1, B.E. Wilson1, T.E. Reagan1, and M. O. Way2 1Department of Entomology, LSU AgCenter 2Texas A&M AgriLife Research and Extension Center at Beaumont, Texas

A study was initiated in the summer of 2011 at the Texas A&M AgriLife Center at Beaumont, TX to assess the effect of predation by the red imported fire ant (Solenopsis invicta) on Mexican rice borer (MRB) injury to sugarcane. The experiment was conducted in plots of the 2010 and 2011 sugarcane variety tests by establishing ant-suppressed and unsuppressed areas. Ant populations were suppressed using a granule bait formulation of hydramethylnon and S- methoprene applied to the rows and bases of plants. In each area of the variety tests, MRB injury was assessed in four sugarcane cultivars of interest; two conventional cultivars and two energy cultivars (Table 1). Bored internodes and emergence holes from MRB were counted on 10 randomly selected stalks from each plot using destructive sampling and a stalk-splitter machine borrowed from the Texas A&M Center at Weslaco. The percentage of bored internodes and number of emergence holes were analyzed using generalized linear models (Proc Glimmix, SAS Institute) with binomial and Poisson distributions, respectively. A 50% increase in the percentage of bored internodes was observed across all ant- suppressed areas. However, statistical analysis did not detect differences (F=1.48, P=0.284) supporting the numerical trend (Table 1). A difference in emergence holes per stalk was associated with ant suppression (F=2.43, P=0.023). The mean number of emergence holes per stalk across all unsuppressed areas was 0.16, and increased to 0.36 in areas where ants were suppressed. This data suggests that predation of the MRB by the red imported fire ant decreases both injury and build- ups of pest populations in sugarcane. Additional data collected from pitfall traps implemented throughout the summer to detect relative abundance of the red imported fire ant may help to better quantify the role of ant predation. MRB infestations in leaf sheaths recorded bi-weekly still need to be analyzed.

Table 1. Mean percentage of bored internodes and emergence per stalk by sugarcane cultivar with ants suppressed and unsuppressed in Beaumont, TX, 2011 Variety Ants Suppressed Ants Not Suppressed % Bored internodes Emergence/stalk % Bored internodes Emergence/stalk HoCP 85-845 (plant and ratoon) 6.28 0.1 3.36 0.07 HoCP 04-838 (plant and ratoon) 11.67 0.4 9.61 0.15 Ho 02-113 (plant) 6.51 0.14 7.79 0.06 L 79-1002 (plant) 6.62 0.23 9.76 0.22 Ho 08-9001 (ratoon) 17.48 0.4 9.19 0.15 Ho 08-9003 (ratoon) 33.88 0.99 13.04 0.3

1 This research is part of the Ph.D. dissertation program of Matt VanWeelden

13 PHEROMONE TRAP ASSISTED SCOUTING AND AERIAL INSECTICIDAL CONTROL OF THE MEXICAN RICE BORER, 2009 AND 2010

Blake E. Wilson1, T.E. Reagan1, J.M. Beuzelin1, and A.T. Showler2 1Department of Entomology and 2USDA-ARS Weslaco, Texas

A 2-year field study was conducted to evaluate the use of pheromone traps to enhance scouting and improve chemical control of the Mexican rice borer (MRB), Eoreuma loftini, in commercial sugarcane fields in the Lower Rio Grande Valley (Cameron County, Texas). Evaluation of aerial insecticide applications for control of MRB was conducted in a large area randomized block design (RBD) with 5 replications. Insecticide treatments were assigned randomly to plots (10 acres/plot) in fields ranging from 36-85 acres of variety CP 72-1210 (ratoon) in 2009 and 2010. Pheromone traps were used to help with scouting and better monitor MRB population densities to more effectively time the need for insecticide applications. Trap catches of >20 moths/trap/week were used as a scouting threshold to initiate monitoring for larval infestations in (Fig. 1A). Treatable larval infestations (on plant surfaces) were determined by examining two ten stalk samples per plot. In 2009, one incident of larval scouting was necessary to determine that infestations exceeded the threshold of 5% of stalks with larvae on plant surfaces. Weekly larval scouting was conducted in 2010 throughout the growing season, and a direct correlation was observed between pheromone trap catches and larval infestations (Fig. 1B). A single aerial application was made in both 2009 and 2010 on mornings of 21 Aug and 13 Aug, respectively, by fixed wing aircraft at 10 GPA with less than 5 mph wind. At the end of the growing season, injury data were collected from 30 stalks/plot. Yield data in 2010 were collected with the core sampling method with each 10 acre plot harvested completely. In both 2009 and 2010, the recently labeled (Section 3 for sugarcane) environmentally friendly insecticide, novaluron (Diamond®), showed the best control with 7.6% bored internodes, which was significantly less than the untreated plots (19.1% bored) averaged over both years. β- cyfluthrin (Baythroid®) provided intermediate control (Table 1). Differences in moth emergence followed the same trend as percent bored internodes, with significant differences detected among treatments (Table 1). Yield data from 2010 indicate that the novaluron treatment led to a 14% increase in sugar production over untreated controls, while β-cyfluthrin treated plots were only significantly different from controls in terms of sugar/ton of cane (Table 1). Based on the current price of sugar (~$695.60/ton), the novaluron application reduced revenue losses by $276/acre. This study demonstrates the potential of pheromone trap-assisted-scouting to reduce scouting effort and optimally time insecticide applications. Additionally, the economics of MRB insecticidal control could be greatly improved if sugar production can be increased with a single, well-timed insecticide application.

Table 1. MRB injury and sugar yield from aerial insecticide tests, LRGV, 2009 and 2010 Rate (fl Sugar(lbs)/ton Sugar Treatment % Bored Emergence/Stalk oz/acre) of cane (tons)/acre Diamond® 12.0 7.6 a 0.26 a 208.2 a 3.16 a Baythroid® 2.8 11.4 a 0.39 ab 203.0 b 2.59 b Untreated NA 19.1 b 0.62 b 197.8 c 2.91 b *Means which are followed by the same letter are not significantly different (P > 0.05).

14 Fig. 1. Pheromone trap monitoring of MRB in Hidalgo and Cameron Counties, TX. (A) Average no. of MRB/trap/week throughout the 2009 growing season. (B) Relationship between adult population densities (no. of MRB/trap/week) and larval infestation (percent of stalks infested with treatable larvae feeding in leaf sheaths), 2010.

15 COMPARISON OF MEXICAN RICE BORER PEST PRESSURE IN BIOENERGY AND CONVENTIONAL SUGARCANE1

T.E. Reagan1, B.E. Wilson1, M.T. VanWeelden1, J.M. Beuzelin1, W.H. White2, and M.O. Way3 1Department of Entomology, LSU AgCenter; 2USDA Sugarcane Research Unit at Houma 3Texas A&M AgriLife Research and Extension Center at Beaumont, Texas

A study conducted at the Texas A&M AgriLife Center at Beaumont, TX compared the effects of Mexican rice borer (MRB), Eoreuma loftini, infestations in energycane cultivar L 79- 1002 and two conventional sugarcane cultivars, HoCP 85-845 (resistant) and HoCP 04-838 (susceptible). The experiment was set up in a randomized block design arrangement with 4 replications. Each 1-row 12-ft-long plot was split into two 6-ft sub-plots. Sub-plots were either protected from MRB infestations or left unprotected. Protected sub-plots received two applications of tebufenozide (Confirm) applied at 15.0 oz/a in Jul and Aug with a back-pack sprayer containing 2 gal of water. From late Jun to late Aug, MRB larval feeding signs in leaf sheaths were monitored every other week. In early Sep, stand counts were taken from each sub- plot and10 stalk samples were collected and weighed. For each stalk, the numbers of bored internodes, total internodes, and emergence holes were recorded. Total juice volume and Brix value were recorded from 4 stalks. Juice volume/6 row-ft was calculated multiplying volume/stalk by the no. stalks/sub-plot. Untreated MRB larval feeding injury in leaf sheaths of energycane L 79-1002 ranged between 60 and 90% of injured stalks during the initial sampling periods, and averaged 20.3 and 12.5% in HoCP 04-83 and HoCP 85-845, respectively (Table 1). Insecticide applications reduced the percentage of bored internodes (F=23.8, P<0.001) and emergence per stalk (F=5.7, P=0.024), with unprotected HoCP 04-838 and protected HoCP 85-845 sustaining the greatest and lowest levels of injury, respectively (Table 2). Energycane L 79-1002 sustained intermediate levels of injury. Differences between cultivars were detected for weight of 10 stalks (F=3.8, P= 0.0366), juice volume (F=13.1, P<0.001), and Brix (F=273.6, P<0.001). Although insecticidal protection decreased MRB injury for all cultivars, increases in yield parameters were only detected for susceptible sugarcane HoCP 04-838 (Table 3). These data suggest that HoCP 85-845 and L 79- 1002 are more tolerant to MRB injury. Future quantification of the impact of MRB infestations and associated injury on yield components will be critical to determine the need for management actions in energycane.

Table 1. MRB injury in leaf sheaths of sugarcane and energycane, Beaumont, TX, 2011 % Injured stalks Cultivar Treatment* 8 Jul 22 Jul 3 Aug (pre-treatment) HoCP 85-845 Protected NA 0 5 (resistant) Unprotected 12.5 10 15 HoCP 04-838 Protected NA 0 10 (susceptible) Unprotected 20.8 15 25 L 79-1002 Protected NA 15 45 (energycane) Unprotected 79.0 60 90 *Protected = Confirm® applied on July 10 and August 3

1 A portion of this study is anticipated to be part of the Ph.D. dissertation program of Matt VanWeelden 16 Table 2. MRB injury and emergence in sugarcane and energycane, Beaumont, TX, 2011 Cultivar Treatment % Bored internodes Emergence/Stalk HoCP 04-838 Unprotected 13.2 0.24 L 79-1002 Unprotected 8.1 0.19 HoCP 85-845 Unprotected 3.8 0.09 L 79-1002 Protected 2.5 0.06 HoCP 04-838 Protected 1.0 0.06 HoCP 85-845 Protected 0.5 0.02 *Means sharing a line are not significantly different (LSD, α=0.05); Protected = Confirm® applied on July 10 and August 3

Table 3. Yield parameters as affected by cultivar and insecticide applications # Stalks/ Weight of 10 Juice volume Cultivar Treatment Brix 6 row ft stalks (Kg) (L / 6 row ft) HoCP 04-838 Protected 20.8 4.96 3.91 15.5 Unprotected 17.2 4.96 3.10 14.4 HoCP 85-845 Protected 23.4 4.46 5.05 13.3 Unprotected 20.8 4.50 4.83 13.0 L 79-1002 Protected 50.2 3.53 5.92 9.9 Unprotected 45.2 3.23 4.61 9.7 *Means sharing a line are not significantly different (LSD, α=0.05)

17 18

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ng Q i arthropods e Department of Entomology, LSU AgCenter Department of Entomology, y Ext 1 N OF I T ASSESSMENT m or d O t L P , J.M. Beuzelin ep 4 F4 l E4 eda B4 C4 e A4 H4 D4 G4 n an m hon hon 1 en r r ond R i p at at ba rade na ag t v v am er T i el ontro onf or esieg ALL h B C D C C Pre Pre B ot Research and Extension Center at Beaumont, Texas Research and Extension Texas A&M AgriLife t SM 2 nd en B.E. Wilson Seven insecticide treatments Seven insecticide m s a ep 5 F5 E5 C5 B5 D5 H5 G5 A5 R reat H C D E F G T A B using a Solo back pack sprayer delivering 10 gpa at 14 psi. SCB surfactant Induce at 0.25% v/v using a Solo back pack sprayer delivering were observed on August 25 in selected plots. internode boring and larvae infesting leaf sheaths among possible differences in control residual These preliminary observations helped to verify application. treatments prior to the second insecticide the total number of internodes from the number of bored internodes and early October. in sugarcane in 2011, Burns Point, LA Table 1. Treatments applied to manage SCB . The treatments were mixed in water and 30, 2011. The treatments on August 4 and fire ant fire

Table 2. Plot map, 2011, Burns Point, LA (F.), in a sugarcane borer (SCB), Diatraea saccharalis -long control of the assessed for season 96 in a field of variety HoCP RBD with five replications s Mary Parish. Lor

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Crop Protection 29 (2010) 1168e1176

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Crop Protection

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Field assessment of novaluron for sugarcane borer, Diatraea saccharalis (F.) (Lepidoptera: Crambidae), management in Louisiana sugarcane

J.M. Beuzelin a,*, W. Akbar b, A. Mészáros a, F.P.F. Reay-Jones c, T.E. Reagan a a Department of Entomology, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, 404 Life Sciences Bldg, Baton Rouge, LA 70803, USA b Monsanto Company, 700 Chesterﬁeld Pkwy West GG3E, Chesterﬁeld, MO 63017, USA c Department of Entomology, Soils and Plant Sciences, Clemson University, Pee Dee Research and Education Center, 2200 Pocket Rd., Florence, SC 29506, USA article info abstract

Article history: On-farm ﬁeld experiments were conducted in 2004 and 2007 to assess the suitability of novaluron, Received 28 January 2010 a chitin synthesis inhibitor, for sugarcane borer, Diatraea saccharalis (F.), management in Louisiana Received in revised form sugarcane (Saccharum spp. hybrids). Aerial insecticide applications reproducing commercial production 24 May 2010 practices were made when D. saccharalis infestation levels exceeded a recommended action threshold. In Accepted 1 June 2010 addition to decreased D. saccharalis infestations, 6.3 e 14.5-fold reductions in end of season injury, expressed as the percentage of bored sugarcane internodes, were observed in plots treated with nova- Keywords: luron. D. saccharalis control in novaluron plots was equivalent to (P > 0.05) or better (P < 0.05) than that Diatraea saccharalis (F.) Sugarcane achieved with tebufenozide, an ecdysone agonist that has been extensively used for over a decade on Biorational insecticide sugarcane. With a numerical trend of a 3.1-fold decrease in percent bored internodes, the pyrethroid Chitin synthesis inhibitor gamma-cyhalothrin seemed less effective than the biorational insecticides in protecting sugarcane Integrated pest management against D. saccharalis. Using continuous pitfall trap sampling, no measurable (P > 0.05) decreases in predaceous and non-predaceous soil-dwelling non-target arthropods were associated with insecticides. However, numerical trends for decreases in immature crickets associated with novaluron and gamma- cyhalothrin were recorded in 2007. Our data suggest that novaluron will ﬁt well in Louisiana sugarcane integrated pest management. Ó 2010 Elsevier Ltd. All rights reserved.

1. Introduction 1982). Spiders (Araneae) are the primary D. saccharalis egg predators and are probably second in importance in the natural enemy The sugarcane borer, Diatraea saccharalis (F.), is a lepidopteran complex (Negm and Hensley, 1969; Ali and Reagan, 1986). Ground pest that has historically been the most damaging arthropod in beetles (Coleoptera: Carabidae), tiger beetles (Coleoptera: Carabidae: Louisiana sugarcane (hybrids of Saccharum L. spp.) (Reagan et al., Cicindelinae), rove beetles (Coleoptera: Staphylinidae), click beetles 1972; Reagan, 2001). Management recommendations for D. sac- (Coleoptera: Elateridae), and earwigs (Dermaptera) have also been charalis emphasize the importance of cultivar resistance, scouting, cited as important components of the D. saccharalis natural enemy properly timed insecticide applications, and conservation of complex in Louisiana (Negm and Hensley, 1967, 1969). beneficial arthropods (Reagan and Posey, 2001; Posey et al., 2006). Natural enemies of D. saccharalis are largely protected in Loui- However, resistant cultivars have been underexploited for the past siana sugarcane by the widespread use of tebufenozide, which decade due to widespread use of susceptible high-yielding culti- represented 90% of the foliar applications in 2007 (Pollet, 2008). vars, and adequate D. saccharalis control with narrow-range This biorational insecticide belonging to the diacylhydrazine class is insecticides and associated conservation of natural enemies (Reay- an ecdysone agonist that causes larvae to produce a malformed Jones et al., 2005). cuticle (Dhadialla et al., 1998). This compound is very specificto The red imported fire ant, Solenopsis invicta Buren, is the dominant certain lepidopterans (Dhadialla et al., 1998) and has shown little to natural enemy of D. saccharalis in Louisiana sugarcane (Reagan,1986), no toxicity to D. saccharalis natural enemies (Reagan and Posey, contributing an estimated savings of as much as two insecticide 2001). In addition to tebufenozide, the pyrethroids esfenvalerate, applications per year for D. saccharalis management (Sauer et al., cyfluthrin, zeta-cypermethrin, lambda-cyhalothrin, and gamma- cyhalothrin are labeled but seldom used (Pollet, 2008). Because the development of resistance to different classes of insecticides in D. * Corresponding author. Tel.: þ1 225 578 1823; fax: þ1 225 578 1643. E-mail address: [email protected] (J.M. Beuzelin). saccharalis populations has been a recurring problem in Louisiana

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J.M. Beuzelin et al. / Crop Protection 29 (2010) 1168e1176 1169 sugarcane (Vines et al., 1984; Akbar et al., 2008), over-reliance on from each block, observing for live larvae (1ste3rd instars) infest- tebufenozide has raised concerns. Depending on cultivar and ing leaf sheaths. The 5% threshold was exceeded on July 15 when agricultural consultant recommendations, growers apply insecti- 10% of the stalks were infested and the first insecticide application cides when the level of stalks infested with at least one live larva was made on July 16. All insecticide treatments were applied in Ò feeding in the leaf sheaths exceeds a 5e10% threshold (Schexnayder water with the surfactant Latron CS-7 at the rate of 0.25% vol/vol. et al., 2001; Posey et al., 2006). After field management failures A Turbo Thrush Commander aircraft equipped with 38 CP-09-3P were reported, Reay-Jones et al. (2005) documented reductions in nozzles (0.125 orifice, 30 deflector, 275.8 kPa pressure, CP Products susceptibility to tebufenozide among D. saccharalis populations in Inc., Tempe, AZ) and delivering 46.7 L per hectare of finished Louisiana. Akbar et al. (2008) obtained a 27.1-fold increase in LC50 formulation was used to spray swaths of 18.3 m at a speed of after 12 generations of selection with tebufenozide in the labora- approximately 210 km/h. Subsequently, post-treatment infestation tory. Appropriate insecticide resistance management strategies are levels were assessed in each plot on July 25, 30, August 5, 13, 21, 26, therefore needed to preserve a balance of D. saccharalis control and September 2. All insecticides were applied again on August 13 tactics for the Louisiana sugarcane industry. when a 10% threshold was exceeded in the high rate novaluron Among potential alternatives to tebufenozide, novaluron is plots. Later infestation levels did not warrant a third insecticide a biorational insecticide belonging to the benzoylphenyl urea class application. At the end of the growing season, D. saccharalis injury that was initially registered in the USA in 2001 (Ishaaya and (no. bored internodes/total no. internodes) and moth production Horowitz, 1998; US EPA, 2001). Benzoylphenyl ureas inhibit chitin (no. adult emergence holes) were recorded from 25 stalks polymerization, thus disrupting cuticle formation in immature randomly selected in each plot on September 16. insects (Oberlander and Silhacek, 1998). Novaluron is therefore not directly toxic to adult insects, but exerts insecticidal activity on egg 2.2. Non-target arthropod pitfall trap sampling e 2004 and larval stages (Barzani, 2001). By 2008, this insecticide had been granted permanent federal labels in the USA for use on cotton, Three pitfall traps were used to determine relative soil-associ- potato, apple, Brassica vegetables, and ornamentals to control or ated arthropod abundance in each plot. Traps consisted of wide suppress caterpillars (Lepidoptera: Gracillariidae, Noctuidae, Plu- mouth 0.47-L glass jars (Ball Corp., Broomfield, CO) filled with tellidae, Pyralidae, Tortricidae), hemipterans (Hemiptera: Aleyr- 150 ml of ethylene glycol and 2 ml of liquid soap to reduce surface odidae, Miridae, Pentatomidae), beetles (Coleoptera: tension. Traps were placed on the 15th, 16th, and 15th row of each Chrysomelidae, Curculionidae), thrips (Thysanoptera: Thripidae), plot, respectively 30, 60, and 90 m from the unplowed front. Pitfall and leafminers (Diptera: Agromyzidae) (CPR, 2008; T&OR, 2008). traps were imbedded to the soil surface and were covered by a 15 Additionally, novaluron has a relatively low mammalian toxicity by 15 cm metal plate, which was supported by a tripod and elevated (Barzani, 2001). 3 cm above the jar to exclude rain, debris, and larger animals. Pitfall In sugarcane, preliminary small-plot studies showed that traps were initially placed in the experimental plots on June 11. For novaluron reduced D. saccharalis infestations below economic pre-treatment sampling, traps were collected and replaced on July levels (Posey et al., 2003; Akbar et al., 2004). Targeting immature 2 (21 days) and July 20 (18 days). For treatment assessment, traps stages, novaluron is expected to have limited non-target effects on were collected and replaced on August 4 (15 days) and August 17 adult natural enemies that are present in the sugarcane agro- (13 days). All traps were collected after a fifth sampling period on ecosystem (Ishaaya et al., 2001, 2002). Thus, this biorational September 2 (16 days). For each sampling period, the non-target pesticide has the potential to become a major component of Loui- arthropods collected were counted after being sorted to the siana sugarcane integrated pest management (IPM). In addition, following 13 groups: S. invicta, spiders, earwigs (Dermaptera: Ani- having a different mode of action from other labeled insecticides, solabididae, Forficulidae), ground beetles, tiger beetles, click novaluron represents an alternative that would reduce the selec- beetles, rove beetles, scarab beetles (Coleoptera: Scarabaeidae), tion pressure on D. saccharalis from other classes of insecticides, other Coleoptera, field crickets (Orthoptera: Gryllidae), Orthoptera mitigating the potential development of insecticide resistance. other than field crickets (Orthoptera: Gryllotalpidae, Tridactylidae), Before novaluron was granted a permanent federal label in 2009 for leafhoppers (Hemiptera: Cicadellidae), and other ground-dwelling use on sugarcane in the USA (www.greenbook.net, 2009), two arthropods. Predator abundance was determined considering four aerial application field studies were conducted in 2004 and 2007. groups of predators: S. invicta, spiders, pooled predaceous beetles These studies reported in this paper were conducted on commer- (ground, tiger, click, and rove), and earwigs. Non-predator abun- cial farms to assess the efficacy and non-target arthropod impacts dance was determined considering four groups: field crickets, of novaluron for D. saccharalis management in Louisiana sugarcane. pooled non-predaceous beetles (scarab and others), leafhoppers, and pooled other arthropods (Orthoptera other than field crickets 2. Material and methods and other ground-dwelling arthropods).

2.1. Experimental plots and D. saccharalis pest severity 2.3. Experimental plots and D. saccharalis pest severity assessment e 2004 assessment e 2007

A study was conducted during the summer of 2004 near Che- A study was conducted during the summer of 2007, near neyville, Rapides Parish, LA (N 31.019, W 92.302) in commercial Broussard, Iberia Parish, LA (N 30.068, W 91.905) in commercial fields planted during the summer of 2003 with sugarcane cultivar fields planted during the summer of 2006 with sugarcane cultivar LCP 85-384. Portions of fields were divided into 16 plots of 2 ha (30 HoCP 96-540. Portions of fields were divided into 20 plots of 0.4 ha rows, 1.83-m row spacing) in a randomized complete block design (12 rows, 1.83-m row spacing) in a randomized complete block arrangement with four blocks. Each plot was assigned one of four design arrangement with five blocks. Each plot was assigned one treatments. In addition to an untreated control, insecticide treat- of four treatments. In addition to an untreated control, insecticide Ò Ò ments were tebufenozide (Confirm 2F) at 140 g(AI)/ha, and treatments were tebufenozide (Confirm 2F) at 140 g(AI)/ha, Ò Ò novaluron (Diamond 0.83EC) at 58 g(AI)/ha and 87 g(AI)/ha. From novaluron (Diamond 0.83EC) at 65 g(AI)/ha, and gamma-cyha- Ò mid-June, pre-treatment D. saccharalis infestation levels were lothrin (Prolex 1.25EC) at 20 g(AI)/ha. From mid-June, weekly determined by weekly examinations of 25 randomly selected stalks examinations of 20 stalks per block indicated that the 5% threshold

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1170 J.M. Beuzelin et al. / Crop Protection 29 (2010) 1168e1176 was exceeded on July 24 when 6.6% of the stalks were infested 3. Results with at least one live D. saccharalis larva in the leaf sheaths. Ò Insecticides were applied in water with the surfactant Latron CS- 3.1. D. saccharalis control e 2004 and 2007 7 (0.25% v/v) on July 26. A Robinson R44 helicopter equipped with 36 TeeJet D6-46 nozzles directed 90 back (TeeJet Technologies, Post-treatment D. saccharalis larval infestations were lower Wheaton, IL) was used to spray swaths of 10.97 m. The helicopter (P < 0.05) in insecticide treated plots relative to untreated plots in was equipped with a flow meter calibrated to deliver 28.1 L per both 2004 and 2007 (Table 1, Fig. 1). In 2004, differences among hectare of finished formulation regardless of ground speed. Post- tebufenozide and novaluron treated plots were not detected. In treatment infestation levels were assessed in each plot on August treated plots, D. saccharalis infestations above the action threshold 8, 16, 24, and 31. Because the threshold was not exceeded in the of 5e10% of infested stalks were observed 28 days after the first novaluron treated plots, there was no second insecticide applica- insecticide application, warranting the second application on tion. At the end of the growing season, D. saccharalis injury (no. August 13. Infestations in untreated plots were above the threshold bored internodes/total no. internodes) and moth production (no. from July 16, date of the first insecticide application, until the end of adult emergence holes) were recorded from 20 stalks randomly the season. Infestations changed over time (P < 0.05, Table 1), with selected in each plot on October 24. a general increase observed over the growing season in untreated plots, attaining a maximum of 25.6% of infested stalks on August 31. 2.4. Non-target arthropod pitfall trap sampling e 2007 In insecticide treated plots, reduced D. saccharalis infestations were observed 8 and 13e15 days after each insecticide application Relative soil-associated arthropod abundance was determined (Fig. 1). using two pitfall traps per plot. The two pitfall traps were placed 38 In 2007, differences in post-treatment D. saccharalis infestations and 76 m from the front of each plot, on the 6th and 7th row, among tebufenozide, novaluron, and gamma-cyhalothrin treated respectively. Traps were placed in plots on June 27, with pre- plots were not detected, with infestations remaining below the treatment sampling conducted from July 17 to 25 (8 days). Trap action threshold of 5e10% after the first insecticide applications. assessment of treatments was conducted from July 25 to August 8 Infestations in untreated plots were near or above the action (14 days), August 8 to 31 (23 days), and August 31 to September 21 threshold of 5e10% from July 26, date of the first insecticide (21 days). For each sampling period, the non-target arthropods applications, until the end of the season. Post-treatment D. sac- collected were counted after being sorted to 17 groups: S. invicta, charalis infestations did not differ in time (P > 0.05, Table 1); ants other than S. invicta, spiders, earwigs, ground beetles, however, a trend for an increase was observed over the growing tiger beetles, click beetles, rove beetles, scarab beetles, other season in untreated plots (Fig. 1). Coleoptera, field crickets, non-field cricket Orthoptera, leafhoppers, Untreated plots had the highest end of season D. saccharalis plant-hoppers (Hemiptera: Delphacidae), other Hemiptera injury with 12.6 and 7.8% bored internodes in 2004 and 2007, (including Cercopidae), centipedes (class Chilopoda), and other respectively (Table 1, Fig. 2). In 2004, a reduction (8.6-fold) in injury ground-dwelling arthropods. Predator abundance was determined was observed in plots treated with the low rate of novaluron. A considering the same four groups of predators as in the 2004 numerical trend for a decrease in bored internodes was observed in experiment. Non-predator abundance was determined considering plots treated with tebufenozide (2.9-fold) and novaluron high rate four groups: field crickets, pooled non-predaceous beetles (scarab (6.3-fold) (Fig. 2). In addition, contrasts comparing novaluron and others), pooled hemipterans (leafhoppers, planthoppers, and treated plots with those treated with tebufenozide (F ¼ 6.56; df ¼ 1, other Hemiptera), and pooled other arthropods (ants other than S. 8.24; P ¼ 0.033) showed that novaluron was associated with lower invicta, Orthoptera other than field crickets, centipedes, and other D. saccharalis injury than tebufenozide. Differences in D. saccharalis ground-dwelling arthropods). moth production associated with insecticide treatments (Fig. 2) were not detected (Table 1). 2.5. Data analyses In 2007, reductions in injury were observed in plots treated with tebufenozide (8.0-fold) and novaluron (14.5-fold). Only a numerical Each experiment was analyzed separately using Proc GLIMMIX trend for a decrease (3.1-fold) in D. saccharalis bored internodes (SAS Institute, 2008). Proportions of D. saccharalis infested stalks was observed in plots treated with gamma-cyhalothrin. A numer- and bored internodes were analyzed using generalized linear ical trend for a decrease (3.4-fold) in D. saccharalis moth emergence mixed models with a binomial distribution and a logit link function. holes was also recorded in plots treated with gamma-cyhalothrin The number of moth emergence holes was analyzed using a one- (Fig. 2). Whereas moth emergence holes averaged 0.37 per stalk in way analysis of variance (ANOVA) with treatment as factor. Non- untreated plots, moth production was reduced (P < 0.05) in plots target arthropod count data, including pre-treatment observations, treated with tebufenozide (9.3-fold). Moth emergence holes were were divided by pitfall trap sampling period duration in days and not observed in stalk samples from novaluron treated plots (Fig. 2). analyzed using a two-way ANOVA with treatment and sampling period as factors. Each pitfall trap was considered a sampling unit. 3.2. Non-target arthropod assessment, 2004 Prior to ANOVA, mothpffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi production and non-target arthropod data were transformed ð x þ 0:5Þ to normalize their distribution. A Non-target arthropod abundances did not differ (P > 0.05) variance component covariance structure was used to model the among insecticide treated and untreated plots (Table 2). However, effects of repeated measures for infestation levels and non-target differences among sampling periods (P < 0.05) were detected for arthropod counts. The KenwardeRoger adjustment for denomi- several soil-associated arthropod groups, as well as significant nator degrees of freedom was used in all the models to correct for treatment by sampling period interactions (P < 0.05) (Table 2). inexact F distributions. Least square means are reported for treat- Spider abundance differed among sampling periods extending ment effects, and were separated with Tukey’s HSD (a ¼ 0.05) when from mid-June to early September, with no treatment by sampling differences among treatments were detected. For the 2004 exper- period interactions detected. Prior to insecticide applications, iment, contrasts were also used to compare D. saccharalis injury spider abundance decreased (1.4-fold) between the first and (proportion of bored internodes) means from novaluron (low and second sampling periods. After the first insecticide applications, high rates combined) vs. tebufenozide plots. spider abundance increased (1.5-fold) between the second and

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J.M. Beuzelin et al. / Crop Protection 29 (2010) 1168e1176 1171

Table 1 Statistical comparisons of insecticide efﬁcacy from on-farm aerial application experiments on sugarcane in Louisiana, 2004 and 2007.

2004 2007

F df P > FF df P > F Post-treatment D. saccharalis larval infestations Treatment 23.42 3, 7.18 <0.001 11.94 3, 63 <0.001 Date 2.68 6, 22.69 0.041 0.93 3, 63 0.432 Treatment Date 1.20 18, 25.26 0.332 0.87 9, 63 0.561 End of season D. saccharalis injury Treatment 4.07 3, 9.09 0.044 12.89 3, 5.98 0.005 D. saccharalis moth production Treatment 1.17 3, 9 0.375 5.41 3, 12 0.014

fourth sampling period, and then decreased (1.5-fold) during the stable during the remaining sampling periods. Overall field cricket fifth period. and leafhopper abundances increased (6.6-fold and 33.7-fold, Predaceous beetle abundance decreased over the five pitfall trap respectively) from mid-June to early September, with lowest sampling periods. However, as shown by the significant treatment abundances observed prior to the first insecticide applications. by sampling period interaction, abundances were stable in plots Abundance of other arthropods increased (4.7-fold) over the five treated with tebufenozide and novaluron high rate, whereas pitfall trap sampling periods. However, as shown by the significant a decrease was observed in novaluron low rate and untreated plots treatment by sampling period interaction, changes in abundance (Fig. 3). When considering each sampling period separately, between the second, third, and fourth sampling periods in nova- predaceous beetle abundances among treatments were not luron low rate plots (increase followed by decrease) were different different. For other beetles, field crickets, and leafhoppers, abun- from those observed in novaluron high rate plots (decrease fol- dances differed among sampling periods, with no treatment by lowed by increase). When considering each sampling period sampling period interactions detected (Table 2). Non-predaceous separately, the abundance of other arthropods among treatments beetle abundance decreased (3.3-fold) prior to insecticide appli- was not significantly different. cations between the first and second sampling periods, and was 3.3. Non-target arthropod assessment e 2007

Except for predaceous beetles, non-target arthropod abundances did not differ (P > 0.05) among untreated and insecticide treated plots (Table 2). In comparison to untreated plots, a 1.5-fold lower predaceous beetle abundance was observed in plots treated with gamma-cyhalothrin. Predaceous beetle abundances in plots treated with novaluron and tebufenozide were not different from those in either untreated or gamma-cyhalothrin treated plots. An overall decrease in abundance over the growing season was also observed (Fig. 3). For several other soil-associated arthropod groups, differences among sampling periods were detected (P < 0.05), as well as significant treatment by period interactions (P < 0.05) (Table 2). For S. invicta and spiders, abundances decreased throughout the four pitfall trap sampling periods extending from mid-July to mid- September, 2.4-fold and 6.9-fold, respectively. Adult cricket abundance differed among sampling periods, with more adult crickets collected during the fourth sampling period than during the second. However, a significant treatment by sampling period interaction was detected. Whereas adult cricket abundance remained relatively stable in tebufenozide and novaluron treated plots, a numerical trend for a decrease (11.9-fold) between the first and second sampling, and a significant increase (13.5-fold) from the second to the fourth sampling were observed in gamma-cyhalothrin treated plots. A similar pattern was observed in untreated plots although differences among periods were not detected. When considering each sampling period separately, adult cricket abundances among treatments were not different. Immature cricket abundance increased (1.7-fold) between the first and third pitfall trap sampling periods (Fig. 4). However, a significant treatment by sampling period interaction was detected. From the first to the third sampling period, a significant increase (4.9-fold) in immature crickets was observed in untreated plots, whereas there was a trend for a decrease from the second to the third sampling in novaluron (1.5-fold) and gamma-cyhalothrin (1.3-fold) treated plots. The total number of field crickets in pitfall traps had the same pattern among sampling dates and treatments as immatures, which represented Fig. 1. Post-treatment levels of live D. saccharalis larval infestations (LSMeans SEM) in the leaf sheath of sugarcane from insecticide aerial application experiments in 81, 91, 90, and 77% of the crickets collected over the four sampling Louisiana, 2004 and 2007. periods, respectively. For hemipterans, pitfall trap catches

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Fig. 2. (A) End of season D. saccharalis bored internodes (LSMeans SEM) and (B) adult emergence (LSMeans SEM) from insecticide aerial application experiments on sugarcane in Louisiana, 2004 and 2007. Bars within each chart followed by the same letter are not significantly different (P > 0.05, Tukey’s HSD). increased (10.5-fold) between the first and third sampling periods, Because a strong association exists between yield losses and before decreasing (3.1-fold) during the fourth period. D. saccharalis injury expressed as % bored internodes (White et al., 2008), yield data were not collected in our study. Whereas bored 4. Discussion internodes represent injury causing yield losses, moth emergence holes estimate D. saccharalis adult production (Bessin et al., 1990) 4.1. Insecticide efficacy and document the efficacy of insecticides in decreasing pest populations produced by the infested crop. Although tebufenozide and Aerial applications of the biorational insecticides tebufenozide novaluron had no measurable effects on D. saccharalis adult and novaluron effectively reduced D. saccharalis larval infestations production in 2004, moth emergence hole data collected in 2007 in sugarcane. Both insecticides also reduced end of season injury provided some evidence that the biorational insecticides could based on D. saccharalis bored internodes, although not always decrease areawide pest populations in addition to protecting yields. significant at a ¼ 0.05. Our on-farm study showed that under Data on post-treatment larval infestations, end of season injury, conditions consistent with Louisiana production practices, the and moth emergence holes collectively suggest that the pyrethroid, chitin synthesis inhibitor novaluron decreased D. saccharalis gamma-cyhalothrin, was less efficacious than the biorational infestations and injury, with efficacy levels equal to or better than insecticides in protecting sugarcane from D. saccharalis. However, those of tebufenozide. Sugarcane growers traditionally accept D. this pyrethroid was studied only during one growing season. saccharalis injury levels at harvest below 10% bored internodes. Gamma-cyhalothrin is the active insecticidal isomer of lambda- Ò Ò Although sugarcane tolerance to injury differs with cultivar, White cyhalothrin. Lambda-cyhalothrin (Karate 1EC or Karate Z 2.08EC) et al. (2008) determined that each 1% bored internode injury was compared to tebufenozide in five previous studies assessing resulted in an average loss of 0.6% in sugar produced per hectare. the efficacy of aerially applied insecticides for D. saccharalis

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Table 2 Statistical comparisons of the abundance of selected non-target arthropods from continuous pitfall trap sampling in sugarcane plots from on-farm insecticide aerial application experiments in Louisiana, 2004 and 2007.

2004 2007

F df P > FF df P > F S. invicta Treatment 0.77 3, 9 0.540 0.22 3, 141 0.882 Period 1.86 4, 176 0.120 4.00 3, 141 0.009 Treatment Period 1.41 12, 176 0.166 0.50 9, 141 0.872 Spiders Treatment 0.56 3, 12 0.649 0.89 3, 31.3 0.458 Period 6.08 4, 176 <0.001 46.59 3, 105 <0.001 Treatment Period 1.08 12, 176 0.382 1.06 9, 105 0.398 Predaceous beetles Treatment 0.14 3, 12 0.936 3.20 3, 32.6 0.036 Period 7.81 4, 176 <0.001 25.97 3, 106 <0.001 Treatment Period 1.92 12, 176 0.035 1.04 9, 106 0.413 Earwigs Treatment 1.43 3, 9.01 0.296 2.10 3, 32.6 0.119 Period 0.73 4, 208 0.575 0.11 3, 107 0.953 Treatment Period 1.45 12, 208 0.147 1.36 9, 107 0.218 Adult ﬁeld crickets Treatment ee e 0.80 3, 11.8 0.516 Period ee e 3.12 3, 125 0.029 Treatment Period ee e 2.28 9, 125 0.021 Immature ﬁeld crickets Treatment ee e 0.28 3, 11.6 0.840 Period ee e 3.18 3, 105 0.027 Treatment Period ee e 2.09 9, 105 0.037 Field crickets Treatment 0.06 3, 9 0.979 0.26 3, 11.5 0.853 Period 57.12 4, 176 <0.001 1.90 3, 105 0.135 Treatment Period 0.79 12, 176 0.658 2.34 9, 105 0.019 Non-predaceous beetles Treatment 0.20 3, 9 0.894 0.56 3, 137 0.645 Period 10.01 4, 176 <0.001 1.34 3, 137 0.263 Treatment Period 0.60 12, 176 0.844 0.85 9, 137 0.571 Hemipterans Treatment ee e 1.75 3, 11.1 0.215 Period ee e 73.63 3, 104 <0.001 Treatment Period ee e 1.12 9, 104 0.352 Leafhoppers Treatment 1.33 3, 12 0.312 ee e Period 21.53 4, 176 <0.001 ee e Treatment Period 1.28 12, 176 0.232 ee e Other arthropods Treatment 0.25 3, 9 0.857 0.66 3, 16.1 0.588 Period 30.36 4, 208 <0.001 0.65 3, 126 0.585 Treatment Period 2.09 12, 208 0.019 0.63 9, 126 0.769

management in sugarcane (Rodriguez et al., 1995, 1998; abundances might have been caused by the initial distribution of Schexnayder et al., 1999; Posey and Reagan, 2000; McAllister beetles among plots. et al., 2002). In all five studies, decreases in percent bored inter- Non-predaceous arthropods are also involved in the balance of nodes below economic levels were associated with lambda-cyha- the sugarcane agroecosystem. For instance, crickets, which have lothrin, showing that this pyrethroid was suitable for D. saccharalis been used as an indicator group in non-target assessment, are management. D. saccharalis injury reductions associated with important as food for S. invicta (Reagan, 2001). No major negative lambda-cyhalothrin were not different (P > 0.05) from those impacts on non-predaceous arthropods were associated with associated with tebufenozide although numerically lower in all but insecticide applications reported in our study. Nevertheless, our one study (McAllister et al., 2002). Although it deserves further data suggest that immature crickets might have been affected by study, gamma-cyhalothrin also seems suitable for managing D. novaluron and gamma-cyhalothrin applications in 2007. Direct or saccharalis below economic levels despite a possible lower efficacy residual contact with novaluron, as well as ingestion of novaluron- compared to the biorational insecticides. exposed plant material, may disrupt cricket development to adulthood and kill immatures. Exposure to broad-spectrum 4.2. Non-target arthropod impact gamma-cyhalothrin may also increase the mortality of smaller and more susceptible crickets. However, non-target assessment for S. invicta plays a central role in Louisiana sugarcane IPM by immature crickets was conducted only in 2007, not allowing suppressing D. saccharalis populations (Negm and Hensley, 1967, a generalization of the results. 1969; Beuzelin et al., 2009). In our study, no disruptive effects on Tebufenozide has been shown to be exceptionally safe to non- S. invicta were observed in association with insecticide applications. target arthropods in both laboratory (e.g., Smagghe and Degheele, Spiders are also key D. saccharalis predators (Ali and Reagan, 1986), 1995; Medina et al., 2003) and field studies (e.g., Butler et al., and because their pitfall trap samples have limited spatial and 1997; Gurr et al., 1999; Reagan and Posey, 2001). In our study, temporal variability, these arthropods have been used as an indi- this ecdysone agonist had no measurable effects on the abundance cator group in insecticide non-target assessment (Reagan and of non-target arthropods. Among four previous insecticide aerial Posey, 2001). No major disruptive effects on spiders and other application sugarcane studies, tebufenozide was associated once predaceous non-target arthropods were observed in association with decreased ground beetles and pygmy mole crickets, but has with insecticide applications reported in our study. Nevertheless, never suppressed other non-target arthropods (Woolwine et al., predaceous beetles may have been affected by aerial applications of 1995, 1997, 1998; McAllister et al., 2002). gamma-cyhalothrin in 2007. However, because a numerical trend Gamma-cyhalothrin aerial applications were conducted for the for more abundant (2.3-fold) predaceous beetles was observed in first time in 2007 for D. saccharalis management, and possible control plots during the pre-treatment sampling period, differential limited non-target effects on predaceous beetles and immature

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Fig. 4. Relative abundance of immature ﬁeld crickets from continuous pitfall trap sampling in sugarcane plots of insecticide aerial application experiments in Louisiana, 2007. The arrow represents the date of insecticide applications. Bars followed by the same letter are not signiﬁcantly different (P > 0.05, Tukey’s HSD).

fold reduction over a 3-week period). Novaluron is considered relatively safe for beneficial arthropods in cotton agroecosystems (Ishaaya et al., 2001) and in greenhouses (Ishaaya et al., 2002). However, laboratory bioassays suggested that all life stages of Podisus maculiventris (Say) (Hemiptera: Pentatomidae), a beneficial predaceous non-target arthropod in potato (Solanum tuberosum L.) fields, were susceptible to novaluron, with both lethal and sublethal effects (Cutler et al., 2006). In laboratory bioassays, novaluron decreased the emergence rates of Trichogramma parasitoids (Bastos et al., 2006). Despite these non-target effects, novaluron seemed more compatible with biological control using Trichogramma wasps than organophosphate, carbamate, and pyrethroid insecticides (Bastos et al., 2006). In addition to data available in the scientific literature, our study suggests that the use of novaluron for D. saccharalis management in sugarcane is compatible with the conservation of most soil-associated non-target arthropod groups. Fig. 3. Relative abundance of predaceous beetles from continuous pitfall trap sampling in sugarcane plots of insecticide aerial application experiments in Louisiana, 2004 and 2007. Arrows represent dates of insecticide applications. Bars within each chart followed by the same letter are not significantly different (P > 0.05, Tukey’s HSD). 4.3. Methodological limitations

Our on-farm study documented the efficacy of aerial applica- crickets were observed. Gamma-cyhalothrin was expected to have tions of insecticides that mimicked commercial production prac- non-target impacts similar to those of lambda-cyhalothrin. In tices, yielding results with direct practical implications compared previous large plot aerial application studies conducted on sugar- to laboratory or small-plot experiments. Plot size (0.4 ha) mini- cane, Woolwine et al. (1997, 1998) did not detect non-target effects mized insecticide drift and arthropod movement from one plot to associated with lambda-cyhalothrin. However, Woolwine et al. another. Our study also documented soil-associated non-target (1995) and McAllister et al. (2002) reported deleterious non- arthropod abundance using continuous pitfall trap sampling. Esti- target effects on spiders and S. invicta, respectively. Pyrethroid mates of arthropod abundance using pitfall traps vary with abso- formulations, emulsifiable concentrate or encapsulated, varied lute population size, but also with arthropod activity and habitat among studies and may have impacted non-target selectivity structure (Southwood and Henderson, 2000). Insecticides may alter (Pogoda et al., 2001). Negative impacts of lambda-cyhalothrin on arthropod activity and bias trap catches in ways not reflecting field populations of non-target arthropods, although often changes in the functional roles of arthropod populations. Our study temporary, have also been reported in several other agro- did not assess the potential sublethal and long-term non-target ecosystems (e.g., Pilling and Kedwards, 1996; Al-Deeb et al., 2001; effects of the insecticides. Musser and Shelton, 2003). In addition to previous data on Pitfall trap estimates for most soil-associated arthropod groups lambda-cyhalothrin, our study suggests possible non-target effects were highly variable, making consistent patterns and differences for gamma-cyhalothrin that warrant a more judicious use of this difficult to detect. Pre-treatment sampling was included in our insecticide. analyses, with the effect of insecticide applications expected to be Novaluron had no measurable negative effects on non-target detected with significant treatment by sampling period interac- arthropods observed in our study, although limited non-target tions. However, the detected interactions showed that observed effects may have occurred on immature crickets (trend for a 1.5- treatment effects were not always consistent across sampling

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J.M. Beuzelin et al. / Crop Protection 29 (2010) 1168e1176 1175 periods. No broad-spectrum insecticides with documented Ali, A.D., Reagan, T.E., 1986. Influence of selected weed control practices on araneid consistent non-target effects were used in our study, as such faunal composition and abundance in sugarcane. Environ. Entomol. 15, 527e531. chemistry is no longer recommended. For experimental purposes, Barzani, A., 2001. Rimon, an IGR insecticide. Phytoparasitica 29, 59e60. future studies should include a broad-spectrum insecticide to allow Bastos, C.S., de Almeida, R.P., Suinaga, F.A., 2006. Selectivity of pesticides used on for a better comparison with biorational insecticides. Using index cotton (Gossypium hirsutum)toTrichogramma pretiosum reared on two laboratory-reared hosts. Pest Manag. Sci. 62, 91e98. cards soaked in peanut oil in addition to pitfall traps (Ali and Bessin, R.T., Reagan, T.E., Martin, F.A., 1990. A moth production index for evaluating Reagan, 1985) for S. invicta abundance estimation may also sugarcane cultivars for resistance to the sugarcane borer (Lepidoptera: Pyr- improve non-target assessment for this group. alidae). J. Econ. Entomol. 83, 221e225. Beuzelin, J.M., Reagan, T.E., Akbar, W., Flanagan, J.W., Cormier, H.J., Blouin, D.C., 2009. Impact of Hurricane Rita storm surge on sugarcane borer (Lepidoptera: Crambidae) management in Louisiana. J. Econ. Entomol. 102, 1054e1061. 4.4. Concluding remarks Butler, L., Kondo, V., Blue, D., 1997. Effects of tebufenozide (RH-5992) for gypsy moth (Lepidoptera: Lymantriidae) suppression on nontarget canopy arthro- e With a better understanding of ecological interactions occurring pods. Environ. Entomol. 26, 1009 1015. [CPR]Crop Protection Reference, Label & Product Listings, 24th ed., 2008 Vance in the agroecosystem and the use of effective but narrow-range Publishing Corp., Lenexa, KS. chemistry, considerable advances have been made over nearly five Cutler, G.C., Scott-Dupree, C.D., Tolman, J.H., Harris, C.R., 2006. Toxicity of the insect decades of Louisiana sugarcane IPM (Hensley, 1971; Reagan, 2001). growth regulator novaluron to the non-target predatory bug Podisus maculiventris (Heteroptera: Pentatomidae). Biol. Contr. 38, 196e204. However, in conjunction with the widespread use of D. saccharalis- Dhadialla, T.S., Carlson, G.R., Le, D.P., 1998. New insecticides with ecdysteroidal and susceptible sugarcane cultivars, insecticides remain the primary juvenile hormone activity. Annu. Rev. Entomol. 43, 545e569. tool for D. saccharalis management when infestations approach Gurr, G., Thwaite, W., Nicol, H., 1999. Field evaluation of the effects of the insect growth regulator tebufenozide on entomophagous arthropods and pests of economically damaging levels (Reay-Jones et al., 2005). Numerous apples. Aust. J. Entomol. 38, 135e140. insecticides have been effective in reducing D. saccharalis infesta- Hensley, S.D., 1971. Management of sugarcane borer populations in Louisiana, tions in sugarcane, but many of these insecticides were subse- a decade of change. Entomophaga 16, 133e146. quently abandoned due to either the development of resistance or Ishaaya, I., Horowitz, A.R., 1998. Insecticides with novel modes of action: an overview. In: Ishaaya, I., Degheele, D. (Eds.), Insecticides with Novel Modes of environmental issues (Vines et al., 1984; Southwick et al., 1995). For Action, Mechanism and Application. Springer-Verlag, New York, NY, pp. 1e24. over a decade, sugarcane growers have had only pyrethroids and Ishaaya, I., Kontsedalov, S., Mazirov, D., Horowitz, A.R., 2001. Biorational agents: a diacylhydrazine available, and need a more diverse array of mechanisms and importance in IPM and IRM programs for controlling agricultural pests. Meded Rijksuniv Gent Fak Landbouwkd Toegep Biol. Wet. 66, labeled chemicals. Novaluron appears to fit well in sugarcane IPM. 363e374. This chemical provides control of economically damaging infesta- Ishaaya, I., Horowitz, A.R., Tirry, L., Barazani, A., 2002. Novaluron (Rimon) a novel tions when employing recommended application timing and action IGR: mechanism, selectivity and importance in IPM programs. Meded Rijksuniv Gent Fak Landbouwkd Toegep Biol. Wet. 67, 617e626. threshold, and also has selectivity characteristics favorable to McAllister, C.D., Posey, F.R., Bacon, T.L., Reagan, T.E., 2002. Aerial insecticidal control natural enemies. Novaluron received a permanent federal label for of the sugarcane borer, 2001. Arthropod Manage. Tests 27, F112. use on sugarcane in the USA during the 2009 growing season Medina, P., Budia, F., Del Estal, P., Vinuel, E., 2003. Effects of three modern insecticides, pyriproxyfen, spinosad and tebufenozide, on survival and reproduction (www.greenbook.net, 2009), providing a needed alternative to of Chrysoperla carnea adults. Ann. Appl. Biol. 142, 55e61. tebufenozide to which D. saccharalis populations have begun to Musser, F.R., Shelton, A.M., 2003. Bt sweet corn and selective insecticides: impacts exhibit resistance. Future research will continue to include moni- on pests and predators. J. Econ. Entomol. 96, 71e80. Negm, A.A., Hensley, S.D., 1967. The relationship of arthropod predators to crop toring D. saccharalis resistance to tebufenozide and potential cross- damage inflicted by the sugarcane borer. J. Econ. Entomol. 60, 1503e1506. resistance with novaluron, but also non-target effects that might Negm, A.A., Hensley, S.D., 1969. Evaluation of certain biological control agents of the not have been detected during the on-farm experiments of 2004 sugarcane borer in Louisiana. J. Econ. Entomol. 62, 1008e1013. and 2007. Oberlander, H., Silhacek, D.L., 1998. New perspectives on the mode of action of benzoylphenyl urea insecticides. In: Ishaaya, I., Degheele, D. (Eds.), Insecticides with Novel Modes of Action, Mechanism and Application. Springer-Verlag, New York, NY, pp. 92e105. Acknowledgements Pilling, E.D., Kedwards, T.J., 18e21 November 1996. Effects of lambda-cyhalothrin on natural enemies of rice insect pests. In: Proceedings of the Brighton Crop Protection Conference: Pests & Diseases e 1996, vol. 1. British Crop Prot. Counc., This work was supported by grants from the American Sugar Farnham, UK, Brighton, UK, pp. 361e366. Cane League, the Environmental Protection Agency Strategic Agri- Pogoda, M.K., Pree, D.J., Marshall, D.B., 2001. Effects of encapsulation on the toxicity cultural Initiative Program and various insecticide companies. We of insecticides to the Oriental fruit moth (Lepidoptera: Tortricidae) and the e thank Grady Coburn (Pest Management Enterprises, Inc.) and predator Typhlodromus pyri (Acari: Phytoseiidae). Can. Entomol. 133, 819 826. Pollet, D.K., 2008. Insecticide applications for 2007. In: Sugarcane Research Annual Blaine Viator (Calvin Viator, Ph.D. and Associates, LLC) for technical Progress Report 2007. LSU AgCenter, Baton Rouge, LA, p. 137. assistance. We thank J.A. Davis, A.M. Hammond, M.J. Stout, and J.H. Posey, F.R., Bacon, T.L., McAllister, C.D., Reay-Jones, F., Reagan, T.E., 2003. Small plot Temple (Louisiana State University) for their review of the manu- assessment of insecticides against the sugarcane borer, 2002. Arthropod Manage. Tests 28, F111. script. This paper is approved for publication by the Director of the Posey, F.R., White, W.H., Reay-Jones, F.P.F., Gravois, K., Salassi, M.E., Leonard, B.R., Louisiana Agricultural Experiment Station as manuscript number Reagan, T.E., 2006. Sugarcane borer (Lepidoptera: Crambidae) Management e 2009-234-4013. threshold assessment on four sugarcane cultivars. J. Econ. Entomol. 99, 966 971. Posey, F.R., Reagan, T.E., 2000. Insecticidal control of the sugarcane borer e aerial application test, 1999. Arthropod Manage. Tests 25 (160F), 323. Reagan, T.E., 1986. Beneficial aspects of the imported fire ant: a field ecology References approach. In: Lofgren, C.S., Vander Meer, R.K. (Eds.), Fire Ants and Leaf Cutting Ants, Biology and Management. Westview Press, Boulder, CO, pp. 58e71. Akbar, W., McAllister, C.D., Reay-Jones, F.P.F., Reagan, T.E., 2004. Small plot assess- Reagan, T.E., 2001. Integrated pest management in sugarcane. LA Agric. 44 (4), 16e18. ment of insecticides against the sugarcane borer, 2003. Arthropod Manage. Reagan, T.E., Coburn, G.E., Hensley, S.D., 1972. Effects of mirex on the arthropod Tests 29, F84. fauna of a Louisiana sugarcane field. Environ. Entomol. 1, 588e591. Akbar, W., Ottea, J.A., Beuzelin, J.M., Reagan, T.E., Huang, F., 2008. Selection and life Reagan, T.E., Posey, F.R., 2001. Development of an insecticide management program history traits of tebufenozide-resistant sugarcane borer (Lepidoptera: Crambi- that enhances biological control. Proc. Int. Soc. Sugar Cane Technol. 24, dae). J. Econ. Entomol. 101, 1903e1910. 370e373. Al-Deeb, M.A., Wilde, G.E., Zhu, K.Y., 2001. Effects of insecticides used in corn, Reay-Jones, F.P.F., Akbar, W., McAllister, C.D., Reagan, T.E., Ottea, J.A., 2005. Reduced sorghum, and alfalfa on the predator Orius insidiosus (Hemiptera: Anthocor- susceptibility to tebufenozide in populations of the sugarcane borer (Lepidop- idae). J. Econ. Entomol. 94, 1353e1360. tera: Crambidae) in Louisiana. J. Econ. Entomol. 98, 955e960. Ali, A.D., Reagan, T.E., 1985. Vegetation manipulation impact on predator and prey Rodriguez, L.M., Ostheimer, E.A., Woolwine, A.E., Reagan, T.E., 1995. Efficacy of aerial populations in Louisiana sugarcane ecosystems. J. Econ. Entomol. 78, application of selected insecticides against sugarcane borer, 1994. Arthropod 1409e1414. Manage. Tests 20 (131F), 254.

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Rodriguez, L.M., Woolwine, A.E., Ostheimer, E.A., Schexnayder Jr., H.P., Reagan, T.E., [T&OR]Turf & Ornamental Reference, Label & Product Listings, seventeenth ed., 1998. Insecticidal control of the sugarcane borer-aerial application test, 1997. 2008 Vance Publishing Corp., Lenexa, KS. Arthropod Manage. Tests 23 (140F), 287. [US EPA] United States Environmental Protection Agency, 2001. EPA Pesticide Fact SAS Institute, 2008. User’s Manual, Version 9.2. SAS Institute, Cary, NC. Sheet, Novaluron. Ofﬁce of Prevention, Pesticides Environmental Protection and Sauer, R.J., Reagan, T.E., Collins, H.L., Allen, G., Campt, D., Canerday, T.D., Larocca, G., Toxic Substances Agency (7501C). Lofgren, C., Shankland, D.L., Trostle, M., Tschinkel, W.R., Vinson, S.B., 7e10 June Vines, R.C., Reagan, T.E., Sparks, T.C., Pollet, D.K., 1984. Laboratory selection of 1982. Imported ﬁre ant management strategies-Panel VI. In: Proceedings of the Diatraea saccharalis (F.) (Lepidoptera: Pyralidae) for resistance to fenvalerate Symposium on the Imported Fire Ant. EPA/USDA (APHIS) 0-389-890/70, and monocrotophos. J. Econ. Entomol. 77, 857e863. Atlanta, GA, pp. 91e110. White, W.H., Viator, R.P., Dufrene, E.O., Dalley, C.D., Richard Jr., E.P., Tew, T.L., 2008. Schexnayder, H.P., Ostheimer, E.A., Younis, A.M., Reagan, T.E., 1999. Insecticidal Re-evaluation of sugarcane borer (Lepidoptera: Crambidae) bioeconomics in control of the sugarcane borer-aerial application test, 1998. Arthropod Manage. Louisiana. Crop Prot. 27, 1256e1261. Tests 24 (120F), 299. Woolwine, A.E., Rodriguez, L.M., Ostheimer, E.A., Reagan, T.E., 1995. Effects of Schexnayder, H.P., Reagan, T.E., Ring, D.R., 2001. Sampling for the sugarcane borer aerially applied insecticide for SCB on non-target arthropods, 1994. Arthropod (Lepidoptera: Crambidae) on sugarcane in Louisiana. J. Econ. Entomol. 94, 766e771. Manage. Tests 20 (134F), 257. Smagghe,G., Degheele,D.,1995. Selectivityofnonsteroidal ecdysteroid agonists RH5849 Woolwine, A.E., Rodriguez, L.M., Ostheimer, E.A., Reagan, T.E., 1997. Effects of and RH 5992 to nymphs and adults of predatory soldier bugs, Podisus nigrispinus and insecticides on non-target insects in sugarcane, 1996. Arthropod Manage. Tests P. maculiventris (Hemiptera: Pentatomidae). J. Econ. Entomol. 88, 40e45. 22 (135F), 322. Southwick, L.M., Willis, G.H., Reagan, T.E., Rodriguez, L.M., 1995. Residues in runoff Woolwine, A.E., Rodriguez, L.M., Ostheimer, E.A., Reagan, T.E., 1998. Impact of and on leaves of azinphosmethyl and esfenvalerate applied to sugarcane. sugarcane borer control insecticides on non-target arthropods, 1997. Arthropod Environ. Entomol. 24, 1013e1017. Manage. Tests 23 (142F), 288. Southwood, T.R.E., Henderson, P.A., 2000. Ecological Methods, third ed. Blackwell Diamond 0.83 EC, supplemental labels. www.greenbook.net, 2009. http://www. Science, Malden, MA. greenbook.net/Products.aspx?PID¼45948&sec¼supp consulted on 09.10.09.

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COMMUNITY AND ECOSYSTEM ECOLOGY Seasonal Infestations of Two Stem Borers (Lepidoptera: Crambidae) in Non-Crop Grasses of Gulf Coast Rice Agroecosystems

J. M. BEUZELIN,1 A. ME´ SZA´ ROS, T. E. REAGAN, L. T. WILSON,2 M. O. WAY,2 3 4 D. C. BLOUIN, AND A. T. SHOWLER Department of Entomology, Louisiana Agricultural Experiment Station, Louisiana State; University Agricultural Center, Baton Rouge, LA 70803

Environ. Entomol. 40(5): 000Ð000 (2011); DOI: 10.1603/EN11044 AQ: 1 ABSTRACT Infestations of two stem borers, Eoreuma loftini (Dyar) and Diatraea saccharalis (F.) (Lepidoptera: Crambidae), were compared in noncrop grasses adjacent to rice (Oryza sativa L.) Þelds. Three farms in the Texas rice Gulf Coast production area were surveyed every 6Ð8 wk between 2007 and 2009 by using quadrat sampling along transects. Although D. saccharalis densities were relatively low, E. loftini average densities ranged from 0.3 to 5.7 immatures per m2 throughout the 2-yr period. Early annual grasses including ryegrass, Lolium spp., and brome, Bromus spp., were infested during the spring, whereas the perennial johnsongrass, Sorghum halepense (L.) Pers., and VaseyÕs grass, Paspalum urvillei Steud., were infested throughout the year. Johnsongrass was the most prevalent host (41Ð78% relative abundance), but VaseyÕs grass (13Ð40% relative abundance) harbored as much as 62% of the recovered E. loftini immatures (during the winter). Young rice in newly planted Þelds did not host stem borers before June. April sampling in fallow rice Þelds showed that any available live grass material, volunteer rice or weed, can serve as a host during the spring. Our study suggests that noncrop grasses are year-round sources of E. loftini in Texas rice agroecosystems and may increase pest populations.

KEY WORDS Mexican rice borer, Eoreuma loftini (Dyar), sugarcane borer, Diatraea saccharalis (F.), alternate hosts

Eoreuma loftini (Dyar) and Diatraea saccharalis (F.) stalk.” E. loftini has been collected from numerous (Lepidoptera: Crambidae) are stem boring pests of grasses (Poaceae), Canna spp. (Cannaceae), and bul- sugarcane (hybrids of Saccharum spp.), rice (Oryza rush (Cyperaceae: Scirpus validus Vahl) (Osborn and sativa L.), corn (Zea mays L.), and sorghum [Sorghum Phillips 1946, Johnson 1984, Showler et al. 2011). D. bicolor (L.) Moench] crops in the Gulf Coast region saccharalis larvae also feed on a range of noncrop (Long and Hensley 1972, Johnson 1984). Although D. grasses comparable to that reported for E. loftini saccharalis has been established in the southeastern (Jones and Bradley 1924, Holloway et al. 1928, Box United States since the 1850s (Stubbs and Morgan 1956, Bessin and Reagan 1990). Beuzelin et al. (2010), 1902), E. loftini has expanded its range in a northeast- by using potted sentinel plants grown under natural erly direction since its Þrst detection in south Texas in infestations, conÞrmed that a number of Gulf Coast 1980 (Reay-Jones et al. 2007). E. loftini was reported region noncrop grasses were hosts for both E. loftini in 2008 for the Þrst time in Louisiana (Hummel et al. and D. saccharalis. Amazon sprangletop [Leptochloa 2010), where annual economic losses in sugarcane and panicoides (Presl) Hitch], a common weed in rice rice may become as severe as $250 million within the Þelds, was a highly suitable host, harboring the highest next decades (Reay-Jones et al. 2008). stem borer infestations with Ͼ75% of the plants in- In addition to crop hosts, Van Zwaluwenburg fested with at least one larva. Johnsongrass [Sorghum (1926) observed that E. loftini “attacks practically all halepense (L.) Pers.] and VaseyÕs grass (Paspalum ur- the grasses large enough to afford it shelter within the villei Steud.), two ubiquitous perennial grasses, also supported complete larval development of both species. In contrast, broadleaf signalgrass [Urochloa platy- 1 Corresponding author, e-mail: [email protected]. 2 Texas A&M AgriLife Research and Extension Center at Beau- phylla (Munro ex C. Wright) R.D. Webster], a com- mont, Texas A&M University, Beaumont, TX 77713. mon weed near rice Þelds, proved to be a poor stem 3 Department of Experimental Statistics, Louisiana Agricultural Ex- borer host (Beuzelin et al. 2010, Showler et al. 2011). periment Station, Louisiana State University Agricultural Center, Ba- In agroecosystems, the effects of vegetation diver- ton Rouge, LA 70803. 4 USDAÐARS, Kika de la Garza Subtropical Agricultural Research sity on arthropod population dynamics are complex Center, Weslaco, TX 78596. and variable (Andow 1991, Norris and Kogan 2005).

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Fig. 1. (A) E. loftini and (B) D. saccharalis immature densities (LS means) in noncrop habitats adjacent to rice Þelds in Texas, 2007Ð2009. Total immatures are the sum of all larvae and pupae. Error bars represent ϩ SE for total immatures LS means.

Nearby plants may increase habitat availability for quadrats randomly selected within 10 m of the center predators and offer additional shelter and food for of each location. If sections of transects were mowed their prey, thus increasing natural enemy density and by rice producers during the growing season (MarchÐ subsequently decreasing insect pest populations (Le- August), they were excluded from sampling for at least tourneau 1987, Russell 1989). Conversely, nearby two consecutive sampling dates. If sections were plants may increase plant host availability and release mowed during the postseason or winter, when plant additional host-Þnding stimuli for insect pests, thus growth is the slowest, they were permanently ex- enhancing pest populations (Karban 1997, Tindall et cluded from sampling. al. 2004). Previous studies have suggested that non- For each quadrat, all grass-like plants, hereafter crop hosts could play a key role in E. loftini and D. referred to as graminoids, were cut at the soil surface saccharalis population dynamics in Gulf Coast agro- level and placed in 50-liter plastic bags. Bags were ecosystems (Beuzelin et al. 2010, Showler et al. 2011). stored at the Texas A&M AgriLife Research and Ex- However, the quantiÞcation of noncrop host presence tension Center at Beaumont, TX, in a cold room at and use has been limited, especially when crop hosts 13Ð15ЊC and processed within 1 wk. Noncrop gramin- are absent or too young to sustain stem borer devel- oids present in each quadrat were identiÞed to genus opment. In this study, surveys were conducted to or species, and their relative abundance was visually quantify the seasonal abundance of E. loftini, D. sac- estimated per volume of sampled plant material. The charalis, and their noncrop hosts in Þeld margins and number of tillers for each graminoid was recorded, surrounding habitats of Texas rice agroecosystems. except during the Þrst two sampling dates in the Þrst year of the study. During the second year of the study (April 2008-February 2009), average tiller size (from Materials and Methods base to farthest tip) was determined for each gramin- AQ: 2 Transect Sampling in Noncrop Habitats. Three oid in each quadrat from all (if tillers Յ4) or four farms were surveyed in the Texas Gulf Coast rice randomly selected tillers. Average tiller stem diameter production area (Jefferson County, 30.059Њ N, 94.279Њ (as measured Ϸ 1 cm below the Þrst apparent node, W; Chambers County, 29.855Њ N, 94.544Њ W; and Jack- or Ϸ 3 cm above the cut if no node present) was also son County, 29.027Њ N, 96.439Њ W). These farms were determined. For tillers with ßattened stems, the av- sampled every 6Ð8 wk for 2 yr (April 2007-February erage between the major and minor stem diameters 2008, April 2008-February 2009). For each year, two was recorded. During the second year of the study, transects were located along noncultivated Þeld mar- plant phenology was determined visually as the pro- gins, roadsides, or ditches on each farm. Transects portion of plant material that was vegetatively grow- averaged 564 Ϯ 63 (SE) m in length and were within ing, ßowering, mature, senescent, and dead. 250Ð500 m of the closest rice Þelds. The minimum and All graminoids collected from the quadrats were maximum distances between two transects on a farm visually examined for stem borer feeding injury. When in a year averaged 302 Ϯ 142 (SE) and 1026 Ϯ 210 (SE) a discoloration of the leaf sheath or a hole in the stem m, respectively. The average distance between the was observed, injured plants were dissected to recover centers of two transects was 678 Ϯ 169 (SE) m. On E. loftini and D. saccharalis larvae and pupae, hereafter F1 each sampling date (Fig. 1), three representative lo- referred to as immatures. Immatures were sight-iden- cations per transect were sampled, with three 1-m2 tiÞed using characters reported in Browning et al.

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(1989), Legaspi et al. (1997), and Solis (1999). For the arcane Research Unit, Houma, LA (Þrst year of the 0Ð6% and 0Ð12% of E. loftini and D. saccharalis larvae, study) and the LSU AgCenter Rice Entomology Lab- respectively, that were recovered in bags on each oratory, Baton Rouge, LA (second year of the study). sampling date because they had crawled out of Trap catches were adjusted by the length of the sam- graminoid stems during sample transportation or stor- pling period to express moth abundance on a moths age, the original host plant was also determined. When per trap per day basis. a quadrat sample was comprised of a single graminoid, Data Analyses. All univariate statistical analyses larvae recovered in the bag were attributed to that were conducted using linear mixed models in Proc graminoid. When several graminoids were in a quadrat GLIMMIX (SAS Institute 2008). The KenwardÐRoger sample, larvae were attributed to a host plant based on adjustment for denominator degrees of freedom was observed injury. The size of larvae was visually de- used in all models to correct for inexact F distributions. termined, with small, medium-sized, and large larvae Unless stated otherwise, least square means Ϯ stan- corresponding approximately to Þrst and second, dard errors from the LSMEANS statement output third, and fourth and Þfth instars, respectively. De- (Proc GLIMMIX, SAS Institute 2008) are reported. pendent on the number of immatures recovered on When Þxed effects were detected (P Ͻ 0.05), TukeyÕs each sampling date, 10Ð60 randomly selected E. loftini honestly signiÞcant difference (HSD) (␣ ϭ 0.05) was and D. saccharalis immatures were reared on artiÞcial used to assist in the interpretation of observed patterns diet (Southland Product Inc., Lake Village, AR) until and differences in least square means. E. loftini and D. adult eclosion to conÞrm species identiÞcation (Klots saccharalis densities (number of immatures per m2) 1970, Legaspi et al. 1997). were compared using univariate models with year, Transect Sampling in Rice Habitats. During the date, and year ϫ date as Þxed effects. Farm, farm ϫ early April sampling date of each year of the study, one year, transect(farm ϫ year), date ϫ transect(farm ϫ fallowed rice Þeld was selected and sampled on each year), and location(date ϫ transect farm ϫ year) were farm to verify whether old rice stubble could host E. random effects. loftini and D. saccharalis. Fallowed rice Þelds were Relative abundance was recorded simultaneously directly adjacent (Ͻ35 m) to one noncrop habitat for numerous graminoids from the same observation transect for at least one-third of the length of that units (i.e., quadrat). Thus, before univariate analyses, transect, or were within 50 m of the end of one non- multivariate analyses including the 12 most prevalent crop habitat transect. In addition, one rice Þeld graminoids (Table 1) were conducted using Proc T1 planted between March and May was selected and GLM (SAS Institute 2008) with a MANOVA state- sampled each year on each farm in early April, late ment. Multivariate and univariate analyses included May, and late June to verify whether newly planted the same Þxed and random effects as for stem borer rice could host stem borers. Newly planted rice Þelds density comparisons. Graminoid tiller densities were were directly adjacent (Ͻ35 m) to one noncrop hab- compared using the same method as for plant relative itat transect for at least one-third of the length of that abundance analyses. Tiller size and stem diameter, transect. For each fallowed and newly planted rice which were recorded during the second year of the Þeld, one transect was drawn and Þve (2007) or three study, were each compared using univariate models (2008) sampling zones with three 1-m2 quadrats in with date as Þxed effect and farm, transect(farm), each were sampled for stem borer injury and imma- date ϫ transect(farm), and location(date ϫ transect ture presence. farm) as random effects. Adult Stem Borer Trapping. E. loftini and D. sac- For each of the six graminoids consistently infested charalis moths were trapped on each farm near the with stem borers (Table 2), percentages of recovered T2 center of each noncrop habitat transect for 7Ð14 d E. loftini as affected by year and date were compared. after transect sampling during the spring, summer, and By transect and sampling date, the percentage of re- fall. After the December and February transect sam- covered E. loftini in a selected graminoid was com- pling of noncrop habitats, moth trapping averaged 33 puted as the sum of E. loftini collected from that and 15 d, respectively, because of reduced accessibil- selected plant multiplied by 100 and divided by the ity to trapping locations. Two traps per transect, one sum of E. loftini collected from all plants. When E. for E. loftini and one for D. saccharalis, were posi- loftini were not collected from a transect on a sampling tioned Ϸ10 m apart and placed 1.5 m above the soil date, percentages of recovered E. loftini were not surface on a metal pole. Bucket traps (Unitrap, Great computed. In addition, when a graminoid was not Lakes IPM, Vestaburg, MI) were used for E. loftini recorded from a transect, the percentage of recovered moth monitoring. Each trap was baited with a syn- E. loftini was considered zero. A multivariate analysis thetic female E. loftini sex pheromone lure (Luresept, including the six graminoids consistently infested with Hercon Environmental, Emigsville, PA) and con- stem borers was conducted before univariate analyses. tained an insecticidal strip (Vaportape II, Hercon En- Fixed effects for the multivariate model (Proc GLM vironmental, Emigsville, PA). Sticky wing traps with MANOVA statement, SAS Institute 2008) were (Pherocon 1C Trap, Tre´ce´ Inc., Adair, OK) were used year, date, and year ϫ date whereas random effects for D. saccharalis moth monitoring. Each trap was were farm, farm ϫ year, and transect(farm ϫ year). baited with two D. saccharalis female pupae nearing Each univariate model for each graminoid shared the adult eclosion. D. saccharalis female pupae from lab- same Þxed and random effects as the multivariate oratory rearing were provided by the USDA-ARS Sug- model. For each of the two most prevalent graminoids

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Table 1. Statistical comparisons for abundance and size estimates of 12 grasses commonly found in non-crop habitats adjacent to rice ﬁelds, Texas, 2007–2009

Relative abundance Tiller density Tiller size Tiller stem diam Plant Year Date Year ϫ date Year Date Year ϫ date Date Date Johnsongrass F 11.28 1.79 1.07 4.76 3.50 6.13 11.73 1.15 df 1, 2.0 6, 227.2 6, 227.2 1, 2.2 6, 194.5 4, 194.6 6, 29.4 6, 22.9 P 0.078 0.103 0.383 0.148 0.003 Ͻ0.001 Ͻ0.001 0.365 VaseyÕs grass F 1.59 1.96 1.58 0.60 1.31 0.45 18.93 2.27 df 1, 2.0 6, 227 6, 227 1, 2.4 6, 194.2 4, 194.2 6, 22.1 6, 56.7 P 0.335 0.073 0.153 0.507 0.255 0.771 Ͻ0.001 0.049 Ryegrass F 3.25 10.41 2.46 0.02 7.76 0.04 12.32 1.55 df 1, 9.9 6, 56.5 6, 56.5 1, 17.4 6, 628.1 4, 628.1 3, 25.6 3, 3.38 P 0.102 Ͻ0.001 0.035 0.877 Ͻ0.001 0.997 Ͻ0.001 0.339 Brome F 0.01 8.55 0.47 0.00 6.09 0.01 7.06 4.02 df 1, 4.0 6, 65.2 6, 65.2 1, 4.9 6, 195.6 4, 195.6 3, 4.6 3, 6.9 P 0.938 Ͻ0.001 0.830 0.947 Ͻ0.001 1.000 0.035 0.060 Canarygrass F 0.26 4.10 0.15 0.00 1.91 0.00 6.48 0.62 df 1, 235 6, 235 6, 235 1, 2.4 6, 195.8 4, 195.8 1, 8.8 1, 1.7 P 0.614 0.001 0.990 0.993 0.081 1.000 0.034 0.526 Angleton bluestem F 0.95 2.51 0.51 0.98 1.40 0.53 0.46 2.96 df 1, 2.0 6, 60.1 6, 60.1 1, 2.1 6, 55.9 6, 55.9 6, 3.2 6, 3.7 P 0.433 0.031 0.798 0.420 0.232 0.716 0.811 0.170 Caucasian bluestem F 0.27 1.51 0.57 0.16 0.80 0.82 0.69 0.38 df 1, 7.9 6, 57.4 6, 57.4 1, 8.1 6, 193.6 4, 193.6 3, 2.5 3, 3.0 P 0.620 0.191 0.754 0.700 0.573 0.512 0.625 0.774 Hairy crabgrass F 1.28 3.41 0.93 1.70 1.96 1.24 1.80 1.58 df 1, 10.0 6, 60.2 6, 60.2 1, 10.1 6, 49.0 4, 49.0 4, 11.2 4, 12.8 P 0.284 0.006 0.482 0.221 0.089 0.308 0.199 0.239 Jungle rice F 0.29 1.52 1.90 0.53 1.00 2.23 2.28 4.86 df 1, 10.0 6, 60.2 6, 60.2 1, 10.4 6, 47.0 4, 47.0 1, 1 1, 4.5 P 0.461 0.187 0.095 0.484 0.484 0.080 0.372 0.085 Longtom F 0.34 1.17 1.37 0.01 0.78 1.46 1.80 0.22 df 1, 4.0 6, 227 6, 227 1, 8.3 6, 193.3 4, 193.3 4, 12 4, 9.9 P 0.589 0.323 0.228 0.920 0.583 0.215 0.195 0.927 Torpedo grass F 0.77 0.80 1.19 0.88 0.93 1.07 2.22 1.21 df 1, 8.0 6, 60.1 6, 60.1 1, 8.0 6, 60.2 4, 60.2 5, 18 5, 5.3 P 0.407 0.570 0.323 0.375 0.482 0.393 0.097 0.414 Non-identiÞed perennial grassa F 0.59 1.78 0.30 0.55 1.20 0.34 9.05 9.86 df 1, 2 6, 60.2 6, 60.2 1, 2.1 6, 49.6 4, 49.6 5, 6.5 4, 14 P 0.523 0.118 0.936 0.533 0.321 0.852 0.007 0.001

a No reproductive parts and non-distinctive vegetative material. consistently infested with E. loftini, the percentage of recovered almost exclusively from the two most prev- recovered E. loftini per percent of plant relative abun- alent graminoid species, only univariate analyses com- dance was determined. By transect and sampling date, paring year and date for these two plant species were it was computed as the percentage of recovered E. conducted (same model as for proportion of recov- loftini in a selected graminoid divided by the average ered E. loftini analysis). E. loftini and D. saccharalis relative abundance for that selected plant. Only uni- moth trap catches as affected by year and date were variate analyses comparing percentages of recovered also compared using the same univariate models. E. loftini per percent of plant relative abundance as affected by year and date were conducted (same Results model as for percentage of recovered E. loftini analysis). Eoreuma loftini and D. saccharalis Infestations in The percentage of recovered D. saccharalis and Noncrop Habitats. E. loftini larvae and pupae were recovered D. saccharalis per percent of plant relative recorded in noncrop habitats during each sampling abundance were computed using the same method as date (Fig. 1A). There was a numerical trend (F ϭ 8.78; for E. loftini. Because D. saccharalis infestations were df ϭ 1, 2.0; P ϭ 0.097) with 2.5-fold greater E. loftini

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Table 2. Statistical comparisons for E. loftini infestations re- differences across dates occurred (WilksÕ Lambda ϭ covered from six grasses commonly found in non-crop habitats 0.0269; F ϭ 2.86; df ϭ 72, 218.0; P Ͻ 0.001) for at least adjacent to rice ﬁelds, Texas, 2007–2009 one of the 12 graminoids. The year ϫ date interaction ϭ ϭ Percentage of was not signiÞcant (WilksÕ Lambda 0.2921; F 1.19; Plant recovered E. loftini df ϭ 48, 152.3; P ϭ 0.210). For both relative abundance Year Date Year ϫ date and tiller density, the multivariate effect of year could not be tested because of an insufÞcient number of Johnsongrass F 9.67 4.99 0.56 error degrees of freedom. df 1, 8.4 6, 55.8 6, 55.7 Johnsongrass was the most often encountered and P 0.014 Ͻ0.001 0.761 abundant graminoid (Fig. 2). However, johnsongrass F2 VaseyÕs grass relative abundance did not differ across dates despite F 0.81 5.88 1.03 Յ df 1, 2.0 6, 55.2 6, 55.1 trends (P 0.1, Table 1) for a minimum in April P 0.464 Ͻ0.001 0.418 (50.4 Ϯ 7.0% across both years). Trends (P Յ 0.1, Table Ryegrass 1) for a greater relative abundance were also observed F 5.82 7.07 3.65 during the second year of the study (70.8 Ϯ 6.2 versus df 1, 2.2 6, 61.7 6, 61.7 Ϯ P 0.126 Ͻ0.001 0.004 51.9 6.2%). Tiller density (Fig. 2B) was affected by Brome date (Table 1), with a maximum observed in August F 1.06 5.24 2.12 (44.8 Ϯ 3.9 tillers per m2). Johnsongrass size changed df 1, 4.2 6, 61.4 6, 61.4 with date (Table 1) with the tallest tillers observed in P 0.360 Ͻ0.001 0.064 Canarygrass October, and the shortest in February and April (Fig. F 2.62 1.44 1.44 3A). In addition, johnsongrass stem diameter in- F3 df 1, 7.0 6, 52.1 6, 52.1 creased from the spring to the winter (Table 1; Fig. P 0.150 0.218 0.218 3B). During the early spring, dead leaßess tillers re- Angleton bluestem F 0.13 1.57 1.22 maining from the previous year as well as young green df 1, 63.1 6, 63.0 6, 63.0 vegetative growth with an occasional emerging ßower P 0.717 0.171 0.310 were recorded (Fig. 4A). Flowering peaked between F4 April and late June, and a mixture of vegetative, ßow- ering, and mature tillers occurred between May and densities in these habitats during the second year of August (Fig. 4A). Mature johnsongrass showed aging the study than during the Þrst year (4.01 Ϯ 0.73 versus foliage and empty seed heads, but also green offshoots 1.63 Ϯ 0.73 immatures per m2). Densities changed growing from nodal buds. During the fall, a majority with date (F ϭ 2.52; df ϭ 6, 60.2; P ϭ 0.030), increasing of mature and senescing tillers were present; but veg- from early spring to late fall (Fig. 1A). Across both etative and ßowering johnsongrass was observed in years, the lowest E. loftini densities were observed in areas mowed in the spring or summer. During the April (1.23 Ϯ 0.83 immatures per m2), whereas den- winter, a majority of tillers were dead or senescing. In sities were greater in October (3.1-fold) and Decem- addition, young vegetative tillers had emerged in Feb- ber (3.2-fold). As shown by the nonsigniÞcant year ϫ ruary with 0Ð14 tillers per m2 for an average of 1.8 date interaction (F ϭ 1.42; df ϭ 6, 60.2, P ϭ 0.222), tillers per m2 (Fig. 4A). differences in E. loftini densities as affected by date did VaseyÕs grass was the second most prevalent gramin- not change between the Þrst and the second year of oid adjacent to rice Þelds (Fig. 2). Although VaseyÕs the study. For D. saccharalis, differences in densities grass relative abundance was not different among in noncrop habitats were not detected (F ϭ 1.51; df ϭ dates (Table 1), trends (P Յ 0.1) for a lower abun- 1, 2.0; P ϭ 0.344) between the Þrst and second year dance in February (15.1 Ϯ 6.0% across both years) and (0.25 Ϯ 0.08 and 0.11 Ϯ 0.08 immatures per m2,re- a greater abundance in late June (29.1 Ϯ 6.0% across spectively) of the study (Fig. 1B). Although changes both years) were observed. Differences in tiller den- in D. saccharalis densities were not detected among sities between years and among dates were not de- dates (F ϭ 1.67; df ϭ 6, 66.2; P ϭ 0.143), densities were tected (Table 1; Fig. 2B). During the early spring, high in October 2007 (0.94 Ϯ 0.19 immatures per m2, VaseyÕs grass bunches exhibited dead plant material Fig. 1B) but not in October 2008, as evidenced by the from earlier growth, green material in a vegetative year ϫ date interaction (F ϭ 2.39; df ϭ 6, 66.2; P ϭ stage, and a small proportion of ßowering tillers (Fig. 0.038). 4B). Flowering peaked in the spring, and during the Graminoid Composition in Noncrop Habitats. The summer, plants showed a mixture of vegetative, ßow- 12 most prevalent graminoids surrounding rice Þelds ering, mature, and senescing tillers. The proportion of in Texas are listed in Table 1. The multivariate analysis senescing tillers increased in the fall. In the winter, shows that the relative abundance of at least one of bunches of VaseyÕs grass were composed of dead and these graminoids changed with date (WilksÕ green vegetative tillers (Fig. 4B). VaseyÕs grass tillers Lambda ϭ 0.0618; F ϭ 2.02, df ϭ 72, 218.0; P Ͻ 0.001), were the tallest in August, 1.9- and 1.5-fold taller than but changes occurred to a different extent between in April and December, respectively (Table 1; Fig. the Þrst and second year of the study (WilksÕ 3A). Tiller stem diameter (Table 1) was larger in May Lambda ϭ 0.2189; F ϭ 1.53; df ϭ 48, 152.3; P ϭ 0.027 than in October (1.2-fold, Fig. 3B). for the year ϫ date interaction). In addition, multi- Ryegrass (Lolium spp.), brome (Bromus spp.), variate analysis comparing tiller density showed that and canarygrass (Phalaris spp.) are annual grasses

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Fig. 2. (A) Relative abundance and (B) tiller density (LS means) for seven of the most commonly sampled grasses in noncrop habitats adjacent to rice Þelds in Texas, 2007Ð2009. When a grass did not occur, markers were not included on the Þgure. that did not occur in August, October, or December. sities in the early spring (April) than during the late Relative abundance for ryegrass showed trends (P Յ winter (February) (Fig. 2B). Ryegrass tiller size 0.1, Table 1) for being greater (2.5-fold) during the differed with date (Table 1). Tillers measured Ϸ 70 Þrst year (Fig. 2A). In addition, ryegrass relative cm during the spring (Fig. 3A), and were the small- abundance peaked in April (Fig. 2A). As shown by est in February (2.9-fold smaller than in April). the year ϫ date interaction (Table 1), changes in Differences in ryegrass tiller stem diameter (Fig. relative abundance between April and May, and 3B) were not detected (Table 1). Brome and ca- between May and late June, occurred to a greater narygrass relative abundances were affected by date extent in 2007 (2.9-fold and 58.4-fold, respectively) (Table 1), peaking in April and May (Fig. 2A). than in 2008 (2.3-fold and 11.5-fold, respectively) Brome tillers occurred at greater densities in Feb- (Fig. 2A). Ryegrass tillers occurred at greater den- ruary and April than in May (Fig. 2B). Canarygrass

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Fig. 3. (A) Tiller size and (B) stem diameter (LS means ϩ SE) for seven of the most commonly sampled grasses in noncrop habitats adjacent to rice Þelds in Texas, 2008Ð2009. was not collected in February, and differences in early April, senescent or dead in May, and dead in tiller density from April to late June were not de- late June (Fig. 4). However, late brome growth tected (Table 1). Similarly to ryegrass, brome tillers appeared in the vegetative stage in May and June. In were the shortest in February (Fig. 3A). In addition, February, while young vegetative ryegrass and brome tillers collected in February showed a trend brome tillers were growing, canarygrass was not (P Յ 0.1, Table 1) for a smaller stem diameter (Fig. (Fig. 4). 3B). Canarygrass tillers collected in April were Angleton bluestem [Dichanthium aristatum (Poir.) shorter (Table 1) than those tillers sampled in May C.E. Hubbard] and Caucasian bluestem [Bothriochloa (1.3-fold, Fig. 3A); however, stem diameter did not bladhii (Retz.) S.T. Blake] are two perennial grasses change (Table 1; Fig. 3B). Ryegrass, brome, and that occurred sporadically on the study farms, but canarygrass typically were ßowering or mature in were sometimes abundant where present. Differences

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Fig. 4. Stem borer noncrop host phenology in habitats adjacent to rice Þelds in Texas, 2008Ð2009. in Angleton bluestem relative abundance were de- spring to the fall, senescent tillers with dry foliage in tected (Table 1), with relative abundance greater in December, and both dead tillers and vegetative the fall and winter than during the spring and summer growth in February. (Fig. 2A). However, differences in tiller density (Fig. Hairy crabgrass [Digitaria sanguinalis (L.) Scop.] 2B), size (Fig. 3A), and stem diameter (Fig. 3B) were and jungle rice [Echinochloa colona (L.) Link] are two not detected (Table 1). For Caucasian bluestem, dif- summer annual grasses that were found in noncrop ferences in relative abundance (Fig. 2A), tiller density habitats directly adjacent to rice Þelds during the (Fig. 2B), size (Fig. 3A), and stem diameter (Fig. 3B) summer and the fall. Hairy crabgrass relative abun- were not detected (Table 1). Angleton bluestemÕs dance changed with date (Table 1), peaking between phenology was similar to that of johnsongrass. Cau- August and October, with a maximum of 4.7 Ϯ 1.1% casian bluestem exhibited vegetative growth from the recorded in October 2007. However, only limited ev-

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October 2011 BEUZELIN ET AL.: STEM BORER INFESTATIONS IN NON-CROP GRASSES 9 idence for differences in tiller density was detected E. loftini Infestations in Noncrop Plants. Multivar- (Table 1), even with a maximum of 4.3 Ϯ 1.3 tillers per iate analyses showed that for at least one of the six m2 (October 2007). When hairy crabgrass tillers were graminoids consistently infested with stem borers present, both size (34.2 Ϯ 28.1Ð94.3 Ϯ 14.2 cm) and (Table 2) the percentage of recovered E. loftini dif- stem diameter (2.1 Ϯ 0.2Ð2.5 Ϯ 0.1 mm) were not fered with date (WilksÕ Lambda ϭ 0.1058; F ϭ 4.12, different among dates (Table 1). Similarly to hairy df ϭ 36, 222.3, P Ͻ 0.001). The year ϫ date interaction crabgrass, jungle rice does not grow in the spring, and was signiÞcant (WilksÕ Lambda ϭ 0.2515; F ϭ 2.28; plants were not collected in April and May. However, df ϭ 36, 222.3; P Ͻ 0.001). The multivariate effect of differences among dates in relative abundance and year could not be tested because of an insufÞcient tiller density (with respective maxima of 3.7 Ϯ 0.7% number of error degrees of freedom. and 6.0 Ϯ 1.3 tillers per m2 in August 2007 were not The percentage of E. loftini recovered from john- detected (Table 1). When jungle rice tillers were songrass differed among dates (Fig. 5A, Table 2), in- F5 present, differences in size (42.5 Ϯ 5.6Ð49.5 Ϯ 5.5 cm) creasing from April to August (2.2-fold) and decreas- were not detected, but there were trends (P Յ 0.1, ing during the fall and winter (2.3-fold). In addition, Table 1) for a larger stem diameter in October com- the univariate analysis (Table 2) suggested that the pared with December (2.3 Ϯ 0.2 and 1.6 Ϯ 0.2 mm, percentage of E. loftini recovered from johnsongrass respectively). Hairy crabgrass and jungle rice were was greater (1.5-fold) during the second year of the vegetative early in the summer, ßowering in August, study than during the Þrst. During the winter, E. loftini and senescing in October. Only decaying tillers were infesting johnsongrass were observed near nodes or observed in December. within 5 cm of the soil surface, where visibly live plant A nonidentiÞed perennial grass with no reproduc- tissue was found inside stems. In addition, dead des- tive parts and nondistinctive vegetative material was iccated E. loftini larvae were observed in February and collected in wet areas of noncrop habitats surrounding early April. The percentage of E. loftini recovered per rice Þelds. The relative abundance and tiller density percent of johnsongrass relative abundance (Fig. 5B) for this grass did not differ throughout the seasons changed with date (F ϭ 4.59; df ϭ 6, 56.3; P ϭ 0.001), (Table 1), with a maximum of 4.0 Ϯ 1.8% (August following a pattern comparable to that of the percent- 2007) and 9.9 Ϯ 2.7 tillers per m2 (June 2007), respec- age of recovered E. loftini. Throughout the seasons, tively. Tiller size and stem diameter changed with date the percentage of E. loftini recovered from VaseyÕs (Table 1), with size increasing from spring to fall grass changed (Table 2), with an increase (3.3-fold) (31.3 Ϯ 5.5 cm in April to 79.0 Ϯ 7.8 cm in October) from April to late June, followed by a decrease (2.2- and stem diameter being larger in the spring (3.6 Ϯ 0.2 fold) in August and an increase (3.2-fold) during the mm in April) than during the summer and fall (2.3 Ϯ fall and winter (Fig. 5A). The percentage of recovered 0.1 mm in June). In poorly drained areas, torpedo grass E. loftini per percent of VaseyÕs grass relative abun- (Panicum repens L.) was also collected. Relative abundance changed with date (F ϭ 7.70; df ϭ 6, 60; P Ͻ dance and tiller density for torpedo grass were not 0.001), peaking during the winter (Fig. 5B). At this different throughout the seasons (Table 1), with a time of the year, pupae were observed in dry sections maximum of 1.5 Ϯ 0.6% (February 2009) and 3.6 Ϯ 1.2 of the plants while larvae fed within green vegetative tillers per m2 (December 2008), respectively. tillers close to soil level. Ryegrass and brome harbored Whereas differences in tiller stem diameter (1.5 Ϯ E. loftini during the spring in 2007 and 2008 (Fig. 5A), 0.2Ð1.9 Ϯ 0.1 mm) were not detected (Table 1), there and one E. loftini larva was recovered from brome in were trends (P Յ 0.1, Table 1) for shorter tillers in the February 2008. The percentage of E. loftini recovered spring than in the fall (34.0 Ϯ 8.2 cm in April versus from ryegrass in April was greater (6.1-fold) during 60.2 Ϯ 6.7 cm in October). the Þrst year of the study than during the second Longtom (Paspalum denticulatum Trin.) was col- (Table 2). A comparable trend (P Յ 0.1, Table 2) was lected sporadically with relative abundance and til- observed for E. loftini recovered from brome (4.0- ler density reaching 2.3 Ϯ 0.7% and 1.6 Ϯ 0.6 tillers fold). E. loftini infestations in canarygrass were found per m2, respectively, in June 2007 (Table 1). When only during the spring 2007 (Fig. 5A), but differences longtom tillers were present, both their size (44.3 Ϯ in percentages of recovered E. loftini were not de- 13.1Ð72.9 Ϯ 7.6 cm) and stem diameter (2.4 Ϯ 0.4Ð tected among dates (Table 2). Angleton bluestem was 2.8 Ϯ 0.3 mm) did not differ among dates (Table 1). infested with E. loftini all year (Fig. 5A). However, Other graminoids collected during this study in- differences in percentages of E. loftini recovered from clude fall panicgrass (Panicum dichotomiﬂorum this perennial grass were not detected among dates Michx.); longspike beardgrass [Bothriochloa longi- (Table 2). paniculata (Gould) Allred & Gould]; browntop sig- In total, 617 and 1,515 E. loftini immatures were nalgrass [Urochloa fusca (Sw.) B.F. Hansen & Wun- recovered during the Þrst and second year of the derlin]; bushy bluestem [Andropogon glomeratus study, respectively. Ninety-six point one and 98.0% of (Walter) Britton, Sterns & Poggenb]; Bermuda these immatures, for the Þrst and second year of the grass [Cynodon dactylon (L.) Pers.]; dallisgrass study, respectively, infested the six graminoids ad- (Paspalum dilatatum Poir.); ßatsedge (Cyperaceae: dressed in the previous paragraph. The remaining E. Cyperus spp.); bristlegrass (Setaria spp.); and Neal- loftini immatures were recovered from 12 of the less leyÕs sprangletop (Leptochloa nealleyi Vasey). abundant grasses and sedges (Table 3). E. loftini was T3

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Fig. 5. Relative stem borer infestations (LS means Ϯ SE) in grasses growing in noncrop habitats adjacent to rice Þelds in Texas, 2007Ð2009. (A) Percentage of recovered E. loftini in six grasses. (B) Percentage of recovered E. loftini per percent johnsongrass and VaseyÕs grass abundance. (C) Percentage of recovered D. saccharalis in johnsongrass and VaseyÕs grass. (D) Percentage of recovered D. saccharalis per percent johnsongrass and VaseyÕs grass abundance. Markers were not included on the Þgure when stem borers were not recovered. not collected from torpedo grass, Bermuda grass, or among dates (F ϭ 1.02; df ϭ 6, 11.1; P ϭ 0.459 and F ϭ bristlegrass. 0.67; df ϭ 6, 6.4; P ϭ 0.681, respectively). In addition, D. saccharalis Infestations in Noncrop Plants. In for johnsongrass and VaseyÕs grass, year ϫ date inter- total, 94 and 42 D. saccharalis immatures were recov- actions were not detected for the percentages of re- ered during the Þrst and second year of the study, covered D. saccharalis (F ϭ 0.30; df ϭ 3, 10.3; P ϭ 0.825 respectively. These immatures were collected almost and F ϭ 0.27; df ϭ 3, 11.3; P ϭ 0.843, respectively) and exclusively from johnsongrass and VaseyÕs grass, recovered D. saccharalis per percent plant relative which harbored together 94 and 100% of the infesta- abundance (F ϭ 0.01; df ϭ 3, 16; P ϭ 0.999 and F ϭ 1.13; tions for the Þrst and second year of the study, re- df ϭ 3, 6.5; P ϭ 0.404, respectively). spectively. The remaining D. saccharalis larvae were Spring Stem Borer Infestations in Rice Fields. In collected from Angleton bluestem (four larvae), jun- early April, old rice stubble was present in all sampled gle rice (one larva), and browntop signalgrass (one fallow Þelds but one, which had been grazed by cattle. larva). Differences in percentages of D. saccharalis When present, rice stubble showed evidence of stem recovered from johnsongrass and percentages of D. borer injury from the previous year, but did not host saccharalis recovered per percent of johnsongrass rel- E. loftini immatures. However, one D. saccharalis pupa ative abundance (Fig. 5) were not detected between was recovered in April 2008 [i.e., 0.04 Ϯ 0.04 imma- the 2 yr of the study (F ϭ 0.77; df ϭ 1, 9.5; P ϭ 0.403 tures per m2 (mean Ϯ SE)]. Although dead rice stub- and F ϭ 0.26; df ϭ 1, 16; P ϭ 0.618, respectively) and ble was the only rice material available in fallow Þelds among dates (F ϭ 1.01; df ϭ 6, 10.3; P ϭ 0.467 and F ϭ during the Þrst year of the study (April 2007), young 1.08; df ϭ 6, 16; P ϭ 0.417, respectively). In VaseyÕs rice plants grew in April 2008. Young rice tillers, pres- grass, differences in percentages of recovered D. sac- ent at a density of 37.7 Ϯ 7.7 tillers per m2, measured charalis and percentages of recovered D. saccharalis 18.3 Ϯ 1.1 cm (mean Ϯ SE) and harbored 0.7 Ϯ 0.2 E. per percent plant relative abundance (Fig. 5) were not loftini immatures per m2 (mean Ϯ SE). Among the 17 detected between years (F ϭ 0.93; df ϭ 1, 8.5; P ϭ 0.361 recovered E. loftini immatures, 64, 18, and 18% were and F ϭ 0.48; df ϭ 1, 8.0; P ϭ 0.508, respectively) and small, medium, and large larvae, respectively. Weedy

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Table 3. Eoreuma loftini larval infestations recovered from 12 grasses and sedges found sporadically in non-crop habitats adjacent to rice ﬁelds, Texas, 2007–2009

2007Ð2008 2008Ð2009 Plant No. quadrats No. E. loftini No. quadrats No. E. loftini infested recovered infested recovered Caucasian bluestem 1 on 19 Dec. 2007 1 0 0 1 on 17 Feb. 2008 2 Hairy crabgrass 2 on 15 Aug. 2007 2 1 on 11 Oct. 2008 1 1 on 19 Dec. 2007 1 1 on 17 Feb. 2008 1a Jungle rice 1 on 15 Aug. 2007 2 0 0 Longtom 0 0 2 on 13 Dec. 2008 6 Non-identiÞed perennial 1 on 12 Oct. 2007 1 0 0 1 on 19 Dec. 2007 2 Fall panicgrass 2 on 30 June 2007 2 0 0 1 on 19 Dec. 2007 3 1 on 17 Feb. 2008 1 Longspike beardgrass 0 0 1 on 24 May 2008 1 2 on 28 June 2008 5 Browntop signalgrass 2 on 15 Aug. 2007 2 0 0 Bushy bluestem 1 on 17 Feb. 2008 1 1 on 13 Dec. 2008 10 Dallisgrass 1 on 30 June 2007 1 0 0 Flatsedge 0 0 1 on 14 Feb. 2009 1 NealleyÕs sprangletop 1 on 15 Aug. 2007 2 0 0

a pupa was collected.

grasses were also collected in fallow rice Þelds. Ca- fall and winter trapping. However, the greatest trap narygrass was present at densities of 1.5 Ϯ 0.5 and 1.0 Ϯ catches during the second year of the study were 0.5 tillers per m2 (mean Ϯ SE) in April 2007 and 2008, associated with greater catches between April and respectively, with one recovered E. loftini larva in August with a peak in May, which was not observed April 2007 (100% of the recovered immatures in fallow during the Þrst year of the study (Fig. 6). D. saccharalis rice). Bristlegrass was present at densities of 0.1 Ϯ 0.1 traps did not function during December and February and 1.9 Ϯ 0.9 tillers per m2 (mean Ϯ SE) in April 2007 samplings of both years because the eclosion of virgin and 2008, respectively, with Þve recovered E. loftini females used as lures did not occur. Thus, data on D. larvae in April 2008 (23% of the recovered immatures saccharalis ßight activity during the winter were not in fallow rice Þelds). collected. D. saccharalis moth trap catches were vari- During both years of the study, stem borer injury or able but showed differences among dates (F ϭ 4.30; infestations in young rice plants were not observed in df ϭ 4, 38.1; P ϭ 0.006), with an increase (8.4 -fold) early April and late May. By late June 2007, newly from April to October (Fig. 6). Differences in D. planted rice Þelds on each of the three farms of the saccharalis moth trap catches between the 2 yr of the study were at panicle differentiation or boot stages. study were not detected (F ϭ 1.80; df ϭ 1, 4.3; P ϭ Stem borer injury, comprised of one bored tiller and 0.247), and the year ϫ date interaction was not sig- one tiller with feeding signs in the leaf sheath [i.e., niÞcant (F ϭ 1.26; df ϭ 4, 38.1; P ϭ 0.303). 0.04 Ϯ 0.03 injured tillers per m2 (mean Ϯ SE)], was recorded in the older rice Þeld (boot stage) in June Discussion 2007. By late June 2008, young rice Þelds were at panicle differentiation, 70% boot and 30% heading, or E. loftini Infestations in Noncrop Hosts. As early as 100% heading stages. Stem borer injury and infesta- in the 1920s (Van Zwaluwenburg 1926), it was rec- tions were observed in one Þeld (70% boot and 30% ognized that many large-stemmed grasses could host heading), with an average of 1.67 Ϯ 0.81 injured tillers E. loftini. However, E. loftini noncrop hosts have only per m2 (mean Ϯ SE) and a total of three D. saccharalis recently received consideration for pest management larvae recovered from one quadrat [i.e., 0.11 Ϯ 0.11 (Beuzelin et al. 2010, Showler et al. 2011). Our study immatures per m2 (mean Ϯ SE)]. provides the Þrst quantiÞcation of seasonal E. loftini Adult Stem Borer Trapping. E. loftini moth trap infestations in plants other than Þeld crops. Under F6 catches (Fig. 6) were two-fold greater during the on-farm conditions of Texas Gulf Coast rice agroeco- second year than during the Þrst year of the study (F ϭ systems, infestations in noncrop grasses occurred early 7.68; df ϭ 1, 7.9; P ϭ 0.025). Differences in trap catches during the spring when young rice does not harbor E. among dates were also detected (F ϭ 5.60; df ϭ 6, 56.9; loftini. E. loftini infestations in noncrop grasses sub- P Ͻ 0.001), with moth catches across both years lowest sequently built up during the rice growing season, and during the winter and greatest in October (Fig. 6). were as high as 4.8 immatures per m2 in December, However, there was a trend (P Յ 0.1) for a year ϫ date suggesting that weedy habitats surrounding rice Þelds interaction (F ϭ 1.97; df ϭ 6, 56.9; P ϭ 0.086). For both are major overwintering areas. April sampling in fal- years of the study, trap catches were comparable for low rice Þelds that had not been plowed showed that

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Fig. 6. E. loftini and D. saccharalis adult trap catches (LS means Ϯ SE) in noncrop habitats adjacent to rice Þelds in Texas, 2008Ð2009. Markers were not included on the Þgure when traps did not function. overwintering E. loftini larvae are not found in rice suitability (Beuzelin 2011, Showler et al. 2011). Our stubble. However, grassy weeds and volunteer rice study suggests that johnsongrass, which is abundant growing in fallowed Þelds can serve as host during the throughout the year, plays a substantial role in E. spring. loftini population build-up during the rice growing Pheromone trap data showed that, despite reduced season. The observed lack of live johnsongrass tissue numbers during the cold season, E. loftini moths ßy during the winter, however, probably decreased year-round in or near noncrop habitats. This is con- host suitability and subsequently E. loftini survival sistent with adult seasonal patterns reported by Beu- during this season. In addition to low temperatures, zelin et al. (2010) and with observations of all devel- desiccation is a primary abiotic stem borer mortality opmental stages present at any time of the year in factor during the winter (Rodriguez-del-Bosque et sugarcane Þelds of the Texas Lower Rio Grande Valley al. 1995). Therefore, we contend that E. loftini lar- (Van Leerdam et al. 1986, Meagher et al. 1994). Ro- vae establishing in johnsongrass during the fall will driguez-del-Bosque et al. (1995) also showed that E. complete their life cycle during the winter despite loftini adults continuously emerged during the winter increased mortality. However, it is unlikely that and spring in northern Tamaulipas, Mexico. Thus, the dead johnsongrass supports the development of relative role of various host plants in E. loftini popu- young larvae from E. loftini moths emerging during lation dynamics is a function of plant availability, at- the winter. For VaseyÕs grass, the high percentage of tractiveness, and suitability throughout the year. recovered E. loftini and percentage of recovered E. Assessment of the seasonal abundance and phe- loftini per percent plant relative abundance in Feb- nology of noncrop graminoids of Texas Gulf Coast ruary indicate that this host becomes increasingly rice agroecosystems, as well as associated E. loftini infested during the winter. VaseyÕs grass is less in- infestations, assisted in identifying primary noncrop fested than johnsongrass at comparable phenolog- hosts and their potential role in the pestÕs popula- ical stages (Beuzelin et al. 2010, Showler et al. 2011) tion dynamics. Johnsongrass, VaseyÕs grass, ryegrass, but maintains numerous green vegetative tillers brome, Angleton bluestem, and hairy crabgrass throughout the year. Thus, the substantial perennial were effective E. loftini hosts that allowed larval availability of live plant tissue suitable for E. loftini feeding and life cycle completion. Other grasses and development likely allows VaseyÕs grass to be a pri- sedges might also be suitable hosts. Graminoids ob- mary overwintering host. In areas with relatively served in our study presented a wide range of plant less johnsongrass or VaseyÕs grass (e.g., transition height and stem diameter. Physical constraints as- between farm roads and Þeld margins), a more di- sociated with these plant size characteristics likely verse mixture of graminoids was observed. Ryegrass affect host suitability for stem borer larval devel- and brome are E. loftini hosts in the spring, also opment, with host suitability increasing with plant playing a role in population build-up early during height and stem diameter (Beuzelin 2011, Showler the rice growing season, even if only for a short et al. 2011). However, stem hardness and nutritional window of time. Our study also indicated that ca- quality are other key factors impacting host plant narygrass may play a comparable role in E. loftini

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population dynamics. Other annual and perennial L., Þelds (Pease and Zalom 2010), and the build-up of grasses (i.e., crabgrass, Angleton bluestem) proba- the pyralid Mussidia nigrivenella Ragoon in Benin (Se´- bly play a minimal role in E. loftini population dy- tamou et al. 2000). Populations of the tarnished plant namics although they may have more substantial bug, Lygus lineolaris (Palisot de Beauvois), and roles if abundant in localized areas. twospotted spider mite, Tetranychus urticae Koch, The current study is the Þrst to our knowledge to feed on weedy hosts before moving into nearby cot- quantitatively describe graminoids in noncrop habi- ton, Gossypium hirsutum L., Þelds (Fleischer and Gay- tats (i.e., Þeld margins, roadsides, ditches) surround- lor 1987, Wilson 1995). Our study showed that non- ing rice Þelds in the Texas Upper Gulf Coast area. crop grasses are sources of E. loftini populations. Thus, These habitats were more variable than adjacent rice noncrop habitat management tactics including mow- Þelds because they were not under intensive manage- ing, applications of herbicides or insecticides, or the ment, and plant species composition was not inten- modiÞcation of weed species composition (Landis et tionally controlled by the producers. However, the al. 2000) could help improve rice integrated pest man- three study farms exhibited comparable noncrop hab- agement (IPM). However, the value of this approach itat compositions, regardless of management (mow- remains to be demonstrated. Relationships between ing, burning, herbicide applications, absence of man- noncrop host abundance, stem borer population lev- agement) or localized soil and weather variations. els, and associated crop yield losses have not been Based on our observations, noncrop habitats sampled quantiÞed. In addition, noncrop habitats can be a in our study appear to be representative of those source of biodiversity enhancing natural enemy abun- habitats encountered throughout rice areas of the dance (Altieri and Letourneau 1982, Norris and Kogan Texas Gulf Coast. The generalization of our results to 2005). Although the red imported Þre ant (Solenopsis other Gulf Coast agroecosystems, however, will re- invicta Buren), spiders, and predaceous beetles sup- quire additional sampling in Texas and Louisiana. press D. saccharalis injury to weedy Louisiana sugar- D. saccharalis Infestations in Noncrop Hosts. Com- cane (Ali and Reagan 1985, Showler and Reagan plementing earlier studies (Jones and Bradley 1924, 1991), their interactions with stem borer populations Bynum et al. 1938, Bessin and Reagan 1990), we pro- in noncrop habitats have not been determined. E. vided the Þrst year-round quantiÞcation of D. saccha- loftini noncrop hosts might also represent refuges for ralis infestations in noncrop habitats. D. saccharalis parasitic wasps (Meagher et al. 1998) observed during was found mostly in johnsongrass and VaseyÕs grass, sampling. Therefore, designing noncrop habitat man- and infestations were low relative to E. loftini infes- agement tactics for rice IPM will have to integrate the tations. Low area-wide D. saccharalis populations in weed contribution to both pest and natural enemy the study areas might explain the predominance of E. populations (Landis et al. 2000, Norris and Kogan loftini. Diatraea saccharalis might also rely less on 2005). noncrop hosts than E. loftini. Adult D. saccharalis trap- Concluding Remarks. Assuming that host-speciÞc ping data from our study provide evidence of moth sympatric stem borer strains do not occur (Pashley activity in the vicinity of noncrop sampling areas. In and Martin 1987, Martel et al. 2003, Vialatte et al. addition, D. saccharalis infestations in experimental 2005), our study showed that noncrop grasses have the rice plots located within 1.25 km of noncrop sampling potential to increase E. loftini pest populations. Thus, transects in Jackson County represented Ͼ99% of the manipulation of E. loftini noncrop sources may stem borer infestations in JulyÐAugust 2007 (Beuzelin help decrease infestations in crop Þelds and slow the 2011). In the Louisiana sugarcane agroecosystem, By- spread of this invasive species through Louisiana. Fur- num et al. (1938) and Ali et al. (1986) concluded that ther research needs to be conducted to quantify the johnsongrass only played a minor role in D. saccharalis relative contribution of E. loftini oviposition prefer- population build-up and overwintering. These obser- ence, immature performance, movement, and natural vations suggest that noncrop hosts might contribute enemy suppression to pest source-sink interactions in less to D. saccharalis populations than to E. loftini the agroecosystem. Subsequently, the efÞcacy and populations. Nevertheless, oviposition preference and economic beneÞts of noncrop habitat management immature performance studies would assist in quan- tactics, implemented at both Þeld and regional scales, tifying the relative role of noncrop hosts in D. saccha- will have to be assessed. Because E. loftini noncrop ralis population dynamics. hosts can sustain D. saccharalis populations, manage- Pest Management Implications. Although weeds in ment tactics targeting noncrop habitats could also rice Þelds such as Amazon sprangletop can increase decrease D. saccharalis pest populations. Together stem borer infestations (Tindall 2004, Beuzelin et al. with previous research (Reay-Jones et al. 2008, Beu- 2010), cultural management typically keeps weed zelin et al. 2010), our study provides a foundation for populations low (Kendig et al. 2003), which is why a more comprehensive stem borer management strat- exclusively noncrop habitats surrounding rice Þelds egy including crop and noncrop components of the were the focus of our study. Research in several agro- agroecosystem. ecosystems showed that alternate hosts in noncrop habitats could contribute to increased pest populations. Examples of this relationship include increased Acknowledgments AQ: 3 consperse stink bug, Euschistus conspersus Uhler, in- We thank rice growers Bill Dishman, Jr., John and Jay festations in California tomato, Solanum lycopersicum Jenkins, and Gary and Michael Skalicky for permitting us use

40 balt2/zen-env-ent/zen-env-ent/zen00511/zen7486d11z xppws Sϭ1 8/12/11 7:48 Art: EN-11-044 1st disk, 2nd kmb

14 ENVIRONMENTAL ENTOMOLOGY Vol. 40, no. 5 of their farmland and for technical assistance. We thank Johnson, K.J.R. 1984. IdentiÞcation of Eoreuma loftini Lowell Urbatsch (Herbarium of Louisiana State University) (Dyar) (Lepidoptera: Pyralidae) in Texas, 1980: Fore- and Eric Webster (LSU AgCenter School of Plant, Environ- runner for other sugarcane boring pest immigrants from mental and Soil Sciences) for identifying numerous grass Mexico? Bull. Entomol. Soc. Am. 30: 47Ð52. samples. We thank Mike Hiller (Texas A&M AgriLife Ex- Johnson, K.J.R., and M. B. Van Leerdam. 1981. Range extension), Waseem Akbar, Blake Wilson, Kyle Baker (LSU tension of Acigona loftini into the Lower Rio Grande AgCenter), and Jannie Castillo (Texas A&M AgriLife Re- Valley of Texas. Sugar Y Azucar 76: 34. AQ: 4 search and Extension Center at Beaumont) for their tech- Jones, T. H., and W. G. Bradley. 1924. Certain wild grasses nical assistance. We thank Jeff Davis, Mike Stout (LSU Ag- in relation to injury to corn by the “borer” (Diatraea Center), and two anonymous referees for participating in the saccharalis Fab.) in Louisiana. J. Econ. Entomol. 17: 393Ð review of the manuscript. This work was supported by 395. USDA-CSREES Crops-At-Risk IPM program grant 2008- Karban, R. 1997. Neighbourhood affects a plantÕs risk of 51100-04415. This paper is approved for publication by the herbivory and subsequent success. Ecol. Entomol. 22: Director of the Louisiana Agricultural Experiment Station as 433Ð439. manuscript number 2011Ð234-5623. Kendig, A., B. Williams, and C. W. Smith. 2003. Rice weed control, pp. 457Ð472. In C. W. Smith and R. H. Dilday (eds.), Rice: Origin, History, Technology, and Produc- References Cited tion. Wiley, Inc. Hoboken, NJ. Klots, A. B. 1970. North American Crambinae: Notes on the Ali, A. D., and T. E. Reagan. 1985. Vegetation manipulation tribe Chiloini and a revision on the genera Eoreuma Ely impact on predator and prey populations in Louisiana and Xubida Schaus (Lepidoptera: Pyralidae). J. N.Y. En- sugarcane ecosystems. J. Econ. Entomol. 78: 1407Ð1414. tomol. Soc. 78: 100Ð120. Ali, A. D., T. E. Reagan, L. M. Kitchen, and J. L. Flynn. 1986. Landis, D. A., S. D. Wratten, and G. M. Gurr. 2000. Habitat Effects of johnsongrass (Sorghum halepense) density on management to conserve natural enemies of arthropod sugarcane (Saccharum ofﬁcinarum) yield. Weed Sci. 34: pests in agriculture. Annu. Rev. Entomol. 45: 175Ð201. 381Ð383. Legaspi, J. C., R. R. Saldan˜ a, and N. Roseff. 1997. Identifying Altieri, M. A., and D. K. Letourneau. 1982. Vegetation man- and managing stalkborers on Texas sugarcane. Texas Ag- agement and biological control in agroecosystems. Crop ricultural Experiment Station Publication MP-1777, Col- Prot. 1: 405Ð430. lege Station, TX. Andow, D. A. 1991. Vegetational diversity and arthropod Letourneau, D. K. 1987. The enemies hypothesis: tritrophic population response. Annu. Rev. Entomol. 36: 561Ð586. interaction and vegetational diversity in tropical agro- Bessin, R. T., and T. E. Reagan. 1990. Fecundity of the sug- ecosystems. Ecology 68: 1616Ð1622. arcane borer (Lepidoptera: Pyralidae) as affected by lar- Long, W. H., and S. D. Hensley. 1972. Insect pests of sugar val development on gramineous host plants. Environ. cane. Annu. Rev. Entomol. 17: 149Ð176. Entomol. 19: 635Ð639. Martel, C., A. Re´jasse, F. Rousset, M.-T. Bethenod, and D. Beuzelin, J. M. 2011. Agroecological factors impacting stem Bourguet. 2003. Host-plant-associated genetic differen- borer (Lepidoptera: Crambidae) dynamics in Gulf Coast tiation in Northern French populations of the European sugarcane and rice. Ph.D. dissertation, Louisiana State corn borer. Heredity 90: 141Ð149. University, Baton Rouge, LA. Meagher, R. L., Jr., J. W. Smith, Jr., H. W. Browning, and Beuzelin, J. M., T. E. Reagan, M. O. Way, A. Meszaros, W. R. R. Saldan˜ a. 1998. Sugarcane stemborers and their Akbar, and L. T. Wilson. 2010. Potential impact of Mex- parasites in southern Texas. Environ. Entomol. 27: 759Ð ican rice borer non-crop hosts on sugarcane IPM, pp. 766. 806Ð814 (Paper BE10). In Proceedings, XXVII Congress Meagher, R. L., Jr., J. W. Smith, and K.J.R. Johnson. 1994. of the International Society of Sugar Cane Technologists, Insecticidal management of Eoreuma loftini (Lepidop- March 7Ð11,Veracruz, Mexico. tera: Pyralidae) on Texas sugarcane: a critical review. J. Box, H. E. 1956. New species and records of Diatraea Guild- Econ. Entomol. 87: 1332Ð1344. ing and Zeadiatraea Box from Mexico, Central and South America (Lepid., Pyral.). Bull. Entomol. Res. 47: 755Ð776. Norris, R. F., and M. Kogan. 2005. Ecology of interactions Browning, H. W., M. O. Way, and B. M. Drees. 1989. Man- between weeds and arthropods. Annu. Rev. Entomol. 50: aging the Mexican rice borer in Texas. Texas Agricultural 479Ð503. Experiment Station Publ. B-1620, College Station, TX. Osborn, H. T., and G. R. Phillips. 1946. Chilo loftini in Cal- Bynum, E. K., W. E. Halley, and L. J. Charpentier. 1938. ifornia, Arizona, and Mexico. J. Econ. Entomol. 39: 755Ð Sources of infestation by the sugarcane borer and trash 759. treatment for the destruction of overwintering borers. Pashley, D. P., and J. A. Martin. 1987. Reproductive incom- Proc. Int. Soc. Sugar Cane Technol. 6: 597Ð611. patibility between host strains of the fall armyworm (Lep- Fleischer, S. J., and M. J. Gaylor. 1987. Seasonal abundance idoptera: Noctuidae). Ann. Entomol. Soc. Am. 80: 731Ð of Lygus lineolaris (Heteroptera: Miridae) and selected 733. predators in early season uncultivated hosts: implications Pease, C. G., and F. G. Zalom. 2010. Inßuence of non-crop for managing movement into cotton. Environ. Entomol. plants on stink bug (Hemiptera: Pentatomidae) and nat- 16: 379Ð389. ural enemy abundance in tomatoes. J. Appl. Entomol. 134: Holloway, T. E., W. E. Halley, U. C. Loftin, and C. Heinrich. 626Ð636. 1928. The sugar-cane borer in the United States. U.S. Reay-Jones, F.P.F., L. T. Wilson, T. E. Reagan, B. L. Leg- Department of Agriculture Technical Bulletin 41: 1Ð77. endre, and M. O. Way. 2008. Predicting economic losses Hummel, N. A., T. Hardy, T. E. Reagan, D. K. Pollet, C. E. from the continued spread of the Mexican rice borer Carlton, M. J. Stout, J. M. Beuzelin, W. Akbar, and W. H. (Lepidoptera: Crambidae). J. Econ. Entomol. 101: 237Ð White. 2010. Monitoring and Þrst discovery of the Mex- 250. ican rice borer Eoreuma loftini (Lepidoptera: Crambi- Reay-Jones, F.P.F., L. T. Wilson, M. O. Way, T. E. Reagan, dae) in Louisiana. Fla. Entomol. 93: 123Ð124. and C. E. Carlton. 2007. Movement of the Mexican rice

41 balt2/zen-env-ent/zen-env-ent/zen00511/zen7486d11z xppws Sϭ1 8/12/11 7:48 Art: EN-11-044 1st disk, 2nd kmb

October 2011 BEUZELIN ET AL.: STEM BORER INFESTATIONS IN NON-CROP GRASSES 15

borer (Lepidoptera: Crambidae) through the Texas rice Stubbs, W. C., and H. A. Morgan. 1902. Sugarcane borer belt. J. Econ. Entomol. 100: 54Ð60. moth. La. Agric. Exp. Stn. Bull. 70: 885Ð927. Rodriguez-del-Bosque, L. A., J. W. Smith, Jr., and J. Martinez. Tindall, K. V. 2004. Investigation of insect-weed interac- 1995. Winter mortality and spring emergence of corn tions in the rice agroecosystem. Ph.D. dissertation. Lou- stalkborers (Lepidoptera: Pyralidae) in subtropical Mex- isiana State University, Baton Rouge, LA. ico. J. Econ. Entomol. 88: 628Ð634. Tindall, K. V., M. J. Stout, and B. J. Williams. 2004. Effects Russell, E. P. 1989. Enemies hypothesis: a review of the of the presence of barnyardgrass on rice water weevil effect of vegetational diversity on predatory insects and (Coleoptera: Curculionidae) and rice stink bug parasitoids. Environ. Entomol. 18: 590Ð599. (Hemiptera: Pentatomidae) populations on rice. Envi- SAS Institute. 2008. UserÕs Manual, Version 9.2. SAS Insti- ron. Entomol. 33: 720Ð726. tute, Cary, NC. Van Leerdam, M. B., K.J.R. Johnson, and J. W. Smith, Jr. Se´tamou, M., F. Schulthess, S. Gounou, H.-M. Poehling, and 1986. Ovipositional sites of Eoreuma loftini (Lepidoptera: C. Borgemeister. 2000. Host plants and population dy- Pyralidae) in sugarcane. Environ. Entomol. 15: 75Ð78. namics of the ear borer Mussidia nigrivenella (Lepidop- Van Zwaluwenburg, R. H. 1926. Insect enemies of sugar- tera: Pyralidae) in Benin. Environ. Entomol. 29: 516Ð524. cane in western Mexico. J. Econ. Entomol. 19: 664Ð669. Showler, A. T., and T. E. Reagan. 1991. Effects of sugarcane Vialatte, A., C.-A. Dedryver, J.-C. Simon, M. Galman, and M. borer, weed, and nematode control strategies in Louisi- Plantegenest. 2005. Limited genetic exchanges between ana sugarcane. Environ. Entomol. 20: 358Ð370. populations of an insect pest living on uncultivated and Showler, A. T., J. M. Beuzelin, and T. E. Reagan. 2011. Al- related cultivated host plants. Proc. R. Soc. B. 272: 1075Ð ternate crop and weed host plant oviposition preferences 1082. by the Mexican rice borer (Lepidoptera: Crambidae). Wilson, L. J. 1995. Habitats of twospotted spider mites (Ac- Crop Prot. 30: 895Ð901. ari: Tetranychidae) during winter and spring in a cotton- Solis, M. A. 1999. Key to selected Pyraloidea (Lepidoptera) producing region of Australia. Environ. Entomol. 24: 332Ð larvae intercepted at U.S. ports of entry: revision of Pyr- 340. aloidea in “Keys to some frequently intercepted Lepi- dopterous larvae” by Weisman 1986. Proc. Entomol. Soc. Wash. 101: 645Ð686. Received 17 February 2011; accepted 5 July 2011.

42 HARVEST CUTTING HEIGHT AND RATOON CROP EFFECTS ON STEM BORER INFESTATIONS IN RICE

J. M. Beuzelin1, A. Mészáros1, M. O. Way2, and T. E. Reagan1 1Department of Entomology, LSU AgCenter 2Texas A&M AgriLife Research and Extension Center at Beaumont

A two-year field study near Ganado, TX compared infestations of the Mexican rice borer (MRB) and sugarcane borer (SCB) in rice as affected by main crop harvest cutting height and the production of a ratoon crop. Substantial infestations (> 0.52 stem borers/ft2) remained in rice culms regardless of main crop cutting height (8 vs. 16 in.). However, the 8-in. cutting height reduced MRB infestations 70 to 81% whereas SCB infestations were not affected (Fig. 1). Plant dissections prior to main crop harvest showed that compared to SCB, relatively more MRB are located above 8 in. from the base of the culm (Fig. 2). In October, the ratoon crop was more infested with stem borers than the unmanaged main crop stubble during the first year of the study. The opposite was observed during the second year. Differences in unmanaged main crop stubble phenology between the two years likely caused these differences in infestation levels. During the post-growing season, infestations in main and ratoon crop stubble decreased over the winter. After favorable winter conditions, infestations in main and ratoon crop stubble were not different, attaining 0.31 MRB/ft2 and 0.04 SCB/ft2 by March 2008 (Fig. 3). In March 2009, rice stubble harbored 0.03 MRB/ft2 and 0.02 SCB/ft2 regardless of whether only a main crop or a main and ratoon crop had been produced (Fig. 3). This study showed that a lower rice harvest cutting height can suppress late season MRB populations. Furthermore, rice stubble under favorable conditions represents a substantial overwintering habitat, thus warranting evaluation of pest management tactics targeting overwintering populations.

August 2007 August 2008

5 8 in 2 8 in 16 in 16 in 4 * 1.5

3 1 2

0.5 1 * No. stem borers / sq. ft No. stem borers / sq. ft 0 0 MRB SCB MRB SCB

Fig. 1. Stem borer infestations in rice main crop stubble as affected by harvest cutting height in 2007 and 2008, Ganado, Texas. For a stem borer species in a year, * indicates infestations differed (P < 0.05).

2 Below 8 in Above 8 in 1.5

0.5 No. stem borers / sq. ft

0 MRB SCB

Fig. 2. Stem borer infestations by location in rice culms prior to main crop harvest in 2008, Ganado, Texas.

2007-2008 2008-2009

Non-ratoon Ratoon Non-ratoon Ratoon

2.5 7 6 2.0 5 1.5 4

1.0 3 2 No. MRB / sq. ft No. MRB / sq. ft 0.5 1 0.0 0 October January March October January March

Fig. 3. Late and post-growing season MRB infestations in rice, Ganado, Texas, 2007-2008 and 2008-2009.

44 TRAPPING FOR MEXICAN RICE BORER IN THE TEXAS RICE BELT, 2010

Mo Way1, Becky Pearson1, Gene Reagan2, Julien Beuzelin2 1Texas A&M AgriLife Research, 2LSU AgCenter

Mexican rice borer (MRB) pheromone traps were set up in selected counties of the Texas Rice Belt (TRB). Although MRB was detected for the first time in Louisiana in November 2008, it was collected for the first time in Orange Co. in September 2010 (Table 1). Data are being used to follow the progress of MRB population densities over time in the TRB. Eventually, the data may be used to predict MRB outbreaks. Trap operators for this study include Becky Pearson (Chambers and Jefferson Cos.), Jack Vawter (Colorado Co.), Ron Holcomb (Liberty Co.), Mike Hiller (Jackson Co.), Kelby Boldt (Jefferson Co. – sugarcane), and Noelle Jordan (Orange Co.).

Table 1. Monthly totals of Mexican rice borer adults from pheromone traps (2 traps/county) located next to rice, sugarcane or fallow fields on the Texas Upper Gulf Coast in 2010 Chambers Co. Colorado Co. Jackson Co. Jefferson Co. Liberty Co. Orange Co. Month rice rice rice rice sugarcanea rice fallow January 0 0 0 0 NA NA NA February 0 2 5 0 NA 2 NA March 15 60 27 18 NA 21 NA April 703 2259 41 160 NA 46 0 May 216 154 71 31 NA 78 0 June 379 181 336 109 87 343 0 July 116 112 81 88 96 74 0 August 347 144 93 118 150 70 0 September 248 267 308 49a 82 272 2 October 997 380 700 26a NA 707 3 November 303 104 449 19a NA 441 1 December 206 59 919 10a NA 784 NA a Monthly total for one trap

RICE INSECTICIDE EVALUATION STUDIES

Mo Way, Mark Nunez, Becky Pearson Texas A&M AgriLife Research and Extension Center at Beaumont

Six studies assessing the efficacy of insecticides for rice water weevil (RWW), Lissorhoptrus oryzophilus Kuschel, and stalk borer management were conducted in 2011 at the Ganado Research Station and the Texas A&M AgriLife Research and Extension center at Beaumont. A study conducted in 2009 is also reported.

1. Cocodrie Seed Treatments, Ganado, TX, 2011 Low populations of RWW were recorded, but these data show Dermacor X-100 significantly reduced whitehead numbers.

Table 1. Mean data for Cocodrie seed treatments. Ganado, TX. 2011 b Rate Paniclesa/ft RWW /5 cores WHsb/4 Yield Treatment (fl oz/cwt) of row Jun 7 Jun 17 rows (lb/A) Untreated --- 29 9 a 5 31 a 7903 CruiserMaxx Rice 7.0 27 4 b 8 23 a 8427 Nipsit Inside 1.92 28 3 b 4 20 a 8261 Dermacor X-100 1.75 fl oz/A 31 1 c 3 5 b 8673 NS NS NS a Panicles counted on Jul 12 b RWW = rice water weevil; WH = whitehead Means in a column followed by the same or no letter are not significantly (NS) different (P > 0.05, ANOVA, LSD)

2. XP753 Seed Treatments, Ganado, TX, 2011 Low populations of RWW were recorded, but Dermacor X-100 significantly reduced whitehead numbers. Hybrids generally produce fewer whiteheads than inbreds, but hybrids are still susceptible (Compare Tables 1 and 2).

Table 2. Mean data for XP753 seed treatment. Ganado, TX. 2011 b Rate Paniclesa/ft RWW /5 cores WHsb/4 Yield Treatment (fl oz/cwt) of row Jun 7 Jun 17 rows (lb/A) Untreated --- 25 6 3 12 a 9303 b CruiserMaxx Rice 7.0 28 6 3 13 a 9303 b Nipsit Inside 1.92 21 6 5 15 a 9551 ab Dermacor X-100 1.75 fl oz/A 26 1 2 2 b 10099 a NS NS NS a Panicles counted on Jul 12 b RWW = rice water weevil; WH = whiteheads Means in a column followed by the same or no letter are not significantly (NS) different (P > 0.05, ANOVA, LSD)

46 3. Dermacor X-100 Ratoon Study, Ganado, TX, 2011 Low populations of RWW were recorded, but Dermacor X-100 significantly reduced whitehead numbers. The observed yield response was primarily due to stalk borer control.

Table 3. Mean data for Dermacor X-100 ratoon study. Ganado, TX. 2011 a b Rate Timing Panicles/ft RWW /5 cores WHsb/ Yield Treatment (lb ai/A) RWW SB of row Jun 7 Jun 17 4 rows (lb/A) Untreated ------28 12 ab 12 a 34 a 7270 b Karate Z 0.03 BF --- 30 4 bc 3 b 35 a 7247 b Karate Z 0.03 --- LB/H 28 18 a 10 a 23 a 7939 a Dermacor X-100 1.75 fl oz/A ST ST 29 2 c 0 b 3 b 8244 a NS a RWW = treated for rice water weevil before permanent flood (BF); LB/H = late boot/heading; ST = seed treatment b RWW = rice water weevil; WH = whitehead Means in a column followed by the same or no letter are not significantly (NS) different (P > 0.05, ANOVA and LSD)

4. Seed Treatment Replant Study, Beaumont, TX, 2011 These data show Dermacor X-100 provided good control of RWW and stalk borers when untreated rice seed was replanted after treated rice seed.

Table 4. Mean data for second planting of seed treatment replant study. Beaumont, TX. 2011 Timing Stand RWWa/5 cores Rate WHsa/ Yield Description st nd (plants/ft (fl oz/cwt) 1 2 4 rows (lb/A) planting planting of row) Jul 19 Jul 29 Untreated ------11 48 a 26 a 23 a 7783 d CruiserMaxx Rice 7 Tb Ub 10 8 bcd 9 b 16 ab 8374 bc CruiserMaxx Rice 7 T T 12 3 d 8 b 17 ab 8089 cd Dermacor X-100 1.75 fl oz/A T U 11 15 b 8 b 0 c 8445 abc Dermacor X-100 1.75 fl oz/A T T 11 3 cd 3 c 1 c 8944 a NipsIt INSIDE 1.92 T U 10 9 bc 7 bc 14 ab 8278 bcd NipsIt INSIDE 1.92 T T 11 5 cd 8 bc 12 b 8645 ab NS a RWW = rice water weevil; WH = whitehead; T = treated; U = untreated b T = treated; U = untreated Means in a column followed by the same or no letter are not significantly (NS) different (P > 0.05, ANOVA and LSD)

47 5. Dermacor X-100 Large Plot Study – Cocodrie, Beaumont, TX, 2011 This non-replicated study with Cocodrie shows Dermacor X-100 reduced whitehead numbers (stalk borer injury) 80%. Stalk borers were a combination of MRB and SCB.

Table 5. Mean insect data for Dermacor X-100 large plot study (Cocodrie). Beaumont, TX. 2011 RWWa Plants Rate RWW/5 cores feeding with WHsa/4 Yield Treatment scars/30 insect rows (lb/A) fl oz/cwt lb ai/A plants damageb Jun 3 Jun 13 NipsIt INSIDE 1.92 0.06 5 11 8 8 56 7601

Dermacor X-100 1.75 fl oz/A 0.071 34 14 8 6 17 7514 c CruiserMaxx Rice 7 0.112 8 13 18 2 102 7661 d Karate Z --- 0.03 41 15 17 16 121 7110 Untreated ------29 9 74 66 87 7361 a RWW = rice water weevil; WH = whitehead b From 20 inspected plants (primarily thrips injury, difficult to separate from non-insect injury) c 0.112 lb ai/A of insecticide d Foliar treatment applied before permanent flood

6. Dermacor X-100 Large Plot Study – XP753, Beaumont, TX, 2011 This non-replicated study with XP753 (hybrid) suggests hybrids do not produce as many whiteheadss as inbreds (compare Tables 5 and 6). However, significant yield losses, probably due to incomplete grain fill, are still observed in hybrids.

Table 6. Mean insect data for Dermacor X-100 large plot study (XP753). Beaumont, TX. 2011 RWWa Plants Rate RWW/5 cores feeding with WHsa/4 Yield Treatment scars/30 insect rows (lb/A) fl oz/cwt lb ai/A plants damageb Jun 6 Jun 16 NipsIt INSIDE 1.92 0.019 14 8 0.8 5.8 5 9340

Dermacor X-100 1.75 fl oz/A 0.071 18 7 1.3 7.8 1 9495 c CruiserMaxx Rice 7 0.035 4 6 1.0 8.3 8 8952 d Karate Z --- 0.03 30 8 5.8 8.0 5 8986 Untreated ------26 9 8.8 23.3 8 9123 a RWW = rice water weevil; WH = whitehead b From 20 inspected plants c 0.035 lb ai/A of insecticide d Foliar treatment applied before permanent flood

48 7. Dermacor X-100 Ratoon Study, Ganado, TX, 2009 These data show control of stalk borers on the main crop can have a positive yield effect on the ratoon crop.

Table 7. Mean data for stem borer control in main and ratoon crop rice. Ganado, TX. 2009 a b Rate Timing WHs /4 rows Yield (lb/A) Treatment lb ai/A Main Ratoon Main Ratoon Main Ratoon Total Cocodrie: 0.025mg Dermacor X-100 ST U 1 b 14 c 7482 a 4516 ab 11998 ab ai/seed Karate Z 0.03 T T 1 b 2 d 7769 a 4867 a 12635 a Karate Z 0.03 T U 3 b 35 b 7642 a 4282 b 11923 ab Karate Z 0.03 U T 10 a 2 d 6747 b 4612 ab 11358 b Untreated --- U U 8 a 51 a 6931 b 3433 c 10363 c XL723: 0.05 mg Dermacor X-100 ST U 0 1 b 9326 ab 5291 14617 ai/seed Karate Z 0.03 T T 0 1 b 9704 a 4953 14657 Karate Z 0.03 T U 0 6 a 9585 a 4361 13945 Karate Z 0.03 U T 0 1 b 8940 b 4793 13734 Untreated --- U U 0 7 a 8942 b 4346 13289 NS NS NS a ST = seed treatment; T = treated with Karate Z @ 1 – 2” panicle and late boot/early heading; U = untreated b WHs = whiteheads Means in a column followed by the same or no letter are not significantly (NS) different (P > 0.05, ANOVA and LSD)

Beaumont Sugarcane Variety Test Plot Plan 2010

US 02-9010 (3 rows) HoCP 91-552 (2 rows) US 07-9027 (2 rows) US 08-9003 Ho 06-563 HoCP 05-961 L07-57 HoCP 05-902

HoCP 85-845 Ho 07-604 Ho 07-612 US 08-9001 Ho 06-537 9076 9019 V - HoCP 04-838 L 03-371 Ho 06-9610 N-24 N-27 -

US 04 L 01-299 Ho 07-613 HoCP 00-950 HoCP 96-540 N-17 US 07 N-21 US 01-40 L 07-68 Ho 07-617 US 93-15 HoCP 05-902 Ho 07-612 US 01-40 HoCP 05-961 Ho 07-604

US 93-15 Ho 07-613 L 01-299 US 08-9003 US 08-9001 838 9612 IV - L 07-57 L 07-68 HoCP 85-845 Ho 06-563 N-24

US 07 HoCP 00-950 L 03-371 HoCP 04-838 N-21 Ho 07-617 HoCP 04 - HoCP N-17 HoCP 96-540 N-27 Ho 06-537 Ho 06-9610 Ho 06-563 Ho 07-612 HoCP 05-961 US 08-9003 L 07-57

Ho 06-9610 HoCP 00-950 N-21 HoCP 04-838 HoCP 96-540 113 9015 - III - Ho 07-617 N-24 N-17 US 93-15 N-27 US 02

US 07 HoCP 85-845 Ho 07-613 L 03-371 HoCP 05-902 US 01-40 US 08-9001 L 01-299 Ho 07-604 L 07-68 Ho 06-537 Ho 07-617 HoCP 04-838 HoCP 85-845 N-27 L 03-371

N-17 Ho 07-613 N-21 Ho 06-9610 HoCP 00-950 9014 9017 II - L 01-299 US 93-15 US 01-40 HoCP 96-540 N-24 -

US 07 Ho 06-563 Ho 06-537 Ho 07-612 US 08-9001 L 07-68 US 07 Ho 07-604 HoCP 05-961 US 08-9003 L 07-57 HoCP 05-902 HoCP 05-902 US 01-40 Ho 07-612 Ho 06-537 L 03-371 L 07-57 L 07-68 HoCP 00-950 HoCP 85-845 US 08-9003 155 299 I - Ho 06-563 HoCP 04-838 N-17 HoCP 05-961 US 08-9001 01 - L L CP 44 L 01-299 N-21 N-27 HoCP 96-540 Ho 07-604 Ho 06-9610 N-24 US 93-15 Ho 07-617 Ho 07-613 HoCP 85-845 (7 rows) ↓ Plot size = 1 row, 5.25 ft row width, 12 ft long with 4 ft alley N Shaded plots = Seed increase as buffer

50 Sugarcane Host Plant Resistance Test Insect Nursery Beaumont, TX 2011

PLOT PLAN US 02-9010 HoCP 08-726 Ho 08-706 L 08-090 L 08-088 Ho 08-711 Ho 08-717 HoL 08-723 L 08-075 V L 08-092 L 79-1002 Ho 08-709 HoCP 85-845 HoCP 91-552 Ho 02-113 HoCP 00-950 Ho 05-961 L 07-57 HoCP 04-838 Ho 07-613 blank L 08-092 L 08-090 blank L 08-088 Ho 08-709 Ho 08-717 HoL 08-723 L 08-075 IV HoCP 85-845 HoCP 08-726 Ho 08-711 Ho 08-706 Ho 05-961 HoCP 91-552 Ho 02-113 HoCP 00-950 HoCP 04-838 L 79-1002 L 07-57 Ho 07-613 HoCP 00-950 L 08-088 L 08-075 Ho 08-717

HoL 08-723 L 08-090 Ho 08-706 Ho 08-711 9010 - III Ho 08-709 HoCP 04-838 HoCP 85-845 blank HoCP 08-726 HoCP 91-552 L 79-1002 Ho 02-113 US 02 Ho 07-613 L 07-57 Ho 05-961 L 08-092 L 08-075 L 08-092 L 08-090 L 79-1002 HoL 08-723 Ho 08-709 Ho 08-717 L 08-088 II blank Ho 08-706 HoCP 08-726 Ho 08-711 Ho 02-113 HoCP 85-845 HoCP 00-950 HoCP 91-552 Ho 05-961 L 07-57 Ho 07-613 HoCP 04-838 L 08-092 L 08-090 blank Ho 05-961 L 07-57 Ho 07-613 Ho 08-709 L 08-075 I Ho 08-717 L 08-088 L 79-1002 HoCP 04-838 Ho 08-706 HoL 08-723 HoCP 08-726 HoCP 00-950 Ho 08-711 Ho 02-113 HoCP 85-845 HoCP 91-552 US 02-9010  Plot size = 1 row, 5.25 ft row width, 12 ft long with 4 ft alley N Buffer rows on north (6 ft), south (6 ft) and east (1 row) ends of test

Example data sheet: Mexican rice borer sugarcane infestation, 2002-2011

Stalk number Larvae position on plant (sheath, node, internode)

Internode position Feeding signs (sheath and leaf)

Larvae instar Bored internodes

Field Ganado Date: Treatment: Stalk P Species SN I SN I SN I SN I SN I SN I S LBored 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Total joints

In each square, number of live larvae found

Borer species (Mexican rice borer or sugarcane borer)