Biology and Management of the Tobacco 2010_TWC77_Rivera.pdf Splitworm, Phthorimaea operculella (Lepidoptera: Gelichiidae) Monique Rivera 20 January 2010 TWC2010(44) - Document not peer-reviewed Outline 2010_TWC77_Rivera.pdf • Introduce Splitworms • Pheromone Trapping • In-Field Caging • Harvest Manipulation TWC2010(44) - Document not peer-reviewed Introduction: What are splitworms??? 2010_TWC77_Rivera.pdf • Previously studied under official name: potato tuberworm – On potato: feeds on leaves and tubers, tubers mostly in storage • Larvae feed on solanceous plants • Poor flier (P.J. Cameron et al., 2002) • Preference for hot/dry temperatures (Langford and Cory, 1934) • Chooses oviposition site by both mechanical and chemical signals (P.G. Fenemore, 1988) TWC2010(44) - Document not peer-reviewed Splitworms as a pest of Tobacco 2010_TWC77_Rivera.pdf • Most obvious damage to plant is mining of leaves but can also mine stalks, stems • Most often seen as a minor late season pest of both flue-cured and burley tobacco • Adult moths lay eggs in the soil beneth the plant (Van Vuuren et al. 1998) TWC2010(44) - Document not peer-reviewed Uncertainty: Chemical Control for Splitworms and Other Changes 2010_TWC77_Rivera.pdf • 2009: Food and Drug Administration gains authority to regulate tobacco products – ? • Currently, Belt® is the only registered chemical control for splitworms – Little efficacy data for product TWC2010(44) - Document not peer-reviewed Pheromone Trapping 2010_TWC77_Rivera.pdf • Synthetic pheromone used to attract male splitworm to sticky trap • Cooperative efforts throughout the SE U.S. • Why? – Tracking persistence post- harvest through the winter months – Can traps be used to predict in- field infestation? – How many generations per season? TWC2010(44) - Document not peer-reviewed Pheromone Trapping in NC 2010_TWC77_Rivera.pdf • At least 7 locations in the eastern half of the state during both 2008-9 • Traps along the edges of the field • Transects: – 3 rows of ~100 plants per trap – On average, ~1000 plants looked at per field TWC2010(44) - Document not peer-reviewed 70 Chowan County 2010_TWC77_Rivera.pdf 0.25 60Splitworm Monitoring 2008 50 0.2 40 Total Proportion Infested Plants 0.15 Proportion Plants with Live Larvae 30 Moths/trap/day 0.1 20 0.05 10 0 0 8/5/08 9/2/08 9/9/08 7/1/08 7/8/08 7/15/08 7/22/08 7/29/08 8/12/08 8/19/08 8/26/08 9/16/08 9/23/08 9/30/08 10/7/08 10/14/08 10/21/08 10/28/08 TWC2010(44) - Document not peer-reviewed 40 0.16 Nash County 2010_TWC77_Rivera.pdf 35 Splitworm Monitoring 0.14 30 0.12 25 Total Proportion Infested Plants 0.1 Proportion Plants with Live Larvae 20 0.08 Moths/trap/day 15 0.06 10 0.04 5 0.02 0 0 9/5/08 8/1/08 8/8/08 7/4/08 9/12/08 9/19/08 9/26/08 10/3/08 8/15/08 8/22/08 8/29/08 7/11/08 7/18/08 7/25/08 6/20/08 6/27/08 10/31/08 10/24/08 10/17/08 10/10/08 TWC2010(44) - Document not peer-reviewed Rainfall Differences: 2008 vs. 2009 2010_TWC77_Rivera.pdf Rainfall (inches) 2008 and 2009 60.00 54.61 55.00 50.00 2008: serious drought 45.91 Rocky Mount, Nash County, 44.72 NC 45.00 42.20 Edenton, Chowan County, NC conditions 40.00 35.00 2009: exit drought, enter 30.00 much very wet spring months Edenton Rocky Mount Location TWC2010(44) - Document not peer-reviewed 60 50 40 active 30 infested moth/trap/ SplitwormChowan Monitori County, 20 10 d 0 6/11/09 6/18/09 6/25/09 7/2/09 N 7/9/09 7/16/09 n 7/23/09 Harvest Comp 7/30/09 8/6/09 8/13/09 8/20/09 e 8/27/09 1.2 9/3/09 1 = total infest 9/10/09 1 Dat 9/17/09 2010_TWC77_Rivera.pdf e 9/24/09 0.8 10/1/09 a 10/8/09 0.6 10/15/09 0.4 10/22/09 10/29/09 0.2 11/5/09 11/12/09 0 TWC2010(44) - Document not peer-reviewed TWC2010(44) - Document not peer-reviewed 2010_TWC77_Rivera.pdf 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 • 6/30/2008 Chowan 7County/11/2008 2008- where mines were found on 7/16/2008 the plant 7/22/2008 7/29/2008 8/5/2008 8/14/2008 8/19/2008 8/29/2008 9/5/2008 9/12/2008 9/16/2008 2010_TWC77_Rivera.pdf 9/26/2008 Upper 3rd 10/3/2008 Middle 3rd 10/11/2008 Lower 3rd 10/17/2008 10/21/2008 10/28/2008 Site Fully Harvested 10/31/08 TWC2010(44) - Document not peer-reviewed Pheromone Trapping: Conclusions 2010_TWC77_Rivera.pdf • Appears to be about three generations per season in NC • Trap captures predate in field damage • Surviving through the winter- but on what? TWC2010(44) - Document not peer-reviewed In-Field Caging Experiments 2010_TWC77_Rivera.pdf Why Caging? • Trapping: noted most feeding on lower leaves – Because first available or •All caging completed on preference for these leaves? flue-cured tobacco at the Central Crops Research • Spatial and temporal Station in Clayton, NC differences in the plant •Survivorship data with relation to splitworm collected: larval feeding development, pupal weight, pupal duration, total life span TWC2010(44) - Document not peer-reviewed Caging: Design 2010_TWC77_Rivera.pdf • Within three rows: placed thirty cages, 10 in each row, with at least 1 plant buffer • Two times: Before flowering, after flower • 10 larvae from colony collected from tobacco, raised on potato per cage TWC2010(44) - Document not peer-reviewed Caging: Pupal Duration 2010_TWC77_Rivera.pdf Pupal Duration of 6.25 and 7.8 7.6 7.6 7.4 7.2 7.2 7.1 7 7 6/25/09 6.8 6.6 7/25/09 6.6 6.4 6.4 6.2 6 5.8 U M L Stalk Position NS.: Trending of quicker development on middle leaves (pupal handling)--- change legends to say date TWC2010(44) - Document not peer-reviewed Cages Placed 6/25/09: Quicker Development on Upper and Lower Leaves 2010_TWC77_Rivera.pdf 6.25: Larval Development 17.5 17 17 16.5 16 15.56 15.5 15.07 15 14.5 ba c ab 14 Lower Middle Upper Stalk Position TWC2010(44) - Document not peer-reviewed Cages placed 7/25/09: No significant differences 2010_TWC77_Rivera.pdf 7.25: Larval Development 17.5 17.2 17.13 16.9 17 16.5 16 15.5 15 14.5 14 Lower Middle Upper Stalk Position TWC2010(44) - Document not peer-reviewed Caging: Increased Similarity in Leaf Size as Nears Maturity 2010_TWC77_Rivera.pdf Average Leaf Area (mm squared) June 25, 2009 (P=<.0001) Also collected leaf area data lower middle upper Values in mm2 20935.4 87967.6 198483.5 Average Leaf Area (mm squared) July 25, 2009 (P=<.0001) lower middle upper 69103.8 Both show leaves at all levels differing significantly but leaves 218924.3 are larger and closer in size on 159706.4 the July 25th date. TWC2010(44) - Document not peer-reviewed Caging: In conclusion 2010_TWC77_Rivera.pdf • Continuing with caging for the 2010 season • Based on collected data, we think splitworm larvae may be better able to exploit the plant in the late season TWC2010(44) - Document not peer-reviewed Flue-Cured Harvest Manipulation 2010_TWC77_Rivera.pdf • Wanted to see how Flue-Cured harvest impacted the success of splitworm establishment • Two Locations: Reidsville and Oxford TWC2010(44) - Document not peer-reviewed 2010_TWC77_Rivera.pdf •Simulated primings by hand •Removed three levels of the plant TWC2010(44) - Document not peer-reviewed Plot Maps 105 104 103 15/21 102 101 10987654321 10 20 10 20 10987654321 10 20 -- -- 2321023210 33 31 33 31 2321023210 33 31 2010_TWC77_Rivera.pdf - -- 2321023210 01 02 01 02 01 02 - -- 1232112321 22 13 22 13 1232112321 22 13 1232112321 0 0 0 3103231032 3103231032 3103231032 205 204 203 202 201 0010300103 31 32 31 32 0010300103 31 32 0010300103 12 13 12 13 20 19 18 17 16 15 14 13 12 11 12 13 1221312213 20 21 20 21 1221312213 20 21 1221312213 03 0 03 0 03 0 2013120131Oxford: Reidsville: 2013120131 2013120131 305 304 303 302 301 3302033020 10 2 1 10 2 1 3302033020 10 2 1 330203302030 Replicates 16 Replicates23 3 2 23 3 2 23 3 2 0130201302 02 1 3 02 1 3 0130201302 02 1 3 0130201302 31 0 31 0 30 29 28 27 26 25 24 23 22 21 31 0 3321033210 0 0 3321033210 0 3321033210 2130221302 405 404 403 402 401 2130221302 2103 2103 2130221302 2103 1210 1210 0203302033 1210 0203302033 3031 3031 0203302033 3031 0322 0322 1012110121 0322 1012110121 1012110121 TWC2010(44) - Document not peer-reviewed Harvest Manipulation: Mines 2010_TWC77_Rivera.pdf Reidsville: Mines Trt 3 1 N=52 Trt 2 1.29 Average Mines Per Trt, Per Plant Treatmen Trt 1 1.33 Oxford: Mines P= 0.0070 Trt 0 1.38 Trt 3 1.21 N= 309 0 0.5 1 1.5 Average Mines Per Trt, Per Plant Trt 2 1.84 Average Mines Per Trt, Per Plant Plant Poor establishment at Reidsville Trt 1 2.06 Treatment 0 1 2 3 Trt 0 2.43 Reidsville 21 15 14 2 Average Mines Per Trt, Per Oxford 217 150 100 81 0 0.5 1 1.5 2 2.5 3 Treatment TWC2010(44) - Document not peer-reviewed C2 Distance C 2010_TWC77_Rivera.pdf A2 B2 • Measured the Oxford: Distance C: p= < .0001 space between 30 28.17 23.65 25 22.34 the three plants 19.94 and the distance 20 up the stalk to 15 mine to calculate 10 distance 5 0 traveled Trt 0 Trt 1 Trt 2 Trt 3 between plants Treatments Treatment 0 1 2 3 Reidsville 21 15 14 2 Oxford 217 150 100 81 TWC2010(44) - Document not peer-reviewed Harvest Manipulation: In Conclusion 2010_TWC77_Rivera.pdf • Will continue this study for the 2010 season • Appears that neonates can best establish in tobacco plants before harvest – Within Plant Microclimate? – More immediate establishment, less risk? • More data and observation will allow us to confirm early harvesting in as a recommendation for splitworm feeding TWC2010(44) - Document not peer-reviewed Summary 2010_TWC77_Rivera.pdf • Pheromone Trapping – Appears to be three generations of splitworms in NC – Trap captures appear to predate in-field damage • Caging – Trends from caging data illustrate that stalk position may only be a factor in early season feeding • Harvest Maniupulation – Splitworms establishing better with less leaves harvested TWC2010(44) - Document not peer-reviewed Additional Studies 2010_TWC77_Rivera.pdf This Spring: • Survivorship and Choice Tests on Weeds and Tobacco Plant Parts – Horsenettle (Solanum carolinense) – Eggplant – Redroot pigweed (Amaranthus retroflexus) – Buffalobur (Solanum rostratum Doug Waylett TWC2010(44) - Document not peer-reviewed Acknowledgements 2010_TWC77_Rivera.pdf • Tobacco Education and Research Council • Pheromone trapping cooperators: – Francis Reay-Jones- Clemson University – Paul Semter- Virginia Tech – Bob McPherson, J.