Development of Lygus Management Strategies for Texas Cotton

Transcription

1 Development of Lygus Management Strategies for Texas Cotton Ram Shrestha, Megha Parajulee, and Stanley Carroll Texas A&M AgriLife Research and Extension Center Lubbock, Texas 3 rd International Lygus Symposium, Scottsdale, AZ, Oct , 2012

2 Outline Lygus pest status in the Texas High Plains Development of Lygus management strategies Issues in current Lygus management Summary

3 Dominant Species: Lygus hesperus 3

4 Cotton Insect Pest Problems in Texas ( ) 4

5 Lygus Bug Management Strategies Landscape Agro-ecosystem Field Habitat management, movement disruption, sterile technique, genetic control, quarantine, biological control, pest eradication, monitoring and forecasting Crop rotation, cropping patterns, biological control, conservation of beneficials, intercrop movement, trap cropping, resistance management Cultivars, irrigation, planting patterns, planting date,fertilizer, tillage, weed management, insecticides, mating disruption, entomopathogens Plant Molecular Resistant/tolerant plant, transgenic plant, endophytes, crop phenology, sampling, damage assesment, economic threshold Development and utilization of molecular tools, population genetics, molecular systematics, genomics, proteomics, transcriptomics.

6 Potential Lygus Management Tools ICM decision making Landscape management decision making Biological control ID, Monitoring and forecasting Chemical control Genetic engineering of insect population Quarantine and regulations Resistant or tolerant crop GMO 6

7 Chemical Control Insecticide resistance monitoring Insecticide evaluation 7

8 Toxicity of Selected Insecticides LC50 mg/l Dawson Hale Lubbock Acephate LC 50 mg/l April May June July Aug Nov Resistance ratios Bifenthrin Acephate Dicrotophos λ-cyhalothrin Lubbock Dawson Hale

9 Lygus Population Suppression by Different Insecticides Mean no. per 6 row-ft a a Untreated a Carbine 2.3 oz Ammo 5.1 oz 29 Aug - 7 DAT Threshold c b b c bb c b b c Orthene lb Vydate 17 oz b b b b b Centric 2.5 oz Adults Nymphs Total b b bc Diamond 10.5 oz D. Kerns, 2009

10 Avoiding Unnecessary Insecticide Applications Lygus boll damage potential Cotton crop compensation potential 10

11 Yield Response to Lygus-Induced Square Loss ( ) % Fruit loss Expected yield Observed yield Yield (lb/a) SC UC 1PP 3PP SC=sprayed control; UC=unsprayed control; 1PP=1 bug/plant; 3PP=3 bugs/plant 11

12 Boll Damage Patterns External lesions and damaged seeds External lesions per boll y = x x x x R² = y = x x R² = 0.73 Damaged seeds per boll Boll age (Heat units >60 0 F) 12

13 Pesticide Termination Rule >350 Heat Units or >25 mm Boll Diameter 13

14 Landscape Level Understanding for Regional Pest Management Survey of potential hosts Intercrop movement Spatial ecology (RAMP) 14

15 Lygus Survey ( )

16 Sink or Source Relationships Lygus per ha Sink Alfalfa Cotton Net movement Source Jul 12-Jul 20-Jul 27-Jul 3-Aug 10-Aug 24-Aug 31-Aug 16

17 Alfalfa-Cotton System for Lygus Management? 17

18 Integration of Molecular Technologies in Pest Management Utilization of molecular markers Population genetics 18

19 Microsatellite Marker Development and Population Genotyping 1. Genomic DNA library development 2. DNA sequencing and primer development 3. SSR genotyping PCR optimization 19

20 Population Structure of L. hesperus Q proportions Southern Cochran population Northern Dumas population Central Happy population Individual Lygus hesperus ID Individuals=256, Loci=10, Populations assumed=1-10, Reps=

21 Current Lygus Management Issues (Opportunities?) Resistant/tolerant cultivars Lack of high throughput cotton line screening technique Quantification of the role of natural enemies Consolidation and synthesis of Lygus information Lygus monitoring network and forecasting system

22 Summary Lygus is an emerging pest in the Texas High Plains Texas Lygus populations are susceptible to all common insecticides Ecologically intensive management approach is the current Lygus management focus Collaborative efforts are needed for developing regional pest management strategies

23 Acknowledgments Cotton Incorporated

24 Thank you 24