Soil insect pests of peanut


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  • Alabama peanut production acres in 2008 = 191,000 acres; average state production = 3,300 lbs; total production = 630,000 lbs; value of crop = $73 million (2007 prices)
  • Soil insect pests of peanut

    1. 1. Scouting and Management Challenges for Soil Insect Pests of Peanut Ayanava Majumdar Extension Entomologist, ACES Gulf Coast Research and Extension Center 8300 State Hwy 104, Fairhope, AL 36532 Email: [email_address] Cell phone: 251-331-8416 Fax: 251-990-8912
    2. 2. What attract insects to peanut pods? Insect types: Foliar insects Soil-air interface Exclusively soil dwelling CO 2 HEAT EXUDATES
    3. 3. Burrower bugs <ul><li>Host range: peanut, cotton, strawberry, spinach, wild plants </li></ul><ul><li>Identification: note wing structure, scutellum, & spines on legs </li></ul><ul><li>Damaging stages: adult, nymph </li></ul><ul><li>Mouthparts are inserted into maturing kernel </li></ul><ul><li>Cause light yellow/brown feeding spots OR “pitting” </li></ul><ul><li>Loss in kernel weight and no. of sound kernel </li></ul><ul><li>Increasing problem in conservation tillage systems </li></ul>Hemiptera: Cydnidae
    4. 4. Scouting techniques (burrower bugs) <ul><li>ET = 2 bugs per three feet row </li></ul><ul><li>Monitoring period: July – Aug. </li></ul><ul><li>Direct examination of pods (after the full seed, R6, stage) </li></ul><ul><li>Underutilized techniques: spade sampling/soil corer ? , light trap ? , pitfall trap √ </li></ul>Pitfall trap with metal guide & cover Spade sampling
    5. 5. Southern corn rootworm <ul><li>Host range: 200 host plants, major pest of corn, sweet potato, peanut </li></ul><ul><li>Identification: wing pattern on adult beetles, larvae have 3 pr of legs </li></ul><ul><li>Damaging stage: larvae </li></ul><ul><li>Stand loss (early season damage) </li></ul><ul><li>Larvae make a hole on one side of the pod and feed on kernel </li></ul><ul><li>High OM, heavy soil >> high risk </li></ul>Coleoptera: Chrysomelidae
    6. 6. Scouting techniques (southern corn rootworm) <ul><li>ET: fresh damage evident OR larvae present in 1/3 rd sites </li></ul><ul><li>Electronic risk index by NCSU >> high risk (score 70+) in wet years, low risk (score <50) in well-drained soil </li></ul><ul><li>Larval infestation – scout close to pegging stage </li></ul><ul><li>Sweep net sampling for adults is reliable (10 sweeps/10 paces X 5 loc./A)…midmorning </li></ul><ul><li>Check pods for circular holes at one side (asymmetric) </li></ul>
    7. 7. Lesser cornstalk borer <ul><li>Occurrence: one of the major insect pests of peanut, sporadic </li></ul><ul><li>Host range: wide, hot-spots in peanut </li></ul><ul><li>Identification: larvae are blue-green with purple bands. Moths are grayish. </li></ul><ul><li>Larvae makes sand tubes on pods and stem (protection?) </li></ul><ul><li>Damaging stage: larvae feed just below soil surface </li></ul><ul><li>High risk to peanut in hot dry years, sandy soil </li></ul><ul><li>Worst of all… Aspergillus & aflatoxins </li></ul>Lepidoptera: Pyralidae
    8. 8. Scouting techniques (lesser cornstalk borer) <ul><li>ET – control when fresh damage is present OR when insect is recovered from 1/3 rd sample sites </li></ul><ul><li>Pod sampling – reliable indicator of infestation </li></ul><ul><li>Scouting maps available from AWIS website – based on the estimation of borer days on a scale of 0 to 5 </li></ul>
    9. 9. Wireworms <ul><li>Host range: several plants (extended life cycle allows use of resources) </li></ul><ul><li>Identification: larvae with cylindrical body, wriggle furiously when touched, adults are click beetles </li></ul><ul><li>Damaging stage: larvae feed at various depths, major problem following sod </li></ul><ul><li>Saturated soil causes migration & spread </li></ul><ul><li>Make a large entry hole on one end </li></ul>Coleoptera: Elateridae
    10. 10. Scouting techniques (wireworms) <ul><li>Study field history – crop rotation, previous infestations </li></ul><ul><li>Germinating seed bait stations in soil – a reliable “relative sampling” technique </li></ul><ul><li>Seed baits could be deployed before planting peanut </li></ul><ul><li>Accuracy of seed baits improves with number of baits and experience of the field personnel </li></ul><ul><li>ET = 1 wireworm per bait station OR 30% pod damage </li></ul>
    11. 11. Whitefringed beetles <ul><li>Occurrence: native of S. Am., Naupactus species complex </li></ul><ul><li>Host range: 350 host plants – peanut, cotton, cowpea, alfalfa, okra </li></ul><ul><li>Identification: weevil w/out snout, adult has white stripes on sides, larva plump with strong mandibles </li></ul><ul><li>Damaging stages: larvae/grubs </li></ul><ul><li>Larvae make irregular holes in tap root, fatal to plants </li></ul><ul><li>Scouting: sweep net for beetles, leaf notching (visual scouting) </li></ul><ul><li>No insecticide registered </li></ul>Coleoptera: Curculionidae
    12. 12. Cutworms <ul><li>Host range: over 60 crops and turf, major pest of peanut </li></ul><ul><li>Identification: greasy plump caterpillars, larvae curl when touched </li></ul><ul><li>Overwintering stage: larva </li></ul><ul><li>Damage: </li></ul><ul><ul><li>cut seedlings at night, may climb plants </li></ul></ul><ul><ul><li>larvae bore into the middle of peanut pod (large hole) </li></ul></ul>Lepidoptera: Noctuidae Black CW Granulate CW
    13. 13. Other sporadic insect pests White grubs ( Phyllophaga spp.) May/June Beetles 1-4 year life cycle Problem after sod Bahiagrass borer ( Derobrachus brevicollis) Large head of larva Problem after bahiagrass
    14. 14. Scouting recommendations <ul><li>Draw soil samples in Winter or Spring. </li></ul><ul><li>Reduce tendency to overestimate – increase sampling locations/numbers! </li></ul><ul><li>Use a variety of sampling methods – pheromone traps and germinating seed bait stations are cost effective! </li></ul><ul><li>Economic thresholds: </li></ul><ul><li>Burrower bug = 2 bugs per 3 foot row </li></ul><ul><li>LCB, SCRW = fresh damage or insect at 30% sites </li></ul><ul><li>Wireworms = 1 per bait station or 30 % pod damage </li></ul>
    15. 15. Management of soil insects (peanut) <ul><li>Future research directions: </li></ul><ul><li>Extend registration of new insecticides </li></ul><ul><li>Focus on bio-based soil insecticides as IPM partner </li></ul><ul><li>Survey of all major production areas (2009) </li></ul><ul><li>Establish economic threshold for emerging pests </li></ul>Cutworms Indoxacarb Cyfluthrin Gamma-cyhalo. Lamdba-cyhalo. Methomyl Zeta-cypermeth. LCSB Chlorpyrifos (banded over row and pegging zone) SCRW Chlorpyrifos (banded over row and pegging zone) Wireworms Chlorpyrifos (preplant broadcast spray on soil + incorporate OR banded) Burrower bugs Chlorpyrifos (banded over row)
    16. 16. New Peanut Entomology Resources <ul><li>ACES Factsheets: </li></ul><ul><ul><li>“ Soil insect pests of peanut”…coming soon </li></ul></ul><ul><ul><li>“ Scouting techniques for soil insect pests of peanut”…review complete </li></ul></ul><ul><li>Timely Information sheets: ( ) </li></ul><ul><ul><li>“ Germinating seed bait technique” (posted) </li></ul></ul><ul><ul><li>“ Peanut insecticide recommendations for 2009” (posted) </li></ul></ul><ul><li>New peanut entomology SharePoint: (PowerPoint shows with narration) </li></ul><ul><li>Conferences (like IPM-WC1, extension technology conf.) </li></ul><ul><li>YouTube Peanut Channel linked to ACES </li></ul><ul><li>CropsBlog: weekly updates in summer, PLEASE SUBSCRIBE! </li></ul>
    17. 17. Take home message for today…
    18. 18. SOIL INSECT PESTS OF PEANUT Questions?