Soil Insect Pests of Peanuts


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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 Peanuts

    1. 1. Below-ground Insect Pests of Peanut Dr. 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. Extension Survey <ul><li>Voluntary participation – please try to respond & return </li></ul><ul><li>General survey (yellow pages) – Designed to assess your changing needs for information & delivery method </li></ul><ul><li>Has been prepared on the basis of published reports (allows comparison with other surveys) </li></ul><ul><li>Survey questions printed on both sides </li></ul><ul><li>Presentation survey (orange sheet) – to assess this presentation and your learning </li></ul><ul><li>Any concerns? Contact Ayanava (251-331-8416) </li></ul><ul><li>THANK YOU FOR YOUR PARTICIPATION </li></ul>
    3. 3. What attract insects to peanut pods? Insect types: Foliar insects Soil-air interface Exclusively soil dwelling CO 2 HEAT EXUDATES
    4. 4. Burrower bugs <ul><li>Six species in peanuts, Pangaeus bilineatus most prevalent, sporadic late-season pest </li></ul><ul><li>Host range: peanut, cotton, strawberry, spinach, wild plants </li></ul><ul><li>Identification: small insects, note wing structure & spines on legs </li></ul><ul><li>Overwintering stage: adult, under rocks, crop stubble, volunteer plants </li></ul><ul><li>Behavioral clues: </li></ul><ul><ul><li>eggs laid singly near roots & pods </li></ul></ul><ul><ul><li>adults/nymphs walk along soil cracks </li></ul></ul><ul><ul><li>soil moisture affect movement </li></ul></ul><ul><ul><li>adults attracted to white light </li></ul></ul>Hemiptera: Cydnidae
    5. 5. Damage by burrower bugs <ul><li>Damaging stages: adult, nymph </li></ul><ul><li>Problem in conservation tillage </li></ul><ul><li>Mouthparts are inserted into maturing kernel </li></ul><ul><li>Light yellow/brown feeding spots “pitting” </li></ul><ul><li>Loss in kernel weight and no. of sound kernel </li></ul>
    6. 6. Scouting techniques (burrower bugs) <ul><li>Spade sampling/soil corer >> sieving (5- to 12 mesh) (July – Aug.) </li></ul><ul><li>ET = 2 bugs per three feet row </li></ul><ul><li>Underutilized techniques: light trap, pitfall trap </li></ul><ul><li>Direct examination of pods (after the full seed, R6, stage) </li></ul>Pitfall trap with metal guide & cover Spade sampling
    7. 7. 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, grasses </li></ul><ul><li>Identification: looks like a boll weevil but no snout, adult has white stripes on sides, larva plump with reduced head </li></ul><ul><li>Overwintering stage: larvae (10-12 in. deep in soil), eggs </li></ul><ul><li>Behavioral clues: </li></ul><ul><ul><li>Emergence starts in April-July </li></ul></ul><ul><ul><li>1 to 2 yr life cycle </li></ul></ul><ul><ul><li>Females have keen host-finding ability, can’t fly… </li></ul></ul>Coleoptera: Curculionidae
    8. 8. Damage by whitefringed beetles <ul><li>Damaging stages: adult, nymph (chewing mps) </li></ul><ul><li>Larvae – irregular holes in tap root, fatal to plants </li></ul><ul><li>Root injury resembles wireworm, rootworm, white grub feeding </li></ul><ul><li>Stand losses early & mid-season </li></ul><ul><li>Can reach high pop. density – 186 per cu m </li></ul><ul><li>Notched leaves?? </li></ul>
    9. 9. Scouting techniques (whitefringed beetles) <ul><li>Soil cores/spade sampling prior to planting season </li></ul><ul><li>Visual & beat cloth sampling for adult beetles (females) </li></ul><ul><li>Underutilized techniques: </li></ul><ul><ul><li>Sweep net for adult beetles </li></ul></ul><ul><ul><li>Floatation technique for small larvae </li></ul></ul>
    10. 10. Southern corn rootworm <ul><li>Occurrence: throughout U.S., immature form of spotted cucumber beetle (Diabrotica u. howardi) </li></ul><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>Overwintering stage: adult beetles (mostly female beetles) </li></ul><ul><li>Behavioral clues: </li></ul><ul><ul><li>short overwintering period </li></ul></ul><ul><ul><li>high fecundity, eggs laid in soil at plant bases </li></ul></ul><ul><ul><li>adaptable to crop rotations?? </li></ul></ul>Coleoptera: Chrysomelidae
    11. 11. Damage by southern corn rootworm <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><ul><li>Adult beetles feed on leaves, but not a problem. </li></ul><ul><li>Electronic risk index by NCSU >> high risk (score 70+) in wet years, low risk (score <60) in well-drained soil </li></ul>
    12. 12. Scouting techniques (southern corn rootworm) <ul><li>Larval infestation – scout close to pegging stage </li></ul><ul><li>Spade sampling with a tray (larvae drop off quickly) </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 end </li></ul><ul><li>ET: fresh damage evident OR larvae present in 1/3 rd sites </li></ul>
    13. 13. 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, wings folded at rest, bushy abdomen (females) </li></ul><ul><li>Overwintering stage: larvae/pupae </li></ul><ul><li>Behavioral clues: </li></ul><ul><ul><li>able to survive dry soils (escapes predation) </li></ul></ul><ul><ul><li>attracted to CO 2 and heat from plant roots </li></ul></ul><ul><ul><li>larvae make sand tubes </li></ul></ul>Lepidoptera: Pyralidae
    14. 14. Damage by lesser cornstalk borer <ul><li>Damaging stage: larvae feed just below soil surface </li></ul><ul><li>Larvae makes sand tubes on pods and stem </li></ul><ul><li>High risk to peanut in hot dry years, sandy soil </li></ul><ul><li>Spreads southern stem rot between plants </li></ul>
    15. 15. Scouting techniques (lesser cornstalk borer) <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><ul><li>ET – control when fresh damage is present OR when insect is recovered from 1/3 rd sample sites </li></ul>
    16. 16. Wireworms <ul><li>Occurrence: many species ( Conoderus ), sporadic/key pest </li></ul><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>Overwintering stage: larva, beetle </li></ul><ul><li>Behavioral clues: </li></ul><ul><ul><li>very attracted to CO 2 and heat from plant roots </li></ul></ul><ul><ul><li>optimum SM for movement = 8 to 16% </li></ul></ul><ul><ul><li>high mobility & chemical repellency </li></ul></ul>Coleoptera: Elateridae
    17. 17. Damage by wireworms <ul><li>Damaging stage: larvae feed at various depths </li></ul><ul><li>Early season damage to peanut >> loss of plant stand </li></ul><ul><li>Doesn’t like saturated SM, causes migration & spread </li></ul><ul><li>Major problem following sod </li></ul><ul><li>Larvae attack pod: make a large entry hole on a side </li></ul><ul><li>Large larvae feeds with part of body outside </li></ul>
    18. 18. Scouting techniques (wireworms) <ul><li>Study field history – crop rotation, previous infestations </li></ul><ul><li>Germinating seed baits in soil – a reliable “relative sampling” technique </li></ul><ul><li>Seed baits could be put previous season or before planting peanut (about 12 in a 40 A field) </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>
    19. 19. Cutworms <ul><li>Occurrence: throughout AL, black cutworm ( Agrotis ipsilon ), granulate cutworm ( A. subterranea ) common </li></ul><ul><li>Host range: over 60 crops and turf, major pest of peanut </li></ul><ul><li>Identification: moths have dark forewings & white hindwings, 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>granulate CW bore into the middle of peanut pod (large hole) </li></ul></ul>Lepidoptera: Noctuidae Agrotis ipsilon Agrotis subterranea
    20. 20. Scouting techniques (cutworms) <ul><li>Often detected when scouting for other insects </li></ul><ul><li>Look directly under the base of cut plants </li></ul><ul><li>Risk higher in dry conditions, well drained soils </li></ul><ul><li>Pheromone trapping (bucket/wing traps for moths) </li></ul><ul><li>Pheromone lure & trap suppliers: </li></ul><ul><li>Phero Tech Inc. </li></ul><ul><li>Scentry Biologicals Inc. </li></ul><ul><li>Great Lakes IPM Inc., </li></ul><ul><li>Gemplers Inc. </li></ul>
    21. 21. 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
    22. 22. Scouting recommendations <ul><li>Draw soil samples in Winter or Spring. </li></ul><ul><li>Reduce tendency to overestimate – increase sampling sites! </li></ul><ul><li>Use a variety of sampling methods – pheromone traps and germinating seed bait stations are cost effective! </li></ul>
    23. 23. Scouting recommendations (contd.) <ul><li>Economic thresholds: </li></ul><ul><li>Soil-dwelling: burrower bug = 2 bugs per 3 foot row </li></ul><ul><li>Soil-air interface: </li></ul><ul><li>Cutworms, armyworms = 4 or more larvae per foot </li></ul><ul><li>LCSB, SCRW = fresh damage or insect at 30% sites </li></ul><ul><li>Wireworms = 1 per bait station or 30 % pod damage </li></ul>
    24. 24. Insecticides for soil insects <ul><li>What affects insecticide efficacy? Timing & placement, soil temp. & moisture, microorganisms </li></ul><ul><li>Additional insecticides need to be registered (suggestions?). </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)
    25. 25. Take home message for today…
    26. 26. Extension Survey <ul><li>Voluntary participation – please try to respond & return </li></ul><ul><li>General survey (yellow pages) – Designed to assess your changing needs for information & delivery method </li></ul><ul><li>Has been prepared on the basis of published reports (allows comparison with other surveys) </li></ul><ul><li>Survey questions printed on both sides </li></ul><ul><li>Presentation survey (orange sheet) – to assess this presentation and your learning </li></ul><ul><li>THANK YOU FOR YOUR PARTICIPATION! </li></ul>Questions?
    27. 27. Armyworms <ul><li>Occurrence: statewide, increasing menace in no till systems </li></ul><ul><li>Host range: wide range of cultivated & wild plants </li></ul><ul><li>Identification: inverted Y mark on larva, brown forewings, hind wings with dark veins, hair tufts on abdomen of females </li></ul><ul><li>Overwintering stage: pupa </li></ul><ul><li>Behavioral clues: day feeders, sever plants at soil level </li></ul><ul><li>Damage: serious defoliator of peanut </li></ul>Lepidoptera: Noctuidae Spodoptera exigua Spodoptera frugiperda
    28. 28. Insect pest management system in peanut Based on Dhaliwal & Arora, 1994
    29. 29. SOIL INSECT PESTS OF PEANUT Questions?