Soil insect pests of peanut

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 protected]
Cell phone: [phone]
Fax: [phone]

2. What attract insects to peanut pods?
Insect types:
Foliar insects
Soil-air interface
Exclusively soil dwelling
CO
2
HEAT
EXUDATES

3. Burrower bugs
•Host range: peanut, cotton,
strawberry, spinach, wild plants
•Identification: note wing structure,
scutellum, & spines on legs
•Damaging stages: adult, nymph
•Mouthparts are inserted into maturing
kernel
•Cause light yellow/brown feeding spots
OR “pitting”
•Loss in kernel weight and no. of sound
kernel
•Increasing problem in conservation
tillage systems
Hemiptera: Cydnidae

4. Scouting techniques (burrower bugs)
•ET = 2 bugs per three feet row
•Monitoring period: July – Aug.
•Direct examination of pods (after the full seed, R6, stage)
•Underutilized techniques: spade sampling/soil corer ?, light
trap ?, pitfall trap √
Pitfall trap with
metal guide & cover
Spade sampling

5. Southern corn rootworm
•Host range: 200 host plants, major pest of
corn, sweet potato, peanut
•Identification: wing pattern on adult beetles,
larvae have 3 pr of legs
• Damaging stage: larvae
Stand loss (early season damage)
Larvae make a hole on one side of the
pod and feed on kernel
High OM, heavy soil >> high risk
Coleoptera: Chrysomelidae

6. Scouting techniques
(southern corn rootworm)
•ET: fresh damage evident OR larvae present in 1/3
rd
sites
•Electronic risk index by NCSU >> high risk (score 70+) in wet
years, low risk (score <50) in well-drained soil
•Larval infestation – scout close to pegging stage
•Sweep net sampling for adults is reliable (10 sweeps/10
paces X 5 loc./A)…midmorning
•Check pods for circular holes at one side (asymmetric)

7. Lesser cornstalk borer
•Occurrence: one of the major insect
pests of peanut, sporadic
•Host range: wide, hot-spots in peanut
•Identification: larvae are blue-green with
purple bands. Moths are grayish.
•Larvae makes sand tubes on pods and
stem (protection?)
•Damaging stage: larvae feed just below
soil surface
•High risk to peanut in hot dry years,
sandy soil
•Worst of all…Aspergillus & aflatoxins
Lepidoptera: Pyralidae

8. Scouting techniques
(lesser cornstalk borer)
•ET – control when fresh damage is present OR when insect
is recovered from 1/3
rd
sample sites
•Pod sampling – reliable indicator of infestation
•Scouting maps available from AWIS website – based on the
estimation of borer days on a scale of 0 to 5

9. Wireworms
•Host range: several plants (extended life
cycle allows use of resources)
•Identification: larvae with cylindrical
body, wriggle furiously when touched,
adults are click beetles
•Damaging stage: larvae feed at various
depths, major problem following sod
•Saturated soil causes migration & spread
•Make a large entry hole on one end
Coleoptera: Elateridae

10. Scouting techniques (wireworms)
•Study field history – crop rotation, previous infestations
•Germinating seed bait stations in soil – a reliable “relative
sampling” technique
•Seed baits could be deployed before planting peanut
•Accuracy of seed baits improves with number of baits and
experience of the field personnel
•ET = 1 wireworm per bait station OR 30% pod damage

11. Whitefringed beetles
•Occurrence: native of S. Am.,
Naupactus species complex
•Host range: 350 host plants –
peanut, cotton, cowpea, alfalfa, okra
•Identification: weevil w/out snout,
adult has white stripes on sides, larva
plump with strong mandibles
•Damaging stages: larvae/grubs
•Larvae make irregular holes in tap
root, fatal to plants
•Scouting: sweep net for beetles, leaf
notching (visual scouting)
•No insecticide registered
Coleoptera: Curculionidae

12. Cutworms
•Host range: over 60 crops and turf, major
pest of peanut
•Identification: greasy plump caterpillars,
larvae curl when touched
•Overwintering stage: larva
•Damage:
•cut seedlings at night, may climb plants
•larvae bore into the middle of peanut
pod (large hole)
Lepidoptera: Noctuidae
Black CW
Granulate CW

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. Scouting recommendations
•Draw soil samples in Winter or Spring.
•Reduce tendency to overestimate – increase sampling
locations/numbers!
•Use a variety of sampling methods – pheromone traps and
germinating seed bait stations are cost effective!
•Economic thresholds:
Burrower bug = 2 bugs per 3 foot row
LCB, SCRW = fresh damage or insect at 30% sites
Wireworms = 1 per bait station or 30 % pod damage

15. Management of soil insects (peanut)
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)
Future research directions:
• Extend registration of new insecticides
• Focus on bio-based soil insecticides as IPM partner
• Survey of all major production areas (2009)
• Establish economic threshold for emerging pests
Burrower bugs
Chlorpyrifos
(banded over
row)

16. New Peanut Entomology Resources
•ACES Factsheets:
–“Soil insect pests of peanut”…coming soon
–“Scouting techniques for soil insect pests of peanut”…review
complete
•Timely Information sheets: (
http://www.aces.edu/timelyinfo/entomology/entomology.php)
–“Germinating seed bait technique” (posted)
–“Peanut insecticide recommendations for 2009” (posted)
•New peanut entomology SharePoint:
https://sites.aces.edu/group/crops/peanut/default.aspx (PowerPoint shows with
narration)
•Conferences (like IPM-WC1, extension technology conf.)
•YouTube Peanut Channel linked to ACES
•CropsBlog: weekly updates in summer, PLEASE SUBSCRIBE!

17. Take home message for today…

18. SOIL INSECT PESTS OF PEANUT
Questions?