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Soybean Insect Identification and Management
Agent TrainingJune 26-27
NCSU and Plymouth, NC
Plant InjuryChewing Piercing-sucking
Insect Mouthparts
Plant InjuryGall making Insect Vectors
Injury vs. Damage
Injury: harm or destruction on the host plant caused by the pest
Damage: measurable loss of the host that affects the yield quantity, quality or aesthetics
Old vs. New InjuryOld New
Economic Injury Level
EIL: the lowest number of insects that causes economic damage
C = Cost of management per unit area
V = market value per unit of product
I = Injury units per insect per production unit; expressed as a proportion
D = Damage per unit injury
K = proportionate reduction in potential injury or damage
EIL =
Economic Threshold
ET = the number of insects that triggers a management action
Corn Earworm/Tobacco Budworm
Thresholds now online!
www.nccrops.com
Will lead to Field Crop Entomology Webpage Link
Click Soybean Insect Pests
Click Corn Earworm
Click CEW Threshold Calculator for Soybeans
Sampling and Monitoring Methods
Direct SamplingTransect Random Sampling
Seedling Pests
• Thrips• Grasshopper/Katydid• Bean Leaf Beetle• Cutworm• Threecornered alfalfa hopper• Lesser cornstalk borer
Thrips
Tobacco thrips predominate after planting, then soybean thrips
Some Eastern flower thrips, very few Western flower thrips
White Margined Burrower Beetle
Grasshoppers
• Most common in reduced till
• Adults more difficult to kill
Katydid
Bean Leaf Beetle
Cutworm
Threecornered Alfalfa Hopper
Check when beans are less than 10 inches tallThreshold is one per sweep
Threecornered Alfalfa Hopper Injury
Stem Borers
• Lesser cornstalk borer• Dectes stem borer
Lesser Cornstalk Borer
Dectes Stem Borer
Vegetative/Flowering Stage Pests (after seedling stage)
• Defoliators– Corn earworm/tobacco budworm– Armyworm complex– Soybean looper (generally late-season)– Green cloverworm (generally NOT a pest)– Velvetbean caterpillar (generally late-season)– Bean leaf beetle– Japanese beetle– Blister beetle– Grape colapsis– Spider mites– Whitefly
Corn Earworm/Tobacco Budworm
Armyworm Complex
Armyworm Complex
Soybean Looper
Green Cloverworm
Generally NOT a pest
Velvetbean Caterpillar
Four pairs of prolegs
Japanese Beetle
• Beetles often congregate• Damage lacy• Usually sub-economic
Blister Beetle
Grape Colaspis
Spider mites
Whitefly
Defoliator Thresholds
• Vegetative stages– 30% defoliation
• Two weeks prior to bloom and during pod-fill– 15% defoliation
Vegetative/Flowering Stage Pests (after seedling stage)
Piercing sucking pests–Kudzu bug–Brown stink bug–Green stink bug
Kudzu Bug
Kudzu Bug
Stink Bug Complex
Stink Bug Complex
Green Stink Bug Nymph
Brown Stink Bug Nymph
Piercing/sucking like Kudzu bug
However, stink bugs prefer and damage pods
Common Beneficial Insects
• Ladybird beetle• Lacewings• Minute pirate bug• Bigeyed bug• Nabids• Spined soldier bug• Praying mantis
Ladybird Beetle
adult
larva
eggs
Common NC ladybird beetles
pink spotted
Asian
pink spotted
Green Lacewing
larva
eggs
adult
Minute Pirate Bug
Bigeyed Bug
Nabis (damsel bug)
Spined Soldier Bug
Praying Mantis
Reproductive Stage Pests
• Defoliators– Soybean looper– Armyworm complex– Bean leaf beetle
• Pod-feeders– Corn earworm/tobacco budworm– Stink bug complex
• Stem feeder– kudzu bug
QUESTIONS?