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?