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Bean Leaf Beetle

 
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Bean Leaf Beetle

Crop Symptoms - Bean Leaf Beetle

Bean leaf beetle injury (2 photos below)
Soybean leaf injury from bean leaf beetles
Soybean leaf defoliation from bean leaf beetles.
  • Impact from bean leaf beetle larvae is unknown, but thought to be insignificant
  • Leaf feeding from adults causes little impact unless defoliation exceeds 25%
  • Pod feeding results in greatest damage and affects both quality and yield
  • Adults also transmit bean pod mottle virus, which:
    • Reduces both soybean quality and yield
    • Causes green stem and delays harvest
Soybean field - Area of green stem.
Area of green stem.
 

 

Pest ID - Bean Leaf Beetle

Bean leaf beetle adults (2 photos below)
Bean leaf beetle adult
Bean leaf beetle adult

Adult bean leaf beetle.

Adult:
  • Bean leaf beetle adults are 1/5 inch long
  • Color is typically dark yellow, but may be orange or red
  • Wing covers often with 4 "rectangular" marks, but may have 2 or no marks
  • Best identifying mark – black triangle behind pronotum (neck region in image below)
Black triangle is an identifying mark for bean leaf beetle adult.
Larvae:
  • Found in soil near roots and resemble corn rootworm larvae
  • Body color is white and head color is dark brown/black
  • Often found feeding in nodule

Pest Facts and Impact on Crop

Bean leaf beetle adults feeding on plant (photo below.)
Adult bean leaf beetles feeding on soybean leaves.
  • Latin name is Ceratoma trifurcata
  • Although the larvae feed on soybean roots, most damage occurs from adult feeding on foliage or pods
  • Found east of the Rocky Mountains wherever soybeans are grown
  • No significant natural enemies are known
  • Hosts: alfalfa, clover, green beans, wild legumes such as tick trefoil
  • Generations per year
    • 3 – Southeast United States
    • 2 – Iowa and Illinois
    • 1 to 2 – Wisconsin
    • 1 – Canada
  • Adults overwinter in woodlots and fence rows
  • Quickly killed if exposed to temperatures below 14 F
  • Adults may feed on alfalfa in spring before soybeans emerge

Life Cycle

Bean leaf beetle life cycle.
 

Management Considerations

Resistance

  • Neither native nor transgenic resistance is currently available for bean leaf beetle.

Beneficial insects (natural enemies)

  • Very little impact documented
  • Not a recognized deterrent to beetle populations

Planting

  • If the field has a history of bean leaf beetle injury or bean pod mottle/green stem, consider planting slightly later after most bean leaf beetle adults have moved away from the area
  • Pioneer Premium Seed Treatment with insecticide may help reduce damage from overwintering bean leaf beetles; effect may vary on bean pod mottle infection prevention

Scouting for Bean Leaf Beetle

Scouting for bean leaf beetle
  • Early pod fill stages: R1-R3 – If defoliation approaches 20% to 25% and large numbers of bean leaf beetle adults are present, consider insecticide application, especially if beetles exceed 20 per 20 sweeps of a sweep net
    • Decision should be based on increasing or decreasing beetle numbers, costs of control and grain price of soybeans
  • Late pod fill stages: R5-R7 – If pod injury is above 10% and beetles exceed 3 per sweep, consider insecticide application, especially if other pod feeding insects (grasshoppers) are present
    • Value of control will depend on continuing injury and pod maturity
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Pioneer Premium Seed Treatment    Components under the Pioneer Premium Seed Treatment offering for soybeans are applied at a DuPont Pioneer production facility or by an independent sales representative of Pioneer. Not all sales representatives offer treatment services, and costs and other charges may vary. See your Pioneer sales representative for details. Seed treatment offering exclusive to DuPont Pioneer and its affiliates.

The foregoing is provided for informational use only. Please contact your authorized Pioneer sales professional for information and suggestions specific to your operation. Product performance is variable and depends on many factors such as moisture and heat stress, soil type, management practices and environmental stress as well as disease and pest pressures. Individual results may vary.

PIONEER® brand products are provided subject to the terms and conditions of purchase which are part of the labeling and purchase documents.