05Soybean Insects

Soybean Insects Overview

  • Course: EPP 4234/6234

Global Soybean Production (2017-2021 averages)

  • Total production area: 311 million acres

  • Average yield: 42 bu/ac

  • Total production: 391 million tons

  • Major producers:

    • Brazil: 93 million acres, 51 bu/ac, 141 million tons

    • US: 84 million acres, 50 bu/ac, 126 million tons

    • Argentina: 41 million acres, 42 bu/ac, 51 million tons

    • China: 22 million acres, 29 bu/ac, 19 million tons

US Soybean Production

  • Total production (thousands of acres): 84,200

  • Average yield: 50 bu/ac

  • Major states:

    • Illinois: 10,330 acres, 60 bu/ac, 18,590 tons

    • Iowa: 9,660 acres, 57 bu/ac, 16,480 tons

    • Minnesota: 7,490 acres, 48 bu/ac, 10,690 tons

    • Mississippi: 2,050 acres, 53 bu/ac, 3,260 tons

Soybean Maturity Groups

  • Defined by photoperiod for reproductive growth

  • Lower groups: less vegetative growth, earlier reproduction

  • Higher groups: risk of late maturation before frost

Soybean Terminology

  • Key terms include:

    • Trifoliolate, petiole, leaflets, unifoliolate leaf, axillary buds, cotyledons, hypocotyl, soil surface, nodules, lateral roots, branched tap root

Soybean Development Stages

  • VE: Emergence

  • VC: Unifoliate open

  • V1 - V(n): Progression through trifoliate development

  • R1: Beginning bloom (1 flower/plant)

  • R2: Full bloom (flowers in top 2 nodes)

  • R3: Beginning pod (pod in top 4 nodes)

  • R4: Full pod (3/4 inch pod in top 4 nodes)

  • R5: Beginning seed (seed in top 4 nodes)

  • R6: Full seed (full seed in top 4 nodes)

  • R7: Beginning maturity (1 mature pod)

  • R8: Full maturity (95% pods mature)

Soybean Cultivation Practices

  • Planting techniques:

    • Wide rows (30-40 inches), narrow rows (15-20 inches), or drilled (7-8 inches)

    • Conventional tilled or no-till systems

    • Seeding density: 120,000 – 200,000 ppa

    • Plant depth: 1-2 inches

Soybean Cultivation Systems in Mississippi

  • Traditional system:

    • Maturity groups 5-6 planted late May-early June

    • Harvest in October-November

    • Yields: 20-30 bu/ac

  • Early soybean production system:

    • Maturity groups 4-5 planted late March-April

    • Harvest in August-September

    • Yields: 30-60 bu/ac

Major Pests of Soybeans in the U.S.

  • Key pests include:

    • Stink bugs (primarily in the South)

    • Corn earworm

    • Defoliators:

      • Loopers

      • Green cloverworm

      • Velvetbean caterpillar

    • Bean leaf beetle

    • Soybean aphid (mainly in the North)

    • Threecornered alfalfa hopper (Southern pest)

Insect Losses in Mississippi (2004-2021)

Insect

% Acres Infested

% Acres Treated

$ Loss + Cost/Acre

Stink bugs

84

46

14.62

Soybean Looper

56

28

8.25

Corn Earworm

29

16

7.55

Bean Leaf Beetle

69

21

3.63

Green Cloverworm

65

9

2.47

Velvetbean Caterpillar

23

5

2.25

Threecornered Alfalfa Hopper

88

10

1.62

Threecornered Alfalfa Hopper (Spissistilus festinus)

  • Life cycle:

    • Overwinters as adult or egg in plant debris

    • Eggs laid on stems, hatch in 7-10 days

    • Life cycle can include 3-4 generations per year

  • Description:

    • Adult: Green/yellowish wedge-shaped with membranous wings

    • Nymph: Wingless with spiny projections

  • Damage:

    • Girdling stems, leading to plant mortality and reduced yields

  • Control:

    • Cultural: Manage plant population, destroy overwinter sites

    • Biological: Utilizes natural enemies like parasitoids and predators

    • Chemical: Neonicotinoids for seed treatment; foliar insecticides for adults

Potato Leafhopper (Empoasca fabae)

  • Feeds on a variety of plants causing damage with piercing-sucking mouthparts.

  • Important identification features include:

    • Adults: 3 mm long, wedge-shaped, greenish

    • Larvae: Wingless and small

  • Life Cycle:

    • Lays eggs in stems, with nymphs feeding underneath leaves.

    • Notable damage includes leaf curling and stunted growth.

  • Control:

    • Host plant resistance and cultural practices are recommended.

Blister Beetles

  • Three species: Margined, Striped, Black (Meloidae family)

  • Damage caused by feeding larvae and adults and by causing blisters in livestock (toxin cantharidin).

  • Management: Monitor populations next to fresh cut areas, use spot treatments when thresholds reached.

Bean Leaf Beetle (Ceratoma trifurcata)

  • Adult description: variable coloration with distinctive black triangle on prothorax.

  • Life cycle: Overwinters as an adult, with damage caused primarily by feeding on foliage and pods.

  • Management: Monitor fields, cultural practices to reduce populations, and use protective insecticides if thresholds met.

General Management Strategies

  • Cultural Controls: Crop rotation, trap cropping, and managing border areas.

  • Biological Controls: Using natural enemies, including parasitoids and predators.

  • Chemical Controls: Utilization of insecticides where necessary based on thresholds.