Feeding Damage

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Soybean plants experience various types of stress that can affect the its development. One type of stress, shown in Picture 2, is a chewing pest called the Saltmarsh Caterpillar, Estigmene acrea (Drury). This caterpillar is feeding on the leaf creating a rigid hole, which is typical for pests with chewing mouthparts. The Saltmarsh Caterpillar can also feed on the pods of the plant, which contain developing seeds. The pod is most vulnerable to feeding damage at its immature stage of development, when the plant is sinking all of its resources into seed growth. Damage from caterpillar feeding at this stage can affect the yield of the plant. However, should the pod be in its mature stage when seeds are hard and fully formed, yield is less likely to be affected. Some types of pest feeding damage can harm plants more than others (direct versus indirect), so it is important for farmers to correctly identify the pest before applying pesticides, which aim to reduce pest numbers and their damage to soybean plants.  The soybean plant has its own mechanisms for defending itself as well. Feeding damage to the plant can activate chemical signals that lure beneficial insects to damaged plants in order to hunt pests like a predator and save the developing soybean seed!

  • Pest: any organism that competes with humans for food, fiber or shelter; it can be economical or just plain annoying (a nuisance).
  • Yield: the total number of beans that is produced from an acre of soybean plants (typically 125,000 plants per acre).
  • Immature Stage: Seed is forming or taking shape within the developing pod.
  • Mature Stage: Seed is hard, filled, fully formed and ready to eat or plant.
  • Pesticide: a chemical applied to plants to kill or reduce the number harmful organisms (i.e., pests)