Evaluating the role of insecticidal seed treatment and refuge for managing soybean aphid virulence

Abstract

BACKGROUND Managing insect virulence can extend the durability of host‐plant resistant crops. Genetically modified resistant crops continue to be successful because of insect‐resistant management strategies that delay resistance such as multiple toxins and a susceptible refuge. These strategies may also be useful for host‐plant resistant crops, but more research is needed on their applicability. We investigated the interaction between a susceptible refuge and an insecticidal seed treatment to manage virulence in the soybean aphid. We tested four scenarios of an insecticidal seed treatment (plus an untreated control) in a microcosm containing 25% aphid‐susceptible (refuge) and 75% aphid‐resistant soybeans. Independent cohorts of plants were infested every week with avirulent and virulent aphids at equal frequencies. We used a molecular marker to estimate the change in virulence frequency across different plant maturities (from 7 to 42 days after planting). RESULTS The presence of an insecticidal seed treatment on either the susceptible or resistant soybean decreased the overall population size of the soybean aphid. However, the insecticidal seed treatment impacted both virulent and avirulent aphids similarly, and only altered frequencies in favor of virulence when the sole susceptible plant (i.e., refuge) was treated. CONCLUSION Under our experimental conditions, the frequency of avirulent aphids persisted with the use of a refuge. Although an insecticidal seed treatment decreased the overall aphid population size, it did not appear to benefit virulence management. © 2021 Society of Chemical Industry.

Exogenous genistein enhances soybean resistance to Xanthomonas axonopodis pv. glycines

“…4,5 Despite the economic and nutritional relevance of soybean, this crop is highly susceptible to a wide range of pathogens that reduce crop quality and yield. [6][7][8][9] Among soybean pathogens, Xanthomonas axonopodis pv. glycines (Xag) is a bacterium that can cause bacterial pustule disease.…”

“…Soybeans are widely consumed as sprouts, soy milk and fermented products, providing essential dietary nutrients and antioxidants 4, 5 . Despite the economic and nutritional relevance of soybean, this crop is highly susceptible to a wide range of pathogens that reduce crop quality and yield 6–9 . Among soybean pathogens, Xanthomonas axonopodis pv.…”