Comparing the cost-benefit probability of management based on early-stage and late-stage economic thresholds with that of seed treatment of Aphis glycines.

Abstract

The current integrated pest management (IPM) curative strategy for soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), relies on responsive spraying foliar insecticides during the R1-R5 soybean stage when aphid abundance reaches the economic threshold (ET) of 250 aphids plant-1 (traditional IPM). By analyzing the relationship between aphid abundance and yield loss before the R1 stage, we developed an early-stage ET. We propose to spray foliar insecticides on plants colonized with aphids using the early-stage ET as a trigger (improved IPM), together with seed treatment to manage A. glycines and delay them exceeding the ET of 250 aphids plant-1 in the late stage for whole-field spraying (traditional IPM). Finally, we compared the cost-benefit probabilities of the three management approaches. The early-stage ET over all potential yields, market prices, and control costs was 64 aphids plant-1 , providing growers 7 days of preparation time to spray foliar insecticides before the economic injury level of 187 aphids plant-1 was reached. Improved IPM achieved the highest cost-benefit probabilities followed by traditional IPM, and the seed treatment achieved the lowest. However, in fields where the pressure from white grubs was high, the probability of achieving a positive net return with seed treatment was higher than that in other locations. Improved IPM based on early-stage ET of 64 aphids plant-1 was the most cost-effective of all the three approaches. Neonicotinoid seed treatment can be applied as an insurance strategy to supplement A. glycines IPM in Liaoning, China. © 2022 Society of Chemical Industry.