Kudzu Bug (Megacopta cribraria) and Associated Egg Parasitoids Emergence Rates in Alabama are Predicted by Weather Indices

Abstract

Abstract The kudzu bug, Megacopta cribraria (Fabricius) (Hemiptera: Plataspidae), is a major economic pest of soybean in the southeastern United States. With climate warming, this pest is expected to move northward and cause additional crop damage. Parasitoid biocontrol is a potential method of integrated pest management for kudzu bug. Two species of egg parasitoid wasps have been observed emerging from kudzu bug egg masses in the southeastern United States: Paratelenomus saccharalis (Dodd) (Hymenoptera: Platygastridae) and Ooencyrtus nezarae (Ishii) (Hymenoptera: Encyrtidae). This paper used egg mass emergence data collected between 2018 and 2020 in Alabama soybean fields and compared the data to weather indices. Indices included the number of days with minimum temperatures below zero, accumulated rainfall (mm m−2), as well as species specific metrics of accumulated growing degree days, accumulated daily minimum temperature (°C), and accumulated daily maximum temperature (°C). Emergence of the generalist parasitoid, O. nezarae, was highly correlated with kudzu bug nymph abundance, accumulated degree day, accumulated daily temperatures, and precipitation. Ooencyrtus nezarae emergence was predicted in a stepwise regression equation by aggregated degree day and date of collection, which indicates that seasonality may be a predictor of its presence. In contrast, collections of the specialist parasitoid, P. saccharalis, were near-zero throughout the collection period, suggesting that this species may no longer be a usable biocontrol agent in the southeastern United States as a result of external limiting factors.