D3297: Analysis of development and oviposition in white-backed planthopper based on pesticide resistance levels

Recently, migratory pests are causing substantial damage and are difficult to control in Korea. Specifically, white-backed planthoppers migrate from southern China to Korea through air during the rainy season between mid-June and mid-July every year; they multiply and cause severe damage. In this study, we aimed to identify pesticide resistance in white-backed planthoppers and to determine its effects on their development and oviposition.
The specimens were collected during 2018–2019 in nine regions in Korea. Bioassays of etofenprox showed a mortality rate of 24.4%–56.7% in white-backed planthoppers after 5 days, indicating pesticide resistance. Four different populations (18Hadong, 19Goseong, 19Jindo, and 19Sinan) were selected to analyze the effect of pesticide resistance on their development and oviposition. The median lethal concentrations were 294.02 ppm (18Hadong), 92.36 ppm (19Goseong), 241.7 ppm (19Jindo), and 127.73 ppm (19Sinan), respectively.
The developmental period was 2.9–6.1 days after five instars. The nymphal duration was shortest at 12 days (18Hadong) and longest at 16.6 days (19Jindo). The highest number of viable eggs was 141.3 (19Goseong) and the highest total eggs was 181.8 (18Hadong). Analysis of life table parameters showed that among the four populations, 18Hadong, which has high pesticide resistance, has the highest net reproduction rate and intrinsic rate of increase, and takes the shortest time for a two-fold increase in population density. Thus, this study shows that pesticide resistance levels has varying effects on the development and oviposition of white-backed planthoppers.