Toxicity and efficacy of spiromesifen, a tetronic acid insecticide, against sweetpotato whitefly (homoptera: aleyrodidae) on melons and collards

Abstract

Laboratory bioassays were conducted to determine the toxicity of spiromesifen, a tetronic acid insecticide to eggs, nymphs, and adults of the sweetpotato whitefly, Bemisia tabaci (Gennadius) biotype “B”, on melon and collard. Two field trails we also conducted to determine the efficacies of spiromesifen at four different rates (96, 112, 114, and/or 149 g [AI]/ha) against B. tabaci on melon and collards. Foliar sprays of thiamethoxam and/or buprofezin were used for comparisons. In laboratory bioassays, spiromesifen was highly toxic to nymphs of B. tabaci on both melon and collard, causing ≈100% mortality to young nymphs (first and second instars). Spiromesifen was moderately toxic to old nymphs (third and fourth instars), but not toxic to eggs (2.8–6.3% on melon and 2.9–6.4% on collard and slightly toxic to adults 4.5–15.1% on melon and 25.1–37.0% on collard). Spiromesifen was also highly toxic to the early first instars or crawlers that hatched from the survived spiromesifen-treated eggs, and they died shortly after they became sessile on treated leaf surfaces. Field efficacy trials indicate that spiromesifen showed excellent promise as a foliar spray. One application of spiromesifen at a rate of 149 g [AI]/ha or two applications at 122 and 149 g [AI]/ha were as effective as two applications of thiamethoxam and buprofezin on melons. On collards, three rates of spiromesifen (96, 114 and 149 g [AI]/ha) provided similar control to buprofezin. Because of its unique mode of action and chemistry, spiromesifen might have potential in integrated whitefly management programs and insecticide resistance management on vegetables and other field crops.