Spinetoram L

Spinetoram, a spinosyn insecticide is used to manage lepidopteran pests, including diamondback moth, Plutella xylostella. In addition to determining the lethal effects, identifying low and/or sublethal effects of an insecticide is crucial to understanding the total impact of an insecticide. We assessed the low lethal and sublethal effects of spinetoram on two successive generations of P. xylostella. The initial bioassay results showed that spinetoram exhibited high toxicity against P. xylostella with an LC50of 0.114 mg L-1after 48 h exposure. The low lethal (LC25) and sublethal (LC10) concentrations of spinetoram showed significant reduction in pupation rate, pupal weight and adult emergence. The fecundity of F1generation was significantly lower in LC25(117.85 eggs/female) and LC10(121.34 eggs/female) treated group than untreated control (145.32 eggs/female). The intrinsic rates of increase (r) was significantly lower (r = 0.1984 day-1) in spinetoram treated P. xylostella F1progeny compared to untreated control (r = 0.2394 day-1). Our results suggest that LC10and LC25concentration of spinetoram might affect P. xylostella population growth by reducing its survival, development, and reproduction.

The bean flower thrips, Megalurothrips usitatus (Bagnall) is an economically important insect pest of cowpea, Vigna unguiculata (L.) Walp in south China. Spinetoram is a newly available commercial active ingredient in the spinosyn mode of action group of insecticides that has been recommended for thrips management in China. In this study, the toxicity and efficacy of spinetoram for controlling M. usitatus were evaluated and compared to six other conventional insecticides. In addition, the synergistic effects of adjuvants (Silwet 806, Silwet 618, AgroSpred 910, and AgroSpred Prime) mixed with spinetoram for thrips control on cowpea were evaluated in both the laboratory and the field. Results of this study showed that spinetoram had higher toxicity and field efficacy of M. usitatus than other tested insecticides. A significant increase in efficacy was observed when spinetoram was applied at a recommended rate of 0.67 ml/L, mixed with Silwets (806 and 618) at the rate of 0.5 ml/L. Reductions of 50% and 40% in thrips infestation in the field over treatments without adjuvants were observed 3- and 7-days posttreatments, respectively. However, no significant reduction of M. usitatus was recorded when spinetoram was mixed with AgroSpreds (910 and Prime). Furthermore, no significant differences were found in thrips infestation between spinetoram sprayed alone at the rate of 0.67 ml/L and a reduced rate of spinetoram (0.45 ml/L) mixed with Silwets (806 and 618). The current research shows that Silwets mixed with spinetoram has a synergistic effect in the management of thrips.

The safety interval period and residue dynamics of two main components (XDE-175-J and XDE-175-L) of spinetoram in wolfberry were measured. Field experiment design and sampling method were carried out according to the "Guideline on pesticide residue trials". The wolfberry samples were extracted with acetonitrile by ultrasonic, and analyzed by UPLC-MS/MS. The wolfberry was sprayed with 6% spinetoram suspension concentrate (SC) at recommended dosage (1 500 times) and doubling dosage (750 times) (one time) at fructescence of wolfberry. The half-lives of spinetoram residue under recommended dosage treatment was 3.65-4.25 d, and all the fresh and dried fruits conform to first order kinetics equation. The dissipation rate was over 95% in fresh and dried fruits at 14 d after application. In conclusion, spinetoram belongs to the easily degradable pesticide type.