Sublethal effect of spirotetramat on the life table and population growth of Frankliniella occidentalis (Thysanoptera: Thripidae)

The age-stage, two-sex life table was used to determine the effects of the novel ketoponic acid insecticide, spirotetramat, on Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) at a concentration of 30mg/L. The results showed that the egg hatch rate was significantly decreased. In addition, the duration of the egg stage was decreased by one day compared to the control cohort. The preadult duration, adult longevity, pre-oviposition period, and total pre-oviposition period of the spirotetramat-treated cohort were all shortened, as were the preadult survival rate, mean fecundity, and net reproductive rate. No significant differences were found in the finite rate of increase and intrinsic rate of increase between the spirotetramat-treated and control cohorts. However, our population projection based on basic data (i.e., survival rate, developmental rate, and fecundity) showed that the population size of F. occidentalis was lower in the spirotetramat-treated cohort than in the control cohort. Our results showed that treatment with spirotetramat (30mg/L) suppressed the population growth of F. occidentalis. Furthermore, by using basic life table data to project population growth, we were able to distinguish differences between the projected growth of the two populations despite not finding a significant difference in their intrinsic rate of increase or finite rate of increase. This novel insecticide can be considered as a suitable candidate for inclusion in pest management programmes.