Demography and Population Projection of Flea Beetle, Agasicles hygrophila (Coleoptera: Chrysomelidae), Fed on Alligator Weed Under Elevated CO2

The flea beetle, Agasicles hygrophila Selman and Vogt, was introduced into China in 1987. For a more comprehensive understanding of the effect of elevated CO2 concentration on the population dynamics, we collected the life table data of the flea beetle, A. hygrophila, at two different CO2 concentration conditions, i.e., ambient (420 µl/liter) and elevated (750 µl/liter). The raw data were analyzed using the age-stage, two-sex life table theory. At 750 µl/liter CO2, shorter developmental durations of the egg, first instar, and pupa were observed, while the duration of the third instar and the total developmental duration of the larva were prolonged. The generation length of A. hygrophila was significantly shortened at the higher concentration. It was observed that the intrinsic rate of increase (r), finite rate (λ), and net reproduction rate (R0) were higher and the mean generation time (T) was shorter at 750 µl/liter compared with that at 420 µl/liter. The bootstrap techniques were adopted to estimate the variances and standard errors of the developmental time, longevity, fecundity, and the population parameters. The bootstrap technique generated a normal distribution that was consistent with the central limit theorem and critical for following statistical analysis and comparison. Population projections based on age-stage, two-sex life tables could reveal the stage structure of A. hygrophila population and the leaf consumption capacity. Data collected in this study can potentially be used to evaluate the efficacy of A. hygrophila as a biological control agent of the alligator weed.