Study on the propagation efficacy of Sycanus croceovittatus feeding on Tenebrio molitor pupae

Sycanus croceovittatus is an important natural enemy insect that can prey on a variety of Lepidoptera and Coleoptera pests, and has good potential for biocontrol development. In order to select suitable hosts for indoor mass rearing of S. croceovittatus, this study used age-stage, two-sex life table technology to investigate the developmental period, survival rate, fecundity, and population parameters under indoor conditions. The size of each state of S. croceovittatus feeding on Tenebrio molitor pupae was measured, the population dynamics were also predicted. The results showed that under the room temperature of 23℃ ± 2℃, the average developmental durations of S. croceovittatus eggs and 1^st to 5^th instars was 20.00 d, 14.75 d, 13.40 d, 11.67 d, 12.76 d and 21.25 d, respectively, and the average longevity of female and male adults was 54.75 d and 49.50 d, respectively. The intrinsic rate of increase r, finite rate of increase (λ), net reproductive rate (R₀) and mean generation period (T) was 0.039 d^-1, 1.040 d^-1, 115.361 eggs/female and 121.909 d, respectively. The body weights, lengths, and widths of the female adults were significantly higher than those of the male adults. Female adults could lay eggs whether they were mated or not, and reproductive parameters such as oviposition times, single fecundity and total fecundity of mated females were significantly higher than those of unmated female adults. The hatching rate of eggs laid by female adults after mating was 92.59%, while eggs laid by unmated female adults failed to hatch normally. The population of S. croceovittatus reared with T. molitor pupae shows positive growth and good individual development, indicating that T. molitor is feasible as an alternative prey for large scale breeding of S. croceovittatus.