Post-mating interactions and their effects on fitness of female and male Echinothrips americanus (Thysanoptera: Thripidae), a new insect pest in China.

Post-mating, sexual interactions of opposite sexes differ considerably in different organisms. Post-mating interactions such as re-mating behavior and male harassment can affect the fitness of both sexes. Echinothrips americanus is a new insect pest in Mainland China, and little is known about its post-mating interactions. In this study, we observed re-mating frequency and male harassment frequency and their effects on fitness parameters and offspring sex ratios of E. americanus females. Furthermore, we tested the impact of mating and post-mating interactions on fitness parameters of males. Our results revealed that the re-mating frequency in female adults was extremely low during a 30-day period. However, post-mating interactions between females and males, consisting mainly of male harassment and female resistance, did occur and significantly reduced female longevity and fecundity. Interestingly, increased access to males did not affect the ratio of female offspring. For males, mating dramatically reduced their longevity. However, post-mating interactions with females had no effects on the longevity of mated males. These results enrich our basic knowledge about female and male mating and post-mating behaviors in this species and provide important information about factors that may influence population regulation of this important pest species.

Comparisons of developmental and reproductive biology between parthenogenetic and sexual Echinothrips americanus (Thysanoptera: Thripidae).

Echinothrips americanus Morgan, an invasive pest on various ornamentals and greenhouse crops, was introduced into mainland China recently, posing a potential threat to ornamentals and greenhouse crops. It exhibits two different reproductive modes: arrhenotokous parthenogenesis and sexual reproduction. Laboratory studies were conducted to compare the developmental and reproductive biology of E. americanus in these two reproductive modes. Results showed that the oviposition period, and longevity of female adults using sexual reproduction were longer than those using parthenogenesis. Furthermore, sexual female adults had higher fecundity and survival rates. However, no significant differences were found among immature stages in the durations of first and second instars, prepupae, and pupae between the two reproductive modes, with the exception of the duration of the egg stadium. The survival rates for eggs and first and second instars were higher in sexual E. americanus whereas there were no survival differences for prepupae and pupae. These results provide valuable insights into the mechanisms of parthenogenesis and sex determination in Thysanoptera.