Season and weather affect the mortality of immature stages ofAscia monusteorseis(Lepidoptera: Pieridae) caused by natural factors

Abstract

AbstractIn this study, we evaluated the causes of mortality in immature stages ofAscia monusteorseisGodart 1918 (Lepidoptera: Pieridae) over each of four seasons, for 2 years, on an experimental cabbage plot using life tables. We addressed two key questions: (1) Do the mortality rates caused by a factor vary by season? And (2) how does the local weather contribute to such variation? We identified five causes of mortality (failure, pathogens, parasitism, predation and rainfall) that together tended to be higher during wet–warm conditions with values up to 94%. However, each cause and its mortality rate varied among seasons. Failure was observed in all stages and tended to increase during cold conditions with a negative relationship with air temperature and relative humidity and positive for precipitation. Larval and pupal predation increased during warm conditions and was positively associated with both air temperature and relative humidity. Conversely, in seasons with intense precipitation, pupal predation was reduced and had a negative relationship. Rainfall caused mortality of eggs and larvae, mostly during intense events, and egg mortality also showed a positive and significant association with precipitation. Larval parasitism was low, and pathogens were noted in larvae and pupae, but we did not find variation by season for these factors. Our results indicate that mortality caused by failure, predation and rainfall on immature stages ofA. monusteorseiscan vary among seasons and appear to be related to local weather. These findings improve our comprehension of how local weather affects the immature stages of a neotropical pest and the associated mortality factors.