The pine sawyer beetle alters oviposition strategy in response to extreme high temperatures

Abstract

The frequency and intensity of extreme high temperatures (EHTs) are increasing due to the climate warming. Insects have evolved a range of thermotolerance mechanisms to cope with EHTs, whereas there is limited research available on the alteration oviposition strategies under EHTs. This study aims to investigate the impacts of EHTs on the fertility and oviposition strategy of pine sawyer beetle, Monochamus alternatus, a destructive forestry pest. Both male and female adults exhibited a decline in reproductive performance under EHTs. Additionally, M. alternatus females generally laid one egg within one oviposition slit to minimize offspring competition. After EHTs treatments, it was firstly found that the females laid multiple eggs, which was characterized as a novel oviposition strategy. The elicitation of this novel oviposition strategy was negatively correlated with the hatchability of offspring and count of sperms in spermatheca. Furthermore, the hatchability of eggs laid by novel oviposition strategy was significantly lower than that of eggs laid individually. The novel oviposition strategy may help alleviate adverse effects of EHTs on M. alternatus by conserving energy, contributing to the long-term survival of the population. Our findings discovered a novel direction for the behavioral adaptation of insect species in the context of climate warming.