Effect of Hsp83 on the survival and reproductive fitness in the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae)

Abstract The heat shock protein 90 (Hsp90) family plays multiple roles in the development and reproduction of insects, but its specific function and importance in moths still need to be elucidated. Here, we investigated the function of Hsp83 (Hsp90 member) in Spodoptera frugiperda for the first time by using gene cloning, gene spatio‐temporal expression in relation to biotic and abiotic stresses, RNAi and bioassay. The identified Sf Hsp83 protein contains the HATPase_c and HSP90 domains, as well as the Hsp family signature sequence YSNKEIFLRE, and four Hsp90 characteristic sequences. The expression of SfHsp83 in the adult stage is relatively higher than in other stages. SfHsp83 exhibited the highest expression in the abdomen and head of female adults. Heat stress (but cold stress did not) significantly induced the up‐regulation of SfHsp83 in female adults but not in males, and Staphylococcus aureus stress, whereas Escherichia coli and Bacillus subtilis did not significantly induce the up‐regulation of SfHsp83 in the larvae. RNAi significantly knocked down the expression of SfHsp83 in female adults, with a reduction rate of over 60%. The biological assay showed that SfHsp83 RNAi significantly increased (up to 30%) the mortality of female adults under heat or bacterial stress, and significantly decreased female fecundity (reduced 50%) and egg‐hatching rate (reduced 30%). RNAi also negatively affected ovarian development and oviposition behaviour of females. These results suggested that Sf Hsp83 has functional diversity, which plays important roles in stress response and tolerance, as well as in egg and embryonic development. To our knowledge, this is the first study to investigate the function of Hsp83 using RNAi in Lepidoptera, and the results have provided an in‐depth understanding of the functional pleiotropy and evolutionary significance of Hsp83 in moths.