Copper Chaperone for Superoxide Dismutase FoCCS1 in Frankliniella occidentalis May Be Associated with Feeding Adaptation after Host Shifting

SIMPLE SUMMARY: Western flower thrips (Frankliniella occidentalis) have a wide range of hosts. Therefore, they can colonize new host plants with each seasonal change. This study examined whether the superoxide dismutase (SOD) gene regulates the feeding adaptation of F. occidentalis after host shifting. The coding sequences for CCS1 and MnSOD2 in F. occidentalis were cloned and the corresponding amino acid sequence was predicted, and the mRNA expression levels of these two genes at different developmental stages were determined. Further, the mRNA expression levels of FoCCS1 and FoMnSOD2 in second-instar larvae and adult females transferred to kidney bean and broad bean plants for rearing were analyzed. Decreasing the mRNA levels of FoCCS1 and SOD activity by RNA interference significantly reduced the survival rate and fecundity of adult F. occidentalis females. These findings provide a reference for analyzing the adaptive mechanism of F. occidentalis after host shifting. ABSTRACT: Western flower thrips (Frankliniella occidentalis) pose a serious threat to the global vegetable and flower crop production. The regulatory mechanism for superoxide dismutase (SOD) in the feeding adaptation of F. occidentalis after host shifting remains unclear. In this study, the copper chaperone for SOD (CCS) and manganese SOD (MnSOD) genes in F. occidentalis were cloned, and their expression levels at different developmental stages was determined. The mRNA expression of FoCCS1 and FoMnSOD2 in F. occidentalis second-instar larvae and adult females of F(1), F(2), and F(3) generations was analyzed after shifting the thrips to kidney bean and broad bean plants, respectively. The F(2) and F(3) second-instar larvae and F(2) adult females showed significantly upregulated FoCCS1 mRNA expression after shifting to kidney bean plants. The F(1) second-instar larvae and F(2) adult females showed significantly upregulated FoCCS1 mRNA expression after shifting to broad bean plants. The RNA interference significantly downregulated the FoCCS1 mRNA expression levels and adult females showed significantly inhibited SOD activity after shifting to kidney bean and broad bean plants. F. occidentalis adult females subjected to RNA interference and released on kidney bean and broad bean leaves for rearing, respectively, significantly reduced the survival rate and fecundity. These findings suggest that FoCCS1 plays an active role in regulating the feeding adaptation ability of F. occidentalis after host shifting.