A very long-chain fatty acid enzyme gene, PxHacd2 affects the temperature adaptability of a cosmopolitan insect by altering epidermal permeability.

Temperature fluctuations pose challenges to poikilotherms, such as insects, especially under climate change conditions. Very long-chain fatty acids (VLCFAs) form important structural components of membranes and epidermal surfaces, so play important roles in adaptation to temperature stress in plants. It has been unclear whether VLCFAs are involved in epidermis formation and thermal resistance in insects. In this study, we focused on the 3-hydroxy acyl-CoA dehydratase 2 (Hacd2), an important enzyme in the synthesis pathway of VLCFAs, in a cosmopolitan pest, the diamondback moth, Plutella xylostella. Hacd2 was cloned from P. xylostella and the relative expression pattern was identified. Epidermal permeability increased with the decreased VLCFAs in the Hacd2-deficient P. xylostella strain, which was constructed by using the CRISPR/Cas9 system. Survival and fecundity of the Hacd2-deficient strain was significantly lower than that of the wildtype strain when subject to desiccating environmental stress. Hacd2 mediates thermal adaptability in P. xylostella by changing epidermal permeability so is likely to be key to its remaining a major pest species under predicted climate change conditions.