Artificial diets can manipulate the reproductive development status of predatory ladybird beetles and hold promise for their shelf-life management

Abstract

With the development of biological control methods, the predatory ladybird beetle Harmonia axyridis Pallas (Coleoptera: Coccinellidae) has been widely used for pest control in agricultural production. Appropriate shelf-life management strategies could synchronize H. axyridis production with pest outbreaks, finally improving the effectiveness of biological control. Herein, we preliminarily explored whether an artificial diet could optimize the shelf-life management of H. axyridis. We compared the survival rate, nutrition accumulation, reproductive development, juvenile hormone (JH) related-gene expression levels, and stress resistance gene expression levels between aphid-fed and artificial diet-fed H. axyridis females. The results revealed that H. axyridis females maintained a high survival rate after being fed an artificial diet for 60 days, whereas the survival rate of aphid-fed females decreased. Continuous feeding of the artificial diet caused H. axyridis females to enter a diapause-like state, which was characterized by low JH levels, high triglycerides and trehalose accumulation, ovarian development inhibition, decreased Vgs expression levels, and increased stress resistance gene expression levels. This diapause-like state could be promptly recovered upon transferring to an aphid diet. These results indicate that the artificial diet could manipulate the reproductive development status of H. axyridis and lay the foundation for its shelf-life management.