Effects of different hormones as dietary supplements on biological characteristics of Coccinella septempunctata L.

Abstract

AbstractWhen Coccinella septempunctata L. was fed on an artificial diet, development was prolonged and survival and reproduction were decreased, thus negatively affecting population growth. Juvenile hormone and moulting hormones are important factors in insect reproduction and development. This study aims to screen out the optimal hormones that can solve the problems such as slow population growth of the C. septempunctata during mass rearing, thus improving their effectiveness as a biological control agent. The effects of juvenile hormone analogues and moulting hormones on C. septempunctata larval growth and adult reproduction were investigated by supplementing an artificial diet with different doses of methoprene, kinoprene, juvenile hormone Ш, fenoxycarb and 20‐hydroxyecdysone. Multiple parameters were measured for C. septempunctata including development, survival, pupation, emergence, pre‐oviposition, fecundity and hatching rates. The addition of juvenile hormone analogues to the diet significantly lengthened larval development times and reduced pupation and emergence. Conversely, juvenile hormone analogues significantly shortened pre‐oviposition period, reduced survival and increased fecundity. The shortest pre‐oviposition period was 9.6 days, and the highest oviposition number was 578 eggs in response to 5 μL kinoprene. The highest hatching rate was 66% in 1.7 mg 20‐hydroxyecdysone treatment. The results of this study provide a theoretical basis for hormone selection and dosage in C. septempunctata artificial diets, thus enhancing the survival, pupation and emergence of larvae and improving the fecundity and hatching rate of ladybird adults.