Beyond Hunger: A Connection Between Diet and Gonadal Development of a Ladybird Beetle

Food availability shapes morphology, physiology, growth, reproduction, and overall fitness of insects. Countless research in coccinellids reported the effect of diet in terms of quality and quantity on reproductive output. But fewer studies have reported the direct effects of food on the gonadal development in both sexes. In nature, ladybird beetle Cheilomenes sexmaculata exhibit food preference, favouring Aphis craccivora (nutritious prey) over Aphis nerii (poor prey). We hypothesized that beetles consuming nutritious prey in abundant quantity will have larger and heavier gonads. The current study assessed the effect of food preferred and its fluctuations on the gonadal development of C. sexmaculata. First instars were collected randomly from experimental stock and reared on two different diet regimes for a lifetime. After eclosion, beetles from each dietary regime were dissected daily to assess gonadal development until maturity. Here, we documented total developmental duration, body weight, weight of gonads, GSI, total area of gonads, length, and number of testicular lobules/ovarioles across different treatments. Both quality and quantity of diet significantly affected development period, body weight, and gonadal parameters in both sexes except for GSI in males and number of ovarioles in females that reared on varied diet quality, which were found to be similar. Aphis craccivora in abundant supply positively affected the growth and development of the gonads in C. sexmaculata. Beetles reared on the abundant supply of nutritious prey with larger and heavier gonads than those reared on limited supply or poor prey. This study improves our understanding of the development of gonads in ladybird beetles, which may be helpful in improving the mass rearing of ladybird beetles.