Biotic factors as key determinants for ovarian and oothecal developmental plasticity of a tortoise beetle

Abstract

Ovarian development in r-selected species is a highly dynamic process widely studied in various insect groups. An array of biotic and abiotic factors may influence it. So, the present investigation was to evaluate the impact of a female's age and mating status on the ovarian development, ootheca formation, body colour polymorphism, and fat content of the tortoise beetle, Aspidomorpha miliaris (Fabricius). Females of a certain age and mating status were dissected to demonstrate changes in their ovarioles, lateral oviduct, accessory gland, elytral colour, fat body content, and body size. It was predicted that age or mating status would not affect the ovarian parameters like length and width of ovarioles, lateral oviducts, accessory glands, body size, fat body content, and elytral colour. However, the ootheca-forming modifications would be initiated by ageing and mating. The current study demonstrated the substantial effect of age and mating status on the growth of the accessory glands and ovarioles. On the other hand, fat body contents declined comparatively in multiply-mated females. Besides this, the beetle exhibits elytral colour polymorphism till sexual maturity. An accessory gland was exclusively detected in multiply-mated females. This discovery opens opportunities for further investigation into the precise function of the gland, which is likely involved in the formation of ootheca.