Studies On The Development Of Female Reproductive System And The Artificial Diets In Propylea Japonica (Thunberg)

Propylea japonica (Thunberg) is subordinated to Coleoptera, Coccinellidae, Propylaea. The ladybird preys on many pests in agriculture. Due to large appetite, high fecundity, adaptability and many generations annually, Propylea japonica is one of important predatory natural enemies in agriculture system. In this paper, the development of female reproductive system and the artificial diets in Propylea japonica are investigated.The vitellogenesis and the characteristics of vitellin were studied using histological and immunological techniques. And then, by the method of biochemistry, an attempt was made to study the effect of artificial diets on the Propylea japonica, including growth and fecundity, nutritional indices, body composition, activity of digestive enzyme in midgut and the functional response to cotton aphid. The purpose is to accumulate basal information for reproductive biology of Propylea japonica, and provide reference for optimum design of artificial diets.Oogenesis in the adult stage could be divided into 3 periods: oocytes differentiation; oocytes growth; the vitellogenesis and the oocytes maturation. And the 3 periods could be divided into 7 stages further.The characterization of vitellin was carried out by PAGE and SDS-PAGE. The results indicated that vitellin had a molecular weight of approximately 294.81±40.70 kDa and was composed of two kinds of subunits, whose molecular weights were 144.68±0.03 kDa and 51.23±0.27 kDa respectively. The content of essential amino acid was 57.48%, which was little higher than that of non-essential amino acid. And the highest contents of amino acids made up of vitellin was Glu, its content was 15.26%, while contents of Try and Met were very low, only 0.50%, 0.11% respectively.Using indirect ELISA, the contents of vitellin in Propylea japonica fat body, haemolymph and ovary were detected. The results suggested that the vitellogenin was synthesized in fat body at the second day after eclosion. The contents of vitellogenin in fat body, haemolymph and ovary increased quickly on the fourth day after eclosion and reached the peak stage on the eighth day approximately in adult stage.