The Study Of Morphological And Biochemical Components Of The Ovomermis Sinensis During Gonadial Development

The mermithoid nematode, Ovomermis sinensis parasitizes many insect pests, for example Prodenia litura, Spodoptera exigua, Pieris rapae, Leucania separata, Agrotis ypsilon and Helicoverpa armigera etc. The pests' hosts invariably die when the juvenile nematodes complete their parasitic development and emerge from the hosts' hemocoele, so it has potential for the biological control agent against undesirable insects. The cross section observations of O.sinensis in vivo demonstrate that genital organs begin to develop in postparasitic stage and mature in adult stage. For this reason, no gonadial development is observed in parasitic stage. The physiologic properties of the parasitic juvenile are to absorb nutrition, so their trophosome develop prominently and the genital systems don't develop. The physiologic characters of the nematodes from the preparasitic to the parasitic stage are that their genital systems develop gradually to mature and the trophosome are used up.We studied the morphological characteristics and the changes of biochemical substances in the different stage during gonadial development in Ovomermis sinensis. The gonadial stage ranges from the beginning of parasitic stage, postparasitic stage, exuviated and mated in adult stage. The cross section observations of O.sinensis in vivo demonstrate that genital organs begin to develop from postparasitic stage to adult stage. For this reason, no gonadial development is observed in parasitic stage. The physiologic properties of the parasitic juvenile are to absorb nutrition, so their trophosome develop prominently and the genital systems don't develop. The postparasitic juvenile nematodes become adult after they have exuviated , mated and laid. The physiologic characters of the nematodes during the postparasitic stage are that their genital systems develop gradually to mature and the trophosome are used up.The biochemical substances changes in the different stage during gonadial developing stage. With the development of the nematodes, both the contents of carbohydrate and comparative contents of fatty acid show marked diversity ,contents of water and carbohydrate decline indistinctively firstly and then rise apparently in postparasitic stage . However, the total contents of protein and comparative contents of fatty acid had little change. The research results have certain for the orginal period of Ovomermis sinensis' sex determination and it's morphological characteristics, and will be foundation for further studying the sex determination mechanism in insect's haemolmph.