Effects Of Azadirachtin On The Development And Immune Activity Of Yellow Mealworm Tenebrio Molitor (Insecta Coleptera)

To investigate the effects of azadirachtin on the development, reproduction, immunocomptence and mechanisms of coleopteran, several energy reserves ,relevant enzymes and some immune parameters in the process of its metabolism in the last instar larvae of Tenebrio molitor were examined. Specimens were weighted after they were fed with the diet dipped in azadirachtin. Then energy reserves and digestive enzymes assays were done by spectrophotometric assays, including the residues method. In this paper,the indicators of immune functions were quantified using standard immunocompetence assays. Our preliminary studies will provide theory evidences for the relationship between antimicrobial response and metabolic processes and reproduction during insects metamorphosis, and provided a valuable insight into the way how azadirachtin plays.With the increase of the concentration of azadirachtin, we observed larval weight loss, developmental delay and a reduction of protein, glycogen and lipid. In addition, the activities of trypsinase, amylase and lipase were reduced at the same time, but the activities of the three enzymes were hardly affected by azadirachtin in vitro.Injected with azadirachtin, the expression of Trypsin was inhibited. Meanwhile we investigated the magnitude variation in phenoloxidase (PO) activity, lysozyme relative activity (LRA), antimicrobial activity, total haemocytes count (THC), total haemocytes microaggregates count (THMC), haemocytes phagocytosis and haemocytes spreading competence in haemolymph at 0h, 4h, 8h, 12h and 20h. It was found that PO activity, LRA, antimicrobial activity, THC, THMC, haemocytes phagocytosis and heamocytes spreading competence in heamolymph were reduced.This work showed clearly that azadirachtin couLd indirectly resuLt in physiological depression of digestive enzymes activities in vivo and then energy reserves were decreased, finally the development of T. molitor was prohibited obviously. The resuLts also showed that last instar larvae kept the highest THC of the control group, while the experimental group had less THC. Haemocytes phagocytosis competence and haemocytes spreading competence were prohibited by azadirachtin of higher concerntration. In addition, last instar larvae assembled less PO activity, LRA and antimicrobial activity than the control group. At the same time, THMC and haemocytes spreading percentage was remarkably decreased when injected with azadirachtin, especially more significant at 1000μg/mL. In conclusion, azadirachtin can not only inhibit the larve's development, but also decrease the immunity of it.