Key Technology Of Mass Rearing Habrobracon Hebetor And It's Molecular Mechanism Response To Low Temperature Stress

Habrobracon hebetor (Say) (=Bracon hebetor)(Hymenoptera:Braconidae), a cosmopolitan ectoparasitoid, was considered as a biological control agents of various lepidopteran pests in worldwide due to its rapid growth and development rates. In order to promote the process of H. hebetor used in biological control, this paper study the indianmeal moth as the host for mass rearing H. hebeotr, and optimized the artificial diet recipe for indianmeal moth; find the best larva stage for rearing H. hebetor; evaluated the performance of newly emerge H. hebetor adult after different stogage duration at 5℃; try to induce diapauses under different conditions, and long term cold storage the adults enter diapauses; clone the heat shpck protein 70 genes which may have relationship with diapauses, and determine the expression patterns of hsp70sin adults which rearing from different conditions. The main results are as follows:Wheat, glycerine, honey, dried jujube and yeast were used as the components of artificial diet for indianmeal moth. According to the orthogonal experimental design, different artificial diet recipes were made up to test the influence of each components to different parameters. The parameters include the development time of larvae stage, pupae rate, eclosion rate and adult fecundity. Analyze the influence of each components in artificial diet to different parameters and got the best artificial diet recipes for each parameters.The interactions between trophic levels during parasitism and host location by H. hebetor Say (Hymenoptera:Braconidae) within a closed environment by carrying out the tests to evaluate the role host instar on the mortality of Plodia interpunctella and on the emergence of H. hebetor were examined. Results showed that H. hebetor was able to parasitize all instars (first through fourth) of P. interpunctella, but significantly fewer early instars (first through fourth) were parasitized. Parasitized third and fourth instars were more profitable to H. hebetor, irrespective of choice factor, as significantly more adult parasitoids emerged from third and fourth instars. H. hebetor females consistently showed a preference for fourth instars of P. interpunctella when they were offered a choice between early and late host instars in arenas. Generally, parasitization of early instars was higher in no-choice than in choice tests. The behavior of H. hebetor in relation to host choice and its influence on the pest mortality are discussed.The effects of low temperature storage on the quality of adult parasitoids and their progeny were investigated. Newly emerged females were stored for 10,20,30,40,50, and 70 d at 5±1℃. Several reproductive and developmental parameters were then assessed to determine the quality of the adult parasitoids and their progeny. After more than 30 d of storage, there was a decrease in parental parasitism, but low temperature storage of parents had no effect on parasitism of the F1 generation. Parental longevity and fecundity decreased after more than 20 d of storage, but there was no effect of storage duration on the fecundity and longevity of the F1 generation until a storage duration of 50 d. Development time varied with storage duration but differences were within 2 d. Storage duration had no effect on the sex ratio of F1 and F2 generations. Our data show that H. hebetor can be cold stored for up to 20 d without adversely affecting the performance of the parasitoid. Therefore, short-term storage of H. hebetor adults could be used for Hmaintaining and accumulating large numbers of parasitoids in mass rearing programs.Several physiological parameters of H. hebetor rearing in different photoperiod at low temperature were investigated. Found that the development time of H. hebetor not only significant effect by temperature, but also the photoperiod. The longevity of female leaving at low temperature after emergence was significant longer than the female move to high temperature, but the fecundity was not. The performance of H. hebetor adult females which rearing from different photoperiod at low temperature were studied. Dissecting result showed that short photoperiod and low temperature would suppress the development of ovary. The female have long preoviposition period when the conditions for rearing and laying eggs are always short photoperiod and low temperature, otherwise, the preoviposition period is very short. When the test temperature set at 20℃, the respiration rate for the female rearing from 20℃,10:14 L:D was significant lower than the female rearing from 20℃, L:D=16:8. But there have no significant difference when the test temperature set at 27.5℃. Our data showed that at 17.5 and 20℃, the wasp can induction into reproductive diapauses at short photoperiod.The effects of long-term cold storage on the performance of diapausing H. hebetor were investigated. We found that the mortality during storage increased with increasing duration and the mortality for diapausing females were lower than nondiapausing females after 8,12, and 16 weeks of storage. Longevity and egg laying of H, hebetor reared at nondiapause condition decreases rapidly with increasing storage duration at 5℃. But for the female rearing from diapauses conditions, the longevity and egg laying have no significant difference with culture when the storage duration are short than 8 weeks, and always significantly higher than nondiapausing female. The female percentage of F1 offspring for the female after storage is always lower than culture regardless pair with male or not, but there have no difference for the female after different storage durations.Three partial genes sequence of heat shock protein 70's in H. hebetor were amplified by degenerate primer, and they were tentatively named as hsp70A6, hsp70B4 and hsp70B6. 3'and 5'RACE were followed to develop the full length clone. Deduced the amino acid sequence and comparison with other insects hsp70s shows high similarity. The theoretical molecular weight and isoelectric point were estimated. Expression patterns of the hsp70s were investigated in adults which rearing from different conditions. Real time quantitative PCR analyse were carried out to determine the different expression on mRNA levels. The expression of hsp70A6 and hsp70B6 mRNA were similar among the different rearing conditions, hsp70B4 mRNA was increase expression in high temperature rearing condition compare to low temperature rearing condition. Results suggest that the expression hsp70A6 and hsp70B6 are constitutive and hsp70B4 is relation to the temperature of rearing condition.