Stady On Reproductive Biology Of Dastarcus Helophoroides, An Important Parasitoid Of Monochamus Alternatus

Dastarcus helophoroides (Fairmaire) is an excellent parasitic natural enemy against longhorn beetle larvae. The population number of D. helophoroides adults was small in the nature, the geographical distribution of D. helophoroides was not balance, and they could not control longhorned beetles effecially. So stady on mass artificial rearing D. helophoroides was very important. Therefore, stady on reproductive biology of D. helophoroides was also important. And we research about determination of inoculation number of newly-hatched larvae of D. helophoroides, on different substitute hosts in mass rearing、effect of rearing density on the adults death ratio and fecundity of D. helophoroides、sexual identification of alive female and male Tenebrionidae host adult. The results were below:1. To distinguish female and male adults of Tenebrionidae host. The results showed there is sexual dimorphism of external morphology of Tenebrionidae host adults. The frons of female Tenebrionidae host adult is flat while that of male adult is sunken. Additionally, the length, width and length-width ratio of the third antennal segment and anal plate were significant different between female and male Tenebrionidae host adults. Above morphological characteristics can be used to efficiently distinguish sex of Tenebrionidae host adults without damage, and also can be used in artificial propagation of Tenebrionidae host.2. In laboratory, host mortality, feeding period, emergence rate, number of emerging adults per host, weight of emerging adults were comprehensively compared among different weight ranges of the same host species, for analyzing the best ability of breeding natural enimy. The results showed the optimum number of first-instar larvae introduced on host Monochamus alternatus Hope larva was as follow:8Dastarcus helophoroides larvae on one host larve whose weight ranged710-900mg,7larvae on520-710mg host,4larvae on330-520mg and2on140-330mg. When another longhorn beetle larva was as a host,4parasitoid larvae were introduced on270-390mg host, and2parasitoid larvae on150-270mg host. While using Tenebrionidae as the host,8,6,5parasitoid larvae could be introduced on host weight range in700-850mg,550-700mg,400-550mg, respectively.3. For determining different density to reproduction of D. helophoroides adults in laboratory, a study on the number of female and male adults in a transparent plastic box which had special-type were carried out, we were processing five rearing density, the sex ratio of D. helophoroides adults were1:1, the female and male adults being64、32、6、8、4as five treatment-groups, and analyzing with the adults fecundity and death ratio. The results showed that the differences in adults death ratio、adults preoviposition period、spawning period、the average fecundity of per female and the total oviposition were all significant between the five treatments (p<0.05). Also among different density groups there were linear relationship in adults death ratio、adults preoviposition period、spawning period、the average fecundity of per female and the total oviposition. And finally we screened out when the sex ratio was8:8had the largest fecundity.