| Ostrinia furnacalis is an important pest of summer crops in China. Using Trichogramma to control Asian corn borer is an efficient way. In this paper, we use Asian corn borer, and two Trichogramma species as research object, observed the ontogeny, parasitizing behavior and ecological of Trichogramma. Results are as follows:(1) At the conditions of25±1℃, the two Trichogramma eggs began to embryonic development after deposition in host C. cephalonica (Stainton) eggs, we found in the beginning of spawning some eggs on both ends of the egg has the0-2gaps. At16h, the Trichogramma embryos start to feed on host nutrition through oral groove. At28h, Trichogramma to start to molt, the slough tissue adhered to its body and disappeared till early pre-pupal stage. Due to the constantly feeding, the permeability of body changed. After68-72h, body of Trichogramma Plum Point appeared, nutrition in host egg is depleted completely. About24h later, Trichogramma began to enter the pre-pupa stage and do not feed any more. After120h, wasps pupated and the Trichogramma ocellus and compound eyes were visible. After192h, Trichogramma emerged and stayed in the host for1day, then bitten out host egg.(2) Volume of two Trichogramma increasing with the increase of the time after the parasitism. First24h after deposition the volume changed only a little, the volume of the early spawning egg of T. dendrolimi and T. ostriniae respectively7.8×10-7mm3and7.8×107mm3. when24hours past,the volume is5.4×10-4mm3and5.3×10-3mm3and volume in28hours is1.1×10-3mm3and1.1×10-3mm3.36h-60h the two Trichogramma volumes sharply increased. To72h, their volumes reached2.6×10-2mm3and2.7×10-2mm3. After96h, the volume grows little. To the late development time, the number of T. ostriniae more than the number of T. dendrolimi in single host egg.(3) With increase of parasitization times by T. dendrolimi, emergence rate and number of wasps emerged per host egg improved remarkably. The total number of hosts that failed to result in either parasitoid wasp or host larva increased with parasitization times, but the female sex ratio decreased. With the same parasitization time, the wasp emergence rate on and number of wasps per host egg of the second generation reared in the laboratory were higher than those of parasitizing O. furnacalis growing in the field, however, the female sex ratio of offsprings is on the contrary.(4) When T. ostriniae that breeding by corn borer egg of multiple generations parasitize C. cephalonica egg and O. furnacalis egg, there are significant differences in time-consuming. For Asian corn borer egg, number of parasitized eggs, total number of offspring and number of female offspring were the most in treatment with8h-16h age host eggs among all ages treated, but the emergence rate is lowest. There are no differences in wasp amount from per single host egg among different host egg ages. Female proportion of8h-16h host egg is the highest. When T. ostriniae that bred multiple generations on C. cephalonica egg parasitized Asian corn borer egg, number of parasitized eggs. total number of offspring and number of female offspring were the most in treatment with8h～16h host eggs, but the emergence rate is lowest among the three host egg ages, and56h～64h host egg is highest. When different ages host eggs were parasitized, the offsping number of per host egg has no significant difference, however, single host egg also can support more than one T. ostriniae. Female proportion of offspring from32h～40h host is the highest among three host ages. |
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