Abstract:

Trichogramma wasps reared on Antheraea pernyi eggs have been widely used throughout China as biological control agent against some pests. Cold storage facilitates more effective commercial rearing, transportation and inundative releases of Trichogramma spp. The effects of storage temperature (4℃, 7℃, 10℃ and 13℃), stage (egg, larva, prepupa and pupa) and period (2 weeks, 4 weeks, 6 weeks and 8 weeks) on Trichogramma dendrolimi reared on A. pernyi eggs were investigated by comparing the adult emergence rate, number of wasps per host egg and female ratio in different combinations of storage temperature, stage and period. The results showed these three factors of storage temperature, stage and period substantially influenced the adult emergence rate, number of wasps per host egg, but not the female ratio, separately or mutually. Among all storage temperatures tested, T. dendrolimi was most susceptive to 10℃, its emergence rate was greatly impacted at this temperature, and therefore 10℃ was considered to be unfavorable temperature for long-time storage. T. dendrolimi was not susceptive to 7℃ comparatively, which could be the favorable temperature for long-time storage. Favorable storage stage for long-term storage was different at different temperatures (4℃ and 7℃). Larva and pupa stages at 4℃ and egg and pupa stages at 7℃were found to be the most appropriate stages for cold storage, and in these combinations of storage temperature and stage less adverse effects on the adult emergence rate and number of wasps per host egg were found compared with other combinations of storage temperature and stage. Evaluated by the adult emergence rate, the optimal stage and temperature combination for cold storage of  T. dendrolimi reared on A.pernyi eggs was egg stage at 7℃; while evaluated by the number of wasps per host egg, the optimal combination was   pupa stage at 4℃ and 7℃.

Key words: Antheraea pernyi, Trichogramma dendrolimi, cold storage, adult emergence rate, number of wasps per host egg