Advantages of diapause in Anastatus japonicus Ashmead mass production on eggs of the Chinese oak silkworm, Antheraea pernyi.

Abstract

Anastatus japonicus Ashmead, a biological control agent utilized in China to control fruit bugs and forest caterpillars, is efficiently raised on large Chinese oak silkworm (Antheraea pernyi) eggs. Here, we investigated the biological parameters of non-diapaused and diapaused Anastatus japonicus after long-term storage within eggs of the host, Antheraea pernyi, under laboratory conditions. Diapaused mature larvae of Anastatus japonicus were more cold-tolerant than non-diapaused mature larvae, as reflected by a lower supercoiling point, lower freezing point, and higher survival rate at cold temperatures. Diapause induction enhanced the lifespan, fecundity and oviposition period of Anastatus japonicus than non-diapaused Anastatus japonicus when refrigerated for 6 months. However, after 12 months of refrigeration, the fecundity and oviposition period of Anastatus japonicus were significantly reduced with and without diapause. No difference in the progeny sex ratio of Anastatus japonicus was observed between diapause-induction treatment and those of non-diapaused. With the extension of refrigeration period from 6 months to 12 months, the lifespan, fecundity and oviposition period of Anastatus japonicus which were treated with diapause induction showed a sharp decrease. No significantly difference in the lifespan, fecundity and oviposition period of Anastatus japonicus was observed between diapause-induction treatment and those of non-diapaused when refrigerated for 12 months. These results suggest that the induction of diapause is an applicable technique to achieve mass production of Anastatus japonicus in long-term storage using eggs of the factitious host Antheraea pernyi, without compromising the quality of the parasitoid. The refrigeration period of diapaused Anastatus japonicus should not exceed 6 months. © 2023 Society of Chemical Industry.