Abstract:  To explore the mechanism of physiological and biochemical effects of wasp parasitization on its hosts, levels of glycogen, trehalose, lipids and proteins in the haemolymph of host Mythimna separata larvae parasitized and unparasitized by Microplitis mediator were examined. The results showed that the content of glycogen in parasitized M. separata larvae was higher than that in unparasitized host larvae. Under diapause condition for 12 days, the content of glycogen in parasitized larvae reached to 7.93 μg/mL which was significantly higher than that in unparasitized hosts (4.70 μg/mL) (P<0.05). Under non-diapause condition for 6 days, the content of glycogen in parasitized larvae reached to 14.35 μg/mL which was significantly higher than that in unparasitized hosts (5.47 μg/mL) (P<0.05). The contents of trehalose were not significantly different between parasitized and unparasitized host larvae under diapause condition. But under non-diapause condition for 4 days, the content of trehalose (46.82 μg/mL) in parasitized larvae was significantly higher than that in unparasitized larvae (26.72 μg/mL). The contents of lipids and proteins were not significantly different between parasitized and unparasitized larvae under diapause or non-diapause conditions. The results suggest that: (1) the content of glycogen was higher in the haemolymph of larvae parasitized by M. mediator; (2) the non-diapause conditions are the main factors which influence the content of trehalose in parasitized larvae; (3) the larvae of M. separata possess higher ability of adaptation and tolerance to the wasp parasitism.

Key words: Microplitis mediator, Mythimna separata, parasitization, diapause, glycogen, trehalose, lipid, protein