Abstract:

Different induction treatments were conducted to investigate the relationship between Larix gmelinii-induced resistance and euryphage insect Lymantria dispar collaborative resistance. In this study, larch seedlings were treated with Methyl Jasmonate (MeJA) insufflation, Z-jasmone insufflation, Lymantria dispar larva feeding, Dendrolimus superans larva feeding, and the change trends of four detoxifying enzymes, i.e. acid phosphatase (ACP), alkaline phosphatase (AKP), carboxylesterase (CarE), and glutathione S-transferase (GSTs), were measured over time after the larch seedlings, treated by different agents, were eaten by Lymantria dispar larva. The results showed that: after feeding larches treated with different agents, ACP activity of the larvae was significantly lower than control. In addition, the AKP activity increased first and then decreased after feeding the larches induced by Lymantria dispar feeding, while it was inhibited after feeding the larches treated with the other three agents. Compared with the control, CarE activities were significantly inhibited to various degrees. GSTs activity of larvae was significantly lower than the control after feeding larches treated with MeJA and Lymantria dispar feeding, while the activity was significantly higher than the control after feeding the larches treated with the other two agents. These results suggested that plant resistance induced by gypsy moth feeding could affect the detoxification mechanism of follow-up feeding in those same stocks, and reflected an integrated performance between resistance of plants and intraspecific competition of insects. MeJA, as an exogenous plant hormones, could induce plant resistance and effectively inhibit the detoxification of those follow-up feeding, and this treatment was very similar to the gypsy moth larvae feeding in strength and time of action. Therefore, MeJA-induced plants can be used as an effective agent in pest management which would have potential value and application prospects.

Key words: induced resistance, Lymantria dispar, detoxifying enzymes