Abstract:

The activities of three detoxification enzymes (α-naphthyl acetate esterase, acetylcholinesterase and glutathione-S-transferase), two protective enzymes (superoxide dismutase and catalase) and midgut proteases (total protease, trypsin-like enzyme and chymotrypsin-like enzyme) in 3rd instar larvae of the Asian corn borer, Ostrinia furnacalis after feeding on Bt-transgenic corn were evaluated in the laboratory. The results showed that the activities of α-naphthylacetate esterase, glutathioneS-transferase in the larvae fed on Bt corn leaf for 48 h were greatly lower than that of the control fed on the nontransgenic corn. However, the acetylcholinesterase activity of the larvae fed on Bt corn for 48 h, 60 h and 72 h increased markedly, being 2.00-, 1.50- and 2.50-fold higher than that of the control, respectively. The activities of protective enzymes, total protease, weak trypsin-like enzyme and chymotrypsin-like enzyme in the larvae fed on Bt corn for 48 h were also significantly lower than that of the control. However, the activities of the active alkaline trypsin-like enzyme were obviously higher than those of the control. The active alkaline trypsin-like enzyme activities of the larvae fed on Bt corn for 48 h, 60 h and 72 h were 4.00, 1.67 and 1.33-fold higher than that of the control. The results suggest that acetylcholinesterase and active alkaline trypsin-like enzyme may be associated with Asian corn borer resistance to Bt.

Key words: Ostrinia furnacalis, CrylAb toxin, Bt-transgenic corn, detoxification enzyme, protective enzyme, protease