Abstract: Fourth-instar nymphs of Oxya chinensis were treated (48h: 14h/3h/31h, dark/illumination/nature) with different dose 5-aminolevulinic acid (ALA) (A1:250mM; A2:450mM; A3:750Mm; A4: 1000mM)，the activities of Acetylcholinesterase (AChE), Glutathione S-transferase (GSTs) and Glutathione peroxidase (GPx) of Oxya chinensis were determinated. The results showed that the mortality of Oxya chinensis increased with increasing dose of ALA. The mortality of high-dose treatments A3, A4 reached 66.19%, 80.21%. Biochemical studies showed that ALA inhibited AChE and GPx activities of Oxya chinensis，the AChE activities of female and male Oxya chinensis in A4 treatment declined 51.53%, 42.65% significantly (P<0.05); the GPx activities of female and male Oxya chinensis in A4 treatments declined 42.82%; 43.85% compared to control respectively(P<0.05). Meanwhile, GSTs activities of Oxya chinensis increased with increasing dose of ALA，the GSTs activities of female and male Oxya chinensis in A4 treatment remarkably increased 171.05%, 97.42% compared to control(P<0.05). The results indicated that ALA had obviously toxic effect on Oxya chinensis. The reasons causing Oxya chinensis dead analyzed, ALA could inhibit AChE and GPx activities of Oxya chinensis which caused nerve transmission blocking and the capabilities to defend oxidation damage declining. Meanwhile high-dose ALA could activate GSTs which caused a feedback inhibition of insect to the phototoxic substance.

Key words: Oxya chinensis, 5-aminolevulinic acid (ALA), acetylcholinesterase (AChE), glutathione S-transferase (GSTs), Glutathione peroxidase (GPx)