Abstract:

By using ultraviolet spectroscopy, a comparative study was made on the distribution and activities of carboxylesterase (CarE) and acetylcholinesterase (AChE) in Pardosa pseudoannulata collected from different rice fields, pest-controlled chemically or biologically. The results showed that the activity of AChE in any part of the body, including cephalothorax with the corresponding value 1.251 nmol/(mg·min), abdomen 0.467 nmol/(mg·min) and appendages 0.760 nmol/(mg·min), of P. pseudoannulata from biologically controlled rice field was higher than that (including cephalothorax with the corresponding value 0.895 nmol/(mg·min), abdomen 0.445 nmol/(mg·min) and appendages 0.724 nmol/(mg·min)) in the spiders from chemically controlled rice field. On the contrary, the activity of CarE in every subsection of the spiders, including cephalothorax with the corresponding value 0.158 nmol/(mg·min), abdomen 0.708 nmol/(mg·min) and appendages 0.115 nmol/(mg·min), from chemically controlled rice field was higher than that (including cephalothorax with the corresponding value 0.122 nmol/(mg·min), abdomen 0.593 nmol/(mg·min) and appendages 0.073 nmol/(mg·min)) in the spiders from biologically controlled rice field. This proved that the spider developed a certain degree of resistance for pesticide in chemically controlled rice field. AChE distributed mainly in the cephalothorax of spiders, while CarE was mainly found in abdomen. This distribution pattern was fit for the mechanism of resistance to pesticide, which was tentatively explored in this paper. The results also suggested that the resistance of P. pseudoannulata to methamidophos was unlikely to be formed within in a short period of time,  and there must exist a long period of adaptation of rice to pests and pests to spiders.
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Key words: Pardosa pseudoannulata, acetylcholinesterase, carboxylesterase, resistance to pesticide, chemical control, biological control