不同啶虫脒剂型对烟粉虱的毒力差异及原因分析

Toxicity difference of different acetamiprid formulations against Bemisia tabaci and reasons

为探讨农药剂型对烟粉虱的毒力差异,分别以甘蓝和黄瓜叶片作为生物测定载体,比较了啶虫脒乳油（EC）、微乳剂（ME）、可溶性液剂（SL）、可溶性粉剂（SP）及可湿性粉剂（WP）等5种剂型对烟粉虱成虫的毒力,并通过对植物叶片临界表面张力、啶虫脒药液表面张力、动态接触角及叶片持液量的测定,分析了不同啶虫脒剂型间毒力差异形成的原因。结果表明：以甘蓝叶片为生物测定载体,不同啶虫脒剂型间对烟粉虱的毒力差异明显;以黄瓜叶片为生物测定载体,不同剂型间毒力差异不明显。啶虫脒SL、SP、WP在两种生物测定载体间的毒力差异大于EC和ME。甘蓝和黄瓜叶片的临界表面张力值分别为30.73 mN.m 1和57.91~63.30 mN.m 1。啶虫脒有效成分浓度大于7.81 mg.L 1时,啶虫脒EC和ME溶液表面张力即小于甘蓝和黄瓜叶片的临界表面张力;啶虫脒有效成分浓度大于500 mg.L 1时,啶虫脒SL、SP、WP溶液的表面张力才小于甘蓝叶片的临界表面张力。啶虫脒ME溶液液滴接触两种植物叶片的瞬间（0 s）,液滴与叶片间的接触角就明显小于90°。甘蓝叶片对低浓度的啶虫脒ME和EC溶液的持液量高于其他3种剂型,黄瓜叶片对啶虫脒各剂型溶液的持液量无明显差异。植物叶片表面性质和不同剂型溶液表面张力的差异是导致剂型间产生毒力变化的重要原因。

The fate of pesticide droplets on plant leaves is significantly influenced by the fine structures of leaf surfaces and the characteristics of pesticide solutions.Deposition quantity is the main factor that influences pesticide toxicity.Using appropriate pesticide formulations greatly increases pesticide utilization and efficiency while it at the same time reduces environmental pollution.Cabbage and cucumber leaves were used as bioassay carriers in order to explore the differences in toxicity among different acetamiprid formulations to Bemisia tabaci Gennadius.The toxicities of five different acetamiprid formulations — emulsifiable concentrate（EC）,microemulsion（ME）,soluble liquid（SL）,soluble powder（SP） and wettable power（WP） — were examined in a laboratory study.The mechanisms of the different toxicities were analyzed through detections of leaf critical surface tension,acetamiprid solution surface tension,dynamic contact angle and leaf retention volume of liquid.The results showed that differences among the pesticide formulations were more obvious when cabbage leaf was used as bioassay carrier.However,differences among the formulations were not so notable when cucumber leaf was used as bioassay carrier.Toxicities differences of SL,SP and WP between two bioassay carries were larger than those of EC and ME.Critical surface tension of cabbage and cucumber leaves were 30.73 mN.m 1 and 57.91~63.30 mN.m 1,respectively.The solution surface tensions of EC and ME were less than critical surface tensions of cabbage and cucumber leaves,if acetamiprid active ingredient concentration reached 7.81 mg.L 1.For SL,SP and WP,however,solution surface tensions were only less than critical surface tensions of cabbage when acetamiprid active ingredient concentration exceeded 500 mg.L 1.Contact angle was significantly lower than 90° when ME droplets instantly dripped on plant leaf surface of two plants.Cabbage leaf retention volumes of low concentration ME and EC solutions were higher than the other three formulations.There was no obvious difference in retention volumes of cucumber leaf for the 5 acetamiprid formulations.Differences in leaf surface characteristics and solution surface tensions were the main reasons for the variations in toxicities of different formulations.