5种杀螨剂对不同螨态荔枝叶螨的毒力评价和田间防效

为了综合评价常用杀螨剂对荔枝叶螨Oligonychus litchii的室内毒力,在室内分别采用Potter喷雾法、浸叶碟法和浸叶法测定了5种常用杀螨剂对荔枝叶螨成螨、卵和若螨的毒力,并测定了5种杀螨剂对荔枝叶螨的田间防效。室内毒力结果表明:哒螨灵、阿维菌素对荔枝叶螨成螨和若螨有较高的毒力,联苯肼酯对成螨和若螨的毒力较低,而螺螨酯和乙螨唑对成螨基本无活性,对若螨有一定的毒力;5种杀螨剂对卵的毒力大小依次为乙螨唑螺螨酯哒螨灵阿维菌素联苯肼酯。田间防效试验中,15%哒螨灵乳油和1.8%阿维菌素乳油对荔枝叶螨的总体防效较好,药后1 d防效高于70%,药后10 d防效达100%,药后20 d防效仍在90%以上,速效性和持效性均较好;240 g/L螺螨酯悬浮剂和110 g/L乙螨唑悬浮剂对荔枝叶螨药后3 d防效均低于70%,而药后20 d的防效高于90%,说明两药剂速效性较差但持效性较好;43%联苯肼酯悬浮剂药后1、3 d防效低于阿维菌素和哒螨灵,高于螺螨酯和乙螨唑,药后15 d防效开始下降。在田间防治荔枝叶螨时,若荔枝叶螨发生早期、成螨较少时建议施用螺螨酯或乙螨唑,而荔枝叶螨种群中成螨、若螨较多时推荐施用阿维菌素、哒螨灵或联苯肼酯。

Toxicity and field efficacy of five acaricides against Oligonychus litchii on different life stage

In order to evaluate the activity of five common acarcides to Oligonychus litchi, the toxicities on adult mite, nymph mite and egg were measured in laboratory using potter spraying method, slide dipping method and leaf dipping method respectively, and the control effects were also tested in the field. The result showed that pyribaden and avermectin displayed relatively higher toxicities to adult and nymph mite, followed by bifenazate. Spirodiclofen and etoxazole showed a certain effect to nymph mite, but very poor effect to adult mite. The toxicities on egg rank (from high to low) of the five acarcides were etoxazole, spirodiclofen, pyribaden, avermectin and bifenazate.In field efficacy trial, 15% pyribaden EC and 1.8% avermectin EC showed relatively good control effect to O.litchi. The control effect was higher than 70% at 1 day after treatment (DAT), and increased to 100% at 10 DAT Moreover, the control effect was still above 90% at 20 DAT .These results indicated that pyribaden and avermectin had quick action speed and long persistence. The control effects of 240 g/L spirodiclofen SC and 110 g/L etoxazole SC were lower than 70% at 3 DAT and higher than 90% at 20 DAT, which indicated slow action speed and long persistence of these two pesticides. At 1 DAT and 3 DAT, the control effect of 43% bifenazate SC was lower than 15% pyribaden EC and 1.8% avermectin EC, but higher than 240 g/L spirodiclofen SC and 110 g/L etoxazole SC. At 15 DAT, the control effect of 43% bifenazate SC began to fall. In the actual application, spirodiclofen and etoxazole are recommended in the early stage with fewer adult mite, and pyribaden, avermectin, and bifenazate are recommended when adult mite and nymph mite predominate the population.