不同杀虫剂防治苜蓿蚜虫效果及对捕食性天敌影响

Effect of Different Insecticides on Alfalfa Aphids and Predatory Natural Enemies

为明确不同杀虫剂对紫花苜蓿蚜虫及其捕食性天敌的影响,本研究比较了吡虫啉、啶虫脒、烯啶虫胺、氟啶虫胺腈、吡蚜酮和螺虫乙酯6种杀虫剂施药后不同时间对苜蓿蚜虫的防治效果及其对捕食性天敌的影响。结果表明,喷药后至10d,6种杀虫剂的防治效果均在85%以上,之后防效均出现不同程度下降,喷药后20d~35d,吡虫啉、啶虫脒、烯啶虫胺和氟啶虫胺腈4种杀虫剂防效为19.17%~40.13%,吡蚜酮和螺虫乙酯防效为58.01%~71.32%,吡蚜酮和螺虫乙酯持续防控效果显著高于前4种杀虫剂。蚜虫和天敌发生动态趋势表明,喷药后蚜虫数量均迅速下降至低水平并保持到4月底;5月上旬吡虫啉、啶虫脒、烯啶虫胺和氟啶虫胺腈4种杀虫剂处理区蚜虫数量开始快速上升,同一调查时间蚜虫数量均显著大于吡蚜酮和螺虫乙酯处理区数量,而天敌数量和益害比却均显著小于吡蚜酮和螺虫乙酯处理区;吡蚜酮和螺虫乙酯防控蚜虫的同时可避免杀伤天敌,自然天敌捕食蚜虫亦抑制蚜虫数量增长,二者协同控制蚜虫危害作用时间长,为苜蓿蚜虫高效绿色防控提供科学依据。

To study the effects of different insecticides on alfalfa aphids and predatory natural enemies,we investigated the control effects of imidacloprid,acetamiprid,nitenpyram,sulfoxaflor,pymetrozine and spirotetramat on alfalfa aphids,as well as the number dynamics of alfalfa aphides and predatory natural enemies.The results indicated that the control effects of 6 insecticides were all above 85%after 10 days,and then the efficacy decreased differently.20-35 days after spraying,the control effects of imidacloprid,acetamiprid,nitenpyram and sulfoxaflor were 19.17%-40.13%,and that of pymetrozine and spirotetramat were 58.01%-71.32%,much higher than that of the four insecticides before.The dynamic trend of aphids and natural enemies showed that,the aphid population decreased rapidly to a low level and remained to the end of April,and the aphid number began to rise rapidly in early May in areas treated with imidacloprid,acetamiprid,nitenpyram,sulfoxaflor,and the number of aphids was significantly higher than that in pymetrozine and spirotetramat treated area at the same time.However,the number of natural enemies and the ratios of beneficial to harmful were significantly smaller than those in pymetrozine and spirotetramat treated areas.Pymetrozine and spirotetramat could control aphids from killing natural enemies,natural predators preying on aphids also inhibited the growth of aphids,and the two cooperated to control the harm of aphids for a long time.Our study provided scientific basis for efficient green control of alfalfa aphids.