使用生命表评价烯啶虫胺对异色瓢虫的影响

为正确评估广谱杀虫剂烯啶虫胺对天敌昆虫异色瓢虫Harmonia axyridis(Pallas)的影响,采取滤纸接触法测定了烯啶虫胺(防治蚜虫田间推荐用量)对异色瓢虫影响,并使用生命表研究了烯啶虫胺对异色瓢虫实验种群的影响,为协调害虫的化学防治与生物防治提供参考。结果表明:该剂量烯啶虫胺对异色瓢虫当代(F0)取食具有显著影响,药剂处理后7d内,成虫取食量显著降低;对F0代成虫寿命及雌虫繁殖能力未见负面影响;烯啶虫胺处理对异色瓢虫初产卵、F1代幼虫及蛹的历期没有显著影响;卵孵化率明显小于对照组,幼虫存活率及蛹羽化率没有显著影响。F0代种群净增值力、周限增长率、内禀增长率与对照相比差异不显著,分别为812.66粒(对照899.73粒)、1.084(对照1.093)、0.081(对照0.089),药剂处理种群加倍时间为8.557d,与对照7.888d相比没有显著延长。这些结果说明,大田中使用烯啶虫胺防治蚜虫时理论上对异色瓢虫种群繁殖及发育没有显著影响,但施药初期会影响异色瓢虫的取食量。

Evaluation of the effect of nitenpyram on Harmonia axyridis (Pallas) using life table technique

Nitenpyram is a class of neonicotinoid insecticide and also a so-called low risk insecticide which targets the pest.Nitenpyram has been registered for controlling a variety of insect pests, such as aphid, whitefly and thrip, in China. In order to investigate its non target effects, we estimated the effect of nitenpyram on Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) which is considered an important generalist predator that can be used as a biological control agent against Hemiptera Sternorrhyncha, Thysanoptera, and the eggs and larvae of Lepidoptera, Coleoptera and Diptera. The filter paper touch method normally used to estimate the killing effect of insecticide on insects was used in our report, and the field recommended dose (25 mg/L) and control (0 mg/L) were adopted. The effects of nitenpyram on Harmonia axyridis (Pallas) were investigated which included assessing fecundity, feeding amount and the longevity of the ladybird in F₀. The results showed that when insecticides were applied at the adult stage, with 25 mg/L dosage or control, there were some negative effects on predation number of F₀. When being treated by nitenpyram, predation of the adult Harmonia axyridis decreased greatly after 1-7 days; but had no negative impact on the longevity and fecundity of F₀ adult Harmonia axyridis, however, the pre-ovipositing period was prolonged from 8.79 days to 9.79 days.At the same time, the survival rate and developmental time of H.axyridis in F₁ were examined. Some characteristics were significantly reduced if treated with the field recommended dose of nitenpyram.The hatching and emergence rate of pupation were significantly decreased from 92.89% to 83.67% and from 77.74% to 59.99%, respectively; but the survival rate of larvae was not obviously influenced. At the same time, the laboratory population life table of ladybirds in F₀ which were treated with 25 mg/L dosage or control was established by calculating the longevity, survival rate and adult reproduction. The net reproduction rate (R₀), finite rate of increase (K), population doubling time (t) and intrinsic rates of increase (r_m) of the F₀ generation were no different from that of the control group. For example, the net reproduction rate (R₀) of the treated population was 812.66 (899.23 for the control). The calculated population doubling time (t) were 7.788 d (control) and treated 8.557 d (treated); intrinsic rates of increase (r_m) were 0.089 (control) and 0.081 (treated), respectively. All these results suggested that in an agricultural ecosystem, at the recommended field dose (25 mg/L), nitenpyram is a safe insecticide for the natural enemy. Nitenpyram has no obvious impact on the population fecundity and growth of Harmonia axyridis (Pallas) in prevention of aphids theoretically, but it has an influence on the predation of Harmonia axyridis (Pallas) in the early stage of pesticide delivery.