Najar-Rodríguez Adriana J, Walter Gimme H, Mensah Robert K
School of Integrative Biology, The University of Queensland, Brisbane QLD 4072, Australia.
Pest Manag Sci. 2007 Jun;63(6):586-95. doi: 10.1002/ps.1385.
Petroleum spray oils (PSOs) kill insect pests on contact, and the composition of modern PSOs is substantially different from the ones introduced earlier. The effects of direct application of a new nC24 PSO on the cotton aphid, Aphis gossypii Glover, were therefore determined. This covered not only aphid mortality rates but also the way in which the oils affected aphid behaviour at the time of contact with the oil. Direct application of the nC24 oil proved to be highly effective in controlling A. gossypii at a range of concentrations between 1 and 10% v/v. The oil killed cotton aphids quickly, with most of the mortality occurring within the first 10 min of spraying. The fast killing action of the oils prevented any behavioural responses by the aphids. Aphids killed by the oils became flaccid and their legs and antennae extended horizontally relative to the body axis. With time, their cuticle became very shiny and began to darken. The quick death of the aphids suggested a contact mode of action of the oils, an interpretation supported by the lack of any negative effect on aphids not initially reached by the oils. However, those aphids not hit by the oils, but that subsequently encountered oil-treated areas when they moved elsewhere, also died, indicating that the oil deposits are also toxic to the aphids. The mode of action of the oil thus seems to be versatile, and the means by which it kills the aphids may be more complex than anoxia, which is the widely claimed mechanism attributed to PSOs. This oil now needs to be tested for any possible indirect effects on the cotton aphid (e.g. through its host-plant acceptance behaviour). The implications of the present findings for cotton aphid control and assessment of PSO efficacy in the field are discussed.
石油喷雾油（PSOs）通过接触杀死害虫，现代PSOs的成分与早期引入的有很大不同。因此，确定了一种新型正二十四烷PSO直接施用于棉蚜（Aphis gossypii Glover）的效果。这不仅涵盖了蚜虫死亡率，还包括油在与蚜虫接触时对其行为的影响方式。事实证明，在1%至10%（v/v）的一系列浓度下，直接施用正二十四烷油对棉蚜具有高效的防治效果。该油能迅速杀死棉蚜，大部分死亡发生在喷雾后的前10分钟内。油的快速致死作用阻止了蚜虫的任何行为反应。被油杀死的蚜虫变得松弛，其腿部和触角相对于身体轴线水平伸展。随着时间的推移，它们的表皮变得非常光亮并开始变黑。蚜虫的快速死亡表明油的作用方式是接触性的，这一解释得到了以下事实的支持：对最初未接触到油的蚜虫没有任何负面影响。然而，那些未被油击中但随后在移动到其他地方时遇到油处理区域的蚜虫也死亡了，这表明油沉积物对蚜虫也有毒性。因此，这种油的作用方式似乎具有多样性，其杀死蚜虫的方式可能比缺氧更为复杂，而缺氧是普遍认为的PSOs的作用机制。现在需要测试这种油对棉蚜是否有任何可能的间接影响（例如通过其对寄主植物的接受行为）。讨论了本研究结果对棉蚜防治和田间PSO功效评估的意义。
