ABSTRACT

The whitefly Aleurodicus cocois is one of the main pests of cashew, Anacardium occidentale L. in Brazil. The use of essential oils and their constituents is an alternative means of controlling pests with low risk to natural enemies. In the present study, the chemical profile and toxicity of a mixture of the essential oils of Lippia sidoides Cham. (Verbenaceae) and Cymbopogon winterianum Jowitt. (Poaceae) on the third and fourth nymphal stages of A. cocois were evaluated, as well as their toxicity to the predator Chrysoperla externa (Hagen, 1861) (Neuroptera: Chrysopidae). Thymol and ρ-cymene were the majority monoterpenes in L. sidoides oil, whereas in C. winterianus, geraniol, citronellal and citronellol oil were the main components. In the concentration-mortality bioassays, the toxicity of the mixture of the two essential oils evaluated on the third and fourth nymphal stages of A. cocois in terms of LC₅₀ was estimated at 11.17 and 16.92 mg/mL, respectively. At all concentrations evaluated, the mixture of essential oils caused low mortality of C. externa eggs and larvae and did not alter predator development time. Additional repellency tests showed that independent of the tested concentrations and exposure times (1, 3, and 24 h), C. externa larvae were repelled by the mixture of essential oils. It is concluded that the mixture of the essential oils of L. sidoides and C. winterianum is toxic to nymphal stages of A. cocois and moderate toxicity to C. externa.

摘要

粉虱Aleurodicus cocois是巴西腰果Anacardium occidentale L.的主要害虫之一。使用精油及其成分是防治天敌风险低的害虫的另一种方法。在本研究中，Lippia sidoides Cham香精油混合物的化学特性和毒性。（马鞭草科）和Cymbopogon winterianum Jowitt。（Poaceae）评估了可可曲霉第三个和第四个若虫阶段，以及它们对捕食者Chrysoperla externa（Hagen，1861）（Neuroptera：Chrysopidae）的毒性。百里香酚和对-异丙基苯醚是L. sidoides油中的主要单萜，而在L. sidoides油中C. winterianus，香叶醇，香茅醛和香茅醇是主要成分。在浓度-死亡率生物测定法中，按LC ₅₀估算，在可可曲霉的第三和第四次若虫阶段评估的两种精油混合物的毒性分别为11.17和16.92 mg / mL。在所评估的所有浓度下，精油的混合物均能降低外层梭菌卵和幼虫的死亡率，并且不会改变捕食者的发育时间。其他驱蚊测试表明，与测试浓度和暴露时间（1、3和24小时）无关，精油混合物可以驱除C. externa幼虫。结论是，香精油的混合物L. sidoides和C. winterianum对A. cocois的若虫期有毒性，对ex。C. externa有中度毒性。