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Abstract: The objective of this work was to assess the fumigant and repellent effects of essential oils on adults of Callosobruchus maculatus and to identify the chemical composition of two of the tested essential oils. For the fumigation test, the oils of Schinus terebinthifolius, Piper aduncum, Syzygium aromaticum, Piper hispidinervum, Cymbopogon citratus, Cinnamomum zeylanicum, and the eugenol compound were tested at different concentrations on C. maculatus adults. For the repellency test, the oils of S. terebinthifolius, P. aduncum, P. hispidinervum, S. aromaticum, Jatropha curcas, and Ricinus communis were evaluated. In the fumigation test, it was observed that P. aduncum and eugenol showed the highest and lowest LC50s, of 169.50 and 0.28 μL L-1 air, respectively. In the repellency test, the oils of S. aromaticum and P. hispidinervum were repellent to C. maculatus. Gas chromatography coupled to mass spectrometry (GC-MS) analysis of these two oils identified 42 compounds, of which safrole was the main component of P. hispidinervum and eugenol of S. aromaticum. The essential oils of S. aromaticum, C. zeylanicum, and the eugenol compound are the most promising to control C. maculatus, via fumigation.

Óleos essenciais de Piper aduncum L. e Piper hispidinervum C.DC. (Piperaceae) foram avaliados quanto ao efeito inseticida em Sitophilus zeamais Motsch. por ação de contato, fumigação e tópica. Na determinação da DL50 e CL50, foi utilizada a análise de Probit. Médias porcentuais de mortalidade dos insetos foram comparadas por meio da análise de regressão linear e superposição das barras do erro padrão. S. zeamais foi mais suscetível ao efeito de contato do óleo de P. hispidinervum em relação ao de P. aduncum, obtendo-se CL50 de 0,51 e 2,87 mL cm- 2 de óleo, respectivamente. Mortalidade próxima a 100% foi obtida nas concentrações de 20 e 30% do óleo de P. hispidinervum. Quanto ao efeito fumigante, a susceptibilidade foi maior no óleo de P. aduncum do que no de P. hispidinervum. Houve diferença significativa entre os óleos somente nas concentrações de 0,1 e 1,0. A DL50 foi semelhante nos dois óleos essenciais por aplicação tópica. No entanto, a mortalidade foi maior com P. aduncum. Óleos essenciais de P. aduncum e P. hispidinervum possuem efeito inseticida em S. zeamais, mas as respostas dependem da concentração e do método de exposição a que o inseto seja submetido.Essential oils of Piper aduncum L. and Piper hispidinervum C. DC. (Piperaceae) were tested against Sitophilus zeamais Motsch. Contact, fumigant toxicity and topical effect were tested. Probit analysis was employed in evaluating the LC50 and LD50 response. Linear regression analysis and superposition of the bars (means error standard) were used for comparison of means percentage mortality. S. zeamais was more susceptible to the contact toxicity of the P. hispidinervum oil than P. aduncum oil with LC50 values of 0.51 and 2.87 mL cm-2 of the oil, respectively. The mortality rate was nearly 100% at P. hispidinervum oil concentrations of 20 and 30%. With respect to the fumigant action, the weevil was more susceptible to the P. aduncum oil than to P. hispidinervum. A significant difference between oils mortality was observed only at 0.1 and 1.0% concentrations. For topical effect, similar values of the LD50 were obtained for essential oils. However, the mortality was higher with P. aduncum. Essential oils of the P. aduncum and P. hispidinervum possess insecticidal effect from S. zeamais, but the responses varied according to concentration of the oils and exposure methods.

ABSTRACT For an important and expensive crop such as corn, the resistance of Spodoptera frugiperda J.E. Smith to various pesticides has led to research throughout the world for a potential insecticide from a natural source. For the management of pest resistance, natural compounds associated with synthetic insecticides can be a promising tool because they can reduce the application of the synthetics molecules while maintaining their effectiveness and promoting the control of the pests. Linalool is a potential insecticide that is easily obtained because it is found in high concentrations in the essential oil of Ocimum basilicum L. Therefore, the present study aimed to evaluate the toxicity of this essential oil and its combination with deltamethrin to control S. frugiperda. Through dose response assays, the acute toxicities (LD50) of the essential oil and deltamethrin were estimated. Additionally, the combination of these materials was also assessed, attaining a reduction of 80% of the LD50 of deltamethrin while obtaining the same result as when the pyrethroid was administered alone. From these results, it is expected that the combination of natural compounds and synthetic insecticides will be a promising practice, helping to manage resistance while reducing the environmental impact of toxic compounds.