The damage caused by spittlebugs varies according to the species of grass, and the losses can reach alarming levels. Measures for population control are currently restricted to the use of resistant grasses and the diversification of pastures. Therefore, alternative control measures are necessary, such as the use of botanical insecticides. The aim of this study was to evaluate the insecticidal activities of thymol, carvacrol, eugenol, cinnamaldehyde, and trans-anethole on Mahanarva spectabilis eggs, nymphs, and adults under laboratory conditions. In the egg tests, treatments with eugenol, carvacrol, and thymol showed the highest mortalities, presenting efficiencies higher than 85% after 48 h of application. In the nymph tests, the treatments with thymol and carvacrol at 2.5% and eugenol at 2.0% and 2.5% showed intermediate efficiencies, with values above 61%. The highest mortality was observed in the treatment with trans-anethole at 2.5%, with an efficiency of 95%. In the tests with adults, only treatment with trans-anethole at 2.5% obtained an efficiency reaching 90%; in the other treatments, the efficiency did not exceed 51%. These results showed that, at these concentrations, trans-anethole presents a high rate of insecticidal activity on M. spectabilis nymphs and adults and, therefore, is recommended as a potential natural insecticide for the control of this pest.

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The spittlebug Mahanarva spectabilis (Distant, 1909) is considered the main and most limiting pest of elephant grass (Pennisetum purpureum Schum.), and has caused economic losses to Brazilian farmers. In this study, we evaluated the insecticidal effects of aqueous extracts of garlic, rue, cinnamon, lemongrass, clove, star anise, eucalyptus, tobacco, and thyme on M. spectabilis nymphs. The results indicated that the tobacco extract was the most effective among all extracts, as it reached a mortality of 76%. The next most effective was star anise extract and cinnamon extract was the least effective. In the second stage of tests, we evaluated the insecticidal potential of five concentrations of tobacco extract. The values of LD50 and LD90 calculated for aqueous tobacco extract were, respectively, 11.5% and 33.3% 24 h after application, and 9.2% and 29.5% 48 h after application. We also evaluated different methods of extraction, through comparative tests, and the methods of infusion and decoction proved to be equivalent to those of the method of extraction by ultrasound. We conclude that among the nine aqueous plant extracts tested, tobacco extract was the only one recommended against M. spectabilis, as it showed insecticidal activity, with better results at a concentration of 25%, and with extraction by infusion and decoction.

The objective of this study was to develop and evaluate an alternative, less laborious and reliable method for investigating the insecticidal effect of thymol on Mahanarva spectabilis (Hemiptera: Cercopidae). Two methods for evaluating the effects of thymol on M. spectabilis (conventional and alternative) were tested for optimum survival rates. The conventional method proved to be the most suitable for investigating the insecticidal effect of thymol on M. spectabilis. Thymol concentrations of 1.2, 2.5, and 5.0% resulted in the highest mortality rates of eggs, nymphs and adults, respectively. Thus, the study determined a methodology to evaluate the effects of insecticide products on spittlebugs, which indicated that thymol may be used effectively for the control of M. spectabilis.