Toxic effects of essential oils against Bemisia tabaci (Gennadius, 1889) (Hemiptera: Aleyrodidae) and its certain important natural enemies

In this study, we aimed to investigate the effects of five different commercially available essential oils; aloe vera, borage, cacao, horse chestnut and nettle seed oils against egg, nymphal and pupal stages of Bemisia tabaci Gennadius and its important natural enemies namely, Encarsia formosa Gahan, Eretmocerus eremicus Rose and Zolnerowich, Macrolophus pygmaeus Rambur, Nesidiocoris tenuis Reuter, and Orius laevigatus Fiber. This study was conducted under laboratory conditions in 2021 at Bursa Uludag University, Turkey. The essential oil solutions were applied at %0.125, 0.25 and 0.5 doses and mortality rates were noted after 24, 48 and 72 hours of essential oils application. As a result, it was determined that the insect species most affected by the plant oils were the predators, the immature stages (egg, nymphal and pupal) of whitefly and the parasitoid species, respectively. Borage and horse chestnut oils showed high effects (100%) on predatory adults after 24 hours. It was determined that all N. tenuis and M. pygmaeus adults died after 48 hours in the trial. The egg, nymphal and pupal stages of B. tabaci were most affected by plant oils, respectively. B. tabaci eggs and pupal stages were the most affected from cacao oil with a mortality rate of 100%. Moreover, nymphal stage of B. tabaci was the most affected by horse chestnut oil with a mortality rate of 100% after 72 hours. Parasitized pupae were found to be the least affected individuals in the trial. Aloe vera oil was the least effective essential oil in the experiment. Eggs and nymphal stages of B. tabaci, O. laevigatus, E. formosa and E. eremicus were affected by aloe vera oil with mortality rates of 53.33%, 46%, 53%, 46% and 36%, respectively. Horse chestnut and cacao oils were harmful to the immature stages (egg, nymphal and pupal) of B. tabaci and all predator adults (M. pygmaeus, N. tenuis, O. laevigatus), but they had slightly harmful on parasitoid species in the experiment.