Toxicidade de óleos essenciais de anonáceas para Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) e compatibilidade para o fungo entomopatogênico Beauveria bassiana (Bals.) Vuill. (Ascomycota: Cordycipitaceae)

Abstract

Poultry house has been standing out economically in Brazil. This increase in the sector raised Brazil in the ranking of chicken production and exports. However, this high demand intensified production and favored the proliferation of pests in poultry. In this context, the lesser mealworm Alphitobius diaperinus (Panzer) (Coleoptera:Tenebrionidade) is considered the main pest of poultry, and the methods used in the management of this insect are inefficient. Thus, this work aimed to evaluate the bioactivity of essential oils from the stem bark of Duguetia lanceolata A.St.-Hil. and Xylopia brasiliensis Spreng. and from the leaves of Annona sylvativa A. St.-Hil. and Xylopia sericea A.St.-Hil. A. diaperinus; and the compatibility of the most toxic essential oil for A. diaperinus to the non-target organism, the entomopathogenic fungus Beauveria bassiana (bals.) Vuill. All oils tested were toxic to A. diaperinus in both topical application and ingestion bioassays. However, the most relevant result was found for the essential oil of D. lanceolata (stem barks) in a bioassay of ingestion, which had its median lethal concentration (LC50), that is, the concentration necessary to cause mortality in 50% of the population estimated at 38.36 µg/mg of diet, whereas (CL90), that is, the concentration necessary to cause the mortality of 90% of individuals was estimated at 98.63 µg/mg of diet. Even after 30 days of the application of the essential oil of D. lanceolata (stem barks) in the diet, the toxicity to A. diaperinus was verified, proving the residual action of the essential oil. The larvae fed with the diet containing the essential oil of D. lanceolata (stem barks) were subjected to ultrastructural analysis in a scanning electron microscope. In this analysis, it was possible to observe morphological changes that prevented the insects from carrying out the process of ecdysis, being verified the presence of the exuvia adhered to the insect's body. When the compatibility with the entomopathogenic fungus B. bassiana was evaluated, it was found that the essential oil of D. lanceolata (stem bark) showed a moderate toxicity index (TM) for this non-target organism. The Gas Chromatography analyzes coupled with Mass Spectrometry (CG / MS) were conducted with the essential oils of A. sylvatica (leaves), D. lanceolata (stem bark) and Xylopia sericea (leaves) allowing the identification of some compounds present in these essential oils However, the results described in the present work describe the toxicity of essential oil from D. lanceolata (stem bark) to A. diaperinus, and the moderate toxicity to the entomopathogenic fungus B. bassiana.