Contributions of γ-Aminobutyric Acid (GABA) Receptors for the Activities of Pectis brevipedunculata Essential Oil against Drosophila suzukii and Pollinator Bees.

Abstract

The γ-aminobutyric acid (GABA) receptors play pivotal roles in the transmission of neuronal information in the nervous system of insects, which has led these proteins to be targeted by synthetic and natural products. Here, we assessed the insecticidal potential of the essential oil of Pectis brevipedunculata (Gardner) Sch. Bip., a neotropical Asteraceae plant used in traditional medicine, for controlling Drosophila suzukii (Matsumura) adults by feeding exposure. By using in silico approaches, we disentangle the contribution of GABA receptors and other potential neuronal targets (e.g., acetylcholinesterase, glutathione-S-transferases) in insects that may explain the essential oil differential activities against D. suzukii and two essential pollinator bees (Apis mellifera Linnaeus and Partamona helleri Friese). Neral (26.7%) and geranial (33.9%) were the main essential oil components which killed D. suzukii with an estimated median lethal concentration (LC50) of 2.25 µL/mL. Both pollinator forager bee species, which would likely contact this compound in the field, were more tolerant to the essential oil and did not have their diet consumptions affected by the essential oil. Based on the molecular predictions for the three potential targets and the essential oil main components, a higher affinity of interaction with the GABA receptors of D. suzukii (geranial -6.2 kcal/mol; neral -5.8 kcal/mol) in relation to A. mellifera (geranial -5.2 kcal/mol; neral -4.9 kcal/mol) would contribute to explaining the difference in toxicities observed in the bioassays. Collectively, our findings indicated the involvement of GABA receptors in the potential of P. brevipedunculata essential oil as an alternative tool for controlling D. suzukii.