Bioatividade de óleos essenciais de Citrus spp. e Cinnamomum spp. e nanoemulsões de Cinnamomum cassia contra Alphitobius diaperinus

Abstract

The lesser mealworm of aviaries Alphitobius diaperinus (Panzer 1970) (Coleoptera: Tenebrionidae) is considered the main pest of poultry. The chemical insecticides currently available for its control cause environmental damage and consumer health, so it is necessary to develop research seeking new methods of control. Thus, this work aimed to evaluate the bioactivity of essential oils (EOs) from Citrus aurantium var. bergamia, Citrus reticulata var. tangerine, Citrus aurantifolia, Citrus aurantium, Cinnamomum camphora var. linalooliferum, Cinnamomum camphora and Cinnamomum cassia and nanoemulsions (NEs) for A. diaperinus. The OE C. aurantium var. bergamia and C. reticulata var. tangerine presented toxicity in a topical way in relation to the other EO, but with low probability of survival (0.68). The EO of C. cassia showed high toxicity for A. diaperinus, in ingestion test, resulting in TL50 = 35 h and LC50 = 29.54 µg/mg, 6.4 times higher compared to the LC50 obtained for the active ingredient cypermethrin (TL50 = 48 h; CL50 = 4 , 57 µg/mg). The analysis of the metabolic profile by GC/MS revealed that E-Cinnamaldehyde (84.21%) was the major compound. Additionally, this EO was selected to be submitted to tests aiming at the development of NEs. Two NEs were selected that were more stable based on a thermodynamic stress test. DLS analyzes of NEs revealed that the average particle diameter was 159.4 and 99.20; zeta potential: -2.3 and -0.647 and polydispersity index: 0.43 and 0.14. When the NEs were subjected to a test with A. diaperinus it was found that they were more toxic (TL50 = 66 h) than the non-nanoemulsified OE (TL50 = 96 h). It is also noteworthy that the NEs were bioactive even after 21 days of their application in A. diaperinus diet. Thus, NEs proved to be more toxic to A. diaperinus than EO.