Danilo Gustavo Rodrigues Silva

Myrciaria floribunda is a plant found in the Northeast region of Brazil with several insecticidal properties that remain little explored. In this sense, this study aims to investigate the harmful effects of essential oil (EO) from M. floribunda leaves against Sitophilus zeamais, an important corn pest. The EO was applied in toxicity tests by fumigation, contact, and ingestion, as well as in in vitro assays to evaluate its effects on the activity of the enzymes α-amylase, trypsin, and acetylcholinesterase. Chromatographic analysis of the oil revealed (E)-caryophyllene (56.41%), viridiflorol (4.02%) and α-selinene (3.85%) as the main compounds. The essential oil (EO) showed fumigation toxicity, with an LC₅₀ of 3.2 μL/L of air, and (E)-caryophyllene with an LC₅₀ of 3.97 μL/L of air. The EO inhibited insect feeding, altering growth rate and feed conversion efficiency starting at 62.5 μL/g. In this study, an increase in amylase and acetylcholinesterase (AChE) activity was observed. This increase in AChE activity may cause an imbalance in the nervous system, leading to insect death. Thus, the EO of M. floribunda may serve as an alternative for the control of S. zeamais in stored corn and help prevent significant post-harvest losses for farmers.

Aedes aegypti is a vector responsible for the transmission of various arboviruses and is considered by the World Health Organization to be one of the main public health problems in the world. This study evaluated the larvicidal and oviposition activity of essential oils from Abies sibirica, Pogostemon cablin and Juniperus communis and their formulations. Chromatographic analysis by GCMS identified a total of 28, 52 and 18 compounds for the oils of the species A. sibirica, J. communis and P. cablin, respectively. The larvicidal bioassays showed an LC₅₀ of 67.53 ppm, 92.45 ppm and 35.95 ppm, respectively, for A. sibirica (A), J. communis (J) and P. cablin (P) as well as their binary (J + P, 39.50 ppm; A + P, 51.64 ppm) and ternary (A + J + P, 66.99 ppm) formulations. These oils and formulations also showed deterrent activity at the larvicidal concentrations tested (A. sibirica: OAI: −0.41; J. communis: OAI: −0.31; P. cablin: OAI: −0.62; A + J + P: −0.30; A + P: −0.68; A + J: −0.29; and J + P: −0.30). The oils and their formulations are a potential larvicidal source for mitigating the proliferation of diseases by this vector.