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.

The mosquito Aedes aegypti is the vector responsible for the transmission of important arboviruses such as dengue fever, Chikungunya, Zika virus, and yellow fever. These diseases affect millions of people and exert impacts on healthcare systems throughout the world. Given the increasing resistance to synthetic insecticides, essential oils from plants constitute an ecologically viable alternative for the control of this vector. The aim of the present study was to investigate the larvicidal activity of the essential oil (EO), aqueous extract, rutin, and hydrolate from the leaves of Myrciaria floribunda against Aedes aegypti larvae in the initial L4 stage. The yield of EO was 0.47%. Thirty-seven chemical constituents were identified and quantified using chromatographic methods. The major constituents were (E)-caryophyllene (27.35%), 1,8-cineole (11.25%), β-selinene (4.92%), and α-muurolene (4.92%). In the larvicidal tests, the lethal concentration (LC₅₀) was 201.73 ppm for the essential oil, 15.85% for the aqueous extract, and 22.46 ppm for rutin. The hydrolate had no larvicidal activity. The compounds that exhibited larvicidal activity against Aedes aegypti constitute a promising option for the development of natural formulations to diminish the propagation of this vector.

The black aphid Aphis craccivora Koch is one of the main pests of the caupi-bean crop Vigna unguiculata (L.) Walp. Due to the need to find effective and safe methods of control, there has been an increase in research seeking natural alternatives. Thus, the objective of this work was to evaluate the potential of essential oils from jatoba Hymenaea courbaril, copaiba Copaifera langsdorffii and aroeira Schinus terebinthifolius to control nymphs and adults of A. craccivora. The oils were extracted from the leaves by the hydrodistillation method, diluted to 0.1% in distilled water with 2% dimethyl sulfoxide (DMSO). Each treatment had four repetitions, plus a control with distilled water + 2% DMSO. The biotests were conducted in two stages: the first was conducted in the laboratory, under controlled conditions of temperature, relative humidity and photophase, and the second was conducted in the greenhouse, using only the treatment with the best laboratory test results. After 24, 48, 72, 96 and 120 hours of exposure, the insect mortalities were checked. In the first phase of the experiment, the aroeira oil showed 83.33% and 75.75% efficiency of mortality in nymphs and adults, respectively. In the greenhouse tests, this same oil showed 73.52% in nymphs and 62.85% in adults, opening new perspectives regarding its use as a natural insecticide for the control of the black aphid of the bean.

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.