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Mosquito control still relies heavily on synthetic molecules, which can lead to the selection of resistant populations and undesirable environmental problems. This study described the preparation of a nanoparticle of the plant-derived molecule, β -myrcene, with chitosan, and the assessment of its toxicity against larvae of the yellow fever mosquito, Aedes aegypti . By producing fluorescent chitosan nanoparticles, we were able to observe their distribution in the digestive tract of larvae of Ae. aegypti . Chitosan-based nanoparticles containing β -myrcene (238 mg/L) could kill 100% of the larvae tested, whereas the blank control (i.e., the nanoparticle without β -myrcene) showed no larvicidal activity. The chitosan nanoparticles with β -myrcene had a zeta potential of +15 mV and a hydrodynamic diameter ranging from 30 to 2800 nm. The blank control, without β -myrcene, had a zeta potential of +26 mV and a diameter of 30 to 830 nm. Fluorescence analysis showed that the nanoparticles were efficiently absorbed and distributed in the digestive tract organs of the Ae. aegypti larvae. In short, our results reinforce the benefits of using chitosan to carry molecules of plant-derived-molecules, such as β -myrcene, in mosquito control, suggesting a broad internal distribution that contributes to their toxicity.

The use of formulations containing botanical products for controlling insects that vector human and animal diseases has increased in recent years. Plant extracts seem to offer fewer risks to the environment and to human health without reducing the application strategy's efficacy when compared to synthetic and conventional insecticides and repellents. Here, we evaluated the potential of extracts obtained from caninana, Chiococca alba (L.) Hitchc. (Rubiaceae), plants as a tool to be integrated into the management of Aedes aegypti , one of the principal vectors for the transmission of arborviruses in humans. We assessed the larvicidal and repellence performance against adult mosquitoes and evaluated the potential undesired effects of the extracts on non-target organisms. We assessed the susceptibility and predatory abilities of the nymphs of Belostoma anurum , a naturally occurring mosquito larva predator, and evaluated the C. alba extract's cytotoxic effects in mammalian cell lines. Our chromatographic analysis revealed 18 compounds, including rutin, naringin, myricetin, morin, and quercetin. The methanolic extracts of C. alba showed larvicidal (LC 50 = 82 (72-94) mg/mL) activity without killing or affecting the abilities of B. anurum to prey upon mosquito larvae. Our in silico predictions revealed the molecular interactions between rutin and the AeagOBP1 receptor to be one possible mechanism for the repellent potential recorded for formulations containing C. alba extracts. Low cytotoxicity against mammalian cell lines reinforces the selectivity of C. alba extracts. Collectively, our findings highlight the potential of C. alba and one of its constituents (rutin) as alternative tools to be integrated into the management of A. aegypti mosquitoes.

Bacillus thuringiensis serovar israelensis (Bti) is used to control insect vectors of human and animal diseases. In the present study, the toxicity of four strains of Bti, named T0124, T0131, T0137, and T0139, toward Aedes aegypti and Culex quinquefasciatus larvae was analyzed. The T0131 strain showed the highest larvicidal activity against A. aegypti (LC 50 = 0.015 µg/ml) and C. quinquefasciatus larvae (LC 50 = 0.035 µg/ml) when compared to the other strains. Furthermore, the genomic sequences of the four strains were obtained and compared. These Bti strains had chromosomes sizes of approximately 5.4 Mb with GC contents of ~35% and 5472-5477 putative coding regions. Three small plasmids (5.4, 6.8, and 7.6 kb) and three large plasmids (127, 235, and 359 kb) were found in the extrachromosomal content of all four strains. The SNP-based phylogeny revealed close relationship among isolates from this study and other Bti isolates, and SNPs analysis of the plasmids 127 kb did not reveal any mutations in δ-endotoxins genes. This newly acquired sequence data for these Bti strains may be useful in the search for novel insecticidal toxins to improve existing ones or develop new strategies for the biological control of important insect vectors of human and animal diseases.