Mathews Otavio Nascimento de Novaes

Essential oils obtained from Siparuna plants, e.g., S. guianensis and S. gesnerioides, have potential for use as biorational insecticides. However, the activities of S. gesnerioides oils remain largely unexplored compared to S. guianensis oils. Using an integrative approach combining toxicological bioassays, geometric morphometrics, and in silico modeling, we assessed the adulticidal potential, selectivity, and the effects of early-life exposure to these oils on the larval susceptibility and adult wing morphometry of Aedes aegypti. Adulticidal assays revealed high toxicity, with S. guianensis (LC₅₀ = 15.0 nL/mL) being 15-fold more potent than S. gesnerioides (LC₅₀ = 233.0 nL/mL). Beyond acute lethality, early-life (i.e., eggs to L2 larvae) exposure to sublethal concentrations (S. guianensis = 7.4 nL/mL and S. gesnerioides = 118.0 nL/mL) was associated with wing morphometric disruptions and increased fluctuating asymmetry in Ae. aegypti adults, especially in those exposed to S. gesnerioides essential oil. Furthermore, early-life exposure to S. gesnerioides modulated L4 larvae susceptibility, which was associated with lower mortality in subsequent exposures. Selectivity assays demonstrated low acute oral toxicity in initial laboratory screenings with Apis mellifera, while molecular docking approaches predicted higher affinity of bicyclogermacrene and α-copaene for Ae. aegypti TRPV channels. Collectively, while S. gesnerioides oil was less acutely toxic, early-life sublethal exposures reduced fourth instar larvae (L4) susceptibility, which may have contributed to developmental instability and morphological alterations in adults. Our findings highlight the potential of Siparuna essential oils in mosquito management by impacting mosquito fitness beyond acute mortality.

The spotted-wing drosophila, Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae), is an invasive pest of thin-skinned and stone fruits with growing economic impact worldwide. In Brazil, it was first reported in 2013 and has since spread across major fruit-producing states. Although previously detected in Rio de Janeiro (RJ), records were limited to isolated individuals, never in commercial orchards. Here, we provide the first evidence of D. suzukii establishment in a commercial ‘Biloxi’ blueberry, Vaccinium corymbosum Linnaeus, field in Sapucaia, RJ. Initial vinegar traps captured seven females, confirmed in the laboratory. Subsequent banana–yeast bait traps collected both sexes, including one male, confirming establishment. Emergence assays from naturally damaged fruits demonstrated reproductive success, resulting in approximately 279 individuals (110 males and 169 females) from a total of 1.6 kg of damaged fruits. Monitoring also detected Zaprionus spp. (Diptera: Drosophilidae), another invasive drosophilid associated with fruit damage. To assess management options, we evaluated susceptibility of this D. suzukii population to imidacloprid. Bioassays showed that exposure to 0.140 mg/mL (LC50 for a susceptible reference strain) killed approximately 50% of adults, indicating local susceptibility, in contrast to reduced susceptibility reported in other Brazilian strains. Collectively, these findings confirm D. suzukii establishment in a new blueberry-producing region, reveal potential phytosanitary risks, and suggest that chemical control options remain effective locally. This integrated evidence highlights the importance of early monitoring and management strategies to safeguard Brazil’s expanding blueberry industry.