RESUMO
BACKGROUND: Illnesses transmitted by Aedes aegypti (Linnaeus, 1762) such as dengue, chikungunya and Zika comprise a considerable global burden; mosquito control is the primary public health tool to reduce disease transmission. Current interventions are inadequate and insecticide resistance threatens the effectiveness of these options. Dried attractive bait stations (DABS) are a novel mechanism to deliver insecticide to Ae. aegypti. The DABS are a high-contrast 28 inch2 surface coated with dried sugar-boric acid solution. Aedes aegypti are attracted to DABS by visual cues only, and the dried sugar solution elicits an ingestion response from Ae. aegypti landing on the surface. The study presents the development of the DABS and tests of their impact on Ae. aegypti mortality in the laboratory and a series of semi-field trials. METHODS: We conducted multiple series of laboratory and semi-field trials to assess the survivability of Ae. aegypti mosquitoes exposed to the DABS. In the laboratory experiments, we assessed the lethality, the killing mechanism, and the shelf life of the device through controlled experiments. In the semi-field trials, we released laboratory-reared female Ae. aegypti into experimental houses typical of peri-urban tropical communities in South America in three trial series with six replicates each. Laboratory experiments were conducted in Quito, Ecuador, and semi-field experiments were conducted in Machala, Ecuador, an area with abundant wild populations of Ae. aegypti and endemic arboviral transmission. RESULTS: In the laboratory, complete lethality was observed after 48 hours regardless of physiological status of the mosquito. The killing mechanism was determined to be through ingestion, as the boric acid disrupted the gut of the mosquito. In experimental houses, total mosquito mortality was greater in the treatment house for all series of experiments (P < 0.0001). CONCLUSIONS: The DABS devices were effective at killing female Ae. aegypti under a variety of laboratory and semi-field conditions. DABS are a promising intervention for interdomiciliary control of Ae. aegypti and arboviral disease prevention.
Assuntos
Inseticidas , Controle de Mosquitos/métodos , Mosquitos Vetores , Açúcares/química , Aedes , Animais , Ingestão de Alimentos , Equador , Feminino , MasculinoRESUMO
Agricultural activities associated mainly with soybean crops affect the natural environment and wildlife by habitat destruction and the extensive use of agrochemicals. The aim of this study was to evaluate immunotoxic effects of the insecticides cypermethrin (CYP) and endosulfan (END) in Caiman latirostris analyzing total blood cell count (TWBC) and differential white blood cell count (DWBC) after in ovo and in vivo exposure. Eggs (in ovo) and hatchlings (in vivo) from nests harvested in natural habitats were artificially incubated and reared under controlled conditions in the Proyecto Yacaré (Gob.Santa Fe/MUPCN) facilities. Exposure of embryos was performed by topication on the eggshell during the first stage of development. The treatments were distilled water (negative control; NC), ethanol (vehicle control; VC), four groups treated with different concentrations of CYP and four groups with END. In vivo exposure was performed by immersion; treatments were NC, VC, two groups exposed to CYP and two to END. After embryonic exposure to the insecticides, no differences were found in TWBC or DWBC among the neonates exposed to pesticides versus controls. In the in vivo scenario, similar results were obtained for TWBC, but DWBC data showed differences between NC hatchlings and CYP-1 hosts for heterophil, lymphocyte and monocyte levels, and between NC and END-1 hosts for lymphocyte and monocyte levels. Research on the effects of pesticide exposure on this species is of special interest not only to assess the impact on caiman populations, but also to further characterize the species as a potential sentinel of ecosystem health.