RESUMO
U.S. military troops are exposed to mosquito-borne pathogens when deployed to endemic regions. Personal protective measures such as permethrin-treated uniforms and dermal repellents are the cornerstones of mosquito-borne disease prevention for the U.S. military. These measures have limitations and additional personal protection tools, such as spatial repellent devices to decrease the risk of vector-borne pathogen transmission, are required. Novel spatial repellent controlled-release devices formulated with metofluthrin were evaluated in an outdoor setting in the northern Amazon of Peru to evaluate performance under field conditions. The metofluthrin emitting devices lowered the number of mosquitoes captured in protected human landing collections (HLC) compared to blank devices, although there were effect differences between Anopheles spp. and species in other mosquito genera. A computational-experimental model was developed to correlate HLC and active ingredient (AI) concentrations as a function of time and space. Results show a strong correlation between the released AI and the decrease in HLC. This model represents the first effort to obtain a predictive analytical tool on device performance using HLC as the entomological endpoint.
RESUMO
Emerging insecticide resistance is a major issue for vector control. It decreases the effectiveness of insecticides, thereby requiring greater quantities for comparable control with a net increase in risk of disease resurgence, product cost, and damage risk to the ecosystem. Pyrethroid resistance has been documented in Puerto Rican populations of Aedes aegypti (L.) mosquitoes. In this study, topical toxicity of five insecticides (permethrin, etofenprox, deltamethrin, DDT, transfluthrin) was determined for susceptible (Orlando-ORL) and resistant (Puerto Rico-PR) strains of Ae. aegypti. Resistance ratios were calculated using LD50 values, and high resistance ratios for permethrin (112) and etofenprox (228) were observed for the Puerto Rico strain. Behavioral differences in blood-feeding activity for pyrethroid-resistant and pyrethroid-susceptible strains of Ae. aegypti when exposed to pyrethroid-treated cloth were also explored. Strains were exposed for 15 min to a range of concentrations of pyrethroid-treated uniform fabric in a cage that contained 60 female Ae. aegypti mosquitoes. Interestingly, the resistance ratios for blood-feeding were similar for permethrin (61) and etofenprox (70), but were lower than their respective resistance ratios for topical toxicity, suggesting that knockdown resistance was the primary mechanism of resistance in the blood feeding assays. Results showed a rightward shift in the dose-response curves for blood-feeding that indicated higher concentrations of pyrethroids were necessary to deter blood-feeding behavior in the pyrethroid-resistant Puerto Rican strain of Ae. aegypti.
Assuntos
Aedes/efeitos dos fármacos , Resistência a Inseticidas , Inseticidas/farmacologia , Piretrinas/farmacologia , Aedes/fisiologia , Animais , Comportamento Alimentar/efeitos dos fármacos , Feminino , Porto Rico , TêxteisRESUMO
The effects of colonization on host-seeking behavior of mosquitoes was examined by comparing attraction responses of newly colonized Aedes aegypti (L.) from field-collected eggs in Puerto Rico to that of the Gainesville (Florida) strain, originally from Orlando (Florida) and in colony since 1952. Females from the Orlando and the F0 through F10 generations of the Puerto Rico strain were evaluated using attractant odors in a triple-cage dual-port olfactometer. Two attractant sources were used: odors from the hand of a volunteer and a standard blend of L-lactic acid, acetone, and dimethyl disulfide. Convergence of the percentage of attraction responses occurred around the F4-F6 generations of the Puerto Rico strain. Both the Orlando and Puerto Rico strains exhibited similar responses for tests with the remaining F7-F10 generations. A temporal effect on mosquito responses was observed for both strains regardless of the attractant blend used in tests. This study indicates that Ae. aegypti host-seeking behavior changes significantly over the first four to six generations after introduction into the laboratory, whereas the field-collected strain increases in attraction response until it stabilizes at a new level.
Assuntos
Aedes/fisiologia , Acetona/farmacologia , Aedes/efeitos dos fármacos , Aedes/genética , Animais , Comportamento Apetitivo/efeitos dos fármacos , Dissulfetos/farmacologia , Comportamento Alimentar/efeitos dos fármacos , Feminino , Ácido Láctico/farmacologia , Odorantes , Porto Rico , Seleção GenéticaRESUMO
A synthetic blend of chemicals comprising volatiles released by the human body has been shown to be an effective attractant for female Aedes aegypti in olfactometer bioassays with laboratory-reared mosquitoes. We report the laboratory evaluation of Ae. aegypti response to a synthetic blend tested with 4 types of mosquito traps (CDC model 512, CDC model 1012, CFG, and Fay-Prince traps). Aedes aegypti females were attracted significantly by the blend. The higher release rate of attractant (320.2 +/- 10.71 mg/h) more efficiently attracted mosquitoes than the lower release rate (42.0 +/- 2.3 mg/h). Although both the Fay-Prince and CFG traps caught higher number of mosquitoes than the other traps, only the CFG trap caught a statistically significant greater number of mosquitoes. The results suggest that the synthetic blend is effective in attracting Ae. aegypti females under controlled laboratory conditions (i.e., a closed system). Further studies are needed to evaluate the efficacy of this blend in baited traps under field conditions.