Caffeine and used coffee grounds effects on biological features of Aedes aegypti (Diptera: Culicidae): Response in successive generations and efficiency versus preparation concentration and age

Aedes aegypti, vector of dengue, hemorrhagic fever and yellow fever was studied as to the effects of treatments with different concentrations of caffeine and used coffee grounds. The observation of developmental blockade and death of the mosquitoes at the larval stage indicated that these substances might be used as an alternative control of that organism. Additional studies were then carried out aiming to obtain important information, such as what would happen to the features mortality and oviposition when mosquitoes are treated with caffeine in successive generations, how long the efficacy of caffeine solutions lasts if we store them before using, and how long preparations with each one of these substances are efficient after putting them in the breeding sites. The results reinforced the adequacy of using both substances in the control of Aedes aegypti. Experiments showed that caffeine blocks the development of Aedes aegypti (Diptera, Culicidae) in the larval stage, consequently inhibiting the production of adults. This second study aimed at obtaining data suggestive of caffeine resistance by these mosquitoes. METHODS: Experiments were carried out in successive generations to assess adult production from eggs laid in previous generation and oviposition rate in every generation using 200 and 500 µg/mL caffeine. Tap water was used as control. Experiments were conducted in the city of São José do Rio Preto, Southeastern Brazil between 2002 and 2005. Statistical tests consisted of exploratory data analysis and smoothing algorithms. RESULTS: Increasing reduction in productivity of adults occurred among generations at both caffeine concentrations but the differences were only significant at 200µg/mL caffeine. As for the oviposition rate, there was a decrease in the mean number of eggs per female over generations at both caffeine concentrations. CONCLUSIONS: There was no evidence of caffeine resistance over generations. The study results corroborate caffeine as an alternative as an important Ae. Aegypti control agent to avoid resistance.