Effects of alcaloids on feeding behavior and metabolism of Rhodnius prolixus, vector of Chagas disease

MUÑOZ, I; SCHILMAN, PE; BARROZO, RB

Foz do Iguazu

Congreso; 32 Annual Meeting of the International Society of Chemical Ecology/ 4th Congress of the Latin American Association of Chemical Ecology; 2016

Through the sense of taste an individual can evaluate what they eat and drink, favoring consumption of nutritious and avoiding intake of harmful and toxic substances that can induce discomfort, illness or even death. Aversive substances can lead an animal to avoid feeding, even if the alimentary source is not toxic per se. In different groups of insects, including triatomines (Reduviidae: Triatominae), it has been demonstrated that alcaloids stimulate taste receptors generating an aversive response. However, it is still not clear if the ingestion of alcaloids produce a physiological change in triatomines. In this work, we investigated the effect of different alcaloids with anti-appetitive potential in the feeding behavior of R. prolixus, and we analyzed its impact on their metabolism. For this purpose, we used an artificial feeder with different solutions at 37 ± 2 °C where the insects fed for 10 minutes. The effect on feeding behavior and metabolism was tested offering an appetitive solution (AS) of ATP in NaCl 0,15M alone or in combination with the potential anti-appetitive alcaloid: caffeine, quinine and theophylline. We calculated the insect weight gain as feeding response and CO2 production as indirect measurement of metabolism. CO2 production was measured by open flow respirometry for individual insects immediately after being fed and three hours later. We found that R. prolixus detect alcaloids in a dose-dependent manner, decreasing feeding frequency and intake amount at higher concentrations. For all treatments, CO2 production slightly decreases after three hours of feeding. In addition, CO2 production was about five times higher for insects that consumed caffeine and theophylline compared to insects that consumed AS or quinine, suggesting costs associated with mechanisms of detoxification. To understand the mode of action of these molecules could help to develop new tools designed to control and reduce host-vector interaction.