Natural feeding stimulants and deterrents of blood-sucking insects

BARROZO, RB; PONTES, G; ESNAULT, J

Congreso; X Congreso Argentino de Entomologia; 2018

The tasteperception is essential for the survival of the animals informing them aboutthe nutritional quality of a food source. Moreover, it provides a means ofdiscrimination between nutrient-rich substrates, from harmful, mostlybitter-tasting. Rhodnius prolixus and Aedes aegypt arehaematophagous insects that transmit many of the most dangerous parasiticdiseases; like Chagas disease, Dengue and Zika virus. Once insects pierced thehost skin, they move their mouthparts until a venule is reached. R. prolixuspump a small quantity of blood initiating the sampling phase of food.During this period, the taste sense might become crucial in terms of theassessment of food quality. However, in mosquitoes this initial sampling phaseduring the feeding was still unknown. Our goal was to determine how deterrent(caffeine and quinine) and stimulant (ATP and amino acids) compounds areperceived by both species. For this, the feeding behavior of A. aegypti andR. prolixus has been examined by recording the muscular activity of thecibarial pump by means of electromyogram recordings (EMGs). The methodologyused consist in one cooper electrode fixed to the metallic mesh where theinsects are supported during the feeding. A second silver electrode is placedinside the feeding recipient in contact with the solution. When the insectinserts its mouthparts in the feeding recipient, it closes the circuitgenerating an electrical signal. When the animal starts pumping, the base linesignal changes as a result of the contractions produced by the cibarialmuscles. Ours results reveals that the triatomine EMGs recording present cleardifferences in the pumping activity to the different feeding solutions. R.prolixus gained significantly more weight while feeding on stimulantsolutions as compared to deterrent solutions. Similarly, and in contrast todeterrents, it presents higher mean pumping frequencies and biting time, andless number of bites. Understanding about the mechanisms and processes relatedto taste perception of these insects could assist on developing vector controltools. Moreover, alternative vector control methodologies are urgently neededto avoid most neglected disease insect vectors transmission. Financial support: PICT2013-1253; PICT2015-2825.