Salts control feeding decisions in a blood-sucking insect.

PONTES, G; PEREIRA, MH; BARROZO, RB

Cerdeña

Congreso; 14th European Symposium for Insect Taste and Olfaction.; 2015

Salts are necessary for all living organisms;although a fine balance of its concentration is essential for maintaininghomeostatic conditions within the body. Like allessential nutrients, deficient or excessive ingestion of salts can result inadverse health effects. The taste system is a primary sensory modality thathelps animals with adequate feeding decisions in terms of salt consumption. Inthis work we show that salt concentration controls feeding in the blood-suckingbug Rhodnius prolixus. Notably, feeding is triggered only by an optimal salt concentration of NaCl orLiCl or KCl, i.e. 0.1-0.15M, isosmotic to blood plasma of vertebrates. Below orabove this narrow range, the feeding response of bugs is significantly reduced;even if solutions were added with the main phagostimulant ATP. Additionally, we recorded the electricalactivity of the cibarial pump while insects were fed on different saltsolutions. Low or high salt concentrations elicit different activity patternsof the pump, even if in both cases the final result was no feeding. At low salt,insects do a few bites and maintain their mouthparts inside the feeder, pumpingat low frequency. On the other hand, at high salt concentration insects donumerous bites but they never start pumping the solution. Furthermore, administrationof amiloride, an epithelial sodium channel blocker, reduces the appetitive response of insects to NaCl or LiCl solutions. Moreover, amiloride treatment exertsa similar pumping pattern to what is observed at low salt concentration. Ourresults confirm the importance of the taste system for a blood-sucking insect,showing that the salt concentration plays a relevant role on insects´ feedingdecisions. Moreover, our results reveal the presence of amiloride-sensitive salt(Na+/Li+) detector involved in high salt recognition in a haematophagousinsect.