Responses of central olfactory neurons: Looking for an odor blend to attract triatomines

IBARRA BOUZADA, LUCIA; MAY-CONCHA, I.J.; BRATOVICH C; GARCIA MAILEN; PERUSSET, SA; CECERE C; ROJAS LEÓN J; GUERENSTEIN P.G.

Simposio; 5th Meeting of the Latin American Association for Chemical Ecology,; 2018

Chagas disease still remains as an important vector-borne neglected tropical disease. In the absence of an effective treatment for chronic human infection or vaccines, the prevention of vector-borne transmission of Chagas disease in endemic areas relies on suppressing house infestations by triatomine bugs. Triatoma infestans is the main triatomine vector species in the southern cone countries of South America. We aim at developing an efficient host-based odor blend attractant to be used as a lure in a trap to monitor triatomines. In insects, odorants are detected by olfactory receptor cells (ORCs) mainly on the antenna. Insect ORCs project to the antennal lobe (AL) in the brain. The AL is the first information-processing center of the olfactory system. It is known that odor mixtures are more attractive than single odorants. In order to understand how information about potentially attractive odor mixtures is processed in the triatomine brain, and to speed up the development of such attractive blends it is necessary to study the responses of AL neurons to single odorants and mixtures of them. Although some information about the odor tuning and physiology of the triatomine ORCs is available, nothing is known about how odor information is processed in the triatomine AL. Using a multichannel recording technique we recorded the activity of neurons in the AL of T.infestans nymphs upon stimulation with synthetic odorants. Responses to a number of synthetic odorants or their mixtures were also obtained. Those synthetic odorants included -pinene, valeric acid, 1-octen-3-ol, nonanal, isobutyric acid, isobutilamine, and ammonia. Response types included cessation of spikes (hereafter inhibition), excitation, inhibition-excitation and excitation-inhibition. Dose-dependent responses to synthetic odorants were found. However, surprisingly, in several cases lower concentrations of odorants evoked higher responses than higher concentrations. Moreover, the response to a single odorant could be opposite (i.e., excitation vs. inhibition) depending on the odorant concentration.Funding: ANPCyT (PICT 2015 N3260) and CONICET (PIP 2015-2017), Argentina.