AN ELECTROPHYSIOLOGICAL CHARACTERIZATION OF ANTENNAL GUSTATORY SENSILLA IN THE ANTS Camponotus aethiops and Linepithema humile

MARIEL MOAURO; ROXANA JOSENS; GABRIELA DE BRITO SÁNCHEZ

VIRTUAL

Congreso; THE 6TH CONGRESS OF THE LATIN AMERICAN ASSOCIATION CHEMICAL ECOLOGY - VI ALAEQ2021; 2021

POSTERAlthough nectivorous ants feed mainly on extrafloral nectar, some genera such as Linepithema and Camponotus exploit additionally resources from the anthropized environments they inhabit. They thus must decide if they feed on food sources with very dissimilar characteristics. Recent studies from our laboratory show that these genera respond differently to salts and acids. We performed extracellular recordings of single gustatory sensilla located on the antennal tip of Linepithema humile and Camponotus aethiops. We characterized their electrophysiological responses to solutions of sucrose, NaCl, ascorbic acid, and mixtures of these substances. The results show that sensilla of C. aethiops are less sensitive to sucrose than sensilla of L. humile. In both species, we classified two types of sensilla. Type-1 sensilla respond essentially to NaCl and maintain their response upon stimulation with mixtures of sucrose (100 mM) and NaCl (10-1000 mM). Type-2 sensilla exhibit potentiated (additive) responses to sucrose and NaCl mixtures.Small amplitudes of action potentials (up to 1.2 mV) were observed in both sensillum types upon stimulation with sucrose and low concentrations of NaCl, possibly corresponding to the same neuron. In both types, stimulation with a high concentration of NaCl (1000 mM) triggers higher amplitude action potentials, thus recruiting a different neuron. In Type-2 sensilla, stimulation with a mixture of sucrose (100 mM) and NaCl (10-1000 mM), small-amplitude potentials decrease while high-amplitude ones increase, suggesting that increase in NaCl within the mixture results in inhibition of sucrose responses.In both species, responses to ascorbic acid (0.01-1mM) were low. Yet, adding this acid to a 100mM sucrose solution inhibits the neural responses to sugar in C. aethiops and, partially, in L. humile.