Effect of nitric oxide on the activity of the antennae of Blatella germanica in response to DEET

V. SFARA, P. GONZÁLEZ AUDINO, AND MOUGABURE CUETO, G.

Congreso; 2nd meeting of the Latin American Association of Chemical Ecology; 2012

Latin American Association of Chemical Ecology

N, N-diethyl-3-methyl benzamide (DEET) is an insect repellent used worldwide. Its effectiveness has been proved in a number of insect species, including haematophagous and non-haematophagous[1].  There are two contrasting hypothesis regarding the mode of action of DEET: the more classical hypothesis proposes that DEET interferes with the detection of odors, in particular host odors in haematophagous, instead of having a repellent effect. On the other hand, recent works demonstrated that DEET acts as an odorant molecule and elicits a behavioral response in the absence of other stimuli. In this work we show with electrophysiological recordings that the antennae of Blattella germanica respond to DEET and become adapted when stimulated with long pulses of the same substance. We also found that treatment of the antenna with the NO donor S-nitroso- acetyl cysteine (SNAC) causes a temporary decrease of the electrical response to DEET. To determine whether continuous stimulation with DEET decrease the response of the antennae to the same compound, we delivered a long pulse of DEET and recorded the response of the antennae before and after the stimulation. We found that a stimulation of 6 or 60 seconds with DEET produced a decrease of 58% in the amplitude of the response to the same compound registered after stimulation. The application of 20 ml of 40 mM SNAC decreases electrical response in a 68 % and the effect is reversible after aproximately 15 minutes post-treatment. These results are in agreement with the role of DEET as an odor molecule, since it produces electrical response of the antennae of B. germanica and it is possible to adapt this response with continuous stimulation of the antennae.