Behavioural response of the blood-sucking bug Triatoma infestans larvae to volatiles released by disturbed adults

PALOTTINI, F.; MANRIQUE, G.

Colonia de Sacramento

Encuentro; 1st Latin American Meeting of Chemical Ecology; 2010

Latin American Association of Chemical Ecology

Behavioural response of the blood-sucking bug Triatoma infestans larvae to volatiles released by disturbed adults Florencia Palottini1, Gabriel Manrique1 E-mail: florpal@bg.fcen.uba.ar 1Laboratorio de Fisiología de Insectos, Departamento de Biodiversidad y Biología Experimental, Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Buenos Aires, Argentina. Triatoma infestans adults possess two pairs of exocrine glands, metasternal and Brindley’s glands. According to previous reports, one of them or both could release their volatiles under different contexts such as alarm, defense or sexual behaviour. Apparently, both types of glands discharge their contents during alarm and defense context, after mechanical disturbance [1]. Isobutiric acid might induce different behavioural effects as a function of concentration [2] and is the main compound released by Brindley’s glands when adults are disturbed. Using a locomotion compensator, we analysed the orientation response of fourth-instars larvae evoked by airstreams loaded with volatiles released by mechanically disturbed adults or different dose of isobutiric acid (0.001, 0.01, 0.1, 1, 10, 100, 1000 and 10000 μg.). The mean walking angle (αi) displayed by each insect along the experimental time was computed and subsequently, for every experimental group a mean angle (αm) and the length of the resultant mean vector (r) were calculated. Besides, an orientation index was calculated. In our results larvae exposed to odours from disturbed adults exhibited an oriented response walking away from the source of the volatiles. This result supports a previous hypothesis which proposes that the blend released by disturbed adults constitutes an alarm pheromone. On the other hand, preliminary results for isobutiric acid bioassays showed variable orientation behaviour in response to different concentrations tested. We propose a possible biological role of this compound within the intraespecific chemical communication. [1] Manrique G. et al. 2006. Chemical communication in Chagas disease vectors. Source, identity, and potential function of volatiles released by the metasternal and Brindley´s glands of Triatoma infestans adults. J. Chem. Ecol. 32: 2035-2052. [2] Guerenstein P. G. and Guerin P. M. 2004. A comparison of volatiles emitted by adults of three triatomine species. The Netherlands Entomological Society. Entomologia Experimentalis et Applicata 111; 151-155. Acknowledgements: ANPCyT (PICT 01191), CONICET and Universidad de Buenos Aires.