Triatoma infestans (Hemiptera: Reduviidae) larvae responses to volatiles released by disturbed adults: searching for active compounds of the alarm pheromone

PALOTTINI F.; MANRIQUE, G.

Congreso; 2nd Latin American Meeting of Chemical Ecology; 2012

Triatoma infestans (Hemiptera: Reduviidae) Larvae Response to Volatiles released by Disturbed Adults. Searching for Active compounds of the Alarm Pheromone Palottini, Florencia1 & Manrique, Gabriel1 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: metasternals and Brindley?s glands. According to previous studies, both glands may release their volatiles when adults are disturbed, suggesting an alarm and defense function. Although a vast number of volatiles emitted by each gland during disturbance was described [1], only the behavioural response to isobutyric acid, the major compound of Brindley?s glands, was analyzed [2]. In this study, using a double choice olfactometer, the orientation response of larvae submitted to individual or mixtures of volatiles released by both kind of glands, was analyzed. First, the larvae response to odours coming from disturbed adults was studied as positive control. In a second step, the behavioural response against different doses (1000, 10 y 0.1 µg) of the main compounds of the secretion released during disturbance: isobutyric acid, butyric acid, propionic acid, 2-methyl-1-butanol, 3-pentanone and 2-butanone, was analyzed. Finally, we examined the behavioural response against combinations of those doses in which an evident escape response was observed. As expected, results showed that odours coming from disturbed adults evoked an escape response in T. infestans larvae. Escape responses of larvae were also observed in bioassays with isobutyric acid (10 µg), butyric acid (10 µg) and 2-methyl-1-butanol (10 µg). Different test mixtures evoked diverse effects in the behaviour of T. infestans larvae. At present, apparently Brindley?s gland volatiles are mostly involved as alarm pheromone although 2-methyl-1-butanol is shared between both gland types. The identification of active compounds of the alarm pheromone of this species and the formulation of a repellent blend could be useful to develop new tools for vector detection to be use in programs of Chagas disease control. [1] Manrique 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] Ward (1981). A comparison of the behavioural responses of the haematophagous bug Triatoma infestans to synthetic homologues of two naturally occuring chemicals (n- and isobutyric acid). Physiol. Entomol. 6: 325-329. Acknowledgements: The research was supported by the ANPCyT (PICT01191), CONICET and Universidad de Buenos Aires.