Female contact sex pheromone components of Triatoma infestans, a major Chagas disease vector

JUÁREZ M.P.; COCCHIARARO BASTÍAS L.; MIJAILOVSKY S.; CALDERÓN FERNÁNDEZ G

Greenwich

Simposio; Symposium on Chemical Ecology: Reception, Detection and Deception; 2011

Royal Entomological Society

Cuticular lipids (CL) are known to participate in insect intraspecific chemical communication as contact cues; e.g. in aggregation and sexual behavior. T. infestans (Hemiptera, Reduviidae) is one of the three major vectors of the parasite Trypanosoma cruzi, the causative agent of Chagas disease. T. infestans CL include a blend of hydrocarbons, free and esterified fatty acids and fatty alcohols, together with minor components. CL extracts were previously shown to trigger aggregation and arresting behavior [1]. Here we report CL contribution to contact sex recognition in T. infestans. Chemical analyses: Male and female hexane extracts of CL were deposited inside vials, and the solvent was evaporated by a nitrogen stream. Vials were sealed and the residual lipids sampled at 150°C by head space solid phase micro extraction (HS-SPME). CL samples were analyzed by capillary gas chromatography (CGC) coupled to mass spectrometry (MS). Bioassays: CL were tested for their role on the copulatory behavior. Male responses were tested to live females, dead and intact females, dead and hexane-washed females, and dead, washed and lipid-reconstituted females. Males were also exposed to female-specific components placed in polypropylene half cylinders. We showed that contact cues are necessary for mate recognition by T. infestans males. The cuticular recognition cues are removed by hexane wash. Males contact females with their antenna and legs prior to elicit mating attempts. Recently freeze-killed females were attractive to males, but no response was observed when males were exposed to hexane-washed females. The attraction was partially recovered when the lipid extract was reloaded on the female dorsal surface. No evident sexual dimorphism was observed for most cuticular components, except that female extracts contained more than 7% of eicosanol and docosanol, whereas male extracts had only trace amounts of these compounds. Polypropylene decoys impregnated with 1 female equivalent of synthetic docosanol and eicosanol either individually, or combined, elicited mate attempting response from males, attempting to mate. We conclude that cuticular lipids trigger mate recognition in T. infestans. Two female-specific fatty alcohols, eicosanol and docosanol, seem to be primarily responsibles for mate recognition in males [2]. Further studies are ongoing to evaluate the usefulness of these chemicals as components of pheromone-based traps for T. infestans. [1] Parasites & Vectors 2009, 2:8 [2] Journal of Chemical Ecology 2011, 37(3): 246-252