The response of the blood-sucking bug Triatoma infestans to carbon dioxide and other host odours.

BARROZO RB, LAZZARI CR.

Chemical Senses

OXFORD JOURNALS

Año: 2004 vol. 29 p. 319 - 329

0379-864X

Behavioural responses of Triatoma infestans larvae to carbon dioxide and other odours of vertebrate origin were investigated in a locomotion compensator. T. infestans oriented towards airstreams enriched with carbon dioxide exhibiting a threshold response between 300 and 400 ppm above the ambient CO2 background. The accuracy of the oriented response to carbon dioxide improved with stimulus intensity. Remarkably, insects did not denote any change in their sensitivity threshold to carbon dioxide with the starvation time. The attractiveness to carbon dioxide depended on the time of the day, i.e., these nocturnal bugs only oriented towards carbon dioxide-loaded airstreams during the first hours of the scotophase. L-lactic acid did not evoke oriented responses when it was presented as a single stimulus in a wide range of intensities. However, a marked synergism was evident when L-lactic acid was combined with a sub-threshold concentration of carbon dioxide. Under this condition, the threshold response to carbon dioxide decreased to 75-150 ppm above ambient CO2 background. The isomer D-lactic acid evoked no response, neither alone nor in combination with carbon dioxide. When insects were stimulated with 1-octen-3-ol a significant positive orientation was found. This response was not modified by the addition of carbon dioxide.