Orientation response of haematophagous bugs to CO2: the effect of the temporal structure of the stimulus
- 137 Downloads
Carbon dioxide is generally recognized as an important cue used by haematophagous insects to locate a food source. When the mammalian hosts of these insects breathe, they normally emanate considerable amounts of CO2 at discrete intervals, i.e. with each exhalation. In this work, we analysed the effect of temporally pulsing CO2 on the host-seeking behaviour of Triatoma infestans. We investigated the ability of T. infestans to follow continuous and intermittent air pulses of 0.25, 0.5 and 1 Hz that included different concentrations of CO2. We found that insects were attracted to pulsed airstreams of 0.25 and 0.5 Hz transporting 400 ppm of CO2 above the ambient levels and to continuous streams added with the same amount of CO2. On the other hand, insects walked away from streams pulsed at rates of 1 Hz regardless of the amount of CO2 they bear. The walking trajectories displayed by bugs to attractive CO2-pulsed streams were as rectilinear and accurate as those to CO2-continuous streams. Our results are discussed in the frame of the interaction between olfactory and mechanoreceptive inputs as affecting the behavioural response of bugs.
KeywordsBlood-sucking insects Pulses Carbon dioxide Triatomines
The authors are deeply indebted to M. Greenfield, K.-E. Kaissling and to S. A. Minoli for critically reading of the manuscript. We also sincerely thank D. Anfossi for designing the software used for recording data from the locomotion compensator. This investigation received financial support from the Universidad de Buenos Aires, CONICET (Argentina) and from the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR). The experiments were conducted in accordance with the highest standards of animal care as outlined in the “Guide for the Care and Use of Laboratory Animals” published in 1996 by the National Institute of Health.
- Batschelet E (1981) Circular statistics in biology. Academic Press, LondonGoogle Scholar
- Kaissling K-E (1997) Pheromone-controlled anemotaxis in moths. In: Lehrer M (ed) Orientation and communication in arthropods. Birkhaeuser, Basel, pp 343–374Google Scholar
- Kramer E (1986) Turbulent diffusion and pheromone-triggered anemotaxis. In: Payne TL, Birch MC, Kennedy CEJ (eds) Mechanisms in insect olfaction. Clarendon Press, Oxford, pp 59–67Google Scholar
- Lehane MJ (2005) The biology of blood-sucking insects. Cambridge University Press, CambridgeGoogle Scholar
- Núñez JA (1987) Behaviour of Triatominae bugs. In: Brenner RR, Stoka AM (eds) Chagas’ disease vectors, vol II. Anatomic and physiological aspects. CRC Press, Boca Raton, pp 1–30Google Scholar
- WHO (2000) (World Health Organization) Weekly epidemiological record. GenevaGoogle Scholar
- Zar JH (1984) Biostatistical analysis. Prentice-Hall, Englewood CliffsGoogle Scholar