The role of the presence of a host in the oviposition behavior of vectors of Chagas disease

GUIDOBALDI F; GUERENSTEIN PG

Huerta Grande - COR

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

Asociacion Latinoamericana de Ecologia Quimica, CICYTTP-CONICET, Fac. Agronomia-UBA

Triatomine first-instar larvae need to feed within the first days after emergence from the egg in order to survive. Taking into account their small size and limited locomotion capacity, it seems reasonable that females should lay their eggs near a host. In fact, the triatomine Rhodnius prolixus often lays (sticks) their eggs on the feathers of avian hosts. The physical characteristics of the substrate certainly play a role in the oviposition behavior [1]. We tested if the presence of a host has an effect on the spatial distribution of the stuck eggs in an experimental arena. The arena consisted of a PVC tube (0.2 m diameter, 1.70 m length). Across the tube, little holes (behind which, a fine mesh was placed to avoid the escape of bugs or eggs) were made to allow air circulation and entrance of sensory cues from a host. Two male and four female adult R. prolixus 1-2 weeks after feeding were placed inside a test and a control arena in rooms with controlled temperature (27±1°C) and 12:12 L/D light cycle, for 3 days. A host was placed below one end of the test tube while the other end remained empty; no host was placed below the control tube. Surprisingly, results show that the presence of a live host (mouse) significantly stimulate oviposition in R. prolixus (total eggs test, 254; total eggs control =172, N=11, α<0.05, Wilcoxon one tailed test). There are significant differences in the distribution of eggs between zones in both test and control (P<0.05, X2 Goodness of fit). However, host sensory cues are not responsible for the spatial distribution of eggs. Preliminary tests using fresh hen feathers showed a similar oviposition stimulation, suggesting that host odor could be involved in the responses obtained. [1] Schilman P. E., Núñez J. A. and Lazzari C. R. 1996. Attributes of oviposition substrates affect fecundity in Rhodnius prolixus. J. Insect physiol 42 (9): 837-841.