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

FABIO GUIDOBALDI; PABLO G. GUERENSTEIN

Huerta Grande

Congreso; 2° Meeting of the Latin American Association of chemical ecology; 2012

Asociación Argentina de Producción animal (AAPA)

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 nearby a host. In fact, the triatomine Rhodnius prolixus may lay (stick) their eggs on the feathers of avian hosts. We tested if the presence of a host has an effect on the spatial distribution of the stuck eggs. We carried out tests in an experimental arena consisting 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 sensory cues from a host to enter the tube. 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). No significance difference was observed in the distribution of the eggs between the zone close respect to the zone far from the host, comparing with the distribution in the control (P˃0.75, G-test). There are significant differences in the distribution of eggs between zones in both test and control (P<0.05, X2 Goodness of fit). 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.   We thank Fundación Bunge y Born and Agencia Nacional de Promoción Científica y Tecnológica, Argentina, for funding this project through grants FBB28/10 and PICT-PRH-2009-43, respectively