Aggregated oviposition in Rhodnius prolixus, sensory cues and physiological consequences

ROLANDI, C.; SCHILMAN, P.E.

JOURNAL OF INSECT PHYSIOLOGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2017 vol. 98 p. 74 - 82

0022-1910

Females of the haematophagous bug Rhodniusprolixus attach their eggs in clusters on substrates related to their hosts,such as nests or avian feathers. Because the hosts are an enormous foodresource as well as potential predators, the choice of the site and pattern of ovipositioncould have an important adaptive value. Here we investigated proximate and apotential ultimate cause of this aggregated pattern of laid eggs. First, we studiedproximal causes by analyzing the use of chemical or physical cues associatedwith aggregated oviposition in R.prolixus. For all terrestrial organisms there is a trade-off between exchangeof respiratory gases and water loss. Particularly, insect eggs are highlysusceptible to this trade-off because they do not obtain water from the environment,hence our second objective is to study the possible mechanisms involved indehydration resistance in this species. Therefore we examined the dynamics ofchange in CO2 release rate ( CO2), and water loss rate ( H2O) in relation to embryo development asenergetic demands increase, and tested the energetic or hygric efficiencyhypothesis as a potential ultimate cause of aggregated oviposition. Thishypothesis states that grouped eggs consume less energy or lose less water thanequal numbers of isolated eggs, the latter being more susceptible todehydration. Results indicated the use of physical external cues such as dummyeggs or edges of the oviposition substrates, but we did not find any chemicalcues associated with the aggregated pattern of oviposition. There are no energeticor hygric benefits associated with egg?s aggregated pattern. However, when weanalyzed the CO2 and H2O change in relation to embryodevelopment, we found a fairly constant and low H2O albeit a clear increase in CO2, suggesting a tightly control of egg´sdesiccation tolerance. This high resistance to desiccation coupled with atemporal strategy of hatching allows R.prolixus embryos to successfully develop and hatch under harsh environmentalconditions.