Barometric pressure is an environmental factor involved in the modulation of a variety of activities in insects. Generally, a drop in barometric pressure precedes the arrival of weather conditions that can affect insect activities and life expectancy. We simulated different scenarios of pressure drop in a modified hermetic chamber and studied their influence on the host-seeking behaviour of the larvae of the robber fly Mallophora ruficauda using air stationary olfactometers. In addition, we studied whether larval density modulates orientation to the host under the same scenarios of pressure drop. We found that motivation to search for hosts is affected by the same slope of pressure drop in both low- and high-density larvae. However, larval density modulates the onset of the responses to pressure decrease, as low-density larvae stop searching for hosts more quickly than high-density larvae. This result reflects an avoidance strategy according to which low-density larvae would have a reduced host range and higher risk of mortality and fewer chances to find a suitable host under adverse pressure conditions. Low-density larvae, known to prefer healthy hosts, do not search for parasitized hosts under normal pressure conditions nor under a range of pressure drops, strongly suggesting that host selectivity is not modulated by barometric pressure. This study paves the way to a better understanding of the changes in crucial insect behaviours induced by weather conditions, and provides more knowledge about the risk factors likely to affect insect survival in the context of foraging ecology.

Author contributions

Conceptualization: M.K.C., J.E.C.; Methodology: J.E.C.; Software: J.E.C.; Formal analysis: J.E.C.; Investigation: J.-N.H.; Resources: M.K.C.; Data curation: J.-N.H.; Writing - original draft: J.-N.H.; Writing - review & editing: J.-N.H., M.K.C., J.E.C.; Supervision: M.K.C., J.E.C.; Project administration: M.K.C.; Funding acquisition: M.K.C., J.E.C.

Funding

This work was supported by the Consejo Nacional de Investigaciones Científicas y Técnicas (grant PIP 2021-2023 no. 11220200101939CO to J.E.C.), the University of Buenos Aires, Argentina (grant UBACyT 2020 no. 20020190100059BA to M.K.C.), and the Agencia Nacional de Promoción de la Investigación, el Desarrollo Tecnológico y la Innovación - FONCyT (grant PICT 2019 no. 2019-I-A-00975 to M.K.C.).

Data availability

All data can be found in the Harvard Dataverse repository at https://doi.org/10.7910/DVN/CQM6HR.

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