Abstract
Feeding success of free-living hematophagous insects depends on their ability to be active when hosts are available and to reach places where hosts are accessible. When the hematophagous insect is a vector of pathogens, determining the components of host-seeking behavior is of primary interest for the assessment of transmission risk. Our aim was to describe endo/exophagy and circadian host-seeking activity of Palaearctic Culicoides species, which are major biting pests and arbovirus vectors, using drop traps and suction traps baited with four sheep, as bluetongue virus hosts. Collections were carried out in the field, a largely-open stable and an enclosed stable during six collection periods of 24 hours in April/May, in late June and in September/October 2010 in western France. A total of 986 Culicoides belonging to 13 species, mainly C. brunnicans and C. obsoletus, was collected on animal baits. Culicoides brunnicans was clearly exophagic, whereas C. obsoletus was able to enter stables. Culicoides brunnicans exhibited a bimodal pattern of host-seeking activity with peaks just after sunrise and sunset. Culicoides obsoletus was active before sunset in spring and autumn and after sunset in summer, thus illustrating influence of other parameters than light, especially temperature. Description of host-seeking behaviors allowed us to discuss control strategies for transmission of Culicoides-borne pathogens, such as bluetongue virus. However, practical vector-control recommendations are difficult to provide because of the variation in the degree of endophagy and time of host-seeking activity.
Highlights
Host-parasite systems are subject to opposing selective processes: on the one hand, parasite fitness is increased by a higher frequency of encounters with hosts and on the other hand, host fitness is increased by avoiding these contacts [1]
We described endo/exophagy and circadian host-seeking activity of Palaearctic Culicoides species using drop trap and suction trap collections
All traps were separated by a minimum of 30 m to minimize interference and to assess the level of endophagy of Culicoides
Summary
Host-parasite systems are subject to opposing selective processes: on the one hand, parasite fitness is increased by a higher frequency of encounters with hosts and on the other hand, host fitness is increased by avoiding these contacts [1]. Circadian and seasonal activities of insect are regulated by endogenous oscillators which are initiated by natural diel alternation of light and darkness [3]. These biological clocks enable organisms to anticipate variations of biotic and abiotic factors associated with seasonal or diel progression rather than follow them [3,4]. Diel timing of hostseeking activity should be selected to ensure temporal encounter of the insect and host and to minimize the risk of dying during hostseeking activities.
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