Assessment of vector/host contact: comparison of animal-baited traps and UV-light/suction trap for collecting Culicoides biting midges (Diptera: Ceratopogonidae), vectors of Orbiviruses

Abstract

BackgroundThe emergence and massive spread of bluetongue in Western Europe during 2006-2008 had disastrous consequences for sheep and cattle production and confirmed the ability of Palaearctic Culicoides (Diptera: Ceratopogonidae) to transmit the virus. Some aspects of Culicoides ecology, especially host-seeking and feeding behaviors, remain insufficiently described due to the difficulty of collecting them directly on a bait animal, the most reliable method to evaluate biting rates.Our aim was to compare typical animal-baited traps (drop trap and direct aspiration) to both a new sticky cover trap and a UV-light/suction trap (the most commonly used method to collect Culicoides).Methods/resultsCollections were made from 1.45 hours before sunset to 1.45 hours after sunset in June/July 2009 at an experimental sheep farm (INRA, Nouzilly, Western France), with 3 replicates of a 4 sites × 4 traps randomized Latin square using one sheep per site. Collected Culicoides individuals were sorted morphologically to species, sex and physiological stages for females. Sibling species were identified using a molecular assay. A total of 534 Culicoides belonging to 17 species was collected. Abundance was maximal in the drop trap (232 females and 4 males from 10 species) whereas the diversity was the highest in the UV-light/suction trap (136 females and 5 males from 15 species). Significant between-trap differences abundance and parity rates were observed.ConclusionsOnly the direct aspiration collected exclusively host-seeking females, despite a concern that human manipulation may influence estimation of the biting rate. The sticky cover trap assessed accurately the biting rate of abundant species even if it might act as an interception trap. The drop trap collected the highest abundance of Culicoides and may have caught individuals not attracted by sheep but by its structure. Finally, abundances obtained using the UV-light/suction trap did not estimate accurately Culicoides biting rate.

First overview of the Culicoides Latreille (Diptera: Ceratopogonidae) livestock associated species of Reunion Island, Indian Ocean

“…The Rieb trap is less efficient than other light traps in terms of number of Culicoides midges collected (del Río et al, 2013); the potential shortcomings of the trapping material might have influence our results on species diversity and distribution. Moreover, light traps do not estimate correctly biting rate and may underestimate -or overestimate -abundance if one peculiar species is not well -or overly -attracted by the light (Viennet et al, 2011).…”

“…Altitude is expressed in meters; latitude and longitude are expressed in decimal degrees; the different animals observed in the area surrounding the trap are described. Genomic DNA was individually extracted following an extraction protocol with Chelex resin in 5% (Resin Chelex100 ® , Chelating Ion Exchange Resin) as previously described (Solano et al, 1997;Viennet et al, 2011). A volume of 500 l of Chelex solution was dispensed into each tube of 1.5 ml.…”

Identification of Cattle-Derived Volatiles that Modulate the Behavioral Response of the Biting Midge Culicoides nubeculosus

“…However, current surveillance methods, which rely primarily on light traps to catch biting midges, may not be optimally effective. Such traps may not attract all potential vector species equally, and may underestimate numbers of blood-seeking midges in the vicinity of animal hosts (Carpenter et al 2008;Gerry et al 2009; Viennet et al 2011). Following the successful use of traps baited with vertebrate host volatiles to monitor and control other blood feeding insects (Logan and Birkett 2007;Pickett et al 2010), similar technology has been trialled…”

The combination of abundance and infection rates of Culicoides sonorensis estimates risk of subsequent bluetongue virus infection of sentinel cattle on California dairy farms

“…These parameters are critical for accurately assessing and modeling the dynamics of virus transmission to livestock (Gerry et al, 2001;Carpenter et al, 2008;Baylis, 2009;Guis et al, 2011). In contrast, enclosure trapping or mechanical aspiration of Culicoides midges directly from "bait' livestock has shown biting rates that can be several fold greater than the capture rate obtained using the conventional CO 2 baited suction trap, perhaps because mammalian -feeding Culicoides midges also respond to stimuli other than CO 2 (Mullens and Gerry, 1998;Gerry et al, 2009;Viennet et al, 2011).…”