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Abstract

In a previous study, comparison of the behavior of teneral Glossina morsitans morsitans on waterbuck, Kobus defassa (a refractory host), and on two preferred hosts, buffalo, Syncerus caffer, and ox, Bos indicus, suggested the presence of allomones in the waterbuck odor. Examination of the volatile odors by coupled gas chromatography-electroantennographic detection showed that the antennal receptors of the flies detected constituents common to the three bovids (phenols and aldehydes), as well as a series of compounds specific to waterbuck, including C8-C13 methyl ketones, delta-octalactone, and phenols. In this study, behavioral respones of teneral G. m. morsitans to different blends of these compounds were evaluated in a choice wind tunnel. The flies' responses to known or putative attractant blends (the latter comprising EAG-active constituents common to all three animals and those common to buffalo and ox, excluding the known tseste attractants, 4-methylphenol and 3-n-propylphenol), and to putative repellent (the blend of EAG-active compounds specific to the waterbuck volatiles), were different. A major difference related to their initial and final behaviors. When a choice of attractant blends (known or putative) and clean air was presented, flies initially responded by flying upwind toward the odor source, but later moved downwind and rested on either side of the tunnel, with some preference for the side with the odor treatments. However, when presented with a choice of waterbuck-specific blend (putative repellent) and clean air, the flies' initial reaction appeared random; flies flew upwind on either side, but eventually settled down on the odorless side of the tunnel. Flies that flew up the odor plume showed an aversion behavior to the blend. The results lend further support to previous indications for the existence of a tsetse repellent blend in waterbuck body odor and additional attractive constituents in buffalo and ox body odors.

Vector host-feeding preferences drive transmission of multi-host pathogens: West Nile virus as a model system

“…Host preferences are not exclusive to mosquitoes: Triatoma bugs that transmit Chagas' disease demonstrated strong feeding preferences for dogs over both chickens and cats in a recent study [65]. At least one species of tsetse fly (Glossina morsitans morsitans), vector of human (sleeping sickness) and animal trypanosomiasis in Africa, show feeding preferences towards buffalo and oxen but avoid other hosts such as waterbuck (reviewed in [66]). Extension of this model to other systems could determine how host preferences influence transmission dynamics.…”

Integrated pest management: the push–pull approach for controlling insect pests and weeds of cereals, and its potential for other agricultural systems including animal husbandry

“…Several synthetic and natural repellents, including a constituent of bovid odours, 2-methoxyphenol, have been evaluated but were found not to be sufficiently effective in protecting cattle in the field (Torr et al 1996). However, recent identification of a potent repellent blend from waterbuck, Kobus defassa (Gikonyo et al 2002(Gikonyo et al , 2003, which is refractory to tsetse, may provide much better protection for cattle and an effective push component in the push-pull approach for faster and more effective suppression of tsetse populations, particularly where cattle are the dominant source of a blood meal for the flies. A preliminary experiment undertaken on the Kenyan coast, comparing the effects of protecting cattle with a synthetic repellent (push), baited traps (pull) and a combination of these two (push-pull), suggests a better performance of the push-pull approach in suppressing tsetse (Spala et al, in preparation).…”

Odorant and Gustatory Receptors in the Tsetse Fly Glossina morsitans morsitans

“…The response to olfactory cues has also been exploited in design of tsetse repellents [14], [15]. The repellents include guaiacol (methylphenols), δ-octalactone and methylketones [16]–[18] and 2-methoxy-4-methylphenol [14]. Natural differential responses among tsetse species and even between sexes and allopatric populations of the same species have been observed [18]–[22], which have stimulated research and design to enhance the efficiencies of the existing attractant-based bait technologies, to develop new ones based on repellent blends (‘push’ tactics) from refractory animals, and to integrate these into ‘push-pull’ strategies.…”

“…The GRs are more conserved in sequence and structure than the ORs [44], [45] probably due to comparatively smaller search space among cues associated with GRs than ORs. The diversity among the ORs and GRs in tsetse can potentially shed light on the natural differential responses observed among them [12], [17], [18], [20]–[29], with potential application in tsetse control. To improve or develop new approaches of vector management, an understanding of the molecular attributes of GRs and ORs and their potential roles in tsetse ecology is essential.…”