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Abstract

A previous study on the feeding responses of tsetse flies, Glossina morsitans morsitans, implicated the existence of allomonal barriers, both volatile and nonvolatile, on the nonpreferred host, waterbuck, Kobus defassa. In the present study, electroantennogram-active compounds in odors from waterbuck were compared with those of two preferred hosts of tsetse flies, buffalo, Syncerus caffer, and ox, Bos indicus. Odors from the three bovids were trapped on activated charcoal and/or reverse-phase (octadecyl bonded) silica and analyzed with a gas chromatography-linked electroantennographic detector (GC-EAD) and, where possible, identified by using gas chromatography-linked mass spectrometry (GC-MS) and chromatographic comparisons with authentic samples. The GC-EAD profiles (with G. m. morsitans antennae) of the odors of the two preferred hosts were comparable, comprising medium-chain, saturated or unsaturated aldehydes and phenols, with buffalo emitting a few more EAG-active aldehydes. Waterbuck odor gave a richer profile, consisting of fewer aldehydes but more phenolic components and a series of 2-ketones (C-C13) and delta-octalactone. This bovid also emits moderate amounts of C5-C9 straight-chain fatty acids, some of which were detected in buffalo and ox only in trace amounts. However, these did not elicit significant GC-EAD responses. Waterbuck profiles from the antennae of G. pallidipes showed broad similarity to those from G. m. morsitans, although the composition of aldehydes and ketones was somewhat different, indicating species-specific difference in the detection of host odors. Certain waterbuck-specific EAG-active components, particularly the 2-ketones and lactone, constitute a candidate allomonal blend in waterbuck odor.

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 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.…”

Vertebrate pheromones and other semiochemicals: the potential for accommodating complexity in signalling by volatile compounds for vertebrate management

“…From work at the icipe (International Centre of Insect Physiology and Ecology), based in Kenya and including unpublished work (R. Saini, personal communication) on the control of tsetse flies, repellents have been developed from the waterbuck Kobus defassa. Although closely related to the preferred host species, this member of the Bovidae is not attacked by G. morsitans and the repellent compounds have been identified [22,23]. A similar example is an arthropod that attacks salmonid fish, the salmon louse Lepeophtheirus salmonis , which is highly developed at the free swimming copopodid stage in locating and attaching to host salmonids, but avoids turbot, Scophthalmus maximus [24–26].…”