Protecting cows in small holder farms in East Africa from tsetse flies by mimicking the odor profile of a non-host bovid

Abstract

BackgroundFor the first time, differential attraction of pathogen vectors to vertebrate animals is investigated for novel repellents which when applied to preferred host animals turn them into non-hosts thereby providing a new paradigm for innovative vector control. For effectively controlling tsetse flies (Glossina spp.), vectors of African trypanosomosis, causing nagana, repellents more powerful than plant derived, from a non-host animal the waterbuck, Kobus ellipsiprymnus defassa, have recently been identified. Here we investigate these repellents in the field to protect cattle from nagana by making cattle as unattractive as the buck.Methodology/Principal findingsTo dispense the waterbuck repellents comprising guaiacol, geranylacetone, pentanoic acid and δ-octalactone, (patent application) we developed an innovative collar-mounted release system for individual cattle. We tested protecting cattle, under natural tsetse challenge, from tsetse transmitted nagana in a large field trial comprising 1,100 cattle with repellent collars in Kenya for 24 months. The collars provided substantial protection to livestock from trypanosome infection by reducing disease levels >80%. Protected cattle were healthier, showed significantly reduced disease levels, higher packed cell volume and significantly increased weight. Collars >60% reduced trypanocide use, 72.7% increase in ownership of oxen per household and enhanced traction power (protected animals ploughed 66% more land than unprotected). Land under cultivation increased by 73.4%. Increase in traction power of protected animals reduced by 69.1% acres tilled by hand per household per ploughing season. Improved food security and household income from very high acceptance of collars (99%) motivated the farmers to form a registered community based organization promoting collars for integrated tsetse control and their commercialization.Conclusion/SignificanceClear demonstration that repellents from un-preferred hosts prevent contact between host and vector, thereby preventing disease transmission: a new paradigm for vector control. Evidence that deploying water buck repellents converts cattle into non-hosts for tsetse flies—‘cows in waterbuck clothing’.

Evaluating Putative Repellent ‘Push’ and Attractive ‘Pull’ Components for Manipulating the Odour-orientation of Host-seeking Malaria Vectors in the Peri-domestic Space

“…An adaptation of this tool for vector control was developed to curb transmission of trypanosomiasis. Cattle provided with a repellent worn on the neck as a push, were supplemented with insecticide-treated targets which acted as attractive pull components that killed the ies that landed on them (37). The reduction in tsetse y populations was more strongly associated with a combined push-pull set up than with the repellent and attractant when used separately or not at all (37).…”

Tsetse blood-meal sources, endosymbionts, and trypanosome infections provide insight into African trypanosomiasis transmission in the Maasai Mara National Reserve, a wildlife-human-livestock interface

“…Visual cues and odors released by vertebrate hosts influence tsetse fly host choice and have been pivotal to the development of baited traps and targets for the control and management of tsetse fly populations, HAT, and AAT. A tsetse repellant formulation mimicking the odor of waterbuck ( Kobus ellipsiprymnus defassa ), a non-host animal, was recently developed and used as an innovative collar device to protect cattle from tsetse bites and AAT [60]. Visual cues have been extensively exploited in the development of improved traps – stationery and mobile targets impregnated with insecticides for riverine/”palpalis” [61–63] and savannah/”morsitans” [49,64] groups of tsetse.…”

“…Better understanding of the molecular mechanisms of tsetse fly olfaction associated with host selection can help to evaluate candidate host semiochemicals as potential attractants or repellants [67–69]. Knowledge of emergent repellant odors (such as those described from zebra and waterbuck) [59,60], coupled with new host attractants, present unique opportunities to further improve tsetse bait technology using “Push-Pull” and/or “Attract-and-Kill” approaches.…”

Biopesticide Research and Product Development in Africa for Sustainable Agriculture and Food Security – Experiences From the International Centre of Insect Physiology and Ecology (icipe)

“…Management of ticks is largely undertaken with acaricides, which is increasingly becoming ineffective due to high levels of acaricide resistance. Management of tsetse flies involves sequential aerosol spraying technique (SAT), ground spraying, insecticide-treated targets such as odor-baited traps, repellent collars and sterile insect technique (Politzar and Cuisance, 1982;Gouteux and Lancien, 1986;Takken et al, 1986;Dransfield et al, 1990;Oladunmade et al, 1990;Bauer et al, 1995;Leak et al, 1995;Saini et al, 2017). These techniques have various limitations ranging from their efficacy, economically viability and environmental sustainability.…”