Expanding the toolbox for tsetse control in Kenya

Biotechnology Research Institute-Kalro, Kikuyu

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Abstract

This application focuses on expanding toolbox for control tsetse fly by formulating eco-friendly novel odor attractant and repellent blends against major tsetse vectors of Human African Trypanosomiasis (HAT) and African Animal Trypanosomiasis (AAT) in eastern Africa. Eastern Africa is under continuous risk of rhodesiense HAT and AAT transmitted by different tsetse species, including Glossina austeni (Gau), Glossina pallidipes(Gpd), and Glossina fuscipes fuscipes (Gff). Tsetse control strategies constitute cornerstones efforts in suppression and eradication of HAT and AAT that can be augmented by effective 1) tsetse lures that attract the flies to traps or insecticide-treated targets, and 2) repellents that minimize contact between flies and their vertebrate hosts. We formulated Novel Attractant Blend (NAB) (ε-nonalactone, nonanoic acid, 2-nonanone and acetone) from waterbuck and buffalo odors that is 1) two- and five-folds more effective against Gau and Gpd, respectively, than POCA (3-propylphenol, octenol, p-cresol and acetone) standard tsetse attractant, 2) 2.4 folds more attractive to Gpd than Fermented Cow Urine (FCU) + acetone (proxy for natural bovine host odor), and 3) seven-fold more attractive to Gpd than POCA when co- deployed with FCU and acetone. We are interested in comparing the performance of NAB with that of natural hosts (cattle) on Gpd and identify other host odor constituents that may enhance the attraction of NAB. There are no effective attractants against Gff while POCA and NAB are suboptimal against Gau, relative to Gpd. We confirmed attraction of Gff by monitor lizard (Varanus niloticus niloticus) and established role of olfaction in the attraction. Gau preferentially feed on bush pig (Potamochoerus larvatus). We are interested in formulating Gff and Gau repellents from monitor lizard and bushpig hosts and integrating their application with NAB for efficacy against multiple (sympatric) species. We also established repellence of Gau by FCU+Acetone and formulated Novel Repellent Blend (NRB) (δ-nonalactone, heptanoic acid, 4- methylguaiacol and geranyl acetone) based on tsetse-refractory waterbuck odor that is effective against most savannah species and two-fold more efficacious than current WRC-icipe blend against these species. We are interested in formulating Gau specific repellents from FCU constituents, evaluate its synergistic effects on NRB through co-deployment and assess efficacy of NRB and Gau repellent in protection of vertebrates, from tsetse, with oxen and domestic pig as proxy. We will extend the efficacy and application of the repellent/attractant blends by masking them with fragrance and micro encapsulating them in nano-particles. We will thus formulate 1) Gff and Gau specific attractants and integrate them with NAB for control of sympatric tsetse populations and 2) Gau repellent and integrate it with NRB and NAB for protection of vertebrate hosts from sympatric tsetse in Kenya as consortium comprising of Kenya Agricultural and Livestock Research Organization and Kenya Wildlife Services in Kenya , and Yale University in USA.