Date of Award

2025

Document Type

Thesis

Abstract

Animal African Trypanosomiasis (AAT) transmitted by the Glossina spp is a major constraint to livestock production in Sub-Saharan Africa (SSA) despite various control efforts. Trypanosome-induced semiochemicals found in urine of infected cattle are predictive AAT biomarkers with potential for use as baits for tsetse trapping enhancement. The objective of this study was to investigate the urine from trypanosome infected cow and its modified semiochemicals as effective attractants for infected Glossina pallidipes with an economical dispenser for field application. Coupled Gas Chromatography-Mass Spectrometry was used to analyze cow urine odor profiles to identify Trypanosoma congolense (T. c) modified semiochemicals. The chemistry of urine from trypanosome-infected cow was mimicked by formulation of blends of T. c modified semiochemicals. The flies’ response to the various treatments were conducted using bioassays in the laboratory and field. Laboratory bioassays involved free flight dual choice testing the fly’s response to urine from trypanosome infected cow. Field evaluations involved comparing the baited trap catches against un-baited trap used as a negative control. Both liquid and dry formulation dispensers were evaluated whereby dry dispensers proved the most economical and effective way of dispensing the test compounds due to its single loading. The urine from trypanosome infected cow and its modified semiochemicals were evaluated for their attractiveness to infected G. pallidipes by screening of field caught flies using ITS1 primers to determine their infection rates. Infection rates were checked through molecular biology techniques which involved DNA extraction, PCR, gel electrophoresis and sequencing. Urine from trypanosome-infected cattle exhibited induced semiochemicals and elevated levels of existing semiochemicals.Urine from trypanosome infected cow attracted significantly more flies in both laboratory (t=3.15, p=0.003) and field bioassays (F=4.2, p=0.03). Traps baited with dihydro-α-ionone and 3-ethylphenol attracted significantly more G. pallidipes compared to un-baited control trap, (dihydro-α-ionone, p=0.04, and 3-ethylphenol, p=0.02). Three blends of T.c modified semiochemicals (NB1, NB2 & NB3) attracted significantly more G. pallidipes compared to un-baited control trap (F=10.31, p= 0.001). NB1 attracted significantly more blood-fed G. pallidipes compared to un-baited negative control trap (Fisher Exact Test, p=0.0001). There was no significant difference between mean G. pallidipes catches using dry and liquid formulation dispensers (p=0.7257). Traps baited with urine from Tc-infected cow attracted five times more infected G. pallidipes compared to those baited with urine from healthy cow (Fisher Exact Test, p=0.001). NB1 attracted twice the number of infected flies whereas NB3 attracted three timesinfected flies as compared to un-baited control trap. Trypanosome-induced semiochemicals demonstrate their ability as effective attractants for infected G. pallidipes. The results of this study are vital for developing new trypanosomiasis control strategies using effective baits for G. pallidipes

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