A comparison of electric-trap and hand-net catches of Glossina palpalis palpalis (Robineau-Desvoidy) and G. tachinoides Westwood (Diptera: Glossinidae) in the Sudan vegetation zone of northern Nigeria

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Abstract
A comparison was made of the efficiencies of catching parties with hand nets and electric back-pack and screen traps for the capture of Glossina palpalis palpalis (R.-D.) and G. tachinoides Westw. in northern Nigeria. Whilst there was little to choose between the various devices during standing catches, one electric back-pack caught up to four times as many G. palpalis as two men with hand nets during moving catches on fly-rounds. Two reasons for the observed variation in success rate of the catching party with hand nets are suggested, and estimates are made of the relative efficiencies of each method at capturing flies during a single traverse of a fly-round. The combined use of the electric back-pack and screen drawn immediately behind the back-pack wearer recorded the arrival height of the flies, whilst hand-net catches tended to reflect the heights at which the flies spent most of their time after arrival. There were differences between the sexes both in arrival height, perhaps related to differences in resting heights on the vegetation, and in the fat and haematin levels of flies caught in hand nets above and below the waist. High ambient temperature reduced the average height of the visits of both sexes to human bait. The relevance of the results obtained in this study to sampling tsets populations is discussed in relation to various seasonal changes in hand-net samples recorded in the literature.