Bloodmeal evacuation from the midgut of Glossina pallidipes in relation to tsetse foraging activity and trappabiIity

Abstract.

• 1 Foraging for bloodmeals is the most frequently recurrent and probably the most targetable of all activities that render tsetse vulnerable to interception with static trapping devices.
• 2 Surgical monitoring of the rnidgut every 24 h during three successive days of food deprivation, showed that a full bloodmeal, irrespective of its size or source, vacated the rnidgut of both sexes of Glossina pallidipes Austen in eight progressive stages.
• 3 Probing responsiveness in both sexes increased exponentially during the first four stages of their midgut evacuation, reaching a peak between stages 3 and 5. Thereafter it decreased, also exponentially.
• 4 Most G.pallidipes caught by NG2G traps baited with cow urine and acetone had midguts in the last three stages (6–8) of bloodmeal evacuation. The same was true of the majority of those that failed to feed on a calf shortly after entrapment.
• 5 The implications of the foregoing for tsetse foraging activity and trappability as well as for the potency of cattle urine and acetone as odour-bait for tsetse are discussed.