The effect of gamma-radiation doses ranging between 10 and 180 Gy on 4-6-day-old adult males of Glossina tachinoides, Glossina fuscipes fuscipes and Glossina brevipalpis was studied. Fecundity of their mates was reduced by 95% following exposure to 120, 80-100 and 50 Gy of adult male G. tachinoides, G. f. fuscipes and G. brevipalpis respectively. Insemination ability of the males and sperm motility were not adversely affected by the radiation treatment. The higher proportion of dominant lethals in the sperm of the three species with increasing radiation doses was reflected in the reproductive status of the female mates, i.e. an increasing percentage of females showing imbalances between intrauterine content and ovarian development (females with an empty uterus due to expulsion of a dead embryo after embryonic arrest or a degenerating egg in utero) and an acceleration in follicle development associated with successive unsuccessful cycles. In the F1 progeny of all treated groups, no significant bias of the sex ratio was found. The average life span of G. tachinoides and G. f. fuscipes males treated with doses of > or = 80 Gy and of G. brevipalpis males treated with doses >140 Gy was significantly reduced as compared with untreated controls. Male G. brevipalpis treated with doses ranging between 10 and 40 Gy, however, showed a significant radiation induced increase in average life span.

Monitoring of Glossina austeni Newstead populations in the forested areas of Unguja island of Zanzibar has since November 1990 routinely been carried out with the sticky panel trap because commonly used tsetse traps (Biconical, Epsilon, F3) have proved to be unsuccessful in catching G. austeni. Initial studies on the catching ability of various types of sticky panels for G. austeni indicated that the monopanel was as efficient in catching flies as the 3-dimensional version and the smaller legpanel. No significant differences in catch rate and sex ratio were observed with monopanels in various colours and colour combinations. Legpanels coloured white on one panel side and blue on the other side caught significantly more flies compared with other colour combinations, but female flies were under-sampled (32%). The type of sticky material applied on the panel influenced significantly the catch rate and female ratio. During long-term trapping with baby blue and white monopanels, females were under-sampled (38-46%) except when polyisobutyleneLMW was used as sticky material. Analysis of the age composition of the sampled G. austeni females revealed that tenerals and nulliparous were well represented (11-24%). More than 20% of the trapped females were older flies, i.e. females with four or more ovulations, but this percentage dropped to 10% when Tanglefoot was used as sticky material.

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In the sterile insect technique, insects are sterilized prior to release in areas where they are pests. The sterile males compete for and with fertile wild individuals for mates, thus reducing the population's reproductive rate. Tsetse fly (Glossina spp.) populations have been eradicated after release of laboratory-bred flies sterilized by gamma irradiation. However, no studies exist on radiation-induced damage to the midgut morphology and function of the radiation-sterilized insects. After G. palpalis palpalis and G. p. gambiensis were subjected to 130 Gy gamma radiation, their midgut damage and recovery were monitored by electron microscopy. The first sign of damage was atrophy and loss of the microvillous border from epithelial cells. The rate of cell degeneration increased, with young as well as old cells being affected and cellular debris filling the ectoperitrophic space. Muscle cells were destroyed, patches of basal lamina were left bare, intracellular virus- and rickettsia-like organisms became more frequent, and many replacement cells became unusually large. Partial recovery occurred from the 10th day postirradiation. Such changes in midgut ultrastructure and the corresponding inhibition of functions may increase the susceptibility of the fly to trypanosome infection.