The feeding behaviour and Plasmodium infection of Anopheles mosquitoes in southern Ethiopia in relation to use of insecticide-treated livestock for malaria control.

Anopheles arabiensis and An. quadriannulatus species B mosquitoes were collected at sites of human and livestock housing and analysed for blood feeding patterns and infection with malaria sporozoites. A low percentage of human blood meals at some sites suggested that zooprophylaxis could be effective in reducing challenge from Plasmodium falciparum

Effects of exposing adults of Amblyomma variegatum to neem cake extracts in traps baited with semiochemicals under semi–laboratory conditions

The efficacy of a trap baited with an attractant blend comprising of attraction aggregation- attachment pheromone (AAAP), 1-octen-3-ol and CO2 and treated with Neem (Azadirachta indica) cake extracts (0.6% of azadirachtin) to attract and expose the ticks, Amblyomma variegatum (Fabricius) (Acari: Ixodidae) to the active constituents of the cake was evaluated in circular field plots.. Ticks were released at various distances from trap placed at the center of the plots. Ticks that arrived at the trap (and exposed to the extracts) and those in control plots were collected and their mortality was monitored in the laboratory over a three-week period. All concentrations of the neem extracts caused mortality of A. variegatum adults with highest mortality rate (97.8%) recorded in the concentration of 30 % of extracts. The mortality of the ticks was also dependent upon the time ticks were exposed to the extracts. The findings suggest the possibility of using semiochemicals-baited traps in combination with neem extracts for off-host control of these ticks in smallholder farms.Key words: Amblyomma variegatum, traps, Azadirachta indica, semiochemical

Bacterial diversity in the intestinal tract of the funguscultivating termite Macrotermes michaelseni (Sjöstedt)

Microorganisms in the intestinal tracts of termites play a crucial role in the nutritional physiology of termites. The bacterial diversity in the fungus-cultivating Macrotermes michaelseni was examined usingboth molecular and culture dependent methods. Total DNA was extracted from the gut of the termite and 16S rRNA genes were amplified using bacterial specific primers. Representatives from forty-one (41) RFLP patterns from a total of one hundred and two (102) clones were sequenced. Most of the clones were affiliated with 3 main groups of the domain Bacteria: Cytophaga-Flexibacter-Bacteriodes(73), Proteobacteria (13), and the low G+C content Gram-positive bacteria (9). Two RFLPs related to planctomycetes, but deeper branching than known members of the phylum, were detected. In addition, 1 and 2 RFLPs represented the spirochetes and TM7-OP11 groups, respectively. In studies using culture dependent techniques, most of the isolates obtained belonged to the Gram-positive bacteriawith a high G+C content. However, only one of the clones represented Gram-positive bacteria with High G+C content. These results show a high bacterial diversity in the intestinal microbiota of M. michaelseni, which continues to escape cultivation. As is the case in other termites many of the clones represent previously uncultured bacteria. The fact that most of the clones clustered with clones from Macrotermes gilvus provides further support for the hypothesis that microorganisms in intestinal tracts of termites have co-evolved with their hosts

Infections with Immunogenic Trypanosomes Reduce Tsetse Reproductive Fitness: Potential Impact of Different Parasite Strains on Vector Population Structure

The parasite Trypanosoma brucei rhodesiense and its insect vector Glossina morsitans morsitans were used to evaluate the effect of parasite clearance (resistance) as well as the cost of midgut infections on tsetse host fitness. Tsetse flies are viviparous and have a low reproductive capacity, giving birth to only 6–8 progeny during their lifetime. Thus, small perturbations to their reproductive fitness can have a major impact on population densities. We measured the fecundity (number of larval progeny deposited) and mortality in parasite-resistant tsetse females and untreated controls and found no differences. There was, however, a typanosome-specific impact on midgut infections. Infections with an immunogenic parasite line that resulted in prolonged activation of the tsetse immune system delayed intrauterine larval development resulting in the production of fewer progeny over the fly's lifetime. In contrast, parasitism with a second line that failed to activate the immune system did not impose a fecundity cost. Coinfections favored the establishment of the immunogenic parasites in the midgut. We show that a decrease in the synthesis of Glossina Milk gland protein (GmmMgp), a major female accessory gland protein associated with larvagenesis, likely contributed to the reproductive lag observed in infected flies. Mathematical analysis of our empirical results indicated that infection with the immunogenic trypanosomes reduced tsetse fecundity by 30% relative to infections with the non-immunogenic strain. We estimate that a moderate infection prevalence of about 26% with immunogenic parasites has the potential to reduce tsetse populations. Potential repercussions for vector population growth, parasite–host coevolution, and disease prevalence are discussed