Abstract: Concentrations and distribution of cadmium, chromium, copper, iron, lead, manganese and zinc in mosquito larval habitats in urban Kisumu and Malindi, Kenya and their effect on the presence of Anopheles gambiae, Aedes aegypti, Culex quinquefasciatus and Anopheles funestus larvae were investigated. Manganese and iron were the most prevalent heavy metals in water of larval habitats in urban Kisumu and Malindi, respectively. Iron was the most prevalent heavy metal in bottom sediments in larval habitats in both cities. The highest concentrations of all heavy metals, except cadmium and iron, were recorded in the poorly planned-well drained stratum in the two cities. All heavy metals were more concentrated in human-made than in natural larval habitats. Copper was positively associated with the presence of Ae. aegypti, and lead was associated with the presence of An. gambiae and Ae. aegypti in urban Kisumu. Absence of significant correlation between the other metals and mosquito species in both cities, despite relatively high concentrations, suggest that the local larval populations, including key malaria vectors have adapted to the detected levels of these metals.

Abstract: Investigations were conducted to establish the magnitude and pattern of differential expression of proteins due to generational selection of third instar Anopheles gambiae s.s. Giles larvae by cadmium, copper and lead heavy metals, the three possible common urban pollutants. A susceptible strain of A. gambiae s.s. third instar larvae was separately placed under selection pressure with cadmium, copper and lead at LC30 and controls through five generations. First, third and fifth generation selection survivors were screened for differentially expressed proteins relative to non-exposed control by two-dimensional gel electrophoresis. Distribution patterns of the spots were analyzed by χ2 or Fishers' exact test and variations in expressions between and within generations by ANOVA. Most differentially expressed spots were acidic and of low molecular weight among all metals and generations. Type of heavy metal and generation were the main indicators of variations in differential expressions. Variation between generations was most significant among cadmium-selected populations of which the most number of spots were induced in the fifth generation. Most spots were induced in the copper-selected population in the third generation. The induced protein spots may be the products from respective genes that respond to heavy metals and counter their toxicity, thus building A. gambiae s.s. tolerance to these pollutants. The differential pattern and magnitude of expressed spots have potential application as molecular markers for assessment of anopheline adaptation status to heavy metals, and provide insight into the extent of environmental pollution.

Abstract: Investigations were conducted to establish field responses of Glossina pallidipes, G. morsitans morsitans, muscoids and tabanids to castor, raw linseed, paraffin and chlorinated paraffin oils in deltamethrin suspension concentrate (sc) formulation, through randomized Latin square experiments. Tsetse landing responses on targets treated with 400 ml/m2 of any of the oils in 2 g/m2 deltamethrin formulation were significantly lower than on non-oil-containing deltamethrin formulations, for both G. pallidipes (F(4,32)=4.855, P=0.00357) and G. m. morsitans (F(4,32)=2.421, P=0.06862). The landing response indices, relative to the control formulation without oil, were 0.60, 0.70, 0.61 and 0.41 in G. pallidipes and 0.92, 0.82, 0.75 and 0.42 in G. m. morsitans and for paraffin, chlorinated paraffin, castor and raw linseed oils respectively. Glossina pallidipes and G. m. morsitans landing responses were inversely proportional to raw linseed oil concentrations. None of the oils significantly affected muscoid (F(4,32)=1.6959, P=0.1753) or tabanid (F(4,32)=1.7546, P=0.1624) landing response, or tsetse fly resting persistence (F(4,32)=0.9641, P=0.4406) on the targets. The reduced tsetse fly response to targets treated with any of the oils can be attributed to adverse effect of the oil treatments on the tsetse fly olfactory responses to the targets. Since the oil formulations reduce target efficiency by reducing tsetse responses to the targets, application of the oil formulations on targets deployed in G. pallidipes and G. m. morsitans control programmes is not recommended.