Malaria infection potential of anopheline mosquitoes sampled by light trapping indoors in coastal Tanzanian villages

Abstract. Anopheline mosquito populations were studied during 1992 in seven villages south of Bagamoyo, coastal Tanzania, prior to malaria control intervention using insecticide treated bednets. To collect mosquitoes, CDC light traps were used in ten houses per village fortnightly for 12 months. Anopheles females were identified and checked by ELISA for the presence of malaria sporozoite antigen and source of bloodmeal. An. funestus peaked in June-July after the long rains. Three members of the An. gambiae complex had different seasonality: An. arabiensis, An. gambiae and small numbers of An. merus were collected.
In most villages transmission was extremely high and perennial with the entomological inoculation rate reaching three to eleven infective bites per person per night in July and persisting at around 0.1 and 1 for most of the remainder of the year. Sporozoite infection rates within the An. gambiae complex ranged from 2% to 25%, with the peaks in January and July following the two rainy periods. An. funestus showed a similar pattern. The light traps were reliable, simple to operate, and proved to be satisfactory to study the mosquito vector population.     

Wild Oat/Barley Interactions: Varietal Differences in Competitiveness in Relation to K+ Supply

Eight cvs of barley (Hordeum vulgare L.) were separately plantedwith Wild Oats (Avena fatua L., genetically pure line CS40)in a sand culture with two external K⁺ concentrations. Substantialdifferences were observed among barley cvs in their abilityto compete with wild oat. The variety Fergus was highly competitiveat both high and low [K⁺]_e, whereas Steptoe was competitiveonly at high [K⁺]_e, and Compana was only weakly competitivewith wild oat. The differences between barley cvs were relatedto their previously reported efficiencies of K⁺ uptake and utilization. Hordeum vulgare L., Avena fatua L., barley, wild oat, competition, K⁺ nutrition, utilization efficiency     

Application of Monoculture Yield/Density Relationships to Plant Competition in Binary Additive Series

Binary additive series experiments involving various pairedcombinations of barnyardgrass (BYG), redroot pigweed (RPW),green foxtail (GFT) and rape (RPS) were undertaken in fieldplots in 1980 and 1981. The experimental design used permittedinvestigation of the performance of a one species (the ‘competitor’) over a range of densities, in the presenceof different constant densities of a second species (the ‘indicator’),and as pure stands. Top growth (d.wt after approximately 95d) in monoculture was found to be well-described by de Wit'sspacing formula where M_s is yield, s is space per seed or plant, is maximum(asymptotic) yield at infinite density and ß is spaceper seed or plant at half the maximum yield (i.e. /2). The formulawas also found to fit the observed yields of a competing speciesover the entire range of densities of an indicator. Correlationcoefficients between observed yields and values calculated bymeans of the spacing formula ranged from 0.934 to 0.999, withmost greater than 0.990. The changes in the slopes of a competingspecies' yield curves as indicator density increases reflectthe competitive abilities of the pair of species present. Barnyardgrassand RPS were found to be strong competitors against RPW andGFT, and RPW strongly competed against GFT. The spacing formulacan thus be used to predict the performance of a competing speciesin additive series experiments, and thereby provides anothermeans of investigating crop-weed and other interactions. Echinochloa crusgalli (L.) Beauv., Setaria viridis (L.) Beauv., Amaranthus retroflexus L., Brassica napus L., barnyardgrass, green foxtail, redroot pigweed, rape, competition, binary additive series, yield/density relationships