Abstract Climate-change leads to extreme droughts, but it is difficult to predict how crop pests are affected. Drought may alter behavior of crop pests such as aphids that facilitate transmission of pathogens like Fusarium graminearum, causing Fusarium foot and root rot in barley crops by feeding close to the susceptible base of plants. Ground dwelling generalist predators like Carabid beetles, and wolf spiders are important aphid enemies during the aphid colonization phase in barley crops i...
Abstract/Overview Prior to the commencement of a large-scale malaria intervention study on Rusinga Island, western Kenya, intensive baseline surveillance of the mosquito population was performed using odour-baited traps. The survey aimed to determine the relative abundance and species composition of malaria vectors, and to measure seasonal and spatial heterogeneity in populations. Human malaria prevalence was combined with entomological data to provide information about malaria transmissi...
Abstract Background. Since Anopheles mosquitoes which transmit and maintain the malaria parasite breed in the outdoor environment, there is an urgent need to manage these mosquito breeding sites. In order to elaborate more on the ecological landscape of mosquito breeding sites, the bacterial community structure and their interactions with physicochemical factors in mosquito larval habitats was characterised in Kwale County (Kenya), where malaria is endemic. Methods. The physical characterist...
Abstract Widespread insecticide resistance in African malaria vectors raises concerns over the potential to compromise malaria vector control interventions. Understanding the evolution of resistance mechanisms, and whether the selective disadvantages are large enough to be useful in resistance management or designing suitable control strategies is crucial. This study assessed whether insecticide resistance to pyrethroids has an effect on the gonotrophic cycle and reproductive potential of ma...
Abstract There is still unexplored reservoir of microorganisms from sediments and water within Lakes Olbolosat and Oloiden using culture dependent technique. The current study compares bacterial diversity within Lake Olbolosat a freshwater lake and Lake Oloiden a saline alkaline lake. Out of 60 isolates obtained from sediments and water samples, 35 were from Lake Olbolosat and 25 from Lake Oloiden. Microbial count ranged between 0-1.75× 10 5 cfu/ml from both lakes. There was a significant d...
Abstract Bemisia tabaci is a widely distributed crop pest affecting the yield of a broad range of agricultural, fiber, vegetableand ornamental crops. It is an extremely polyphagous pest that causes direct damage and can act as a vector ofviral plant diseases. Populations of Bemisia tabaci that are morphologically indistinguishable and with differentbiological traits have been known to exist; they show differences in rates of development, host range, insecticideresistance and virus transmissi...
Abstract In order to reduce parasite-induced mortality, hosts may be involved in mutualistic interactions in which the partner contributes to resistance against the parasite. The pea aphid, Acyrthosiphon pisum Harris (Hemiptera: Aphididae), harbours secondary bacterial endosymbionts, some of which have been reported to confer resistance against aphid parasitoids. Although this resistance often results in death of the developing parasitoid larvae, some parasitoid individuals succeed in develo...
Abstract: In South Africa, white grubs are important pests of sugarcane and wattle. There is need for a sustainable management alternative since their control has mainly been through the use of chemical insecticides. Such alternatives can include the use of entomopathogenic nematodes, EPNs. A review of the available literature revealed that EPNs can potentially provide a higher percentage control of white grubs, when compared to chemical insecticides. However, this control efficacy is charac...
Abstract: Patterns of invertebrate species richness and body size across elevational gradients have been well-documented in a variety of studies. However, very little is known about the factors that govern these patterns along elevational gradients. A number of studies have have reported a monotonic decrease in species richness with increasing elevation; while others have observed a hump-shaped pattern, where the peak of species richness occurs at an intermediate elevation. For body size, st...
Abstract: Winged Rhopalosiphum padi in search of good quality host plants transmit the non-persistent Potato virus Y (PVY) to seed potatoes. Planting a non-virus host plant as a border around the main crop can reduce PVY incidence, because aphids tend to land in high numbers at the edge of a field and the crop border acts as a virus sink. Using a trap crop could increase the number of aphids landing in the border. During host-plant searching behaviour, alate (winged) aphids respond to short ...
Abstract: In the past 3 decades, arboviruses have become a major cause of re-emerging epidemic diseases in the world. Amongst the arboviruses, dengue and chikungunya fevers which are transmitted by Aedes spp have become more prevalent and have spread far beyond traditional areas of distribution - mainly in Africa and Asia - to cause severe morbidity, mortality, and economic harm. Currently control of these diseases solely depends on vector control as there is no treatment or vaccine. This ca...
Abstract: Mining activities greatly contribute to economic growth and development in South Africa. However, post-mining soils have limited land-use potential due to low fertility, deficiency in organic matter content and poor physical, chemical, and microbiological properties. Mechanical methods to improve soil conditions, such as ripping, are expensive and provide temporary improvements. Alternatively, exploring biological methods could aid in creating arable land from degraded soils, where...
Abstract: The reproductive biology of spotted hyaenas was studied from a sample of 39 females and 36 males collected in game reserves in south~rn Africa. A method for age estimation, based on the relative attrition of PM2 was developed. Female spotted hyaenas attain sexual maturity at three years of age, are polyoestrus with recurring oestrous cycles throughout the lactation period. Females were still reproducing when 16 years old. Breeding was not restricted to a particular season, as bi...
Abstract: The presence of huge quantities of nutrients in water bodies heavily promotes the growth of algae. Excess nitrogen and phosphorus in discharged wastewaters can lead to downstream eutrophication thereby damaging the ecosystem. Algae bioremediation involves the use of live algae in the removal of excess dissolved nutrients from wastewater and subsequently diminish the pollution load. It is an alternative economical and sustainable way of treating sewage wastewater compared to convent...
Abstract: Patterns of ectoparasite burden among hosts can be linked to differences in abiotic (i.e. climatic conditions) and biotic (i.e. host characteristics) factors. Although this is well documented for small mammals in the northern hemisphere, similar data for southern Africa, particularly South Africa, is scant. In addition, interspecific interactions in parasite communities may contribute to the distribution of parasites across a host population, however, they are not fully understood ...