Abstract
BackgroundIn Sub Saharan Africa malaria remains one of the major health problems and its control represents an important public health measure. Integrated malaria control comprises the use of impregnated mosquito nets and indoor residual spraying. The use of drugs to treat patients can create additional pressure on the equation of malaria transmission. Vector control may target the adult mosquitoes or their aquatic larval stages. Biological larvicides such as Bacillus thuringiensis israelensis (Bti) represent a promising approach to support malaria control programs by creating additional pressure on the equation of malaria transmission.MethodsIn this study we examined the efficacy of a water-dispersible granule formulation (WDG) of the biological larvicide Bti (VectoBac®) against wild Anopheles spp. larvae. Different concentrations of the larvicide were tested in standardized plastic tubs in the field against untreated controls. In weekly intervals tubs were treated with fixed concentrations of larvicide and the percentage reduction of larvae and pupae was calculated.ResultsAll used concentrations successfully killed 100 percent of the larvae within 24 hours, while the higher concentrations showed a slightly prolonged residual effect. Natural reconolization of larvae took place after two and three days respectively, late instar larvae were not found before 5 days after treatment. For the higher concentrations, up to three days no new larvae were found, implicating that the residual effect of WDG in tropical conditions is approximately one to two days. The overall pupae reduction in treated tubs was 98.5%.ConclusionsBiological larviciding with Bti can be a promising, additional tool in the fight against malaria in Africa. Environmental particularities in tropical Africa, first and foremost the rapid development of mosquitoes from oviposition to imago have to be taken into account before implementing such counter measures in national or international vector control programs. Nonetheless biological larviciding seems to be an appropriate measure for selected conditions, offering a significant contribution to the future of malaria control.
Highlights
In Sub Saharan Africa malaria remains one of the major health problems and its control represents an important public health measure
In many environmental settings larvae are found in high densities in their respective breeding sites and can be accessed, adult vector populations can be reduced by orders of magnitude with larval source management (LSM) [7,8,9]
It is the first time of testing Bacillus thuringiensis israelensis (Bti) in that region, which was performed within the framework of a large scale intervention program which uses satellite derived risk maps to predict larval densities [13]
Summary
In Sub Saharan Africa malaria remains one of the major health problems and its control represents an important public health measure. Vector control may target the adult mosquitoes or their aquatic larval stages Biological larvicides such as Bacillus thuringiensis israelensis (Bti) represent a promising approach to support malaria control programs by creating additional pressure on the equation of malaria transmission. Resistance to Bs has been reported [5,6] but seems to play a minor part in field application, in particular when Bs is combined with Bti. Depending on the environmental setting, and in particular, the number, size and accessibility of breeding sites, larviciding with Bti can be an important additional tool for vector population control in integrated control programs. Each geographic region features a characteristic combination of those factors and gives reason for testing the larvicide’s efficacy under the respective field conditions It is the first time of testing Bti in that region, which was performed within the framework of a large scale intervention program which uses satellite derived risk maps to predict larval densities [13]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
