Current Trends in the Control of Mosquito Vectors by Means of Biological Larvicides

Abstract

Bacillus sphaericus Neide (B) and B. thuringiensis serovar israelensis (Bti) de Barjac provides effective alternatives to broad spectrum larvicides in many situations, with little or no environmental impact. Taking into account environmental benefits including safety for humans and other non-target organisms, reduction of pesticide residues in the aquatic environment, increased activity of most other natural enemies and increased biodiversity in aquatic ecosystems, their advantages are numerous. In addition to recombinant bacteria used as larvicides, research is also underway to develop transgenic algae and cyanobacteria using larvicidal endotoxins of Bti and Bs. The advent of recombinant DNA technology is now having an enormous impact on agriculture and medicine, and it is appropriate that the ability to manipulate and recombine genes with this technology be applied to improving larvicides for vector control. These new recombinant bacteria are as potent as many synthetic chemical insecticides, yet are much less prone to resistance, as they typically contain a mixture of endotoxins with different modes of action. The existing recombinants also have what can be considered disadvantageous, in that they do not show significantly improved activity against aedine and anopheline mosquitoes, in comparison to Bti. But it may be possible to overcome this limitation using some of the newly discovered mosquitocidal proteins, such as the Mtx proteins and peptides such as the trypsin-modulating oostatic factor, which could be easily engineered for high expression in recombinant bacteria. While other microbial technologies such as recombinant algae and other bacteria are being evaluated, it has yet to be shown that these are as efficacious and environment friendly as Bti and Bs. By combining the genes from a variety of organisms, it should ultimately be possible to design 'smart' bacteria that will seek out and kill larvae of specific vector mosquitoes. Thus, recombinant bacteria show excellent promise for development and use in operational vector control programs, hopefully within the next few years. documented [5,6]. Vector control is recognized as an effective tool for controlling tropical diseases. Several strategies have been adopted to control these dipteran pests, and to reduce vector-borne diseases. Synthetic insecticides have been effectively used during the past several decades for mosquito-control operations. But the chemical approach has several demerits, such as the development of insecticide resistance, environmental pollution, bio-amplification of contamination of food chain, and harmful effects to beneficial insects. Hence, there has been an increased interest in recent years, in the use of biological agents for mosquito control. Bio-Pesticides as Effective Tools for Mosquito Control In recent years, it has been witnessed, an increased interest in the usage of bio-pesticides as effective tool for mosquito control. Several bio-control agents were screened for their potency, mammalian safety and environmental imp...

Beauveria bassiana (Clavicipitaceae): a potent fungal agent for controlling mosquito vectors of Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti (Diptera: Culicidae)

“…Microbial control is recommended as an alternative way, and microbial based larvicides are employed for minimizing the mosquito population, which provides an effective, environmentally friendly and sociable approach to bring the mosquito population to the lowest level. 9,10 Beauveria bassiana (Clavicipitaceae) is a soil borne fungus that feeds on insects and can be used effectively to control thrips, aphids, whitey, caterpillars, beetles, and subterranean insects like ants and termites. B. bassiana is non-toxic to mammals, birds and plants, and its use is not expected to have any deleterious effects on human health or the environment.…”

Forest canopy, water level, and biopesticide interact to determine oviposition habitat selection inAedes albopictus

“…albopictus populations globally (Lacey , Poopathi ). After ingestion by larvae, crystals on the bacterial endospores bind to and disrupt cell surface proteins in the intestine to induce rapid death (Poopathi ). Responses of ovipositing females to biopesticides at larval sites have been enigmatic, with all possible outcomes (avoidance, no response, and attraction) being documented (Stoops , Carrieri et al , Binckley and Thomas, in press).…”

Fly ash-based Bacillus thuringiensis israelensis formulation: An ecofriendly approach

“…Although biopesticides represent only 2.89 per cent of the overall pesticide market in India 2 , its demand is rising steadily in all parts of the world 3 . An increased concern of biopesticides as an effective tool for mosquito control has been witnessed 4 . Amongst the various biopesticides, microbial pesticides represent the major component.…”

“…Bacillus sphaericus Neide ( Bs ) and B. thuringiensis serovar israelensis ( Bti ) are proven potential mosquito larvicides that stand effective in many operational levels under field conditions. These have numerous advantages such as safety for humans and other non-target organisms, minimal residues in the treated habitats, safe to most other natural enemies and increased biodiversity in aquatic ecosystems 4 . Bti has been successfully advocated for the management of mosquitoes since the last two decades, and its formulations are highly efficient against all three mosquito genera Anopheles , Aedes and Culex 12 .…”

“…Bti has been successfully advocated for the management of mosquitoes since the last two decades, and its formulations are highly efficient against all three mosquito genera Anopheles , Aedes and Culex 12 . It has also been documented that B. sphaericus recycles in the field conditions and exhibits prolonged larvicidal activity, mainly against Culex and a few Aedes species, whereas Bti shows a wide spectrum of activities against all three species 4 . However, repeated application of B. sphaericus in the same habitat has evolved resistance in larvae 13 .…”