Changes in the populations ofBacillus thuringiensis H-14 andBacillus sphaericus applied to vector breeding sites

Summary A dark brown mutant ofBacillus thuringiensis H-14 (BT-MB24) and a macrofibre mutant ofBacillus sphaericus H5 ab (BS-MS3) were applied to mosquito breeding habitats such as rain-water pools, casuarina garden pits, paddy fields and cesspits. The population of these bacilli in the water and soil of these habitats was monitored. The results show that the population of the two bacteria recovered from the water decrease with simultaneous increase in the soil populations within one hour of application: by day 19, the bacilli are virtually absent from the water. Only a few cells remain viable in the water for up to 200 days and in the soil for up to 270 days. Even though both these bacilli persist in the waters for a long time at about 100 CFU mL^–1 they do not cause any significant reduction in the mosquito larval density.The authors form part of the research team at the Vector Control Research Centre of the Indian Council of Medical Research, Indira Nagar, Pondicherry.     

Evaluation of the inhibitory effect of abamectin on mammalian butyrylcholinesterase: Enzyme kinetic and molecular docking studies

ABSTRACT

Abamectin, a blend of the natural avermectins B_1a and B_1b, is a widely-used insecticide/miticide with relatively low toxicity to mammals. Exposure to high doses of it, however, leads to cholinergic-like neurotoxic effects. Butyrylcholinesterase, which is best known for its abundant presence in plasma, is a serine hydrolase loosely coupled with the cholinergic system. It protects and supports the neurotransmitter function of its sister enzyme acetylcholinesterase. Here, using experimental and computational studies, we provide evidence demonstrating that abamectin is a potent (IC₅₀ = 10.6 μM; K_i = 2.26 ± 0.35 μM) inhibitor of horse serum butyrylcholinesterase and that it interacts with the enzyme in a reversible, competitive manner predictively to block the mouth of the active-site gorge of the enzyme and to bind to several critical residues that normally bind/hydrolyze choline esters.     

Comparative costs of mosquito control with larvicidal bacilli and insecticides

Summary The production costs of the larvicidal bacilli, Bacillus thuringiensis H14 and Bacillus sphaericus were worked out based upon the inputs used to produce them in a 13 litre working capacity laboratory fermenter. Whereas the production cost of one batch of B. thuringiensis H14 was US$11.02 the production cost of B. sphaericus was US$13.34. Also, the costs involved in controlling mosquito larvae in an area of one hectare with the bacilli and chemical larvicides were compared. The analysis showed that the cost of larval control with the bacilli was more or less equivalent to that incurred if fenthion was used, but significantly less than that incurred if malaria oil, paris green or abate was used.The authors currently undertake research at the Vector Control Research Centre of the Indian Council of Medical Research, Indira Nagar, Pondicherry.     

Sustainable mechanochemical synthesis of β-cyclodextrin polymers by twin screw extrusion

Environmental Science and Pollution Research - Cyclodextrin nanosponges (CD-NS) are cross-linked cyclodextrin polymers characterized by a nanostructured three-dimensional network. CD-NSs in the...