Production of the bioinsecticide Bacillus thuringiensis subsp. israelensis with deltamethrin increases toxicity towards mosquito larvae

Abstract

Significance and Impact of the Study: This study is the first report of an increased efficacy of the mosquitocidal bioinsecticide Bacillus thuringiensis subsp. israelensis (Bti) when produced with a chemical insecticide. The results clearly demonstrate that deltamethrin is able to synergize the insecticidal activity of Bti through inclusion into spore membranes, reducing off-target and nonspecific toxicity occurring when the chemical is used alone as sprays. Abstract Bacillus thuringiensis subsp. israelensis is a bioinsecticide used for larval mosquito control and it represents a safe alternative to chemical insecticides. Despite its environmental safety, it is less efficient and persistent than chemical insecticides. To bypass these limitations, we propose to combine the advantages of chemical and biological insecticides by producing Bti in a medium supplemented with a chemical insecticide (DDT, deltamethrin, permethrin, propoxur or temephos). Among the investigated insecticides, the addition of deltamethrin in the medium induced a higher toxicity (over 6Á72-fold) of the composite deltamethrin-Bti towards mosquito larvae as compared to Bti alone. This was mainly due to the insertion of deltamethrin into the membranes of Bti spores, as evidenced by a quantification of membraneextracted deltamethrin by HPLC. This composite larvicide is a promising tool to decrease the quantity of chemicals dispersed in the environment, to increase the efficacy of Bti and to facilitate its widespread use as a transition between chemical and biological insecticides. Further experiments are required to characterize the mechanisms that underline the incorporation of deltamethrin into Bti to optimize the production and the toxicity of this composite larvicide.

Synthetic predator cues impair immune function and make the biological pesticide Bti more lethal for vector mosquitoes

“…Moreover, Bti is less efficient than chemical pesticides and is therefore sometimes used in combination with those to increase its efficacy in controlling mosquitoes (Tetreau et al. ). As Notonecta are important natural predators that may control mosquito populations (Becker et al.…”

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“…There have been reports of Bti being produced in various formulations, such as powders, tablets and liquids, for different purposes (that is, research or commercial applications to breeding sites) (Tetreau et al, 2013;El-Bendary, 2016). These products have to be evaluated for potency, measured in international toxic units (ITU/mg), and efficiency against the target mosquito species (Rishikesk and Qulennec, 1983).…”

Isolasi Bacillus thuringiensis Lokal dari Tanah Kota Bandung Berdasarkan Ketinggian

“…3,4 Salah satu agen biologis yang sudah digunakan dan terbukti mampu mengendalikan populasi larva adalah Bacillus thuringiensis (Bt). [4][5][6][7][8] Bt dapat ditemukan di berbagai belahan bumi karena merupakan bakteri yang hidup di alam terutama di dalam tanah. Bt dapat diisolasi dari tanah pertanian, tanah perkebunan, bangkai serangga, dan dedaunan.…”

“…8 Meskipun demikian, habitat normal bakteri ini adalah di dalam tanah. Bakteri ini tumbuh secara alami sebagai saprofit yang memperoleh makanan dari sisa pembusukan materi organik, 5,[9][10][11] Tetapi belum pernah dilakukan upaya eksplorasi untuk dapat menemukan isolat lokal di Kota Bandung.…”