Screening of different adjuvants for wastewater/wastewater sludge-based Bacillus thuringiensis formulations.
Screening of different adjuvants, namely, suspending agents, phagostimulants, stickers, antimicrobial agents, and UV screens to develop aqueous biopesticidal suspensions of Bacillus thuringiensis (Bt) variety kurstaki HD-1 fermented broths, specifically, nonhydrolyzed sludge, hydrolyzed sludge, starch industry wastewater, and soya (commercial medium), were investigated. The selected suspending agents [20% (wt:vol)] included sorbitol, sodium monophosphate, and sodium metabisulfite with corresponding suspendibility of 74-92, 69-85, and 71-82%, respectively. Molasses [0.2% (wt:vol)] increased adherence by 84-90% for all fermented broths. The optimal phagostimulants [0.5% (wt:vol)], namely, soya and molasses, caused entomotoxicity increase of 3-13 and 7-13%, respectively. Sorbic and propionic acids showed high antimicrobial action [0.5% (wt:vol)], irrespective of fermentation medium. Sodium lignosulfonate, molasses, and Congo red, when used as UV screens [0.2% (wt:vol)], showed percent corresponding entomotoxicity losses of 3-5, 0.5-5 and 2-16, respectively. The Bt formulations, when exposed to UV radiation, showed higher half-lives (with and without UV screens) than the fermented broths or semisynthetic soya medium and commercial Bt formulation. UV screen-amended nonhydrolyzed, hydrolyzed, and starch industry wastewater formulations showed 1.3-1.5-fold higher half-lives than commercial Bt formulation. Thus, the recommended formulation comprises sorbitol, sodium monophosphate, sodium metabisulfite (suspending agents); molasses, soya flour (phagostimulants); molasses and skimmed milk powder (rainfasteners); sorbic and propionic acids (antimicrobial agents) and sodium lignosulfate; and molasses and Congo red (UV screens). These waste-based Bt formulations offer better UV resistance in comparison with commercial formulation.
Brar
Satinder K
SK
INRS-ETE, Université du Québec, 490, Rue de la Couronne, Québec, Canada G1K 9A9.
Verma
M
M
Tyagi
R D
RD
Valéro
J R
JR
Surampalli
R Y
RY
D000269:Adhesives; D000818:Animals; D000890:Anti-Infective Agents; D001413:Bacillus thuringiensis / Q000254:growth & development* / Q000528:radiation effects; D005079:Excipients; D009036:Moths; D010572:Pest Control, Biological / Q000379:methods*; D010574:Pesticide Synergists; D013025:Glycine max; D013213:Starch; D014466:Ultraviolet Rays; D014866:Waste Products
D000269:Adhesives; D000890:Anti-Infective Agents; D005079:Excipients; D010574:Pesticide Synergists; D014866:Waste Products; D013213:Starch