Comparing formulations for a mixed-microbial biopesticide with Bacillus thuringiensis var. kurstaki and Beauveria bassiana blastospores

摘要

Developing a dual agent biopesticide formulation made with blastospores of Beauveria bassiana (Balsamo) Vuillemin strain GHA (Bb) at the ratio of 1:1 mixed with traditional fermentation production of Bacillus thuringiensis kurstaki (Btk) spores and crystals were studied. Twelve potential formulation ingredients were screened for their impact on insecticidal activity, microbe viability, UV protection and product suspensibility of a spray dried Bt/Bb (1:1) mixture applications to cabbage plants againstcabbage looper, Trichoplusia ni. Based on the results, Spray-dried mixtures of Bt/Bb made with biochar, chitosan and skim milk powder formulations gave the greatest efficacy and higher solar stability when exposed to simulated sunlight. They therefore can be used as a formulation that combines Bt with Bb in one product. However, the formulation made with aitkin component had significantly more colony forming units (CFUs) of Bf, whereas, formulations made with albumin, sodium carbonate and pharmamedia had more Bb CFUs than other formulations. Albumin, pharmamedia, skim milk powder and biochar had significantly better suspension in water (less settling) than others.These results support the concept of formulating the two biocontrol agents, B. thuringiensis and B. bassiana blastospores for greater efficacy, more viability and longer field persistence as an environmentally friendly sustainable pest control tool.