Location: Crop Bioprotection ResearchTitle: Comparing formulations for a mixed-microbial biopesticide with Bacillus thuringiensis var. kurstaki and Beauveria bassiana blastospores
|SAYED, ATEF - Plant Protection Research Institute|
Submitted to: Archives of Phytopathology and Plant Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2017
Publication Date: 9/24/2017
Citation: Sayed, A.M., Behle, R.W. 2017. Comparing formulations for a mixed-microbial biopesticide with Bacillus thuringiensis var. kurstaki and Beauveria bassiana blastospores. Archives of Phytopathology and Plant Protection. 50:15-16, 745-760. http://dx.doi.org/10.1080/03235408.2017.1372942.
Interpretive Summary: Development of proper formulations for biological pesticides is an important part of product development that must be tailored to each microbial active agent. We recently demonstrated control benefits by combining two agents, the bacteria Bacillus thuringiensis with the fungus Beauveria bassiana, which when applied as one product resulted in enhanced insect mortality. In this research, ingredients were screened to identify benefits for physical mixing characteristics of product samples, to maintain viability of both microbes, to resist degradation by UV exposure after application, and maintain or improve insecticidal activity. Successful formulation development of microbial-based biopesticides will support commercial development thus providing safe products to replace the chemicals currently used for pest control.
Technical Abstract: Developing a dual agent biopesticide formulation made with blastospores of Beauveria bassiana (Balsamo) Vuillemin strain GHA (Bb) at ratio of 0.5:0.5 mixed with traditional fermentation production of Bacillus thuringiensis kurstaki (Bt) spores and crystals were studied. Twelve potential formulation ingredients were screened for their impact on insecticidal activity, microbe viability, product suspensibility and UV protection of a spray dried Bt/Bb (0.5:0.5) mixture applications to cabbage plants. Spray-dried ingredient formulations of Bt mixed with Bb blastospores had different levels of activity. 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 and can be used as a formulation that combines Bt with Bb in one product. However, the formulation made with aitkin had significantly more colony forming units (CFUs) of Bt, whereas, formulations made with albumin, sodium carbonate and pharmedia had more Bb CFUs than other formulations. Albumin, pharmedia, skim milk powder and biochar had significantly better suspension in water (less settling) than others, while the formulation made with chitosan had least suspensibility. These results support the concept of formulating the two bioagents, B. thuringiensis and B. bassiana blastospores for greater efficacy, wider host range, and longer field persistence as an environmentally friendly pest control tool.