Microbial community and nutrient dynamics in experimental mesocosms following a biorational larval mosquito control application

The interaction of biopesticides such as Bacillus thuringiensis subsp. israelensis (Bti) and native microbiota is not well studied. Using sequences from 16S rRNA Bacteria genes, we compared Bacteria communities in three (a one-time application of two levels of Bti and untreated control) treatments in experimental mesocosms. Mosquito abundance and water quality parameters in the treatments were also assessed. Beta diversity analysis of Bacteria communities revealed that samples from low and control treatments were significantly separated from samples from the high Bti application rate. Bacteria communities in the low Bti application rate and untreated control mesocosms were dominated by Cyanobacteria, Cytophagales and Cyclobacteriaceae (Bacteroidetes), Sphingomonas (Alphaproteobacteria), and Polaromanas (Betaproteobacteria). These taxa were suppressed in mesocosms subjected to the high Bti application rate. Mosquito abundance, algal biomass, sestonic particles, nutrients and other water quality parameters were also significantly reduced in the high Bti treatment. Isolating whether other components of the Bti formulation or the active ingredient of Bti caused changes in microbiota and physicochemistry of water is underway.