Evaluating the Elimination of Brazilian Entomopathogenic Bacillus by Non-target Aquatic Species: An Experimental Study

Abstract

Ecotoxicity tests are key to predict environmental hazards resulting from chemical and biological pesticides in non-target species. In order to assess the effects of microbial pesticides it is important to determine if they cause infection in test organisms. At present the microbial elimination rate or clearance is not included in ecotoxicological regulatory protocols. This study evaluated the elimination of Bacillus thuringiensis and Bacillus sphaericus from fish and snails, after 30 days' exposure to commercial formulations of such entomopathogens. Data obtained showed that in clean water the tendency to eliminate microbial agents from the body of the exposed organisms is gradual over time but after 7 days the fish and snails were free of the two tested Bacillus spp.

The Ecotoxicology of Microbial Insecticides and Their Toxins in Genetically Modified Crops: An Overview

“…This author showed that spores were rarely detected in fish after 8 days (192 h). In a similar study [ 28 ], it was demonstrated that the Brazilian fish Hyphessobrycon eques and snail B. glabrata eliminated the spores of B. thuringiensis and B. sphaericus tested strains from their body after 7 days of recovery in clean water. In snails, it was observed that CFUs of B. sphaericus were found in higher numbers after 68 h of recovery, but in any case, the tendency presented by the obtained data shows that total elimination is imminent and that the persistence of spores or the bacteria for a time does not seem to be deleterious to the organism.…”

“…In another publication, B. thuringiensis and B. sphaericus in concentrations of 10 6 spores/mL were not lethal to the fish Hyphessobrycon eques , also called Mato Grosso fish, in Brazil [ 28 ].…”

Dissecting the Environmental Consequences of Bacillus thuringiensis Application for Natural Ecosystems

“…israelensis ( Bti ) on fathead minnows, Pimephales promelasandas , or fish mortality. Moreover, upon the transfer to Bt -free water, fishes effectively excreted the toxins from their organisms [ 157 , 158 ]. No genotoxic or mutagenic effects of Bt toxins on peripheral erythrocyte cells of Oreochromis niloticus were observed [ 154 ].…”