Toxicity for mosquito larvae has been associated with the formation of toxic proteins during sporulation and/or vegetative growth.
In this study, we aimed to determine the nature and origin of the high toxicity toward mosquito larvae found in decaying leaf litter collected in several natural mosquito breeding sites in the Rhône-Alpes region.
The obtained bioassay results confirmed the superiority of the locally isolated strains compared to the two reference strains with respect to toxicity against mosquito larvae.
Significant differences in toxicity against mosquito larvae were observed between P and NYS media, local (Bacillus sphaericus EMCC 1931, EMCC 1932) and reference (B. sphaericus 1593, B. sphaericus 2297) strains.
Cry11A and Cry4Ba mutants in helix α-4 were affected in toxicity against mosquito larvae [23], [24].
In our study, not only was Bti found in two untreated sites, but it was also detected at high levels in some samples associated with an acute toxicity towards mosquito larvae.
Post-iron overdose caused by blood feeding also induces synthesis and secretion of iron storing molecules like ferritin, which defend mosquito cells from iron toxicity [ 46].
Preliminary experiments revealed that fluoranthene, atrazine or copper did not show any toxicity on mosquito larvae even at higher concentrations than those used in the present study.
The same explanation, that is, the sensitivity of brain AChE to oxon derivatives, has been suggested for chlorpyrifos, parathion, and methyl parathion toxicity in mosquito fish (Gambusia affinis) [ 23].
Two Aedes aegypti laboratory strains were compared for the purpose of this study: the Bora Bora reference strain, known to be susceptible to most insecticides, and a strain artificially selected for resistance to a decomposed tree leaf litter showing a high toxicity for mosquito larvae.
