Protezione degli anfibi, effetti del Bacillus thuringiensis var. israelensis su larve di Chironomus

The Bacillus thuringiensis subsp. israelensis (B.t.i.) d -endotoxin is widely employed as a biological control agent against culicidae; in fact, it is efficacious and highly selective. It is not toxic to batrachian fauna; still, it is also possible to observe an indirect action. As a matter of fact, the B.t.i. is used against dipteran culicidae, but, even at low concentrations, is harmful to the black fly larvae (Diptera: Simuliidae) and chironomid larvae (Diptera: Chironomidae). According to the studies of Dolce and Stoch (Atti Mus.civ. Stor. nat. Trieste, 36: 31-45, 1984), it appears that chironomids larvae form up to 97.4% of the diet of larval and adult Triturus vulgaris in unhealthy moist areas. On the basis of our studies, the B.t.i., also at very low doses, is deadly for larval chironomids. Consequently, to preserve Triturus and the other species already highly compromised, it is advisable to perform a preliminary census of them in the moist areas involved in the programs to keep within bounds the mosquitoes. So, the use of B.t.i. can be prevented at the presence of endangered amphibia.