Mortality of adult Stomoxys calcitrans fed isolates of Bacillus thuringiensis

Abstract

We examined the ability of five isolates of Bacillus thuringiensis Berliner to cause mortality in adult stable flies, Stomoxys calcitrans (L.). Isolates Bacillus thuringiensis tolworthi 4L3 (serotype 9), Bacillus thuringiensis darmstadiensis 4M1 (serotype 10a10b), Bacillus thuringiensis thompsoni 4O1 (serotype 12), Bacillus thuringiensis thuringiensis HD2 (serotype 1), and Bacillus thuringiensis kurstaki HD945 (serotype 3a3b3c) were administered to adult flies in diets containing blood only, sugar only, and both sugar and blood combined. B. t. tolworthi 4L3 had no effect on adult mortality regardless of the feeding substrate. The remaining isolates tended to cause the greatest mortality when administered in blood alone. B. t. thompsoni 4O1 was the only isolate that consistently caused adult mortality when fed in blood at concentrations ranging from 0.21 to 50.0 g of protein per ml of blood. This isolate also caused mortality when applied topically. The time to 50% mortality declined with dose and reached a lower asymptote at ≈1.3 d at an oral dose of 8.75 g/ml and at a topical dose of 0.14 g per fly. © 2012 Entomological Society of America.