Activity of <I>Bacillus thuringiensis</I> Isolates Against Immature Horn Fly and Stable Fly (Diptera: Muscidae)

Abstract

We screened 85 isolates of Bacillus thuringiensis (Berliner), making up 57 different subspecies, and two isolates of Bacillus sphaericus (Meyer and Neide) for activity against immature horn flies, Haematobia irritans (L.), and stable flies, Stomoxys calcitrans (L.). The majority of B. thuringiensis and the B. sphaericus isolates had little or no activity against horn fly and stable fly. Approximately 87% of the isolates caused < 50% mortality of horn fly larvae and 64% caused < 25% mortality. For stable fly, 95% of the isolates caused < 50% mortality, and 93% caused < 25% mortality. Five isolates were highly toxic to horn fly and stable fly immatures. These isolates were B. t. tolworthi 4L3, B. t. darmstadiensis 4M1, B. t. thompsoni 401, B. t. thuringiensis HD2, and B. t. kurstaki HD945. The LD50 values ranged from 2.2 to 7.9 x 10(6) spores per g manure for horn fly and from 6.3 to 35 x 10(6) spores per g media for stable fly. These were consistently more toxic compared with the B. t. israelensis isolates examined. All had DNA that hybridized with cry1Aa, cry1Ab, and cry1Ac toxin probes, three hybridized with a cry1B probe, and two hybridized with a cry2A probe. These may have potential for use in integrated management of pest flies.

Effects of Temperature on Mortality of Larval Stable Fly (Diptera: Muscidae) Caused by Five Isolates of Bacillus thuringiensis

“…Five isolates of B. thuringiensis were used that had previously shown activity against stable ßy (Lysyk et al 2010 Bacterial Spore Cultures. Bacterial isolates were cultured separately in medium containing 8 g/liter nutrient broth (BD Biosciences, Cockeysville, MD), 2-mM MgSO 4 , 1-mM CaCl 2 , 10 Ϫ5 -M MnCl 2 , and 10 Ϫ6 -M FeSO 4 .…”

“…Recently, we identiÞed several isolates of Bacillus thuringiensis that have activity against larval stable ßies (Lysyk et al 2010). These isolates included B. t. tolworthi 4L3,B.…”

Entomopathogens in control of urban pests

“…Early research with exotoxin-producing strains of B. thuringiensis was promising, but the shift in emphasis to endotoxin-only strains with high activity against Lepidoptera limited discovery of fly-active strains (1,36,50). Surveys have suggested that strains with high levels of the Cry1B endotoxin are more virulent than other strains for muscoid flies (37). Recent successes with B. thuringiensis var.…”

Mortality of Adult <I>Stomoxys calcitrans</I> Fed Isolates of <I>Bacillus thuringiensis</I>

“…Several reports have indicated activity against tick species as well (Zhioua et al 1999, Fernández-Ruvalcaba et al 2010. Recently, we have reported on several isolates that have activity against immature stable ßy (Lysyk et al 2010, Lysyk andSelinger 2012). Because these isolates have already shown activity against immature stable ßies, we conducted the current study to examine whether they had activity against adult stable ßy.…”