%0 Journal Article %J Journal Invertebrate Pathology %D 1987 %T Studies on the Culicine Mosquito Host Range of Bacillus sphaericus and Bacillus thuringiensis var. israelensis with Notes on the Effects of Temperature and Instar on Bacterial Efficacy %A Wraight, S. P. %A D. P. Molloy %A Singer, S. %K Aedes %K Bacillus sphaericus %K Bacillus thuringiensis %K Biological control %K Culex %K Culiseta %K israelensis %X
Toxicity tests of three strains of Bacillus sphaericus against late instars of 12 culicine mosquito species indicated a wide range of susceptibility. Culex pipiens and C. salinarius were highly susceptible (LC50s < 104 spores/ml) to strain 1593, and C. pipiens and C. restuans were highly susceptible to strain 2013-4. The potency of strain SSII-1 was approximately one-tenth that of strains 1593 and 2013-4 against C. pipiens. Susceptibility of Aedes species to strain 1593 was highly variable. At temperatures ≥ 20°C, A. fitchii, A. intrudens, A. stimulans, and A. vexans were moderately to highly susceptible (LC50s 6 × 103−4 × 104 spores/ml), A. triseriatus was only slightly susceptible (LC50 > 106 spores/ml), and A. aegypti was refractory. Susceptibility of Aedes mosquitoes to strain SSII-1 was less variable, with LC50s against A. aegypti, A. canadensis, A. stimulans, and A. triseriatus all being between 104 and 106 vegetative cells + spores/ml. All species of mosquitoes tested were, in general, highly susceptible to B. thuringiensis var. israelensis (LC50s 2.3 × 103−2.5 × 104 spores/ml). In B. sphaericus toxicity tests, decreased temperatures resulted in up to a 16-fold increase in LC50 and a substantial reduction in probit line slope. First-instar A. aegypti larvae were more susceptible to B. sphaericus strain SSII-1 than the three later instars, which were approximately equally susceptible; however, no significant difference was observed in the susceptibility of the four instars of A. triseriatus.
%B Journal Invertebrate Pathology %V 49 %P 291-302 %G eng %U http://www.sciencedirect.com/science/article/pii/0022201187900619 %R 10.1016/0022-2011(87)90061-9 %0 Journal Article %J The Canadian Entomologist %D 1982 %T A Comparison of Laboratory and Field Tests of Bacillus sphaericus Strain 1593 and Bacillus thuringiensis var. israelensis Against Aedes stimulans Larvae %A Wraight, S. P. %A D. P. Molloy %A McCoy, P. %K biology %X

Bacillus thuringiensis var. israelensis (serotype H-14) and B. sphaericus strain 1593 were tested against Aedes stimulons larvae in the laboratory and in 38-cm-diam, open-ended cylinders embedded in the bottom detritus of a woodland pool. Estimates of LC50 were lower against fourth instars in the field at a mean temperature of 15.9 °C than in the laboratory at 21.1 °C. The greater efficacy in the field was attributed to high daytime water temperatures (mean 20.5 °C) following treatment and exposure of the larvae to substantially greater amounts of toxic material in a larger volume of water than in the laboratory. The regression of probit on log10 concentration was not linear over the entire range of mortality caused by B. sphaericus, increasing the difficulty of estimation of LC values. Bacillus sphaericus was significantly less active than B. thuringiensis.

%B The Canadian Entomologist %V 114 %P 55-61 %G eng %R 10.4039/Ent11455-1 %0 Journal Article %J Journal of Invertebrate Pathology %D 1981 %T Effects of Temperature and Instar on the Efficacy of Bacillus thuringiensis var. israelensis and Bacillus sphaericus Strain 1593 Against Aedes stimulans Larvae %A Wraight, S. P. %A D. P. Molloy %A H. Jamnback %A McCoy, P. %K Aedes stimulans %K Bacillus sphaericus strain 1593 %K Bacillus thuringiensis var %K Biological control %K israelensis %X
Laboratory trials of Bacillus thuringiensis var. israelensis (serotype 14) and B. sphaericus strain 1593 against field-collected Aedes stimulans showed that susceptibility declined with increasing instar and decreasing temperature. Test results with B. sphaericus were more erratic than with B. thuringiensis, and the efficacy of the former declined more rapidly with decreasing temperature. B. thuringiensis was significantly more active than B. sphaericus under all treatment conditions. These results indicate that the effective use of this strain of B. sphaericus as a mosquito biological control agent may be limited to warm water situations against more susceptible species.
%B Journal of Invertebrate Pathology %V 38 %P 78-87 %G eng %U http://www.sciencedirect.com/science/article/pii/0022201181900379 %R 10.1016/0022-2011(81)90037-9 %0 Journal Article %J The Canadian Entomologist %D 1981 %T Efficacy of Bacillus sphaericus Strain 1593 Against the Four Instars of Laboratory Reared and Field Collected Culex pipiens and Laboratory Reared Culex salinarius %A Wraight, S. P. %A D. P. Molloy %A H. Jamnback %K biology %X

Culex pipiens pipiens and C. salinarius were found equally susceptible in laboratory tests to Bacillus sphaericus strain 1593 with LC50 values for the four instars ranging between 20 and 137 ppb (approximately 820 and 5600 spores/ml). Tests against field collected C. p. pipiens larvae revealed a regularly decreasing susceptibility with increasing larval age, the first instars being between 2 and 5 times more susceptible than fourth instars. In contrast, no significant differences in the susceptibility of second, third, and fourth instars were found in tests of laboratory reared larvae.

%B The Canadian Entomologist %V 113 %P 379-386 %G eng %U http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8542389&fileId=S0008347X0001912X %R 10.4039/Ent113379-5