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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

TitleStudies 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
Publication TypeJournal Article
Year of Publication1987
AuthorsWraight, SP, Molloy, DP, Singer, S
JournalJournal Invertebrate Pathology
Volume49
Pagination291-302
KeywordsAedes, Bacillus sphaericus, Bacillus thuringiensis, Biological control, Culex, Culiseta, israelensis
Abstract
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.
URLhttp://www.sciencedirect.com/science/article/pii/0022201187900619
DOI10.1016/0022-2011(87)90061-9