Toxicity, parasporal body composition, and plasmid complements of nine isolates of the mosquitocidal bacterium Bacillus thuringiensis subsp. israelensis (H-14) obtained from international standards (Institute Pasteur Standard 78, IPS-80, IPS-82), field isolations (2013-9, 2013-9+),and experimental or commercial formulations (R-153-78, Bactimos, Teknar, Vectobac) were compared. For all isolates, LC50's for fourth-instar Aedes aegypti (L.) were in the range of 9–13 ng/ml, except for R-153-78 (392 ng/ml) and 2013-9 (2,767 ng/ml). Toxicity of the latter two isolates was low because most colonies produced low levels of parasporal bodies, a situation corrected by selecting for colonies that were high in numbers of parasporal bodies. LC50's for the purified parasporal bodies of all isolates were 3–4 ng/ml; no significant differences were obtained among the isolates. Plasmid complements and parasporal body composition of all isolates were also similar. However, isolates IPS-80, IPS-82, Bactimos, and Vectobac lacked a small plasmid of 4.9 megadaltons (mDa). The marked similarity of the nine isolates suggests that most, if not all, isolates of B. thuringiensis subsp.israelensis under study or development as insecticides are closely related to ONR 60A, the original isolate from Israel.
Document Type: Research Article
Publication date: December 1, 1987
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Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.