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Formulation of a flowable liquid concentrate of Bacillus thuringiensis serotype H‐14 spores and crystals as mosquito larvicide
Author(s) -
Ejiofor A.O.,
Okafor N.
Publication year - 1991
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1991.tb04448.x
Subject(s) - spore , bacillus thuringiensis , population , larvicide , food science , biology , chemistry , toxicology , aedes aegypti , botany , larva , bacteria , demography , genetics , sociology
A.O. EJIOFOR AND N. OKAFOR. 1991. Bacillus thuringiensis serotype H‐14 spores and crystals, produced in 5 1 fermenters, were centrifuged and resuspended in emulsified palm olein to give 3.2 × 10 11 colony forming units (cfu)/ml. The suspension was mixed with a cassava—molasses—palm olein—charcoal (CMPC‐2) mixture which served as the carrier, adhesive, dispersant and protectant. The final concentration of the formulation was 3.2 × 10 9 cfu/ml. The lethal concentrations capable of killing 50% of the test population (LC 50 ) of CMPC‐2 during 0, 1 and 2 years of storage at 32 ± 4.C were 0.056, 0.058 and 0.058 mg/ml respectively as against 0.054, 0.051 and 0.054 mg/ml for the Institut Pasteur Standard—1978 (IPS‐78) during the corresponding period. The 2 tests showed that the results were homogeneous at P = 0.05. The relative potencies of the preparation were 964.3, 879.3 and 931 International toxic units (ITU) Aedes aegypti as compared with the 1000 ITU assigned to IPS‐78. At 95% confidence limits there was no significant difference between the potencies of CMPC‐2 and IPS‐78. Field tests showed that CMPC‐2 provided between 87.5 and 100% control of natural populations of Aedes spp. and Cutex spp. Sedimentation tests showed that CMPC‐2 settled markedly during storage. This, therefore, required that the product be thoroughly shaken before use.