Document Detail

Evaluation of polymer-based granular formulations of Bacillus thuringiensis israelensis against larval Aedes aegypti in the laboratory.
MedLine Citation:
PMID:  12542194     Owner:  NLM     Status:  MEDLINE    
A strategy to increase residual activity of Bacillus thuringiensis serovar. israelensis (Bti) extract through slow-release formulations and protection from solar radiation was studied. The median lethal concentration (LC50) and 90% lethal concentration (LC90) levels of laboratory-reared early 4th-stage larval Aedes aegypti after exposure to Bti extract were determined. Formulations with 4 polymers and 1 solar protectant were prepared, and their shelf lives were evaluated for year-long storage at 20-35 degrees C and 50-80% relative humidity. Also, the effect of ultraviolet light on unformulated (extract) and formulated Bti larvicidal activity persistence was determined. Laboratory bioassays were conducted with larval Ae. aegypti introduced into treated and control containers at 1, 2, 7, 14, 21, 28, 35, and 42 days after treatment, and larval mortalities were checked 24 h after introduction. Probit analysis of Bti extract showed LC50 and LC90 values of 0.016 and 0.051 mg/liter, respectively. The polymer-based Bti formulations showed no significant loss of insecticidal activity after 8 months of storage. Ultraviolet irradiation reduced activity of unformulated Bti extract after different exposure times, up to 40-46%, whereas Bti formulated with gelatin or acacia gum showed lower variation in larvicidal activity than formulations with sodium alginate and paraffin for protecting the activity of Bti toxin. Residual activity against 4th-stage Ae. aegypti in the laboratory for the formulation containing acacia gum at 10% (w/w) was 80% mortality at 14 days after treatment, whereas the Bti formulation containing gelatin (10%, w/w) caused 65% mortality. In addition, Bti formulations made with paraffin at 5% (w/w) sustained up to 60% mortality for 21 days. Unformulated Bti showed only 2.6% mortality, and a commercial preparation maintained 37% mortality, both at 14 days after treatment.
María Guadalupe Maldonado Blanco; Luis Jesús Galán Wong; Cristina Rodríguez Padilla; Humberto Quiroz Martínez
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of the American Mosquito Control Association     Volume:  18     ISSN:  8756-971X     ISO Abbreviation:  J. Am. Mosq. Control Assoc.     Publication Date:  2002 Dec 
Date Detail:
Created Date:  2003-01-24     Completed Date:  2003-02-10     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8511299     Medline TA:  J Am Mosq Control Assoc     Country:  United States    
Other Details:
Languages:  eng     Pagination:  352-8     Citation Subset:  IM    
Departamento de Microbiología e Inmunología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, C.P. 66450, A.P. 105-F, San Nicolás de los Garza, Nuevo León, México.
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MeSH Terms
Bacillus thuringiensis* / radiation effects
Delayed-Action Preparations
Glucuronic Acid
Gum Arabic
Hexuronic Acids
Pest Control, Biological*
Time Factors
Ultraviolet Rays
Reg. No./Substance:
0/Alginates; 0/Delayed-Action Preparations; 0/Hexuronic Acids; 0/Polymers; 576-37-4/Glucuronic Acid; 8002-74-2/Paraffin; 9000-01-5/Gum Arabic; 9000-70-8/Gelatin; 9005-32-7/alginic acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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