Chemical insecticides may be toxic and cause environmental degradation. Consequently, biological control for insects represents an alternative with low ecological impact. In this work, three soil isolates (A21, A51 and C17) from different regions of the Cuban archipelago were identified, characterized and evaluated against Aedes aegypti and Culex quinquefasciatus. The new isolates were compared with reference IPS82 strain and two strains isolated from biolarvicides Bactivec and Bactoculicida, respectively. The differentiation was done by morphological, biochemical, bioassays activity and molecular methods (SDS-PAGE, plasmid profile and random amplified polymorphic analysis). All isolates were identified as Bacillus thuringiensis. The A21, A51 and C17 isolates showed higher larvicide activity than Bactivec's isolated reference strain, against both A. aegypti and C. quinquefasciatus. A21 isolate had a protein profile similar to IPS82 and Bactivec strain. A51 and C17 isolates produced a characteristic proteins pattern. A21 and A51 isolates had plasmid patterns similar to IPS82 standard strain, while C17 isolate had different both plasmid profile and protein bands. All the studied isolates showed a diverse RAPD patterns and were different from the strains previously used in biological con
The sterile insect technique (SIT) is a promising pest control method in terms of
efficacy and environmental compatibility. In this study, we determined the efficacy
of thiotepa-sterilised males in reducing the target Aedes aegypti
populations. Treated male pupae were released weekly into large laboratory
cages at a constant ratio of either 5:1 or 2:1 sterile-to-fertile males. A two-to-one
release ratio reduced the hatch rate of eggs laid in the cage by approximately a
third and reduced the adult catch rate by approximately a quarter, but a 5:1 release
drove the population to elimination after 15 weeks of release. These results indicate
that thiotepa exposure is an effective means of sterilising Ae. aegypti
and males thus treated are able to reduce the reproductive capacity of a
stable population under laboratory conditions. Further testing of the method in
semi-field enclosures is required to evaluate the mating competitiveness of sterile
males when exposed to natural environmental conditions. If proven effective, SIT
using thiotepa-sterilised males may be incorporated into an integrated programme of
vector control to combat dengue in Cuba.
The use of insect pathogens is a viable alternative for insect control because of their relative specificity and lower environmental impact. The search for wild strains against dipterans could have an impact on mosquito control programs. We have made an extensive screening of soil in western Cuba to find bacteria with larvicidal activity against mosquitoes. A total of 150 soil samples were collected and isolates were identifying using the API 50 CHB gallery. Phenotypic characteristics were analyzed by hierarchical ascending classification. Quantitative bioassays were conducted under laboratory conditions following the World Health Organization protocol in order to ascertain the toxicity and efficacy of isolates. The protein profiles of the crystal components were determined by SDS-PAGE. Eight hundred and eighty-one bacterial isolates were obtained, and 13 isolates with entomopathogenic activity were isolated from nine samples. Nine isolates displayed higher entomopathogenic activity against both Cx. quinquefasciatus and Ae. aegypti compared with the reference strain 266/2. All toxic isolates showed higher biological potency than the 266/2 strain. These isolates with high entomopathogenic activity displayed a protein pattern similar to the B. thuringiensis var. israelensis IPS-82 and 266/2 strains. These results are a valuable tool for the control of Diptera of medical importance. Journal of Vector Ecology 38 (1): 46-52. 2013.
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