Long-lasting effects of a Bacillus thuringiensis serovar israelensis experimental tablet formulation for Aedes aegypti (Diptera: Culicidae) control.
Dengue is a growing public health problem in many tropical and subtropical countries worldwide. At present, the only method of controlling or preventing the disease is to eliminate its vector, Aedes aegypti (L.) (Diptera: Culicidae). In the current study, an experimental larvicide tablet formulation XL-47 based on Bacillus thuringiensis serovar israelensis (Bti) and containing 4.8% of technical powder was developed. This formulation was evaluated against Ae. aegypti in three different sets of experiments, under field-simulated conditions: two experiments were indoors and under partial sunlight exposure and one experiment was outdoors with sunlight exposure. Larvae were added throughout the experiment two times per week, and the residual larvicidal activity was recorded daily. Pupal formation was reduced in the containers with Bti by > 80% in relation to the containers without treatment for 12 wk; to our knowledge, this is the longest period of control reported for a Bti tablet formulation outdoors under sunlight exposure. Moreover, samples from the top, middle, and bottom of the water column were collected to perform bacterial plate counts and toxicity assays. The Bti population and the active ingredient of the tablet formulation remained mainly at the bottom of the containers and mosquito larvae reached the formulation by diving and shredding the tablet's material. In conclusion, the experimental tablet formulation XL-47 showed an inhibition of pupal formation that lasted for long periods under sunlight exposure.
Armengol
Gemma
G
Unidad de Biotecnología y Control Biológico, Corporaci6ón para Investigaciones Biológicas, Medellín, Colombia. gemma.armengol@uab.es
Hernandez
Johana
J
Velez
Jose G
JG
Orduz
Sergio
S
D000330:Aedes; D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000008:administration & dosage*; D001427:Bacterial Toxins / Q000008:administration & dosage*; D004731:Endotoxins / Q000008:administration & dosage*; D006460:Hemolysin Proteins / Q000008:administration & dosage*; D007306:Insecticides / Q000008:administration & dosage*; D007814:Larva; D010572:Pest Control, Biological / Q000379:methods*; D013997:Time Factors; D014867:Water
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis; D014867:Water