The damage caused by bloodsucking insects to the health of people is enormous. They are mass bloodsuckers, as well as carriers of pathogens of a number of diseases. At present, several billion people live on the Earth in epidemic zones, where malaria, yellow fever, Dengue fever, encephalitis and other vector-borne diseases are spread by blood-sucking mosquitoes.
There are about 3,000 mosquito species, of which more than 100 are carriers of human pathogens.
At present, chemical insecticides remain the main means of fighting blood-sucking insects, to which insects develop resistance fast enough, which requires either increasing dosages or rotating of insecticides. Without selective action, chemical insecticides cause the death of non-target, and often beneficial organisms. The accumulation of insecticides in natural components (water, soil, etc.) makes them environmentally hazardous, so biological agents are increasingly used to destroy larvae.
One of the most promising bioinsecticides are preparations derived from the microorganism Bacillus thuringiensis . For various subspecies of B. thuringiensis , the formation of insecticidal proteins (δ-endotoxins) characterized by high specificity of the biological effect is characteristic. These toxins are active against insect larvae from various orders of Lepidoptera , Coleoptera and Diptera , as well as nematodes. At the same time, they are absolutely harmless for most non-target objects. In particular, the toxins produced by Bacillus thuringiensis var. Israelensis , eliminate many species of mosquitos’ larvae, including malaria mosquito or anopheles, but are harmless to the rest of the reservoir’s fauna.
The main advantage of biological preparations when compared with chemical ones is the action selectivity. For all the time of use of biopreparations, no cases of their negative impact on other organisms have been recorded. There was also no evidence of insect resistance to these preparations. Given the ability of Bacillus thuringiensis var. Israelensis to synthesize 4 types of protein toxins, it is hardly possible to predict the resistance appearance in the future.
The biological effect of the δ-endotoxins of the Bactoculicide preparation is based on their cytopathological effect on the epithelial cells of the insect intestine.
In turn, the specificity of these proteins is determined by their interaction with receptors located in the apical membrane of epithelial cells. Bactoculicide is an intestinal poison for all mosquitoes’ larvae kinds. Getting into the larvae’s body, the toxin causes digestive process violation, toxicosis and death.
The larvae’s timing of death varies from several hours to several days and depends on the concentration of working suspension, the age and physiological state of the larvae, and the reservoir’s hydrological and biocenotic characteristics.
Bactoculicide is intended for use in reservoirs of any type, basements, hydroconstructions and other breeding grounds for mosquitoes.
Form of product release and composition
Sporocrystalline complex which contains δ-endotoxin of entomopathogenic spore bacteria Bacillus thuringiensis var. israelensis , which appears in the process of culture fermentation.
Method of preparation of working suspension
Bactoculicide is used as 0,5-5,0 % water suspensions (on preparation) for the larvae control of mosquitoes, and also in the concentration 5,0-10,0 % water suspensions. Workings liquids are prepared just before the application. Before the carrying out of treatments the necessary amount of preparation is determined based on the type of reservoirs.
The preparation of working suspension is carried out in two stages:
1) to dissolve the preparation in the small quantity of water for the receiving of homogeneous paste-like mass;
2) then the got paste is diluted with water at continuous mixing to the necessary volume of working suspension. For the preparation of working suspension it is necessary to use any water with the temperature not higher then + 30°C.
The method and rate of application
The mosquitoes’ larvae control.
The control of the mosquitoes’ larvae is conducted by the land method or with the use of aviation (helicopters). To begin the treatment is expedient in the period of predominance of larvae of 2-3 ages. The application rate of the preparation is determined on base of the specific kind of mosquitoes’ larvae, size and type of reservoir, degree of water pollution.
- shallow (depth 0,3-0,5 m) with little and middle plant-filled reservoirs, settled with larvae of 1 and 2 ages 0,5% water suspension is used at the application rate 0,5 kg/hectare; settled with larvae 3-4 ages 1% water suspension is used at the application rate 1,0 kg/hectare;
- reservoirs with depth over 0,5 m with high plant-filled reservoirs, settled with larvae 1 -2 age, 1,0 % water suspension is used at the application rate 1,0 kg/hectare; settled with larvae 3-4 age - 1,5 % water suspension at the application rate 1,5 kg/hectare;
- reservoirs badly polluted with organic substances (dehydration boxes, drain ditches etc.) 3,0% water suspension is used at the application rate 3,0 kg/hectare. The application rate of water suspension makes 100 l per hectare.
- For elimination of malaria mosquito larvae the preparation is used at the application rate 2-3 kg/hectare.
- At treatment of reservoirs which are in basement and reservoirs formed by subsoil waters for elimination of larvae 1-2 ages 2,0% water suspension is used at the application rate 0,1 g/m^2; for elimination of larvae 3-4 ages 3,0 % water suspension is used at the application rate 0,15 g/m^2.
- At treatment of reservoirs formed by waste water the application rate of the preparation is increased to 0,3 g/m^2 the application rate of water suspension makes 50 l/hectare. The repeated treatments are conducted according to entomological certificate.
- The residual larvicidal effect of the preparation depends on chemical composition of water, content of organic admixtures, illuminance and temperature condition of reservoir, age of larvae, and varies within 5-10 days. For treatment of basements the hydraulic sprayers, quasars, hand or knapsack sprayers with a long bar are used.
- Small area basement reservoirs can be treated by dry preparation which is sprayed on a surface.
Mosquitoes’ larvae (chironomids) control.
At treatment of reservoirs which are in basements and reservoirs formed by subsoil waters for elimination of larvae 1-2 ages 2,0% water suspension is used at the application rate 0,3 g/m^2; for elimination of larvae 3-4 ages 3,0% water suspension is used at the application rate 0,5 g/m^2. For the treatment of natural reservoirs the places of mosquitoes’ larvae development are treated. The application rate is 3-9 kg/hectare. The treatment of water intake is prohibited.
In accordance with government standards it refers to low-hazard for human health and the environment - IV Hazard class – «low-hazard».