Bacterial infection of black flies larvae and bacterial preparations application for quantity control of Simuliidae

Abstract

Considerable attention is paid to the biological method of controlling the number of blood-sucking insects, as it is highly selective, effective and environmentally safe. 340 reservoirs were examined within Volyn Polissia, among which 86 (14,9%) contained Simuliidae larvae with signs of bacterial lesion. Damaged larvae were recorded in small rivers and ameliorative canals, most of which, 71,5%, were mesosaprobic in terms of water quality. Bacterial infection was detected in the larvae of 10 species: S. pusillum, S. nigrum, S. equinum, S. erythrocephalum, S. ornatum, S. dolini, S. noelleri S. paramorsitans, S. promorsitans, S. morsitans. Оn Volyn Polissia a study was conducted on the effectiveness of reservoirs delarvation with three preparations based on Bacillus thuringiensis H14 bacteria - bactoculicide, bactolarvicide and BLP-2477. Experiments were carried out in ameliorative canals with a bed up to 2 m wide, 0.5 m deep and with a current speed of 0.7 m/s, which were densely populated by preimaginal phases of black flies. Treatment of the reservoir with preparations was carried out in two ways. The first consists in a one-time introduction of the entire dose, the second - in a gradual introduction of the dose over 6 and 24 hours. It was established that a single application of the entire dose of the preparation ensures only partial death (up to 75%) of black flies. An uneven death of larvae was registered in the entire area of treatment. The method of gradual introduction of the preparation, when it is washed out over 6 or 24 hours, is more effective (death of larvae up to 100%). To the quantity control of the black flies pre-imaginal phases development, preparations BLP-2477 and bactolarvicide are recommended as the most effective. The optimal dose for the death of black flies larvae at a distance of up to 1.5 km in ameliorative canals with width of up to 2 m, depth of 0.5 m and a flow speed of 0.7 m/s should be considered 400 g of the preparation. The deaths of non-target hydrobionts, caddisflies, mayflies, molluscs, and fishes were not registered. Key words: Simuliidae, Bacillus thuringiensis, reservoirs delarvation, bactoculicide, bactolarvicide, BLP-2477.