Black fly (Diptera: Simuliidae) control in the catchment area of the river Rur (Nordrhein-Westfalen) with biological larvicide Bacillus thuringiensis var. israelensis (B.t.H-14)
1988
Deschle, W.E. (Tuebingen Univ. (Germany, F.R.). Inst. fuer Tropenmedizin) | Rutschke, J. | Hagen, H.-E. | Stamer, M.
In 1986 and 1987 a pest control was carried out in the districts of Dueren and Heinsberg with the nonsporing B.t.H-14 formulation Teknar(R) HP-D (Sandoz Inc., Basle), because of an increasing number of injuries to cattle and men caused by black flies in spring during the last few years. After a careful examination of the breeding sites, 116 kms of 12 streams in the district of Dueren were treated in March and April 1986 with 1082 l Teknar(R) HP-D. During a second treatment op approximately 188 kms of 25 streams in the early spring of 1987, which included both districts, 1860 l of the same formulation were used. The larvicide was applied subject to the water discharge, water temperature, flow rate, and the level of pollution at a concentration of 1-5 ppm/10 min. The distance between the application sites ranged from 50 to 1.000 m due to the differing characteristics of the streams. Almost all larvae, mainly from the most important pest-species Odagmia ornata s.1., were eradicated. Thus the attacks of female black flies of the spring generation, causing most of the injuries to cattle and men could be decisively reduced. Because of reinvasion, surviving larvae and previously existing pupae at the time of treatment, the black fly population can be rebuilt to its original density. Therefore the treatments have to be repeated every year before pupation of the spring generation
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