A BROAD EVALUATION OF BTI FOR BLACK FLY (DIPTERA, SIMULIIDAE) CONTROL IN A MICHIGAN RIVER - EFFICACY, CARRY AND NONTARGET EFFECTS ON INVERTEBRATES AND FISH

Authors:
  • EWED WALKER
    ED WALKER
  • MWMA WILZBACH
    MA WILZBACH
  • KCKW CUMMINS
    KW CUMMINS
  • WMWT MORGAN
    WT MORGAN
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  • 1 September 1989
    • journal article
    • research article
    • Vol. 5  (3) , 397-415
    • PMID:2584974
Abstract
Efficacy for black fly control, carry and nontarget effects of B.t.i. (Teknar HP-D), applied in the Betsie River, Michigan, were studied in June 1988. Black fly mortality was high (.apprx. 100%) for a 2,200 m stretch downstream from the application site, declined to 30% at 3,200 m, and was nil at 4,500 m. Drift of black flies greatly increased after application at a downstream site, but did not change at an upstream site. There were no detectable nontarget effects of B.t.i. application on: 1) invertebrate macro- or micro-drift; 2) numbers of invertebrates in benthic Surber samples; 3) mortality or feeding of drifting and nondrifting insects; 4) growth or mortality of caged Stenomena sp. larvae; 5) invertebrate functional group composition; 6) mortality or weight change of caged rock bass; or 7) fish numbers, species composition, length-weight (rock bass only) relationships or rock bass diet. Sampling of Rheotanytarsus sp. midges on natural substrates indicated low (27%) mortality owing to B.t.i. at only 100 m downstream from the application site, with negligible mortality at all other downstream and upstream sites. This information, combined with no pronounced changes in numbers of midges in macro-drift after application, indicated that midge populations were not adversely affected by B.t.i. in the study.

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