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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Lentic Ecology
MIDGES, COOTS AND CONDOS: TROUBLE IN PARADISE! PART II. EXPERIMENTAL RESULTS AND CONCLUSIONS.
M.B. Berg1, R.W. Merritt2, and A. Ali3. 1Department of Biology, Loyola University Chicago, Chicago, Illinois 60626, 2Departments of Entomology and Fisheries and Wildlife, Michigan State University, East Lansing, MI 48824, 3Mid-Florida Research and Education Center, IFAS, University of Florida, Apopka, FL 32703
A 7-wk study was conducted in Kealia Pond, Maui, HI, to assess the efficacy of Bacillus thuringiensis serovar. israelensis (Bti) and methoprene in controlling populations of an introduced, pestiferous chironomid, Polypedilum nubifer, and to determine whether treatments affected non-target organisms or organisms in off-treated sites. Four experimental plots along each of six transects were established in the pond with plots on each transect receiving either Bti (13.9 lbs/acre), low methoprene (5 lbs/acre), high methoprene (10 lbs/acre), or no treatment (control). Benthic invertebrates were sampled using a PVC core and emerging adults were collected using submerged emergence traps. The only benthic non-target organism collected was a native chironomid, Chironomus hawaiiensis. Polypedilum nubifer emergence was significantly reduced (p<0.05) only in methoprene plots with reductions lasting for 10-d (low rate) and 17-d (high rate) post-treatment. Chironomus hawaiiensis emergence was not significantly affected. Larval densities of both species in Bti and methoprene plots were not significantly different from control plots. In addition, larval densities or adult emergence of either species were not affected at off-treated sites. These results suggest that methoprene is effective at reducing the emergence of P. nubifer, and will not impact larval populations, an important forage base for endangered waterbirds.
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