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EFFICIENCY OF SUCROSE FLOTATION IN RECOVERING INSECT LARVAE FROM BENTHIC STREAM SAMPLES

Published online by Cambridge University Press:  31 May 2012

Wayne M. Pask
Affiliation:
Department of Biological Sciences, State University of New York, Brockport
Robert R. Costa
Affiliation:
Department of Biological Sciences, State University of New York, Brockport

Abstract

Duplicate benthic stream samples were collected from three sites on Sandy Creek (Lake Ontario Watershed) in Western New York, 8 and 22 September, 1970. Samples taken on 8 September were preserved in 10% formalin. Samples taken on 22 September were not preserved. Insect specimens were removed from both sets of samples by flotation with a sucrose solution of 1.12 sp. gr. Preserved and unpreserved samples were compared for efficiency of recovery of insect larvae. Mean recovery for preserved samples was 90.78% compared with 83.03% for unpreserved samples. The range of recovery values for unpreserved samples (66.7%) was more than twice as great as that of preserved samples (29.5%). A paired t-test for means of all taxa showed no significant difference (P < 0.001) between recovery values for preserved and unpreserved samples. In fact, preservation may enhance the recovery of certain groups—Zygoptera, Hemiptera, Trichoptera, and Chironomidae. Apparently samples may be preserved without sacrificing recovery of any specific groups of insect larvae.

Type
Articles
Copyright
Copyright © Entomological Society of Canada 1971

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