Hexagenia Bilineata Research Articles

Activation of Insect Cholinesterase by n-Butanol, Autolysis, and Surfactants1

Several workers have observed the enhancement of insect cholinesterase (ChE) activity by (1) water-miscible organic solvents, (2) autolysis, and (3) surfactants (e.g., sodium taurocholate and Triton X-100) (Metcalf and March 1950, Colhoun 1961, Dauterman et al. 1962, Shatoury 1963, Edwards and Gomez 1966, Lewis 1967, Krysan and Chadwick 1970, Krysan and Kruckeberg 1970). These same agents can solubilize insect ChE (Edwards and Gomez 1966, Krysan and Chadwick 1970, Krysan and Kruckeberg 1970). It has been concluded that all 3 of these treatments increase ChE activity by the same mechanism (Edwards and Gomez 1966, Lewis 1967) and further that activation is related to solubilization (Edwards and Gomez 1966). We record here Ch1E observations of the house fly, Musca domestica L.; the mayfly Hexagenia bilineata (Say); and the honey bee, Apis mellifera L., which show that the several phenomena cannot be explained by a single mechanism. Enzyme extraction conditions and ChE activity-measurement methods have been described (Krysan and Chadwick 1962, 1970). During autolysis, a drop of toluene was added to retard bacterial action. Each datum is the mean of 3 independent measurements.

A Pre-Impoundment Bottom-Fauna Study of Watts Bar Reservoir Area (Tennessee)

Abstract Pre-impoundment bottom-fauna data are presented for the Watts Bar Reservoir area (Tennessee). A salting-out technique is described which was used to facilitate the separation of organisms from debris. In deep water four major taxonomic groups made up 98.93 per cent of the total number and practically 100 per cent of the total volume. Nymphs of Hexagenia bilineata (Say) composed 82.43 per cent of the total volume. This species probably has a 1-year life cycle in Tennessee. Production was highest on the muddy bottom and lowest on sand. Data on depth distribution showed the first 10 feet to be most productive. The seasonal peak of production was reached during September and October. This maximum was due almost entirely to mayflies. The rate of growth of Hexagenia nymphs was most rapid during August and September or immediately following hatching. The riffles and flats at the shallow-water station were less productive than the mud-sand bottom of the deep water. The fauna of the riffles and flats will...

NOTES ON THE SPECIES OF THE GENUS HEXAGENIA WITH DESCRIPTION OF A NEW SPECIES (EPHEMEROPTERA)

In a pamphlet entitled “Burrowing Mayflies of Our Larger Lakes and Streams,” published in 1920 in the Bulletin United States Bureau of Fisheries, Vol. XXXVI, pp. 269-292, Professor Needham, discussing the species of the genus Hexagenia, makes the statement (op. cit. p. 279) that he is “unable to recognize more than two good and distinct species in the Eastern United States—a lowland species from lakes and rivers, Hexagenia bilineata Say. and an upland bog-stream species, H. recurvata Morg.” He amplifies this statement in previous paragraphs (p. 278) by applying the name bilineata Say. “to all the variants of the species that occupies the beds of our larger lakes and streams. The color differences appear to be only differences of degree. Even the differences of male genitalia—usually our ultimate criteria of species—are intergradient.”