John B. Dimond

Persistence of DDT in Crayfish in a Natural Environment

DDT residues were measured by gas chromatography in crayfish collected in streams sprayed a single time but in various past years, in streams sprayed two and three times, and in streams never sprayed. Residues in the year of treatment ranged from 0.5 to 2.5 ppm. By 2 yr after treatment, residues had declined to about 0.1 ppm but remained near this level through 9 yr after treatment. Crayfish in unsprayed streams carried uniformly low residues, 0.009-0.014 ppm. Prolonged contamination in crayfish in sprayed watersheds apparently derives from highly persistent soil residues. Ecological significance of these residue

IPM and the spruce budworm: Lessons learned in Maine 1950–1985

Abstract The outbreak of the spruce budworm (Choristoneura fumiferana (Clemens)) from 1970 to 1985 has declined drastically in Maine, remaining only in about 2000 ha along the southeast coast. Because a new, severe outbreak may not be anticipated for a few decades, we have prepared an analysis and history of Maines experience with the recent outbreak as a guide for managers of any forthcoming outbreak. In this paper, we review our conclusions on the effects of the outbreak on the forest resource and its users, on the effectiveness of spraying, and on the silvicultural responses to the outbreak, and we make predictions for the nature management of outbreaks and the roles of the responsible agencies.