Studies on coleophora caespititiella zell. (Lep.) associated with juncos squarrosus L

Abstract

- being a thesis presented by Anthony M. Jordan in candidature for the Degree of Doctor of Philosophy in the University of Durham, 1955. Investigations on the relationship between the moth, Coleophora caespititiella Zell., and the rush, Juncas sauarrosus L., were carried out on the Moor House Nature Reserve, in the northern Pennines, from 1952 to 1954.Details of the life-history of G. caespititiella. which in the larval stage feeds on the seeds of various rush species, are given. Behaviour studies were carried/out on the final instar larvae (marking experiments showed that these visited a mean of 2.28 rush capsules during their feeding period in 1953) and also on the imagines. J. squarrosus is shown to 'be broadly distributed over the study area. The capacity of the rush to produce ripe seeds diminished with increasing altitude, and fruiting was less extensive in the cool summer of 1954 than in the two preceeding seasons. The distribution of Coleophora closely corresponded to the degree of ripe seed production by the rush in each season. In all years ripe seed production and Coleophora infestation of the rush to any given extent, occurred about 300’ higher on the eastern Pennine slopes than on the western. Hymenopterous parasites of the Coleophora. Larvae were recorded only in populations below 1050’ on the western and 1525’ on the eastern Pennine slopes. Seasonal surveys of two Coleothora populations are described. Heavy mortality was demonstrated in the egg and early larval stages and also in the overwintering larval population in the ground litter. Some evidence for competition between early instar Coleophora larvae inside mature rush capsules is presented. It is suggested that competition at this stage would result in a degree of mortality dependent on the density of the initial larval population. The various mortality factors affecting different Coleophora populations are discussed.