Parasites of the larch casebearer, <i>Coleophora laricella</i> (Lepidoptera: Coleophoridae), in the West Kootenay area, British Columbia

Abstract

The parasite complex of the larch casebearer, <i>Coleophora laricella</i> (Hbn.), was investigated in the Kootenay area of British Columbia in 1973 and 1974. Forty-one species of hymenopterous parasites were obtained from rearings of almost 153,000 final-instar host larvae and pupae. In 1973 and 1974, 31 and 24 species, respectively, were reared, with 14 common to both years. Twenty-nine of these, in 24 genera, were confirmed as larch casebearer parasites by individual rearings and by reports in the literature. No parasites were obtained from eggs, needle-mining larvae, or third-instar case-bearing larvae. The highest total percentage parasitism was 17.7% in 1973 and 24.5% in 1974, both at Rossland. In Collection II the <i>Dicladocerus</i> spp. complex comprised 46.0% of the total parasitism in 1973. and 63.8% of the total in 1974: it was the most abundant at four of the eight collecting sites in 1973 and 13 of the 14 sites in 1974. <i>Spilochalcis albifroms</i> (Walsh) comprised 32.8% and 23.5% of the total parasitism in the years 1973 and 1974 respectively; it was most abundant at three collection sites in 1973 and at two in 1974. <i>Mesopolobus</i> sp. constituted 4.9% of the total in 1973 and 9.9% in 1974. Larch case bearer densities in the first collection in 1973 were highest at Fruitvale and Shoreacres with 150 and 130 cases per 100 fascicles respectively; in 1974, the highest host densities in the first collection were at Kootenay Bay and Fruitvale with 48 and 41 cases per 100 fascicles respectively.