Parasitoids of the western spruce budworm, <i>Choristoneura occidentalis</i> (Lepidoptera: Tortricidae), in British Columbia, 1977-78
Keywords:
western spruce budworm, <i>Choristoneura occidentalis</i>, Lepidoptera, TortricidaeAbstract
In 1977, the western spruce budworm, <i>Choristoneura occidentalis</i> Free., caused serious defoliation of Douglas-fir (<i>Pseudotsuga menziesii</i> [Mirb.] Franco) over 246,000 hectares, the largest area ever infested by the budworm in British Columbia. The budworm was surveyed in 1977 and 1978, as the population declined; 25 parasitoid species were found. Early-stage larval parasitism averaged 40%, late-stage 20%, and pupal 16% (1977) and 25% (1978). Total parasitism was 61% (1977) and 69% (1978); in 1977, 17% of the egg masses were attacked. Disease incidence was very low. The sudden decline of the budworm in 1978 over the entire infestation, regardless of parasitoid populations, suggested that parasitism was not a major factor. The widespread occurrence of parasitoids throughout the infestation suggests that they would not have been seriously affected overall by pesticide applications on limited areas.
References
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