SOME POPULATIONAL RELATIONSHIPS BETWEEN SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE) AND SPRUCE CONEWORM, DIORYCTRIA RENICULELLOIDES (LEPIDOPTERA: PYRALIDAE)

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Abstract
Coincident populations of spruce budworm, Choristoneura fumiferana (Clem.) and spruce coneworm, Dioryctria reniculelloides (Mutuura and Munroe) were studied to compare spatial distribution, temporal abundance, relative abundance on spruce species, and the relative efficacy of aerial insecticide treatments.Most individuals of both species were found overwintering on the mid-crown branches of red spruce, and a whole branch is a suitable unit for simultaneous sampling of overwintering budworm/coneworm populations on red spruce. Survey records since 1949 show similar geographical and temporal population trends for these 2 insects in Maine. A correlation analysis (r = 0.87) indicates that the size of their coincident populations is related spatially. Both species were found overwintering in nearly equal proportions on red and white spruce sampled from the same stands. But twice as many budworm and coneworm were found overwintering on red spruce when red and black spruce were sampled on the same stands. Due to behavioral or physiological traits the coneworm appeared resistant to aerial spray treatments that significantly reduced budworm populations.