Detection of Pissodes strobi (Coleoptera: Curculiondae) using large-scale 70 mm colour photography

S. P. Taylor, B. S. Lindgren, J. Johnson

Abstract


A 17 year old white spruce plantation with a current rate of white pine weevil infestation of 23% was photographed using 70 null colour photography at scales of 1:500 and 1:650. The two photo-scales were then interpreted by two different sets of photo-interpreters, with varying degrees of experience, and compared to ground surveys. Results showed that the use of skilled photo-interpreters improved the accuracy of interpretation of current weevil attacks by 18% to 79% over the use of unskilled interpreters. A significant relationship was also observed between the amount of red foliage remaining on the leader and the accuracy of interpretation of current attacks. Large-scale 70 mm photography can detect currently attacked spruce leaders as small as 35 by 30 cm with an accuracy approaching 90% providing at least 30% of the red needles remain on the damaged leader and experienced photo-interpreters assess the results.

Key words: white pine weevil; Pissodes strobi; colour photography; aerial survey


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