Bionomics of the four‐eyed spruce bark beetle, Polygraphus rufipennis(Kirby) (Col., Scolytidae) in Newfoundland I. Emergence and flight patterns

• Published in: Journal of Applied Entomology
• Main Authors: Bowers, W. W., Borden, J. H., Raske, A. G.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1996
• Subjects: Newfoundland
• Online Access: http://dx.doi.org/10.1111/j.1439-0418.1996.tb01625.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1439-0418.1996.tb01625.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1439-0418.1996.tb01625.x

Abstract: Emergence patterns and sex ratios of P. rufipennis infesting black spruce were investigated using on‐tree emergence traps. Totals of 242 and 255 beetles (5.0 and 4.0 per 100 cm 2 ) emerged in the traps in 1983 and 1984, respectively. Emergence began on 23 May 1983, and continued for c . 11 weeks; 50% of the adults had emerged by 15 (1983) and 20 June (1984). Generally, fewer beetles emerged as bole height increased. Thinner bark higher in the bole was correlated with decreased beetle emergence and probably reflects lower brood survival. In both years female‐biased sex ratios occurred early in the emergence period but overall female to male sex ratios for 1983 and 1984 were 1.1:1 and 1.9:1, respectively. Differential mortality caused by the interaction of cold temperatures and host characteristics may have accounted for departure from 1:1 brood sex ratio. Two peaks of flight activity corresponded strongly to patterns of brood emergence in spring and to parent adult re‐emergence in summer.