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

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 cm2) 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.

Bark beetles and fungal associates colonizing white spruce in the Great Lakes region

“…in Colorado, are the most common associates of spruce trees infested with Dendroctonus rufipennis. Eleven of the 12 insect species collected in this study have been recorded previously in spruce in Canada, Alaska, and Colorado (McCambridge and Knight 1972;Werner and Holsten 1984;Gara et al 1995;Bowers et al 1996aBowers et al , 1996bPoland and Borden 1998a). To the best of our knowledge Ips grandicollis (Eichoff) (Bright 1976;Wood 1982;Drooz 1985) has not been recorded in Picea previous to this study.…”

“…These beetles are approximately half the size (Wood 1982) of species such as Dendroctonus rufipennis (Knight 1960;Lister et al 1975;Schmid and Fryes 1977) and Dendroctonus ponderosae (Hopkins) (Amman 1972;Rassmussen 1974) that prefer large diameter trees. Likewise, Bowers et al (1996a) found no difference in emergence of Polygraphus rufipennis at various heights along white spruce boles, and Haack (1984aHaack ( , 1984b found only a weak relationship between diameter and emergence of Ips calligraphus (Germar). Some temporal (Fig.…”

“…Most colonization by Dryocoetes affaber occurred in July-August (Fig. 2), in contrast to June in Newfoundland (Bowers at al. 1996a), and July in Alaska and Colorado (Beckwith 1972;McCambridge and Knight 1972).…”

“…1996a), and July in Alaska and Colorado (Beckwith 1972;McCambridge and Knight 1972). Most colonization by P. rufipennis occured in May-June, compared with June in Newfoundland and Maine (Hoskings and Knight 1975;Bowers et al 1996a), and July in Alaska and Colorado (Beckwith 1972;McCambridge and Knight 1972). The peak colonization period of I. pini, July-August, was similar to that reported in red pine plantations in southern Wisconsin (Aukema et al 2000) and pine and spruce stands in Ontario, Canada (Thomas 1961).…”

Bionomics of the four‐eyed spruce bark beetle, Polygraphus rufipennis (Kirby) (Col., Scolytidae) in Newfoundland II. Host colonization sequence

“…The present paper describes the host colonization sequence of P. rufipennis. Results relating to emergence and flight patterns are reported seperately ( BOWERS et al, 1996).…”