Sammanfattning

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera, occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine. P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta. however. there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.

Nyckelord

defoliation; Diptera : Cecidiomyiidae; extended larval diapause; insect outbreak; novel host associations; Pinus contorta; Pinus sylvestris; plant vigour

Publicerad i

Scandinavian Journal of Forest Research
2002, Volym: 17, nummer: 2, sidor: 150-157
Utgivare: TAYLOR & FRANCIS AS

SLU författare

• Glynn, Carolyn

  • Institutionen för entomologi, Sveriges lantbruksuniversitet
    
  • Skogforsk

• Lindelöw, Åke

  • Institutionen för entomologi, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Ekologi
Skogsvetenskap


Publikationens identifierare

DOI: https://doi.org/10.1080/028275802753626791

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/68801