The Epidemiology of the Swaine Jack-pine Sawfly, Neodiprion Swainei Midd.

Abstract

Neodiprion swainei, a defoliating s a w f l y specific t o jack pine

Population studies of tree-defoliating insects in Canada: a century in review

“…Between 1940 and1970, outbreaks of jack pine sawfly had a periodicity of around eight years and may have been synchronised regionally (McLeod 1972), although no sufficiently long time series have been published to confirm this periodicity. Although outbreaks are often intense, leading to complete tree-wide defoliation, they are also typically short, often lasting only two to five years (McLeod 1970(McLeod , 1972. Surveys indicated, however, that when outbreaks occurred, populations rose quickly.…”

“…At the time, jack pine was a cheap and easily harvested resource for the pulp and paper industry, and the extensive tree mortality that often followed outbreaks was cause for significant concern (McLeod 1970). Between 1940 and1970, outbreaks of jack pine sawfly had a periodicity of around eight years and may have been synchronised regionally (McLeod 1972), although no sufficiently long time series have been published to confirm this periodicity. Although outbreaks are often intense, leading to complete tree-wide defoliation, they are also typically short, often lasting only two to five years (McLeod 1970(McLeod , 1972.…”

“…Surveys indicated, however, that when outbreaks occurred, populations rose quickly. During an outbreak in Roberval, Québec during the 1960s, for example, populations rose at a rate of 2.6-fold per year (McLeod 1970). At such high growth rates, populations reached tree-killing densities within as few as four years, and peak larval densities rose as high as 9.8 million per ha (McLeod 1970).…”

“…The Swaine jack pine sawfly is a major but infrequent native pest of mature jack pine, Pinus banksiana Lambert (Pinaceae), which has been studied primarily in Ontario and Québec. As of the 1970s, there were approximately two million ha of jack pine stands that were considered susceptible to sawfly outbreaks (McLeod 1970). At the time, jack pine was a cheap and easily harvested resource for the pulp and paper industry, and the extensive tree mortality that often followed outbreaks was cause for significant concern (McLeod 1970).…”

“…As of the 1970s, there were approximately two million ha of jack pine stands that were considered susceptible to sawfly outbreaks (McLeod 1970). At the time, jack pine was a cheap and easily harvested resource for the pulp and paper industry, and the extensive tree mortality that often followed outbreaks was cause for significant concern (McLeod 1970). Between 1940 and1970, outbreaks of jack pine sawfly had a periodicity of around eight years and may have been synchronised regionally (McLeod 1972), although no sufficiently long time series have been published to confirm this periodicity.…”