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Pest Status
Background
Releases and Recoveries
Chapter 59 341
Neodiprion swainei (Middleton), Swaine
Jack Pine Sawfly (Hymenoptera:
Diprionidae)
R.J. FINNEGAN and W.A. SMIRNOFF
At the time of the last review by McLeod & Smirnoff (1971), the population of
Neodiprion swainei (Middleton), Swaine jack pine sawfly, was approaching endemic
levels over most of its range in eastern Ontario and southwestern Quebec, where it has
occurred extensively since the early 1950s. This was thought to be due partly to the
natural collapse of a prolonged infestation and partly to the application of chemical
insecticides in 1965 (Mcleod 1968). Mcleod & Smirnoff (1971) had expected a
recurrence of N. swainei in the 19705, but this did not materialize, probably due to earlier
applications of chemical insecticides against both Swaine jack pine sawfly, N. swainei,
(McNeil et al. 1979) and spruce budworm, Choristoneurafumiferana (Clem.). (Mcleod
1975) in the same general area. The population remained low throughout the 1970s. with
the occurrence of only a few localized light infestations in northern Ontario and western
Quebec.
Parasitoids, predators, and pathogens have all been introduced in attempts to control
sawfly populations. McLeod & Smirnoff (1971) reported that "Before 1958, only small
numbers of Ple%phus basizonlls (Grav.) and Drino bohemica Mesn. were released
against Neodiprion swainei in a few localities in Ontario. However, massive releases of
these two parasitoids, as well as Exenterlls amictorius Panzer and Dahlbominus fuseipennis
(Zett.) were also made in the early 1940s against Diprion hercyniae Htg. in both
Ontario and Quebec. All four species have been recovered from N. swainei in a number
of localities in Quebec since 1958 ... but none in Ontario. E. amictorius and P. basizonus
were most abundant, D. fllseipennis was less common, and only one specimen of D.
bohemica was found". A brief description of the interaction of each parasitoid with N.
swainei was given. Mcleod & Smirnoff also reported on the discovery and successive
recoveries of the Borrelina viral pathogen. The results of one experimental aerial
dispersion of the virus in 1960 and a second in 1964 were reported as "excellent" and
"not as good" respectively. The ecology of the virus was briefly considered, stating that
certain predators, such as wasps and pentatomids act as vectors of the virus. In
conclusion, McLeod & Smirnoff stated that the releases of E. amictorillS and P.
basizonus seemed to have been beneficial, and that the use of virus as a control was
promising.
During the past decade, no further release of parasitoids, and few recoveries, were
made. Nonetheless, considerable research was completed during this period. In anticipation
of an impending resurgence of the N. swainei population in Quebec, two foreign
species of predacious red wood ants, Formica lugubris Zett. and F. obscuripes Forel,