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Recommendations
Neocliprioll sertifer (Geoffroy). 339
There is no doubt that European pine sawfly NPV is a highly efficacious biological
control agent when applied on early instar larvae, and treatments continue to give control
in the years following application. The longevity of this control depends on such factors as
the initial population density of the host and the size of the trees, but infectious PIBs
remain in the environment for at least 3 years following a virus epizootic (Kaupp 1981).
Given this respite from defoliation, trees grow considerably and are much less susceptible
to damage if further European pine sawfly outbreaks occur.
To date, there are no viruses registered for operational use in Canada. In the USA, a
petition has been prepared for registration of European pine sawfly virus under the name
"Neochek-S". Extensive animal safety testing has been conducted by the Americans, but
it is not known if these data will be acceptable to Canadian authorities. With the limited
areas of European pine sawfly infestation currently reported, registration of its NPV in
Canada is not of high priority in comparison to viruses of certain other insect pests. Even
if European pine sawfly NPV is eventually registered in Canada, there is little commercial
incentive for production and marketing owing to its limited and specialized use. Virus
production and distribution, therefore, will almost certainly remain in the hands of
federal and provincial governments.
In view of the successful establishment of L. lutealor in five areas of Ontario, all following
a single release, the failure to establish this species in Newfoundland following three
releases in 3 successive years suggests a fundamental difference between the situations in
Ontario and Newfoundland. We recommend that no more releases be made there after
the 1981 release until further study reveals success or the reasons for failure.
It was pointed out by Griffithsetal. (1971) that there are 62 species of native parasitoids
known to attack other pine-feeding diprionids in Ontario that had not been recovered
from N. serlifer. We have not recovered any of them in the limited sampling in the last
decade in southern Ontario. It is possible that some of them are now attacking N. serlifer
in northern Ontario and we recommend that sampling be done to determine if this is so.
No more releases of D. diprioni or E. abruptorills should be made. However, sampling
to determine whether the former species has become established can be continued with
little cost for several years. Collections to determine the presence of E. abruplorius
should only be undertaken when they can provide adequate numbers of hosts in order to
justify the work that the processing of collections requires.
As stated earlier, the operational use ofNPV at Sandbanks Provincial Park in Ontario
was considered to be an unqualified success. However, after assessing aerial applications
of European pine sawfly NPV and evaluating reports of operations conducted outside
Canada, two recommendations can be made. Firstly. the dosage of virus applied is about
10 times more than required for satisfactory control. A dosage of 5 x Hf PIBlha is
adequate. Secondly, adjuvants in the tank mix are unnecessary and virus in water alone
will suffice.
Although it is not within the discipline of biological control, we are concerned about the
dispersal of the European pine sawfly beyond its present boundaries in Canada. Sullivan
(1965) pointed out that the overwintering eggs of this species can survive a temperature of
-26°C and that, with conditioning and selection, they may be able to withstand
temperatures even lower. Thus the possibility of this pest spreading throughout the range
of its widely distributed hosts, Scots pine, jack pine, and red pine, is great unless efforts
are made to prevent it. We recommend that some attempt be made to fumigate stock
before transport to reduce this possibility, using techniques outlined by Monro & Kirby
(1963).