BESSA SELECTA (MEIGEN) (DIPTERA: TACHINIDAE) AS A PARASITE OF GILPINIA HERCYNIAE (HARTIG) (HYMENOPTERA: DIPRIONIDAE)

1947 ◽  
Vol 79 (5) ◽  
pp. 84-104 ◽  
Author(s):  
L. S. Hawboldt

This project arose out of studies of the European spruce sawfly, Gilpinia hercyniae (Htg.), in connection with the Canadian Forest Insect Survey at the Dominion Entomological Laboratories, Fredericton, N.B. Bessa selecta (Mg.) had been observed as a parasite of the larch sawfly, Pristiphora erichsoni (Htg.), but particular interest was aroused in it as a parasite occurring on the European spruce sawfly. The latter host was frequently found to bear the eggs and integumental funnels of B. selecta. The object was to study its biology and effectivness as a possible control factor of the spruce sawfly. However, great difficulty was experienced in rearing the host due to high mortality caused by disease. Hence the original aims were not attained to the entire satisfaction of the author.

1959 ◽  
Vol 91 (8) ◽  
pp. 496-500 ◽  
Author(s):  
W. G. H. Ives ◽  
R. M. Prentice

The Forest Insect Survey at the Forest Biology Laboratory, Winnipeg, has been compiling records for a number of years on the percentage of cocoons of the larch sawfly, Pristiphora erichsonii (Htg.), parasitized by the tachinid Bessa harveyi Tnsd. Sawfly cocoons were collected each fall from the soil in infested stands, and those containing living larvae were dissected to determine the percentage of parasitism by B. harveyi. These estimates have been used to provide an index of parasitism (Lejeune and Hildahl, 1954), but are of limited value for a number of reasons: (1) estimates can be expressed only as percentage of sound cocoons parasitized; (2) total parasitism cannot be estimated because a portion of the parasites emerge from the cocoons before collection; and (3) estimates of parasitism may not be representative of the stand because there is a tendency to collect cocoons where they are easiest to find; hence all the cocoons in a collection may be from one or two small areas. If the proportion of cocoons containing B. harveyi varies within a stand such collections may give unreliable estimates of parasitism.


1954 ◽  
Vol 86 (10) ◽  
pp. 471-480 ◽  
Author(s):  
W. A. Reeks

At least four outbreaks of the larch sawfly, Pristiphora erichsonii (Htg.), have occurred in the Maritime Provinces within the past 70 years. The first (1) occurred from about 1883 to 1885, the second from about 1906 to 1909 (1), and the third from 1919 to 1927. The last outbreak started in 1933 and ended in 1942. Despite extensive sampling by the Forest Insect Survey from 1943 to 1953, only six samples have been taken during this period in the three Maritime Provinces, and each was an isolated colony. Although an ecological study of the insect was not attempted during the latest outbreak, general observations were made by the writer and other staff members of the Survey. These observations are summarized in the present paper to record the outbreak and some of the factors that contributed to its termination. Another outbreak has persisted in Newfoundland from 1942 and perhaps earlier, but the present discussion is largely confined to events in New Brunswick, Nova Scotia, and Prince Edward Island.


1962 ◽  
Vol 94 (3) ◽  
pp. 242-255 ◽  
Author(s):  
L. D. Nairn ◽  
W. A. Reeks ◽  
F. E. Webb ◽  
V. Hildahl

The larch sawfly, Pristiphora erichsonii (Htg.), has been under observation in Manitoba and Saskatchewan since early in the present century. Recorded observations were somewhat fragmentary until 1937; since then systematic and detailed annual reports have been provided by the Forest Insect Survey and since 1948 intensive ecological and life table studies have been conducted by staff of the Winnipeg Laboratory at the Whiteshell Forest Reserve, Manitoba.


1955 ◽  
Vol 87 (3) ◽  
pp. 103-111 ◽  
Author(s):  
H. C. Coppel ◽  
K. Leius

The larch sawfly, Pristiphora erichronii (Htg.), is currently considered a major forest insect pest in Canada. At the present time within Canada, the sawfly reacts to parasitism by Mesoleius tenthredinis Morley in two ways. In Manitoba and Saslratchewan the sawfly encapsulates approximately 100 per cent of the parasite eggs deposited, whereas in British Columbia encapsulation rarely exceeds four per cent (Muldrew, 1953). The reasons for the difference in degree of encapsulation are apparently unknown; however, since the origin of the sawfly itself is obscure, the possibility exists that a native species, an introduced species, Or a combination of both may he present, or that geographical or ecological units may have arisen. Studies now under way by officers of the Forest Biology and Entomology divisions are attacking the problem of identity and origin following the pattern established for the European spruce sawfly, Diprion hercyniae (Htg.). In this instance, as with the larch sawfly, parasites were introduced on the assumption that the pest had been introduced from Europe. Critical investigations by Reeks (1941) and Balch, Reeks, and Smith (1941), involving morphological, cytological, and other biological characters, showed that the species occurring in North America was one of two species common in Europe, and previously referred to there as Gilpinia polytoma (Htg.). Balch et al. (1941) showed that D. hercyniae had been introduced into North America.


1962 ◽  
Vol 94 (10) ◽  
pp. 1103-1107 ◽  
Author(s):  
C. E. Brown

The Bruce spanworrn, Operophtera bruceata (Hulst), is most common in the mid latitudes of the North American Continent; in Canada it occurs from Newfoundland to the interior of British Columbia (Prentice, In Press) and has been reported from Vermont and Wisconsin in the United States (Craighead, 1950.) Three outbreaks of this insect have been recorded in Alberta. The first occurred in 1903 (de Gryse, 1925) and was apparently of short duration. The second reported by Wolley Dod (1913) occurred in 1913 and denuded hundreds of acres of aspen poplar. Heavy defoliation in the third outbreak became evident in 1957 (Brown, 1957) but an examination of Forest Insect Survey records revealed that population buildup began about 1951. The outbreak continued to expand until 1958 and began to decline in 1959; by 1961 populations were again low except for one or two isolated areas where moderate to low populations persisted. At the peak of the outbreak in 1958 approximately 50,000 square miies were moderately or heavily infested and many more lightly infested.


1961 ◽  
Vol 93 (3) ◽  
pp. 228-238 ◽  
Author(s):  
F. T. Bird ◽  
J. M. Burk

An outbreak of the European spruce sawfly, Diprion hercyniae (Htg.), occurring in Eastern Canada between 1930 and 1942, was controlled by a virus disease (Balch and Bird, 1944). The sawfly has been kept at a low level by the disease and by parasitic insects introduced from Europe (Bird and Elgee, 1957).An infestation of the sawfly was discovered in 1947 near Sault Ste. Marie, Ontario, by the Forest Insect Survey Section of the Forest Biology Laboratory at Sault Ste. Marie. This infestation was about 100 miles beyond the previously known western distribution of the insect. Intensive larval sampling in 1949 showed that it was free from virus and practically free from introduced parasites. Thus, an excellent opportunity was provided to introduce the virus into a disease-free population, to study its establishment and spread, and to compare the long term effects of virus alone on population trends with the effects that virus plus introduced parasites were shown to have on population trends in New Brunswick (Bird and Elgee, 1957). The virus was introduced into the infestation in 1950 and studies were carried out each year from 1950 to 1959.


1940 ◽  
Vol 72 (4) ◽  
pp. 85-86 ◽  
Author(s):  
G. Stuart Walley

It was with some surprise that the writer encountered a representative of this rare and, until recently, little known genus, from a locality in south-eastern British Columbia. The specimen in question is a female reared at Ottawa, by officers of the Forest Insect Survey of the Division of Entomology, Irom the cocoon of a Chrysopid beaten from Engelmann spruce, Aug. 26, 1938, by Mr. D. N. Ross of the British Columbia Forest Service, in the vicinity of Bayne's Lake, B. C. The adult parasite emerged in the laboratory, Feb. 20, 1939.


1962 ◽  
Vol 94 (5) ◽  
pp. 522-523 ◽  
Author(s):  
T. N. Freeman

In 1957, some officers of the Forest Insect Survey of Canada discovered a species ofNepticulamining the leaves of white birch (Betula papyriferaMarsh.) and yellow birch (Betula luteaMichx. f.) in Ontario. At that time the species was considered to be undescribed, but to confirm this it was necessary to study the life-history. This has been done by Mr. O. H. Lindquist, Forest Insect Laboratory, Sault Ste. Marie, Ontario, and the results of his studies are being presented in a companion paper. His investigations confirmed that the species had not been named and the following description is presented.


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