We have discovered that, contrary to the long-held belief, 1st-instar spruce budworm, Choristoneura fumiferana Clemens, do feed. They display red alimentary tracts if they are provided with diet containing the red dye amaranth. They graze on the surface of balsam fir needles sprayed with rhodamine and ingest the fluorescent material, which can be detected in the frass pellets deposited inside the hibernacula. When emerging 1st instars were allowed to crawl on the inside surface of a glass tube coated with the polyhedral inclusion bodies of a recombinant C. fumiferana virus containing the gene for the green fluorescent protein, the larvae showed the characteristic green fluorescence, indicating that not only had they ingested the occlusion bodies but also the virus had replicated and infected different tissues. Similar results were obtained with the jack pine budworm, Choristoneura pinus pinus Freeman, which has an identical life history. The advantages of early-instar intervention to minimize defoliation by using control agents such as the ecdysteroid agonist, tebufenozide (RH-5992, Mimic® formulation), are discussed.

Spores of the microsporidium Pleistophora schubergi were fed to second- and fifth-instar larvae of the spruce budworm, Choristoneura fumiferana. A treatment of 2 × 108 spores applied to the surface of the host's diet resulted in 100% mortality to second- and 60% to fifth-instar larvae. Suceptibility of the host to the parasite decreased as the larvae became older. Other effects on host development were not significant at the dosages tested.

A two-choice feeding bioassay was used to investigate the effects of larval source (colony versus wild larvae) and rearing medium (artificial versus foliar diet) on the feeding-deterrent activity of the oral exudate of the spruce budworm and the western spruce budworm, Choristoneura fumiferana (Clem.) and Choristoneura occidentalis Free., respectively. Feeding by both wild and colony larvae was deterred by conspecific oral exudate. Larvae reared on artificial diet responded to exudate from both diet- and foliage-reared larvae, whereas the foliage-reared larvae responded only to exudate from other foliage-reared larvae. These results suggest that differences exist between artificial diet- and foliage-reared larvae in the composition of oral exudate, in the concentrations of its biologically active constituents, or in differential sensitivity of diet- and foliage-reared larvae to exudate from foliage-reared larvae.

The extent and intensity of the present infestation of the spruce budworm, Archips fumiferana Clem., in eastern Canada has become a problem of immense national concern (I). The necessity for further knowledge in formulating adequate control programmes has emphasized the importance of considering the possible utilization of natural insect parasites. As part of the more conprehensive study of control being carried on by the Federal Division of Entomology, the Dominion Parasite Laboratory in cooperation with the Forest Insect Unit instituted a programme of parasite introduction in 1943.

Bioassays of Bacillus thuringiensis (Bt.) are commonly performed by applying a serial dilution of the test sample to either foliage or artificial diet (Burges and Thompson 1971). In these assays the ingested dose is not measured directly, but is assumed to be proportional to the concentration of the sample applied to the diet. This assumption is valid only if the total amount of food ingested during the experiment is the same at all dosage levels. However, this assumption may not be true because Bt. inhibits feeding of some lepidoptera larvae (Burges and Thompson 1971). Furthermore, artificial diets usually contain nutrients and possibly antimicrobial agents which may interact with Bt.

Wind tunnel experiments confirmed the optimum blend of the two major components of the sex pheromone of the spruce bud worm Choristoneura fumiferana (Clem.), (E)- and (Z)-11-tetradecenal, to be close to a ratio of 95(E):5(Z). The addition of two minor components, (E)-11-tetradecenyl acetate and the saturated tetradecanal, previously identified in the effluvia of calling virgin females, showed that the acetate alone reduced the level of some responses, while the addition of tetradecanal to the acetate:aldehyde blend restored response to previous levels. Addition of tetradecanal alone showed only minor effects on responses. Males responding to calling females showed higher levels of response and sustained flight longer than did males responding to the four-component blend, and this fact suggests that the blend is incomplete.

The balsam twig aphid, Mindarus abietinus Koch, infested nearly all trees in a range-wide provenance plantation of balsam fir, Abies balsamea (L.) Mill., in Michigan. Infestation levels were highest on eastern and lowest on western seed sources of fir. Large populations of the aphid were correlated with low survival and reduced developmental rates of the spruce budworm, Choristoneura fumiferana (Clemens). We propose that chronic, high susceptibility of trees to aphids could reduce concomitant susceptibility to budworm through direct (competition) and indirect (host and community-level) effects.

Formates analogous to the aldehyde sex pheromones of several species of Lepidoptera have been shown to have biological activity, (E)-9-Dodecen-1-yl formate was therefore tested against male spruce budworm (C. fumiferana) by EAGs and by field trapping experiments designed to test for attraction, inhibition, and disruption. No biological activity was detected.

Trichogramma minutum Riley entered diapause, in the prepupal stage, in eggs of Lambdina fiscellaria fiscellaria Guenée held at 15°C, 12L:12D, but failed to do so in eggs of Ephestia kuehniella (Zeller), Sitotroga cerealella (Olivier), or Choristoneura fumiferana (Clemens) held under these conditions. The parasitoids emerged without diapause from eggs of all host species held at 25°C, 16L:8D, indicating a role of temperature or photoperiod, or both, in the diapause of the parasitoids in eggs of L. fiscellaria held at 15°C, 12L:12D. Percentage emergence of parasitoids from eggs of L. fiscellaria was virtually the same (>80%) after passing the winter outdoors or after approximately 3 months at 2 °C in the laboratory as it was when reared indoors in this host at 25°C, 16L:8D. Emergence of T. minutum was very poor (<20%) after long-term, low-temperature storage in eggs of C. fumiferana, E. kuehniella, or S. cerealella. Apparently, T. minutum must parasitize diapause host eggs in order to enter diapause, and good survival after long-term low-temperature storage is possible only when T. minutum is in diapause. Trichogramma minutum will enter diapause in L. fiscellaria after 14 days at 15°C, 12L:12D, but the parasitoids need a period of storage at 2°C, 0L:24D for a high percentage of emergence to happen. Over 50% emergence was recorded for T. minutum, held for 300 days in eggs of L. fiscellaria.

Release rates of synthetic attractant of the spruce budworm, Choristoneura fumiferana (Clem.), from a PVC formulation were determined by weight loss. They varied in direct proportion to the initial concentration of the attractant and also with the size of the pellet. Release rates declined by about 50% over the time intervals of 10–40 days and 40–100 days. Initially they were two to three times lower at 10°C than at 21°C, but were far more constant over time at the lower temperature. A pellet weighing 130 mg containing 42 μg of attractant released an estimated .1–1 μg/day, or 4–40 ng/h, which is close to the rate of emission by a calling female (Silk et al. 1980), and field trapping data showed that a lure this size attracted the same number of males as a calling female.

The spruce budworm, Choristoneura fumiferana (Clem.), nuclear polyhedrosis virus (CfMNPV) has been studied extensively for its potential use as a bio-insecticide (Cunningham 1995). Recent advances in recombinant DNA technology have been impetuous in the genetic engineering of this virus to increase its virulence and (or) speed of action. This aspect of research has been concentrated on the modification of a plaque purified (Ireland strain) isolate obtained from the wild-type virus population (Arif et al. 1984). To assess any improvement in the effectiveness against the target pest, the virulence of the unaltered virus must first be determined. Bioassay results that have been previously reported by Kaupp and Ebling (1990) were conducted on the wild-type virus found in nature which consists of a mixture of viruses (Arif et al. 1994). Results of bioassays conducted to determine dose–response and time–response of fifth-instar spruce budworm larvae to the Ireland strain of CfMNPV are reported here.

The frequent failure of parasite development beyong the immature stages during insectary rearing work often results in incomplete qualitative and quantitative data on insect parasites. Keys to the larval and pupal stages are therefore an extremely useful aid in completing the picture in a study of A parasite complex.

The following illustrated key makes it feasible to obtain reasonably accurate specific determinations of the puparia of the dipterous parasites of the spruce budworm, Choristoneura fumiferana Clem., that occur in Canada. The writer gratefully acknowledges the inspiration and co-operation of A. R. Brooks during the preliminary preparations for the key. The illustrations were executed by Miss M. MacKay (Figs. 1-14) and R. Sugden (Fig. 15). Each figure illustratis the following: (a) posterior aspect of a puparium showing the location of the stigmal plates and the anal aperture, and any protuberances that are present; (b) one stigmal place and the stigmal slits; (c) lateral aspect of the outline of a puparium.

The effectiveness of topical applications of the juvenile hormone analog Fenoxycarb against selected developmental stages of the eastern spruce budworm, Choristoneura fumiferana (Clemens), was determined. Eggs at an early stage of embryogenesis (0–24 h old) were prevented from hatching and were more sensitive to the compound than older eggs (48–72 h old) and larval stages. Fifth-instar larvae displayed lethal morphogenetic effects following Fenoxycarb treatment, but third-instar larvae were refractory. Adult females constituted the most sensitive stage; treated insects laid eggs that failed to hatch. Untreated adult females that mated with Fenoxycarb-treated males also laid infertile eggs.

This paper has been extracted mainly from the manuscript of a revision of the tortricid subfamily Archipinae, to make available a scientific name for an injurious, undescribed Choristoneura species that feeds in the larval stage upon pines, particularly jack pine, Pinkus banksiana Lamb., and red pine, P. resinosa Ait. This insect and the closely allied Choristorneura fumiferana Clem. are compared under the following topics: taxonomic history, maculation, morphology, and distribution. References are cited only if they contain information of taxonomic significance; the vast amount of economic literature dealing with these species has been omitted. This paper is followed by a comparative study of the larvae of the two species by Miss M. MacKay, by one by Miss C. E. Cox on the mathematical significance of the anatomical differences in the larvae and adults of both species, by a discussion of some of the parasites of the pine species by G. S. Walley, and by a discussion by S. G. Smith of the isolating mechanisms aperating between the two species.

This paper describes all stages of the spruce budworm parasite Apanteles fumiferanae Viereck, including the adult. Illustrations of all stages are presented. A short account of the life history of the host is included.

The susceptibility of the spruce budworm, Choristoneura fmiferana (Clemens), under laboratory conditions, to commercial preparations of Bacillus thuringiensis var. thuringiensis Berliner was reported by Angus et al. in 1961. This bacterium was recently tested, under field conditions, both as dusts and sprays. The results of ehese tests are presented here with comments on the effect of the environment and other factors.

It has long been known that a series of late-instar larvae of Choristoneura fumiferana (Clem.) may be distinguished from one of C. pinus Free. by colour differences of the head and prothoracic shield: specimens of the former usually have dark heads and light prothoracic shields; specimens of the latter usually have light heads and dark prothoracic shields. However, intensive study of the larvae, including numerous specimens of C. fumiferana from the spruce-balsam fir areas of Algonquin Park, Ontario, and of C. pinus from jack-pine areas at Normandale, Ontario, has shown that there are highly significant structural differences in the head; these differences serve to identify small series of either species and most single specimens.

It was found that five different starches incorporated into artificial diet in place of sucrose made the diets significantly less nutritious for spruce budworm larvae (Choristoneura fumiferana (Clem.)).

The applicability of this to the natural situation — budworm larvae feeding on growing foliage — is unknown.

Parasite studies were carried out in two residual spruce budworm outbreaks in Quebec. Investigations were conducted during the last three years of the outbreak in the Lower St. Lawrence region and during the last year of the one in the Saguenay region. In the Lower St. Lawrence region decline of the insect population was initiated through aerial application of DDT over a period of three years, while in the Saguenay region the unfavourable condition of the forest stands apparently kept budworm numbers below peak outbreak levels. The incidence of mortality through the action of parasites was very high during the last year of both of these outbreaks and probably contributed to bringing about their collapse. Meteorus trachynotus Vier. has repeatedly been recovered in abundance during the last year of a number of budworm outbreaks and it was amongst the important parasites recovered in both outbreaks under discussion. Other species, however, that were abundant in one or the other of these two outbreaks had not been recovered in numbers before. The parasite complex and the relative abundance of each parasite species during budworm outbreaks is fairly constant at the time of peak host populations, but it is now apparent that they vary considerably at the time of outbreak collapse. Variations in the presence and relative abundance of alternate hosts probably account for this situation.

Diet incorporation assays detected no difference in susceptibility of instars IV, V, and VI of spruce budworm exposed to Bacillus thuringiensis, either in terms of dose, LC50, or time, LT50. The hypothesis that the dose–response for larvae of each instar fitted a common regression line was statistically acceptable. Differences in the pattern of changes in larval weight of instars IV, V, VI larvae in response to dose were not detected.

Small plots were sprayed with 5.5, 10.9, 21.9 BIU/ha at times corresponding to peak instar III, early IV, peak IV, peak V, and peak VI. Instar III larvae were controlled less effectively than were instar IV or V larvae which were controlled equally well. Instar VI larvae were also less effectively controlled than instar IV and V larvae probably because a significant proportion had reached the non-feeding prepupal stage before the full effect of B.t. was obtained.