The Canadian registration in 2007 of Disrupt SBW Micro-Flakes®, a pheromone-based product for control of spruce budworm, Choristoneura fumiferana (Clemens), paved the way for large-scale trials to test the practicality of mating disruption as a commercial pest management strategy. We review results from field and laboratory experiments on pheromone-based mating disruption of spruce budworm conducted from 1974 to 2008. Application of pheromone from the ground or the air consistently reduced the orientation of males toward pheromone sources. Mating disruption also reduced the mating success of caged or tethered females in 15 of 16 field studies where this parameter was recorded, but had only a limited effect on the mating success of feral females. No consistent difference in the density of egg masses in control and treated plots was observed, which has often been attributed to immigration of gravid females into pheromone-treated plots. Laboratory studies suggest that false-trail following is the predominant mechanism underlying mating disruption in spruce budworm. The enhanced mating success of females with increasing population density suggests that mating disruption should target low-density emergent populations during the initial phase of an outbreak. Constraints that may limit the potential of mating disruption as a management tool include (1) difficulties associated with obtaining accurate sampling estimates at low population density to forecast the onset of outbreaks, (2) potential behavioral adaptations by which females enhance their mating success when the atmosphere is treated with pheromone, and (3) long-range dispersal of females by flight.

The mass production of Nosema fumiferanae spores using second, third, and fourth instar larvae of Choristoneura fumiferana is described. In general, second instar larvae inoculated with 2 × 105 spores per millilitre of suspension resulted in a maximum spore yield of 1.3 × 108 spores per larva. A spore concentration of 2 × 107 reduced larval weights and increased larval mortality.

Laboratory observations revealed that late-instar larvae of the eastern spruce budworm (Choristoneura fumiferana (Clemens)) (Lepidoptera: Tortricidae) spend most of their time spinning, wandering, and resting; less than 10% is spent feeding. Larvae feed in a discontinuous pattern of short feeding bouts separated by much longer intervals of nonfeeding activity. Over a 2 h observation period, feeding bouts averaged 2.2 min and were separated by 17.4 min intervals for 4th-instar larvae as compared to 3.3 min bouts separated by 33.4 min intervals for 5th-instar larvae. The duration of a feeding bout was positively correlated with the duration of the subsequent interval, not with the duration of preceding intervals, suggesting that feeding-bout frequency is governed primarily by post-ingestion processes. It is postulated that short feeding bouts followed by long intervals limit the window for ingesting an efficacious dose of aerially applied insecticides such as Bacillus thuringiensis.

The disruption of chemical communication between adult insects by the use of synthetic sex pheromones is an attractive method of insect control. However the mechanism of disruption is not clearly understood. It is generally considered that 3 mechanisms are in operation (see review by Bartell 1982): masking of the natural-pheromone plumes by permeation of the atmosphere with synthetic pheromone; orientation of males to false trails; and habituation of the central nervous system by prolonged or repeated exposure to the pheromone. The relative importance of these 3 mechanisms in disruption is of concern, as this can affect the strategy for disseminating the pheromone.

Spruce budworm, Choristoneurafumiferana (Clemens) (Lepidoptera: Tortricidae), larvae can cause extensive defoliation in balsam fir (Abies balsamea [Linnaeus] Miller) and exhibit high temporal and spatial variability in individual behaviour. We gathered field data to determine the influence of daily and hourly variation in abiotic conditions on daytime activity patterns of late-instar budworm larvae on balsam fir. In both years of our study, less than 10% of larvae were observed feeding during the daytime. Most larvae observed were either resting, spinning silk, or roaming, although the proportion of individuals engaged in each activity varied between years, with more larvae in the first year roaming (48%) and in the second year either resting (38%) or spinning silk (42%). Daily and hourly variation in abiotic conditions had a limited influence on activity patterns. Our results indicate that in nature, mid- to late-instar budworm larvae maintain fairly consistent activity patterns across a wide range of abiotic conditions. We suggest that site-specific conditions such as variation in host-plant quality and/or budworm population density may be more important than weather in determining the relative frequencies of different larval activities in space and time.

Selected carbamate, chlorinated hydrocarbon, organophosphorous, and pyrethroid insecticides were tested on six Choristoneura species: conflictana (Walker), fumiferana (Clemens), lambertiana ponderosana Obraztsov, occidentalis Freeman, pinus Freeman, and viridis Freeman. When probit regression lines were compared by likelihood ratio tests, the hypothesis of equality was uniformly rejected. The hypothesis of parallelism was accepted for some chemicals within each insecticide class except the chlorinated hydrocarbon. These results suggest that extrapolating the response of one species to another species should be avoided.

The morphology and histology of the internal reproductive system of the male spruce budworm moth, Choristoneura fumiferana (Clemens), is described and discussed.

The western spruce budworm, Choiistoneura occidentalis Freeman, which normally passes through an obligate diapause in nature, was reared in the laboratory without diapause. The critical factor for preventing diapause appeared to be the physical environment presented to the first stage larvae. The response of C. occidentalis was flexible. The 2nd stage larvae could be made to diapause or forego diapause, depending on their rearing experience in the first stage. By eliminating diapause it was possible to rear about 7½ generations per year as against about 2¼ under normal diapause conditions. The diapause of the jack-pine budworm, C. pinus pinus Freeman, and C. lambertiana californica Powell, could be prevented by the same technique. The diapause of the spruce budworm, C. fumiferana (Clemens), could not be eliminated except after several generations of selection.

No correlation was found between the size of male spruce budworm (Choristoneura fumiferana [Clem.]) moths and the duration of their flight in a sustained-flight wind tunnel. The numbers of male moths caught in traps baited with virgin female spruce budworm moths increased as the size of the females increased, but the relationship was significant in only one of eight experiments. Infection with the microsporidium Nosema fumiferanae (Thomson) resulted in smaller insects, but there were no significant relationships between the incidence of infection and male flight duration or female attractiveness.

This paper describes a method of rearing the spruce budwom, Choristoneura fumiferana (Clem.) under laboratory conditions. The development of such a method has been necessary as a preliminary step in a program of investigations into the genetics of the spruce budworm. The method therefore attempts to satisfy primarily the requirements of genetical studies but, since these are as exacting as may be necessary for any biological investigation, a wider applicability may be anticipated.

Larval biomass of the spruce bud worm, Choristoneura fumiferana (Clem.), in balsam fir, Abies balsamea L., stands was significantly reduced following aerial applications of commercial Bacillus thuringiensis (B.t.) (Thuricide 16B®, 24B and 32BX and Dipel 85®). Treatment with Dipel vehicle (Dipel 88® without B.t.) did not affect larval biomass. Biomass reduction following the Thuricide treatment was directly related to feeding activity. These findings support published observations on the long-term effect of B.t. on budworm populations.

During preoutbreak periods before spruce budworm, Choristoneura fumiferana (Clemens), populations reach epidemic levels, birds can play an important role in regulating budworm abundance (Gage and Miller 1978). All life stages of the spruce budworm are subject to predation by birds, but documentation of predation on budworm eggs is sparse (Hope 1945).

Research on operational use of Bacillus thuringiensis 3a3b against spruce budworm, Choristoneura fumijerana (Clem.), led to the development of a concentrated B. thuringiensis formulation containing the required potency of 20 B.I.U. of B. thuringiensis in a final volume of 4.7 l./ha (Smirnoff 1978). Aerial operational applications of this formulation were highly effective against the spruce budworm and resulted in acceptable foliage protection (Smirnoff 1979, 1980a). However, it is felt that B. thuringiensis will be used extensively against C. fumiferana only when its cost is lowered to that of chemical insecticides. heref fore, several B. thuringiensis + chitinase formulations were developed leading to an even more concentrated B. thuringiensis formulation, which we call Futura, in which the required 20 B.I.U./ha is applied in a final volume of 2.5 l./ha. We describe the composition of Futura and discuss the bacteriological and physical qualities of the formulations and its efficacy.

Five types of hemocytes (plasmatocytes, granular cells, spherule cells, oenocytoids, and prohemocytes) were identified in the larval, prepupal, and pupal stages of the spruce budworm, Choristoneura fumiferana (Clem.). Hemocyte numbers (total hemocyte counts and absolute hemocyte counts) increased during larval development. The absolute counts were greater in female larvae than in the male larvae during the fourth instar but were higher in the males during the fifth and sixth instars. Hemocyte numbers peaked in the prepupal stage in females and in the early pupal stage in males. The plasmatocytes and granular cells were the predominant hemocytes in both sexes. The plasmatocytes decreased and the granular cells increased throughout larval development of both sexes. There were more plasmatocytes in the males than in the females in all stages of development. There were more granular cells in the males than the females until the sixth instar when the reverse occurred.

Choristoneura fumiferana (Clemens) and C. pinus pinus Freeman are redescribed, and the following five forms are described as new: C. biennis, British Columbia; C. occidentalis, Washington; C. orae, British Columbia; C. viridis, California, Oregon; C. pinus maritima, Pennsylvania, Massachusetts, New Jersey, Kentucky.

Barrier-pitfall traps and tree bands were used to sample adult carabid beetles in five forest stands of different tree species composition and spruce budworm infestation levels. Twenty genera and 37 species were collected over the 2-year period. Adult carabid populations were highest in the red spruce stand while carabid species diversity was greater in hardwood and fir stands having the most tree species diversity. Potential adult carabid predators of spruce budworm were identified using 5 criteria: number of individuals, habitat preferences, seasonal abundance, size, and food. We conclude that adults of Pterostichus pensylvanicus (Lec.) had the highest potential as predators of spruce budworm followed by Platynus decentis Say, Calosoma frigidum Kby., Pterostichus tristis (Dej.), Cymindis cribricollis Dej., Pterostichus rostratus (Newm.), Calathus ingratus Dej., and Pterostichus adoxus (Say).

In the late 1940's significant increases in the population of the spruce budworm, worm, Choristoneura fumiferana (Clem.), occurred in northern New Brunswick and culminated in a severe outbreak of this major forest pest. The outbreak has been the subject of intensive investigations dealing with emergency chemical control operations (Webb, 1956) and with a long-term study of the population dynamics of the budworm. The latter program, called the Green River Project, is located on the Green River Watershed in northwestern New Brunswick. Its objectives, the co-operating agencies involved, the mortality factors being studied, and methodology have been discussed elsewhere by Morris et al. (1956), Morris (1951), Morris and Miller (1954), and Morris (1955).

Induction of supernumerary larval instars in the spruce budworm, Choristoneura fumiferana Clemens, by applying ZR-515, a potent juvenile hormone analogue, is explained in terms of larval differentiation. Application to the early sixth instar where structures are relatively indeterminate results in the formation of a supernumerary larval instar, whereas treatment of the late-larva wherein many structures are committed to differentiate towards the pupa, results in a larval–pupal mosaic.

Pigmentation of heads and prothoracic shields of last-instar larvae, colour of pupae, and frequencies of haemolymph colour morphs in fresh pupae are used to support the taxonomic differentiation of the following members of the genus Choristoneura: fumiferana, biennis, orae, occidentalis, viridis, subretiniana, pinus pinus, p. maritima, and lambertiana. These characters are statistical in nature and not competent to relate a single individual unequivocally to a taxonomic group; nevertheless, a key is developed to assist identification of populations on the basis of the characters described. Interspecific relationships within the genus are considered.

We present calculations of droplet sizes and product potencies that are theoretically required to deliver a lethal dose of Bacillus thuringiensis in one droplet to larvae of the eastern spruce budworm in aerial spray applications. The calculations are based on estimates of the dose required for 50% and 95% mortality [4.3 and 26.9 International Units (IU), respectively] and of the lowest dose that caused discernable feeding inhibition (0.5 IU) in force-feeding assays with sixth-instar larvae. For products containing 12.7–16.9 billion IU (BIU) per litre, the most widely used potency range, a 150- to 160-μm droplet is needed to deliver an LD95 and an 80- to 90-μm droplet to deliver an LD50, whereas droplets down to 40 μm are expected to cause extensive feeding inhibition. Our calculations suggest that current application prescriptions result in the delivery of a marginally effective dose to the target foliage and that budworm larvae have to ingest multiple droplets to obtain a lethal dose, a process that is thought to contribute to inconsistent spray efficacy. We predict that dose acquisition can be maximized by increasing product potency to 95 BIU/L, which would enable larvae to acquire a lethal dose by ingestion of only one or two droplets in the size range that is most commonly encountered on coniferous foliage (≤ 80 µm) after aerial application.