Species in the family Aphidiidae (Hymenoptera) parasitize exclusively ovoviviparous aphids. Females use a variety of information to detect and evaluate suitable hosts. Olfactory cues associated with aphids, or the aphids’ host plant, are important for host location. Visual cues including aphid colour, shape, and movement can be evaluated from a distance without physical contact; aphid movement may act as a releasing stimulus for attack. Contact chemosensory cues (gustatory cues) are evaluated by antennation of the host cuticle and during ovipositor probing. A potential host must conform to the wasp’s response profile and satisfy minimum physiological and dietary requirements for immature development and growth. Host quality is determined in part by attributes specific to each aphid species and in part by each aphid’s individual-specific growth potential. Host quality for male and female progeny may vary as a result of different patterns of resource allocation and sexual size dimorphism. For an encountered aphid to be accepted as a host, its perceived value must exceed the wasp’s response threshold for oviposition. Host value, as opposed to host quality, varies dynamically with parasitoid state variables such as age, egg load, and prior experience. A conceptual model of host choice by aphidiid wasps is presented.

Conophthorus radiatae Hopkins, Ernobius punctulatus Fall, and Pityophthorus spp. infest cones and twigs of Monterey pines (Pinus radiata D. Don) and thus may be important vectors of the pitch canker fungus Fusarium subglutinans f. sp. pini in the central coast of California. Fifteen percent of 1st-year Monterey pine conelets infested with C. radiatae prior to August 1990 developed pitch canker by May 1991. Conophthorus radiatae, E. punctulatus, and Pityophthorus spp. were dissected from some of these conelets and found carrying F. s. pini. Between June 1990 and May 1991, 16% of 695 randomly selected uninfested 1st-year conelets from a total of 329 separate cone whorls were infested by at least one of the above beetle species, and F. s. pini was isolated from 42% of the attacked conelets. Average percentage contamination of beetles per conelet was highest for adults of Pityophthorus spp. (38%), followed by adults of C. radiatae (33%), larvae of E. punctulatus (24%), and larvae of Pityophthorus spp. (5%). There were significant associations between conelets that contained contaminated C. radiatae, Pityophthorus spp., and/or E. punctulatus and conelets with F. s. pini.

Under experimental conditions, C. radiatae and E. punctulatus transmitted the fungus to healthy cones. Ernobius punctulatus required an entrance tunnel by C. radiatae to enter and infect the cone. Artificially wounded cones did not develop pitch canker. Intra- and interspecific transmission of F. s. pini was demonstrated among these beetle species. In infested branch tips without cones, interspecific transmission of F. s. pini between E. punctulatus and Pityophthorus spp. was also demonstrated.

The roles of C. radiatae and E. punctulatus as vectors of F. s. pini and of Pityophthorus spp. as potential vectors are discussed in relation to the epidemiology of pitch canker disease. The spread of pitch canker to California’s native pines as well as other conifers may be enhanced by interspecific transmission of F. s. pini between E. punctulatus and C. radiatae in cones and between E. punctulatus and Pityophthorus spp. in branch tips. Ernobius punctulatus provides a pathway for the fungus to potential insect vectors that attack several hosts and a variety of plant parts.

During 1992 and 1993, we studied the life cycle of Lambdina athasaria (Walker) developing on eastern hemlock, Tsuga canadensis (L.) Carrière, in Connecticut. The geometrid was univoltine, overwintering as a pupa. Adults emerged during 4 weeks in May and June after hemlock budbreak. Males emerged significantly earlier than females, and both sexes emerged earlier in 1993 than in 1992. Males flew for 4–5 weeks annually. Based on measurements of head capsule width, larvae had five or six instars, which fed from June to October. Early instars ate new growth, and older ones fed on old growth. Until mid-August, larval development was more advanced in 1993 than in 1992. Larvae descended from trees in September and October to pupate in the duff beneath trees. Lambdina athasaria can be distinguished from congeneric species that feed on conifers by its overwintering stage, flight period, larval size, and host.

Neothelaxes gen.nov., type-species N. viticola sp.nov., as well as N. parthenocissi sp.nov., are described. The host-plant of the two species is Parthenocissus semicordata. The taxonomic position of the aphids is discussed.

Myzocallis (Neomyzocallis) pseudodiscolor sp.nov. from Quercus macrocarpa in North America, and Tuberculatus pilosulus sp.nov. from Quercus serrata in Japan are described. The affinities of the two species are discussed.

Gall inducers are favoured as biocontrol agents of weeds because they tend to have a narrow host range. Six insect and one nematode gall inducer used in Canada are described in terms of their biology, gall morphology, gall physiology, and effectiveness in weed control. The species differ in plant organ attacked, requirement for moisture, whether the galls are induced by secretions or by severing xylem, and effectiveness, which in part relates to the ability of the gall to import nutrients. The most powerful galls divert assimilates from other sinks via a gall’s vascular system joined to that of their host. One of our examples also has mechanisms to compensate for reduction of turgor during drought. Two of the gall inducers enhance their nutrient supply by severing xylem in a plant nutrient sink. One, in the short-term sink of a thistle capitulum, obtains about a quarter of its assimilates at the expense of other capitula. The other, in the long-term sink of a rosette root, approximately halves seed production. Hypotheses are presented to explain various aspects of gall development and function.

Atmospheric permeation of apple orchards with 16:1 butyl butyrate (BB): 2(E)-crotyl butyrate (CB), the sex pheromone of the mullein bug, Campylomma verbasci (Meyer) (Heteroptera: Miridae), demonstrated potential for pheromone-based mating disruption; atmospheric permeation with single components did not. In traps baited with 16:1 BB:CB, catches of male C. verbasci were 3, 64, and 105% of catches in nontreated controls for disruption treatments of 16:1 BB:CB, CB alone, and BB alone, respectively. With the two-component pheromone as a disruptant, catches of male C. verbasci were significantly reduced relative to controls at dispenser densities of 250, 500, and 1000 per hectare; catches were lowest at 1000 dispensers per hectare. For monitoring of operational trials, pheromone-baited open wing traps hung 1.5 m above ground were judged to be more practical than open wing traps hung 2.5 m above ground, or closed wing traps or white sticky cards at either height. Atmospheric permeation with pheromone did not affect numbers of males and females captured on nonbaited white sticky cards, and trap height did not affect catches of females. However, in pheromone-treated plots, significantly more males were captured on 2.5-m-high nonbaited cards than on 1.5-m-high cards, probably representing incidental catches of males following false trails to pheromone dispensers hung in the upper canopy. This study is the first reported example of pheromone-based disruption of orientation behavior in the Heteroptera.

Leptoglossus occidentalis Heidemann (Hemiptera: Coreidae) is considered to be an important cone and seed pest in seed orchards in British Columbia; however, no impact studies have been done in Canada. Surveys to determine the distribution of L. occidentalis were conducted over a 3-year period in three coastal seed orchards of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco, and over a 2-year period in two seed orchards of lodgepole pine, Pinus contorta var. latifolia Engelmann. Leptoglossus occidentalis was found to distribute itself in patches, coinciding with a clonal preference. Seed losses were assessed for 2 years in the coastal Douglas-fir orchards and for 1 year in one lodgepole pine orchard. The percentages of partially filled seed that could have been caused by feeding of L. occidentalis or by a number of other factors were < 5% in coastal Douglas-fir for both 1992 and 1993 and ~14% in lodgepole pine in 1993. Apparently because populations of L. occidentalis were low, there was no correlation between the percentage of partially filled seed and number of insects per tree. Except in unusual circumstances, management measures in Canada are judged not to be necessary as populations of L. occidentalis are consistently below the calculated threshold levels required to cause ≥5% loss in seed production.

The responses of adult cabbage maggot [Delia radicum (L.)], turnip maggot [D. floralis (Fallén)], radish maggot [D. planipalpis (Stein)], and seedcorn maggot [D. platura (Meigen)] to sticky traps painted blue, yellow, green, non-UV-reflecting white, or UV-reflecting white, were determined in a field of canola (Brassica rapa cv. Tobin) at the rosette and flowering stages. Traps colored white, blue, or yellow generally caught higher numbers of D. radicum, D. floralis, and D. planipalpis than did traps colored green or UV-reflecting white. Depending on the crop developmental stage and its background color, response to color sometimes differed both within and between the sexes. This was most pronounced for D. floralis, for which blue and white traps were preferred by males at the rosette stage but not die flowering stage, and for which white, but not blue, traps were preferred by females at the rosette siage. White and blue, but not yellow, were the colors preferred by male and female D. platura in our study, with UV-reflecting white also being preferred by males during the flowering stage. It was observed dial catches on white and yellow traps were often significantly different and [hat white versus yellow preferences could be reversed within or between males and females of certain species during the rosette or flowering stages. The data suggest dial the concurrent use of white and yellow sticky traps should be considered when conducting relative abundance surveys of Delia spp. in canola fields.

The seasonal change in the level of cold tolerance in a field population of Colorado potato beetle, Leptinotarsa decemlineata (Say), is described for a northern location. Survival of overwintering adult beetles is highest from September through January. After that it falls to a lower level that is maintained until beetle emergence in May or June. The seasonal change in the level of cold tolerance is parallel to the change in the intensity of diapause but not to the change in the low temperature exotherm. The value of the low temperature exotherm is variable but averages −8.8°C for active beetles on plants and −11.7°C for soil-collected overwintering beetles in their deep diapause phase. Experimental results suggest that reduction of the gut content and increase in the amount of body fat in diapausing beetles is sufficient to lower the low temperature exotherm by a few degrees. The diapausing state itself, without cold acclimation, is sufficient to increase cold tolerance. However, results suggest that it is not the level of cold tolerance of the Colorado potato beetle provided by the diapausing process that has allowed this species to extend its range northward into New Brunswick but its accompanying burrowing behaviour.

During a severe outbreak of spruce budworm, Choristoneura fumiferana (Clem.), some balsam fir trees, Abies balsamea (L.) Mill., remain noticeably greener than others in the same stand. We show that this ‘green’ tree phenomenon is not caused by differential defoliation in which certain trees experience consistently low defoliation pressure throughout an outbreak. Rather, these trees remain ‘green’ because of their prolific, epicormic shoot production which is consistently high during an outbreak, giving them a ‘greener’ appearance than other trees that produce lower numbers of epicormic shoots.

Detailed estimates of defoliation caused by spruce budworm [Choristoneura fumiferana (Clem.)] over the crown length of young balsam fir [Abies balsamea (L.) Mill.] were made throughout a spruce budworm outbreak from 1976 to 1984 in the Cape Breton Highlands, Nova Scotia. The results show no clear tendency for a particular level of the crown to be damaged more heavily than any other. Thus, there is no reason to continue the common practice of taking samples from the mid-crown level on the assumption that they represent an ‘average’ level of defoliation either for high or low populations. Sampling from the bottom of the crown should provide a more convenient and cost-effective approach for estimating defoliation.

In laboratory bioassays, four carabid species [Agonum dorsale (Pontoppidan), Bembidion lampros (Herbst), B. obtusum Serville, and Demetrias atricapillus (L.)] that are important predators of aphids in cereals in the United Kingdom were exposed to deposits of deltamethrin, dimethoate, or pirimicarb on glass for up to 72 h. We detected differences between compounds and species that are discussed in the context of exposure of these predators to insecticides in the field. We also describe problems involved in obtaining comparative toxicity data when dilutions of field application rates for target species are used in bioassays with nontarget species. Such problems add another dimension to risk assessment based on laboratory data.

We determined the distribution of root weevil larvae feeding on the roots of young ornamental conifers in field studies using a new non-destructive sampling technique. Most root weevil larvae fed on the roots during summer, fall, and late spring with significantly more larvae found at 10 cm than at 20 and 30 cm and more at 20 cm than at 30 cm. Larvae moved down into the soil to overwinter and moved closer to the surface (<15 cm) in the spring. Soil samples predicted the population density of larvae under individual trees. Four samples (0.0076 m3), 9 cm in diameter by 30 cm long, taken equidistantly 20 cm from the tree stem provided the best estimate. The equation, T = 64.04 M, where T is the total number of larvae beneath a tree, and M is the mean number of root weevil larvae from four soil samples, described the linear relationship between the number of larvae in soil samples and the total population of larvae beneath a tree. Implications for the timing and location of sampling and control measures are discussed.

(E)-11,13-Tetradecadienal (E11,13-14:Ald) is the major component of the sex pheromone of the western blackheaded budworm (WBB), Acleris gloverana Walsingham. The compound was identified in extracts of the female’s pheromone gland by coupled gas chromatographic - electroantennographic detection (GC-EAD) and coupled GC - mass spectrometry in selected ion monitoring mode. In field experiments, E11,13-14:Ald by itself was attractive, but addition of (Z)-11,13-tetradecadienal doubled trap catches of male WBB. (E)-11,13-Tetradecadienol or (E)-11,13-tetradecadienyl acetate in binary or ternary combination with E11,13-14:Ald did not enhance attractiveness of the bait. In comparative assessments of five different trap designs, Uni-traps appeared to be the most suitable for use in pheromone-based monitoring of populations of WBB.

Sampling procedures for estimating within-tree populations of second-stage larvae (L2) of Matsucoccus feytaudi Duc., infesting maritime pine (Pinus pinaster Ait.), were investigated. These included random sampling without replacement, and systematic sampling with and without a linear model. The relative precision of the sampling was affected by the number, size, and bark thickness of the sample units. Because of symmetrical vertical distribution of within-tree populations, systematic sampling with a linear model did not increase precision when compared with simple systematic sampling. Sampling can be profitably reduced to below the crown portion of the bole, after removal of the part with either smooth or very thick and pyramidal bark. Counting L2 exuviae in the upper 10 cm of each 20-cm-long log, using one in every three logs, provided a relative precision of about 40%. The numbers of male M. feytaudi caught in sticky traps baited with 5 or 30 μg of synthetic pheromone were compared with the numbers of L2 estimated according to the sampling method previously developed. There was a significant positive correlation between number of scales caught and L2 estimates, at the level of individual trees for the lower dose lures, and at the level of groups of trees for the higher dose lures, used in 20-year-old stands. Large captures in younger, weakly infested stands were related to a possible immigration of flying scale insects.

The effect of four tillage regimes on the emergence of root maggots (Delia spp.) (Diptera: Anthomyiidae) was determined on experimental plots seeded the previous year to either Brassica rupa L. or Brassica napus L. The tillage regimes evaluated comprised no tillage, tillage in the spring only, tillage in the fall only, and tillage in both the fall and the spring. Emergence trap collections of Delia radicum (L.) and Delia floralis (Fallén) were made from the experimental plots from early May to mid-July of 1991 and 1992. In both years, emergence from untilled plots significantly exceeded that from plots subjected to any other tillage treatment. Tillage resulted in a decrease in emergence of 55–64% for D. radicum, and reduction of 53–72% for D. floralis. For D. floralis, greatest reductions in emergence following a tillage treatment occurred in plots tilled only in the fall or in plots tilled in both the fall and the spring; however for D. radicum, tillage in the fall, the spring, and in both the fall and the spring reduced emergence to approximately the same extent. Results of our study indicated that canola growers in regions of high population densities of root maggot should cultivate infested fields, preferably in fall, to reduce the emergence success of Delia spp.

An illustrated key is given to 28 genera, representing 10 families of at least 50 chalcidoid parasitoids and hyperparasitoids recorded from Choristoneura species (Tortricidae), or their primary parasitoids, in America north of Mexico. We include species reared throughout a 12-year study of the parasitoids and hyperparasitoids associated with the spruce budworm, Choristoneura fumiferana (Clemens), in New Brunswick, Canada, as well as those listed in various catalogs. Notes are provided for all the chalcidoid species, whether or not they are recorded in the literature. Nine species doubtfully or incorrectly recorded from Choristoneura species are also discussed.

Primary parasitoids belonging to the Ichneumonidae, Braconidae, and Tachinidae have been recorded from 10 of the 16 Nearctic Choristoneura species but chalcidoid parasitoids are recorded, usually as hyperparasitoids, from only four of the 16 species. The species of primary parasitoids of Choristoneura checked for records of parasitism by Chalcidoidea are tabulated by host species. Also listed are species of primary parasitoids serving as hosts for each of the chalcidoid species. We report 51 new host records of primary parasitoids and hyperparasitoids from C. fumiferana and its parasitoids collected in New Brunswick.

A new generic combination is given: Mesopolobus tortricis (Brues) comb.nov. from Psychophagus (proposed by Z. Boucek).

We tested the prediction that larvae of the fir coneworm, Dioryctria abietivorella (Groté), preferentially exploit cones previously damaged by cone maggots, Strobilomyia spp. In most years sampled, fir coneworm attacked a significantly greater proportion of maggot-damaged than healthy cones of both white spruce and black spruce. The ecological implications for pest management are briefly discussed.

Various biological parameters of Liriomyza trifolii (Burgess) were investigated to maximize mass-rearing efficiency of this insect. Average percentage emergence from a cohort of uniformly aged pupae was 90.0% of which 37.0% were males. A significant difference in the among-day emergence sequences from a pupal cohort was detected with 77.5% of all females and 80.1% of all males emerging during the first 2 days of the emergence sequence. Adults emerging on day 3 within the emergence sequence lived significantly longer than did flies emerging on the other days within the sequence. Male flies lived an average of 9.9 days or 33.1% less than the 14.8-day average for female flies. Cage size was also found to influence adult longevity significantly with the greatest average longevity (20 days for females and 12 days for males) occurring in 385.6-cm3 cages. Emergence time within an emergence sequence and the physical size of an experimental unit are two previously experimentally undocumented sources of variation influencing longevity of Liriomyza. A significant nonlinear relationship between the number of flies leaving the rearing cages (as a result of normal rearing procedures) and the daily number of pupal L. trifolii added to each cage was detected. From these biological parameters, a birth and death rate simulation model was developed to predict adult population sizes of L. trifolii within a mass-rearing program. The gender-specific simulation model consisted of adult emergence (quantified in terms of the adult emergence sequence from a known number of pupae entered into each rearing culture), and adult death rate (quantified in terms of the survivorship of adults within the culture and the number of adults escaping from the culture). The adult population sizes predicted by the simulation model were not significantly different from the average population sizes observed from the rearing cages in validation studies utilizing normal mass-rearing practices. Use of this model should reduce the effort expended on maintaining host populations for commercial mass-production of natural enemies of L. trifolii.