Twenty-three characters or character systems of adults and larvae of Terebrantes are analyzed for evidence of monophyly and phyletic relationships of Chalcidoidea, Mymaridae, and Mymarommatidae. The taxa are considered to be a monophyletic group based on 3 hypothesized synapomorphies: mesotrochanteral depressor without fu2-tr2 or mesoscutal portion of t2-tr2; axillar phragma as site of origin for all or part of t,-tr2 muscle; and independent basal ring absent from male genitalia. The family Mymaridae is considered to be monophyletic based on at least 3 apomorphies: fore wing with hypochaeta; head with frontal, median, and supraorbital sulci; and toruli distinctly closer to inner margin of eye than to each other. Chalcidoidea, including Mymaridae, is considered to be a monophyletic taxon based on 3 apomorphies: prepectus externally visible, at least dorsally adjacent to lateral edge of mesoscutum; mesothoracic spiracle positioned at exposed lateral edge of mesoscutum; and multiporous plate sensilla of antenna with unique structure, as described in text. Mymarommatidae is considered to be the monophyletic sister group of Chalcidoidea based on several apomorphies, including 4 autapomorphies: head composed of frontal and occipital sclerites, which are connected by pleated membrane along hyperoccipital region; hind wing stalk-like, without membrane and terminated in bifurcation that clasps fore wing; fore wing with reticulate pattern formed by raised lineations of membrane; and axillar portion of t2-tr2 muscle absent. Phyletic relationship of Serphitidae with Mymarommatidae is deemed inconclusive because relevant internal character states of amber fossil serphitids cannot be determined. It is suggested that mymarommatids be accorded family status, but not be assigned to superfamily until phyletic relationships are more accurately determined in Terebrantes. A matrix summarizes character-state distribution of most characters analyzed for Terebrantes, and a cladogram illustrates hypotheses of character-state evolution and proposed relationships.

Bark beetles (Coleoptera: Curculionidae: Scolytinae) play important roles in temperate conifer ecosystems, and also cause substantial economic losses. Although their general life histories are relatively similar, different species vary markedly in the physiological condition of the hosts they select. Most of ∼6000 known species colonise dead or stressed trees, a resource they share with a large diversity of insects and other organisms. A small number of bark beetle species kill healthy, live trees. These few are of particular interest as they compete directly with humans for resources. We propose that tree killing evolved when intense interspecific competition in the ephemeral, scarce resource of defence-impaired trees selected for genotypes that allowed them to escape this limitation by attacking relatively healthy trees. These transitions were uncommon, and we suggest they were facilitated by (a) genetically and phenotypically flexible host selection behaviours, (b) biochemical adaptations for detoxifying a wide range of defence compounds, and (c) associations with symbionts, which together aided bark beetles in overcoming formidable constitutive and induced host defences. The ability to detoxify terpenes influenced the evolutionary course of pheromonal communication. Specifically, a mate attraction system, which was exploited by intraspecific competitors in locating poorly defended hosts, became a system of cooperative attack in which emitters benefit from the contributions responders make in overcoming defence. This functional shift in communication was driven in part by linkage of beetle semiochemistry to host defence chemistry. Behavioural and phenological adaptations also improved the beetles’ abilities to detect when tree defences are impaired, and, where compatible with life history adaptations to other selective forces, for flight to coincide with seasonally predictable host stress agents. We propose a conceptual model, whereby the above mechanisms enable beetles to concentrate on those trees that offer an optimal trade-off between host defence and interspecific competition, along dynamic gradients of tree vigour and stand-level beetle density. We offer suggestions for future research on testing elements of this model.

Beginning 1 year after an intense forest fire in the Interlace region of Manitoba, carabid beetles were sampled by pitfall trapping in two burned sites and two unburned control sites. Before the tire, one burned site had been dominated by aspen, Populus tremuloides Michx,, and the other by conifers (mostly Picea spp.). During the 11-year study, burned sites became dominated by aspen saplings. Three carabid species were caught significantly more frequently in burned sites than in control sites. Two of these, Harpalus laticeps LeConte and H. egregius Casey, invaded soon after the fire and were caught in the burned sites for several years after the fire. Seventeen species were caught significantly less often in burned than in control sites; catches of another 13 common species were not significantly affected by burning of the site. Burning influenced the seasonal patterns of catches of Carabus taedatus F. and Pterostichus adstrictus Eschscholtz; this was attributed to higher litter and soil temperatures in burned sites. Seasonal patterns of other common species were not markedly affected by burning. In burned sites, the incidence of brachypterous species and the size of beetles increased with time after the fire. In control sites, the incidence of brachyptery was independent of time, but the percentage of brachypterous species was significantly higher in the conifer site than in the aspen site. Trends of brachyptery and size are those expected if early colonizers are super-tramp r-strategists and later invaders are K-strategists. Patterns of species occurrence during forest regeneration can be explained in terms of dispersal and competitive abilities, preference for physical attributes of the habitat, and responses to prey availability.

Landing rates as monitored by landing traps indicate that the mountain pine beetle, Dendroctonus ponderosae Hopkins, is not attracted to lodgepole pine, Pinus contorta Dougl., prior to the first gallery start. Bark terpene odors and DBH were not correlated with beetle landing rates, with the exception of beta-phellandrene which accounted for a statistically significant 18% of the variation in landing rates. Beetles were unable to distinguish between hosts, dead hosts and nonhosts during landing. The elderberry pith bioassay indicated the presence of a gallery initiation stimulant in the bark.

Monoterpenes affected the attraction of three sympatric species of bark beetles (Coleoptera: Scolytidae) to pheromone-baited multiple-funnel traps in stands of lodgepole pine. Catches of Ips pini (Say) in traps baited with its pheromone, ipsdienol, were directly related to the release rates of 3-carene, β-phellandrene, and β-pinene. Catches of Dendroctonus ponderosae Hopkins in traps baited with exo-brevicomin and cis- and trans-verbenol were directly related to the release rates of 3-carene, myrcene, and β-phellandrene. Ips latidens (LeConte) exhibited preferences for traps baited with ipsenol and β-phellandrene or β-pinene but not in a dose-dependent fashion. Catches of I. latidens in traps baited with its pheromone, ipsenol, were inversely proportional to the release rates of 3-carene, myrcene, and terpinolene. Similarly, catches of I. pini in traps baited with its pheromone, ipsdienol, were inversely proportional to the release rates of myrcene and terpinolene. These results demonstrate a degree of species specificity among three phloeophagous species with respect to preferred host odours. The bark beetle predators–associates Lasconotus complex LeConte (Coleoptera: Colydiidae) and Corticeus Piller and Mitterpacher sp. (Coleoptera: Tenebrionidae) demonstrated some measure of specificity to monoterpenes in their responses to ipsdienol-baited funnel traps. γ-Terpinene increased attraction of L. complex but had no effect on Corticeus sp., whereas α- and β-pinene increased attraction of Corticeus sp. but had no effect on L. complex.

Pea aphids can avoid ladybug predators by dropping from the food plant when disturbed. Once off the plant the aphid must find another food plant. If temperatures on the ground are high, the aphid may die before finding a new food plant. In Kamloops, B.C., summers are hot and dry, compared with Vancouver where the climate is warm and moist. Pea aphids from Kamloops generally exhibit back-up behaviour and rarely drop from the plant when approached by a ladybug. By contrast, Vancouver pea aphids readily drop from the plant when disturbed by a predator. Adult aphids from Kamloops are more tolerant of heat under moist conditions at 37.5 °C than Vancouver adults but under dry conditions and at 42 °C, both groups have similar survival times. First instars of both aphid biotypes die sooner at high temperatures than adults. Mortality of aphids on the ground is sufficiently high to select against dropping behaviour as a first line defense against predators in areas with hot, dry climates.

The European pine sawfly, Neodiprion sertifer (Geoffr.), is a serious defoliator of pine in many parts of Europe and Asia. Infestations of this insect have been controlled by weather, and frequently high percentages are destroyed by parasitic and predacinus insects, by small mammals, and by birds. Infectious diseases are most frequently reported as having controlled outbreaks, namely: virus disease (4, 5), bacterial disease (12). fungus disease (8), bacterial and fungus diseases (7, 11), a disease not diagnosed (9).

The internal reproductive organs of both sexes are described with regard to their functions during mating and the transfer, storage and use of sperm during oviposition. Although generally hymenopteran in structure they differ in some details from species previously described. The sperm storage organ and glands in the oviducts are more precisely defined and an account given of a structure which regulates the number of sperm entering the sperm bundle prior to its transfer to the female.

During copulation thread-like sperm with helical heads are deposited in bundles of 300 in a funnel-like extension of the oviducts produced by a single contraction of the ovaries. Sperm move along the duct to the sperm capsule largely by their own motility. Sperm remain active in the capsule with their heads toward the opening where they are prevented from escaping by a U-shaped loop in the duct. The loop straightens when ova pass through the oviducts, allowing sperm to descend one at a time. Although the precise mechanism by which the storage organ releases sperm is not fully understood, it is unlikely that discontinuity in the release of sperm is the regulating mechanism involved in the production of haploid males in this species.

Many of the early papers on the spruce budworm, Choristoneura fumiferana (Clem.), included accounts of the general habits and seasonal history of the insect (9, 13, 18, 10, 22). Later papers have heen concerned principally with ecological or pathological relations, current infestations and damage, or chemical control. There has not been, however, any detailed account of the salient features of the development of the spruce budworm.

The history of the winter moth, Operophtera brumata (Linnaeus), a geometrid introduced into Nova Scotia, is reviewed and an assessment is made of two introduced parasites: a tachinid, Cyzenis albicans (Fallen), and an ichneumonid, Agrypon flaveolatum (Gravenhorst). Functional response curves of both species are discussed, particularly the atypical S-shaped curve of C. albicans, which demonstrates regulatory properties. Biological control efforts to date have been successful but a virus that appeared in winter moth populations may change initial relationships between the introduced parasites and the host.

Many authors observed that mosquitoes respond to a large variety of artificial sounds (for references see Roth. 1948). Efforts to attract males of Aedes aegypti (L.) by play-back recoridings of the flight sound of the female have met with moderate success (Kahn et al., 1945; Offenhauser and Kahn, 1949; Kahn and Offenhauser, 1949). Roth (1948) demonstrated that males of A. aegypti approached the sounds of tuninh forks and sine sounds from a speaker. He also determined the upper and lower limits of frequencies that stimulated males, but in these experiments he did not use attraction to the source of the sound as the criterion of response, but the “seizing and clasping”reaction. He exposed the maIe mosquitoes in cages, three inches by three inches by one inch, placed against a box that housed a loud speaker. Under these conditions the mosquitoes had little opportunity to fly to orient themselves toward the sound source. Moreover the sound used was of such intensity (108 db at 2½ inches) that the whole cage vibrated, so that at least part of the response was undoubtedly caused by vibration of the substratum on which the mosquitoes rested. Sounds of such intensity do not normally occur in the natural environment of the mosquito. Moreover, the “seizing and clasping” response does not occur until the male approaches the female in response to sound or other stimulus. If the place of sound in the attraction of thc males is to be studied, the primary response, that of approach, should be the criterion and the amount of sound used should bear a reasonable relation to that occurring in nature.

Experiments were carried out on excised leaves to determine the form of the functional response curve of the phytoseiid predators Amblyseius largoensis (Muma), A. concordis (Chant), and Typhlodromus floridanus (Muma), to increases in density of the prey, Oligonychus punicae (Hirst). The curve for each species was curvilinear to a plateau from prey densities of 1 to 70/arena, the average number killed/24 hours at the plateau being 8.5/female for A. largoensis, 5.5/female for A. concordis, and 2.0/female for T. floridanus. From prey densities of 70–300/arena, there was an accelerated rise to another plateau, in which the average number of prey killed in a 24 hour period was double that of the first plateau.Detailed analysis of A. largoensis at a density of 200 prey/arena showed the effect to be due to a stimulation–interference component, which resulted in the predator killing several prey in close succession because of increased prey contact, and because total utilization of each was minimal. During a 1 hour period, A. largoensis captured an average of 1.25 prey/predator at a prey density of 35/arena, while at a prey density of 200/arena, 3.87 prey/predator were captured. More than four times longer was spent feeding on the first prey at a density of 35 than at a density of 200 prey/arena. During the time that the predator was hungry, it was stimulated to capture and kill interfering prey that bumped into it.The functional response curve of the three predators increased in magnitude when waterproofed paper arenas were used. Four possible reasons for this increase are discussed: reduced number of prey eggs for consumption by T. floridanus; lack of webbing, which interferes with searching; increased prey activity; and dehydration of prey, affecting their relative palatability to the predator.

A general population model for cotton growth and development is presented. The model captures the essential properties of the biological processes, and is sufficiently flexible to the incorporation of complex physiological and behavioral characteristics. The model has been used successfully to simulate the growth and development of Acala SJ-II cotton in California. The mathematical framework for coupling plants and herbivores has been presented, and the biological implications of their damage to the plant examined in a very general way.

Three types of cages, suitable for rearing potato-infesting aphids on whole plants, parts of plants, and excised leaves, have been developed during aphid investigations at the Fredericton laboratory. These cages have been used in the greenhouse and insectary with the four potato-infesting aphids Myzus persicae (Sulz.), Macrosiphum solanifolii (Ashm.), Aphis abbreviata Patch, and Aulacorthum solani (Kltb.).

The impacts of insect outbreaks on tree mortality, productivity, and stand development in Canada are reviewed, emphasising spruce budworm (Choristoneura fumiferana (Clemens), Lepidoptera: Tortricidae) and mountain pine beetle (Dendroctonus ponderosae Hopkins, Coleoptera: Curculionidae). Reduced growth and survival are a function of insect population and defoliation level. It is feasible to make short-term (annual) predictions of insect population and defoliation based upon sampling, but long-term, multi-year predictions are problematic. Given the historical record, it is expected that outbreaks will occur with relatively predictable frequency and basic host relationships and abiotic constraints will not change dramatically. However, the precision of predictions at fine scales is variable and reduced over time. Relationships between tree growth reduction, survival, and cumulative defoliation or beetle population level are available for major insect species. Understanding insect outbreak effects hinges on mortality, changes in interspecies competition, regeneration, and succession. Altered stand dynamics caused by insects can be interpreted for indicators such as wildlife habitat, old forest, riparian buffer cover, viewscapes, and connectivity. Anthropogenic changes are altering impacts via range expansions, northward shifts, and changes in forest composition. We can better understand effects of insect outbreaks and how best to ameliorate damage through a combination of empirical permanent plot studies, modelling, and manipulative experiments.

The behaviour of Dendroctonus pseudotsugae Hopk. in different physiological states was studied in relation to temperature, light, and host.

Newly emerged beetles preferred temperatures near the threshold for flight. When conditioned in dry air at room temperature for 16 hours they preferred cooler temperatures.

At room temperature, most newly emerged beetles settled in the brightest zone of a light gradient (55 foot-candles), although some settled in dimmer zones. If the beetles' emergence was delayed or if they were stored after emergence, more remained in the zone between 0.5 and 10 foot-candles.

In light-dark tests at room temperature most newly emerged beetles were photopositive, but some were indifferent and a few were photonegative. Increasing the temperature and humidity increased the proportion of photonegative individuals. Newly emerged females oriented more directly to a single source of light than males, bur after conditioning or aging both reacted similarly.

Females were separated into three behavioural types based on their reactions. Photopositive individuals flew more readily than indifferent or photonegative beetles; some photonegative females showed no inclination to fly.

Photopositive females were usually host negative but photonegative females were host positive. The proportion of these behavioural types within different samples varied. A group that emerged early contained a higher incidence of photopositive host-negative individuals than a group that emerged late, or was stored for 10 days after emergence. But host-negative beetles would attack logs after starvation, flight exercise, or exposure to more attractive hosts.

Host-positive females contained less fat than host-negative siblings. The decline in lipids during aging, starvation or flight thus may induce behavioural changes.

There is a co-ordination of successive activities in the Douglas-fir beetle similar to that reported for aphids. The initial urge to disperse outweighs responses to host stimuli, but this balance changes as the beetles fly or as host stimuli increase. The balance between thresholds for dispersal and attack also varies in relation to the conditions under which the emerging beetles developed. Consequently, each individual behaves differently when it emerges. The behaviour of a population changes as the season progresses and from year to year owing to changes in the state of individuals and in the attractiveness of hosts.

The flight range of Culicoides variipennis was studied in a bluetongue virus enzootic area during the summer of 1977. Field-collected larvae and pupae were reared to the adult stage in a field laboratory. Approximately 82,200 flies were marked with micronized fluorescent dusts and released and 403 were recaptured in CO2-baited baffle traps. The maximum distance traveled was 0.8 km by a male and 4.0 km by a female. One female was recovered on the release night 2.8 km from the release point. The mean distance traveled (MDT) was 0.8 km on the release night, 2.02 km on one night postrelease, and 2.11 km on two nights postrelease. The MDT for all flies recovered up to eight nights postrelease was 1.89 km.

Based on the overall MDT of 1.89 km, the transmission of a disease agent by C. variipennis becomes theoretically possible if the host population density is greater than one per 3.57 km2. The probability of transmission can be significantly reduced if a 3.57 km2 area surrounding a single C. variipennis breeding site is treated with an effective insecticide.

Adults of five species of flea beetles were found attacking rape crops (Brassica napus L. and Brassica campestris L.) in the Canadian prairie provinces from 1971 to 1974. Phyllotreta cruciferae (Goeze) was the most abundant and serious pest, followed in order by Psylliodes punctulata Melsh. and Phyllotreta striolata (F.) (= vittata (F.)), while Phyllotreta albionica (Lec.) and Phyllotreta robusta Lec. were present only occasionally. The four Phyllotreta species confined their feeding largely to cruciferous plants, but Psyl. punctulata had a broader host range. All of the five species overwintered as adults, usually in leaf litter or turf beneath hedges, poplar groves, or fencerows, or sometimes in the soil in fields, and all became active with the arrival of warm sunny weather in the spring, with Psyl. punctulata usually being the first to appear. All appeared to have but one generation per year, with mating and egg laying occurring in the spring, the larvae inhabiting the soil and feeding on host-plant roots, and the new generation of adults emerging from pupae in the soil in late July and in August. The overwintered adults usually died in late June or early July, so there was a period in July when adult flea beetles were scarce. The most serious damage to rape crops by flea beetles was caused by overwintered adults attacking seedling crops in the spring; movement of these beetles into crops took the form of a creeping infestation moving from plant to plant into the field from nearby volunteer rape of cruciferous weed feeding grounds, or a more rapid and even infestation of a whole field with flight probably being the major method of movement. Flea beetles fed most actively when the weather was sunny, warm, and dry; cool damp weather reduced the intensity of attack and aided plant growth. Shade, such as exists in a healthy stand of rape beyond the pre-bloom stage, also inhibited attack. Occasionally, late-maturing rape crops were damaged in late summer by new generation adult flea beetles, particularly P. cruciferae, feeding on the green epidermis of the stems, leaves, and pods.

A field key for separating the five flea beetle species attacking rape crops in the Canadian prairie provinces is given.

The annual emergence of 11 chironomid species from more or less shallow ponds in the area of Hazen Camp (81°49′ N., 71°18′ W.) is considered. Features of emergence are very similar in all these arctic species, although different species emerge at slightly different times in the same habitat.In the deeper habitats, emergence from a deep site is slightly later than that from a shallower one in the same pond. There are very marked differences in times of emergence from pond to pond: emergence of 50% of the annual total for a given species may be reached in different ponds up to 3 weeks apart. These differences from habitat to habitat mean that adults are present over the general Hazen area throughout the arctic summer.The time at which emergence begins in a given pond (or given site within a deeper pond) is primarily dictated by the temperature required for pre-emergence development, but also by other features of individual ponds. Pond temperatures near 4° or 5 °C are most important in this respect. The time of first emergence differs between years in the same pond according to year-to-year temperature differences.Emergence of a given species is basically highly synchronized within a pond, but the emergence period may be prolonged by lowered temperatures acting as a threshold for adult emergence at about 7 °C. The emergence pattern is less regular in shallow ponds in which the temperature fluctuates greatly, and it is more regular with lower peaks in deeper ponds.Males of a number of species generally emerge slightly before the females.Emergence of given species within given ponds is synchronized because only larvae which are ready to pupate without further feeding in spring emerge in any year. There must therefore be control of a ’diapause’ type.Aquatic insect species are characterized as ’absolute spring species’ if all potential émergents overwinter as mature larvae (i.e. larvae in which no further growth is necessary before emergence) and also ’diapause’ is present at this stage. To this category all of these high arctic species belong. They are apparently derived from ’absolute spring species’ farther south, the life-cycles of which are pre-adapted to the shortness of the arctic season. Despite the potential for highly synchronized emergence which such species possess, this potential is not fully realized in the arctic because the irregular fluctuations of temperature there operate near values which may directly inhibit development and emergence.

During the past spring and summer glass barrier traps have been used as a means of sampling the flying populations of an ambrosia beetle, Trypodendron sp., and other scolytid beetles. The “window” trap has functioned well enough to warrant its brief description. A piece of window glass (2 × 2 ft.) is set in a three-sided wooden frame from which a sheet metal trough is hung. The trough is filled with fuel oil or water to which a wetting agent is added. Screened outlets provide for drainage of excess rain water in the laner case and when oil is present an inverted “L” tube drains this water from beneath the oil. Insects are collected by removing the trough and pouring its contents through a strainer. Traps are hung from various types of pole framework depending on their location, and guy wires are used to keep them from swinging.