This study describes an image analysis method that reliably quantifies feeding damage by leaf beetle larvae (Altica spp.) to Canada thistle leaf disks. Quantification is objective, uncomplicated, precise, rapid, and usable with any image analyzer. Image analysis of dried, pressed leaf disks is not recommended, as the amount of shrinkage of the eaten area upon drying varies with the amount eaten. Analysis of fresh material is advised. Image analysis of fresh leaf disks will be a useful method of comparing rates of consumption of two Altica species, one of which is being considered as a new candidate for the biocontrol of Canada thistle, and also other insects with similar feeding habits.

The discovery of egg masses of Asian gypsy moth onboard Russian freighters in Pacific ports of North America and the capture of adult male gypsy moths in pheromone traps underscored the need for a positive identification of Asian and European gypsy moth males. We have devised a method for differentiation of these two populations based on restriction endonuclease cleavage of a polymerase chain reaction (PCR) generated product. DNA primers for the 5S and 28S rDNA were employed to amplify the ITS2 region using PCR. The ends of the amplified DNA products were sequenced and gypsy moth specific oligonucleotide primers were designed to amplify the gypsy moth ITS2 region. Eleven of 28 restriction enzymes tested cleaved the amplified product. The restriction enzymes ClaI, PvuI, and TaqI generated distinct restriction fragment patterns for the Asian and European gypsy moth PCR product. This diagnostic was applied to samples of field-collected gypsy moths in a double blind test and correctly identified them as Asian or European. Additional studies demonstrated that these primers and restriction enzymes could be used to differentiate among Lymantria dispar, L. monacha, and L. mathura.

Larvae of the black spruce cone maggot, Strobilomyia appalachensis, were infected and killed by Steinernema carpocapsae (Weiser) All and Umeå strains, S. feltiae (Filipjev) (= bibionis) strain 27, and S. glaseri Steiner strain 326, in laboratory tests. After formation of puparia, however, cone maggots were practically resistant to all species and strains tested. Very few or no maggots were infected when nematodes were sprayed on or injected into infested spruce cones. The survival, activity, and infectivity of infective juveniles held in an aerated infusion of black spruce cones were significantly lower compared with those held in aerated water. In peat–sand columns, the proportion of larvae infected with S. feltiae, but not S. carpocapsae Umeå strain, was significantly greater when larvae were dropped immediately or 1 day following nematode application compared with 1 day before or 3 days following nematode application. Our results suggest that, in field trials for cone maggot suppression, nematodes should be applied within a day prior to larval drop and that repeated applications may be required for persistence of sufficient infectivity.

New information concerning Palaearctic species of Spalangiopelta is provided. Two new species are described and illustrated: S. alboaculeatasp. nov. (type locality: England, Cambridgeshire, Santon Downham) and S. hikosp. nov. (type locality: Japan, Kyushu, Mt. Hiko). Additional information and illustrations are provided for S. procera; the male is described and illustrated for the first time, and notes and photomicrographs of the forewing and antenna are used to augment the previous descriptions of the female. The male of S. dudichi is also described and illustrated for the first time. Notes are provided to accommodate these new species and males in the key to world species of Spalangiopelta (Darling 1991) and the phylogenetic and biogeographic implications are discussed.

Fleas (Siphonaptera: notably species of Ceratophyllidae) parasitize many species of birds. Although adult fleas rely on the birds as their principal means of dispersal, they are not commonly collected on the host itself. Most of these fleas spend the greatest portion of their life cycle in or near the host's nest. Colonial nesting habits facilitate transfer of fleas among hosts (Hoogland and Sherman 1976), and reuse of nests or nesting cavities in successive breeding seasons enhances transmission from one generation to the next (Hopla and Loye 1983). This stability of nest habitat and reliability of host presence favours fleas that are truly nest-bound. On the other hand, birds that defend exclusive breeding territories and construct new nests for each breeding attempt are usually host to vagabond, generalist species (Darskaya 1964).

Eggs of Ephoron album and E. shigae were studied by scanning electron microscopy. They showed similar structure of both polar cap and micropyles, but had different chorionic patterns. Micropyles were of the tagenoform type and, whereas in most mayflies thev are equatorial or subequatorial, in these eggs they were located close to the apical pole. The chorion was smooth in E. album and had a large mesh reticulation in E. shigae. The effect of water in causing the cap to swell and expand was tested by fixing eggs of E. album at different lime intervals after their mechanical deposition in water. The polar cap was a composite apparatus, consisting of finger-like projections with slight terminal enlargements, which arose from a common hood. The latter was connected via a thread bundle to the chorionic surface. In turn, the thread bundle arose from a chorionic collar located immediately underneath the hood. Each finger-like projection was composed of a large number of thin threads packed together, each ending in a small terminal knob. The function of the polar cap was discussed in relation to egg–water interaction.

Similarities in population parameters among aphid species led us to investigate the potential for a single set of parameters that can be used to develop a ‘generic’ sampling plan for multiple small grain aphid species. A weighted average for the slope and intercept used to relate the proportion of infested tillers to the number of aphids per tiller was determined from the data in 15 published reports. These average parameter estimates were used to predict the number of aphids per tiller in 48 wheat fields sampled for four aphid species. The predicted estimates were regressed on the observed estimates with neither slopes nor intercepts differing significantly from one or zero, respectively. Therefore, it appears the single model is adequate for predicting aphid density for the aphid species tested.

A reliable method for rearing the subterranean summer morph of the sugarbeet root aphid, Pemphigus betae Doane, is described. Field-collected aphids were reared using hydroponic growth pouches that allowed exposed root tissue to be fed on by P. betae. The aphid has been maintained in continuous culture for over 3 years. Open pouches were subsequently modified with cages to provide more successful mass rearing. Cages placed on the pouch were devised to provide an arena that concentrated aphids on one area of the pouch, minimized wandering behavior, and ensured a more vigorous colony. During a 10-week mass rearing experiment, caged pouches consistently averaged 120.8 ± 9.6(se) aphids per cage (fourth instars and adults) following 2-week incubation periods. Caged pouches also were used to isolate individual aphids for development and fecundity studies. Age-specific life tables were developed for P. betae using both open pouches at 20°C, and caged pouches at 24°C. Although the intrinsic rate of increase (rm) was lower at 20°C on a daily time scale (rm = 0.2314 versus 0.2591), rm was significantly greater at 20°C on a degree-day (DD > 7.6°C) time scale (rm = 0.0187 versus 0.0158). The difference on a DD basis resulted primarily from a longer time interval from birth to first reproduction (TFR) at 24°C(TFR = 158.5 versus 147.1 DD at 20°C). These results corroborate previous experience with P. betae, indicating that 20°C appeared to be an optimum temperature for mass rearing. Stable age distributions for P. betae cohorts were only slightly affected by temperature; on average approximately 55, 22, 11, 7, and 5% of the aphids were first, second, third, and fourth instars, and adults, respectively. Though similar studies have not been reported for other Pemphigus spp., all demographic statistics were characteristic of many foliar-feeding aphids held under similar constant temperature conditions.

Larval and pupal parasitoids were studied from collections made in endemic, outbreak, and post-outbreak populations of forest tent caterpillar (FTC), Malacosoma disstria, at 21 sites in Alberta, Canada, from 1989 to 1994. The parasitoid complex included 18 identified species. Aleiodes malacosomatos (Mason) (Hymenoptera: Braconidae) was common in low density populations and was the only species to attack FTC larvae prior to the fourth instar. Leschenaultia exul (Townsend) (Diptera: Tachinidae) was the most abundant larval parasitoid in endemic populations and after the 2nd year of outbreak. Although prevalent early in outbreaks, Patelloa pachypyga (Aldrich and Webber) (Diptera: Tachinidae) declined in older outbreaks possibly because it completes larval development later than other tachinids, leaving it vulnerable to competition from aggressive pupal parasitoids. I hypothesize that early initiation of oviposition allows L. exul to be more successful than P. pachypyga in low density populations because caterpillars have dispersed before the latter species initiates oviposition. I recorded lower pupal parasitism by Arachnidomyia aldrichi (Parker) (Diptera: Sarcophagidae) in Alberta than has been recorded in other regions, although it was still the most abundant parasitoid reared in this study. Parasitism by A. aldrichi was significantly higher in cocoons collected from undergrowth vegetation than from the forest canopy. Other pupal parasitoids contributed relatively little to FTC mortality.

The spatial distribution of the eulophid Sympiesis marylandensis Girault was examined in Connecticut in October 1988 and 1989 by vacuum-sampling apple trees in three zones of two apple orchards infested by its gracillariid host, the apple blotch leafminer, Phyllonorycter crataegella (Clemens). The abundance of females of S. marylandensis decreased with increasing distance of the zone or the sampled apple tree from the forest. The abundance of males in different regions of the orchard was similar. In two of three samples, the density of mines of leafminers was significantly higher near the edge than in the center of orchards. Parasitization of leafminers of the second generation and the number of female parasitoids vacuum-sampled during the third generation did not have a similar distributional pattern. We suggest that the amount of parasitism by S. marylandensis would be affected negatively by spraying trees at the border of orchards to kill immigrating pests.

The western flower thrips [Frankliniella occidentalis (Pergrande)] (Thysanoptera: Thripidae) is a major pest of greenhouse crops (Broadbent et al. 1987; van der Veire and Degheele 1992; Chambers et al. 1993). Chemical control of F. occidentalis is difficult because of its cryptic behaviour and widespread resistance to insecticides (Immaraju et al. 1992). The insidious flower bug, Orius insidiosus (Say), is widely promoted as an effective biological control agent for this pest (Chambers et al. 1993; van der Veire and Degheele 1992; Castane and Zalom 1994) and its use has increased steadily since their introduction in the late 1980s. When our project was initiated in 1989, O. insidiosus was a little known and largely unavailable biological control agent. Now there are several domestic and international commercial sources of Orius spp. and these predatory bugs have become a focus of research in Canada, the United States, and Europe. At first it was difficult and costly to maintain cultures of only 100 or 200 individuals but now we can rear 50000 — 100000 Orius per week for less than $0.03 (Canadian) each.

Puparia of Delia radicum collected in late autumn at Winnipeg and Portage la Prairie (Manitoba), St-Jean-sur-Richelieu (Quebec), London (Ontario), and St. John’s (Newfoundland) were parasitized mainly by Aleochara bilineata (Gyllenhal) (Coleoptera: Staphylinidae) and Trybliographa rapae (Westwood) (Hymenoptera: Cynipidae). At Winnipeg, St-Jean, and St. John’s parasitism by A. bilineata was high (<94%) and by T. rapae was low (<3%). At London, both parasitoids attacked less than 14% of the host puparia. At Winnipeg, host population density was related to parasitism by A. bilineata and to the temperature and rainfall during June and July. Parasitism by A. bilineata may be related to cumulative degree-days over 5°C during June and July at Winnipeg and during June and September at London. In Canada, the parasitoid complex is not effectively stabilizing host population density. The introduction of additional parasitoid species should be considered.

The seasonal occurrence and number of generations of Lygus lineolaris (Palisot de Beauvois) were studied on alfalfa (Medicago sativa L.), everbearing strawberries (Fragaria × ananassa Duchesne), oilseed rape (Brassica napus L.), and stinkweed (Thlaspi arvense L.) in field plots at Winnipeg, Manitoba, and in commercial alfalfa and oilseed rape fields throughout the agricultural areas of Manitoba in 1990–1993. Lygus borealis (Kelton) was studied only during 1993. Lygus lineolaris had two non-overlapping generations in southern Manitoba. Overwintered adults migrated onto host plants during die first 3 weeks of May, and females containing chorionated eggs were found in relatively small numbers for 5–6 weeks until the last 3 weeks of June. First-generation nymphs were present from the last half of May until the last half of July. During the last 2 weeks of June, the overwintered adults disappeared suddenly and were replaced completely by first-generation adults. First-generation adults eclosed during the last 2 weeks of June and in July, and first-generation females containing chorionated eggs were present for about 6–7 weeks until mid-August. Second-generation nymphs first appeared in late July or early August and most completed development by the end of September. Second-generation adults were found from the first half of August until they hibernated in October and November. Most second-generation females contained previtellogenic eggs and. therefore, were in reproductive diapause. In 3 of the 4 years, the overwintered adults appeared to include all second-generation adults plus 0–20% of the first-generation adults. The data from commercial alfalfa and oilseed rape fields indicated that the seasonal occurrence of L. lineolaris was relatively uniform in most or all agricultural areas of Manitoba. Lygus lineolaris has one generation (the second generation) on oilseed rape, and the eclosion and dispersal of reproductively active first-generation adults were well synchronized with the bud and flower stages of this host plant in southern Manitoba. In 1993, L. borealis had two generations and its seasonal occurrence was similar to that of L. lineolaris.

The role of adult nutrition in longevity, progeny production, and offspring sex ratio of Trichogramma minutum Riley was examined. On average, honey-fed females lived 26.4 days and produced 260 offspring; unfed females lived 3.5 days and produced 80 offspring. Feeding on fructose or sucrose also significantly increased longevity and fecundity over unfed females (fructose, 23 days and 230 offspring; sucrose, 21 days and 230 offspring) but to a lesser degree than feeding on pure honey. Females fed yeast suspension or water had no significant increases in longevity or fecundity compared to unfed females. Offspring sex ratios of long-lived females were male-biased (50–62% males), those of short-lived females were female-biased (74–82% females). Lifetime reproduction of honey-fed females was highest at 20–25 °C and relative humidities of 20–80%, but short-term offspring production (during the first 2 days after emergence) was highest at 30 °C and 60–80% RH. Females that had access to honey for only a 24-h period did not increase their offspring production over the first 4 days of their lives when compared to unfed females. The potential benefits of feeding adult T. minutum for mass-rearing and field release are discussed.

The objective of this study was to determine the quantitative and seasonal association between the pitch canker fungus, Fusarium subglutinans f. sp. pini, and two potential beetle vectors, Conophthorus radiatae Hopkins and Ernobius punctulatus Fall. In samples of reared and dissected cones, 21.4 ± 2.5% of C. radiatae and 30.1 ± 8.0% of E. punctulatus adults carried propagules of F. s. pini. Seasonal variation in mean percentage of contaminated C. radiatae and E. punctulatus emerged from cones ranged from 0 to 67% and was highest for both species February through April. In sticky traps 12.5 ± 2.3% and 11.8 ± 3.6% of E. punctulatus and Pityophthorus spp., respectively, were contaminated with propagules of F. s. pini.

Conophthorus radiatae and E. punctulatus co-occurred in 26% of the cones. The percentage of cones containing contaminated C. radiatae was greater when E. punctulatus progeny were also contaminated than when E. punctulatus was not. When contamination status of E. punctulatus was not considered, there was no significant difference in C. radiatae contamination between cones with and without E. punctulatus. Because C. radiatae appears to be a vector of the pitch canker fungus, interspecific transmission of inoculum may increase the incidence of this disease.

The parasitoid, Cephalonomia utahensis Brues (Hymenoptera: Bethylidae), was frequently observed parasitizing late-instar larvae of E. punctulatus, but was not found on larvae of C. radiatae. Emergence of large numbers of C. utahensis represents another potential source of inoculum for transmission to prey species.

Morphological, allozyme, and chromosomal characters and ecological traits have limited value for discriminating among four closely related Pissodes spp. known from western Canada. We amplified a 1585-bp segment of mitochondrial DNA (mtDNA), including half of the cytochrome oxidase I (COI) and all of the tRNA leucine and COII genes, using the polymerase chain reaction, and studied mtDNA variation within and among all four species of Pissodes with restriction enzymes. Twenty-four haplotypes were found among the 121 maternal lineages surveyed. Haplotype distributions suggest intermediate levels of gene flow for each species. Interspecific estimated sequence divergences ranged from 0 to 28.7%. Phylogenetic relationships among species were reconstructed using P. affinis Randall as an outgroup. Pissodes terminalis Hopping and P. nemorensis Germar were the most closely related species, and this clade was most closely related to P. strobi (Peck); P. schwarzi Hopkins branched off below these three. Restriction site variation is sufficient to discriminate unambiguously among most species. However, P. terminalis and P. nemorensis haplotypes were very similar, which may complicate discrimination between these two species, using mtDNA characters, where their ranges putatively overlap in Manitoba. A diagnostic protocol using three restriction enzymes, Bcl I, Dra I, and Hinf I, is recommended.

Through an analysis of the primary setae and pores (campaniform sensilla) of first-instar larvae of 32 species of Colymbetinae, 33 species belonging to other dytiscid subfamilies, and seven species belonging to other families of Hydradephaga, the ancestral system of primary setae and pores of the legs, the last abdominal segment, and the urogomphi of Colymbetinae is deduced. Seventy-four setae and 24 pores have been assigned to the generalized colymbetine larva: 51 setae and 18 pores on the legs, 15 setae and three pores on the last abdominal segment, and eight setae and three pores on each urogomphus. A comparison with the ground-plan pattern of the subfamily Hydroporinae is provided. Members of Colymbetinae differ from those of Hydroporinae by the presence of setae TR3, AB14, and AB15, the absence of pore ABd, and the presence of a variable number of additional setae on the femur. A tentative phylogenetic reconstruction of the colymbetine genera provided is based on 24 larval characteristics. The monophyletic origin of the subfamily Colymbetinae is confirmed based on the shared presence of seta AB14. Two monophyletic lineages unite basally: (1) [(Agabus Leach + Ilybius Erichson) + Agabinus Crotch], and (2) {[Colymbetes Clairville + (Rhantus Dejean + Neoscutopterus Balfour-Browne)] + Matus Aubé}. The genera Agabinus and Matus are postulated as a sister-group of (Agabus + Ilybius) and [(Colymbetes + (Rhantus + Neoscutopterus)], respectively. Compared with other Colymbetinae, both Neoscutopterus and Matus stand out by the presence of several strikingly peculiar features. The subgenus Rhantus (Nartus) is postulated to be the sister-group of Neoscutopterus based on the shared presence of additional setae on the dorsal margin of the femur.

Four new species are described: Commellus cedilla from Alaska, Canada, and adjacent northeastern states; C. hyphen from the aspen parkland of Saskatchewan to North Dakota; C. semicolon from southern Montana; and Extrusanus oryssus widespread in northern prairies (Alberta to Kentucky). Alary polymorphism in both genera is discussed. Species-specific characters from enclosed male genitalic structures are described and illustrated in detail for the first time, for all species except C. hyphen. Keys are presented to the species of both genera.

The population dynamics of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Pyralidae), were documented on potatoes grown in Prince Edward Island (P.E.I.) from 1990 to 1992. By comparing degree-day accumulations above 10°C, both first occurrence and peak flights of male adults occurred earlier than elsewhere in North America. Because potatoes in P.E.I. are attacked earlier and over a longer period of time than potatoes grown in other regions, the insect is an important pest of potatoes in P.E.I. The correlation between peak numbers of male adults caught in pheromone traps and egg masses on potato plants was not significant (p = 0.22). However, the correlation between egg masses per potato stalk and larvae per potato stalk was significant (p = 0.003). Trapping adults and monitoring potato plants for the presence of egg masses during the period from 250 to 500 degree-days appears to be a reliable way to determine the presence of adults and the potential impact of larvae on yield of potatoes.

The control of the red sunflower seed weevil, Smicronyx fulvus LeConte, relies on the use of insecticides. An economic injury level is essential to the judicious deployment of insecticidal control. Field studies were conducted in 1992 and 1993 to quantify the weight loss and oil content loss of damaged kernels as a result of larval infestation and the relationship between the adult weevil population and the subsequent number of damaged achenes. We found that for each weevil sampled in plant stages R5.0–5.3, 26.88 damaged achenes resulted. Damaged kernels lost an average of 9.86 ± 2.36 mg (mean ± SD) per kernel, approximately equal to the amount consumed by a single larva. The oil content loss in damaged kernels was 3.34%. Economic injury levels were calculated as a function of the cost of controls, the market value, and the plant population density. Use of adult weevil counts when most plants in the fields are in plant stages R5.0–5.3 are recommended for calculating economic status.