The reliability of three methods for sampling aphidophagous coccinellids and syrphids in a winter wheat field was compared.

In the first method, an observer recorded predators seen during 2 min per 25-m2 sub-plot. In the second, two observers worked successively through each plot, scanning the full height of wheat plants and collecting predators. This method enables calculation of predator density using De Lury’s technique. The third method consisted of collecting wheat plants from each sub-plot for examination in the laboratory.

The first method may be used for appraising populations of adult coccinellids on a large scale. The detailed searching method is appropriate for studies of the population dynamics of adult and fourth-instar coccinellids. The plant sampling method is the most accurate for assesssing densities of syrphid larvae and pupae.

Parasitism of the Colorado potato beetle, Leptinotarsa decemlineata (Say), by Edovum puttleri Grissell, an exotic egg parasitoid, was studied in relation to the age of host eggs, the age of adult, female parasitoids, and temperature. Parasitism was greater in eggs ≤2 days old than in eggs older than 2 days. Eggs older than 2 days were killed primarily by probing and consequent desiccation. The percentage of eggs killed by probing was positively correlated with host age and negatively correlated with percentage parasitism. Total mortality of eggs from parasitism and probing did not differ among age classes. Following a 3-day preoviposition period, parasitism and probing increased with an increase in the age of females, peaked when adults were ca. 13 days old, and subsequently declined. Parasitism and probing were influenced by temperature: at 15 °C, no parasitism or probing was observed; above 15 °C, mortality from parasitism and probing increased with an increase in temperature up to 30 °C; above 30 °C, the number of eggs that were parasitized and probed decreased with an increase in temperature.

Dacnusa dryas (Nixon), a multivoltine parasite of the alfalfa blotch leafminer, Agromyza frontella (Rondani), has become established in eastern Canada. Adults deposit their eggs singly in the hemocoel of the actively feeding host larvae. A trophamnion forms between the chorion and the embryo and the elliptical egg swells, becoming spherical and transparent. On hatching, the trophamnion adheres to the 1st instar throughout its development. The first moult occurs in the newly formed puparium where development of the parasite is completed. Winter is passed as a mature larva within the soil-borne host. Descriptions of the immature stages are given.

Both sexes of Hybomitra agora new species are described and differentiated from similar species in western North America. Notes are given on the known habitat of H. agora and on differences in mating behavior between this and three other sympatric species of Hybomitra. Known distribution of H. agora is summarized with a map.

Morphometric analysis was studied on the measurements of the forewings, ovipositor, hind tibia, and antenna of female Anagrus giraulti Crawford reared from the following hosts: Circulifer tenellus Baker, Empoasca fabae (Harris), and Scaphytopius nitridus (DeLong). Results showed that A. giraulti emerging from E. fabae had significantly shorter antennal segments, ovipositor, and tibia III than those reared from the other two host species. Host eggs of C. tenellus produced female A. giraulti with significantly longer wing lengths than did the other two species and wider wing widths than did E. fabae.

Fumigants that are liquid formulations at room temperature have been widely used to kill insects in stored products, containers, and soil. Carbon bisulfide was one of the first fumigants used on a large scale as early as 1869 and is still the main fumigant used in some parts of the world (Bond 1984). Carbon bisulfide is highly flammable (Fleming and Baker 1935) and is usually formulated with carbon tetrachloride to aid distribution of fumigants in grain masses (Berck 1958) and to reduce the fire hazard. Although carbon tetrachloride is of low toxicity to insects it causes extensive liver damage in humans (Rouiller 1964). Liquid fumigants were widely used to disinfest stored grain in the USA until recently (White et al. 1985), and are still used in many other parts of the world (FA0 1985).

A study conducted between 1982 and 1985 established the presence of a limited number of populations of Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), resistant to carbofuran in New Brunswick. Additional laboratory tests with two field-collected strains indicated that both were resistant to endosulfan; one strain also showed 43- and 37-fold levels of resistance to carbofuran and phosmet, respectively, and low-level (< 10-fold) resistance to permethrin, fenvalerate, disulfoton, and aldicarb. There has been no measurable spread of resistance.

Two cone-orifice-type traps baited with (Z)-11-hexadecen-1-ol acetate (1.0 mg) and (Z)-9-tetradecen-1-ol acetate (0.05 mg) were placed in each of 5–13 canola (Brassica spp.) fields per year for 7 years at locations distributed throughout the area in Manitoba subject to outbreaks of the bertha armyworm, Mamestra configurata Wlk. (Lepidoptera: Noctuidae). The number of male moths per trap varied from 0 to 821 in the 90 fields trapped. Larval density, in the trap fields and in 185 nearby canola fields, varied from 0 to 105 per square metre. There was a direct relationship between the number of moths per trap and the density of late-instar larvae (L4–L6) for the trap fields and for nearby (within 5 km) fields but variability was loo high to allow accurate prediction of larval densities for individual fields. However, the number of moths per trap could be used to predict the proportion of fields in the vicinity of the trap field that would have larval densities above the economic threshold. No fields with above-threshold larval densities occurred with captures of <20 moths per trap. The proportion of fields with larval densities above the economic threshold increased from 0.10 with 20–30 moths per trap, lo 0.19 with 30–60 moths per trap, 0.64 with 70–100 moths per trap, and 0.91 with over 100 moths per trap. Contamination of catches by non-target species of noctuid moths had insignificant effects on the accuracy of these predictions because even if they were misidentified as M. configurata the number of moths per trap changed only marginally. Populations of M. configurara were higher and local outbreaks occurred more frequently in canola-growing areas adjacent to morainic hills along the Manitoba Escarpment, whereas populations were low in areas of the Manitoba Lowlands and of the Western Uplands. A proposed monitoring system for M. configurata in Manitoba is described.

Stethynium Enock, a mainly old world genus most of whose members occur in Australia, is redescribed based on study of the non-Australian species. The subgenus Neostethynium Ogloblin is removed from Stethynium and given generic status. The names S. faunum Girault and S. empoascae Subba Rao are synonymized under S. triclavatum Enock. A lectotype is designated for S. triclavatum. Stethynium angustipennesp. n. is described.

Schizophragma Ogloblin, formerly a subgenus of Patasson, is redescribed as a genus. Anaphes bicolor Dozier and Stethynium annulatum Doutt are transferred to Schizophragma. The names S. annulatum and S. nana Ogloblin are synonymized, respectively, under S. bicolor and S. parvula Ogloblin. Lectotypes are designated for S. bicolor (Dozier) and S. latipennis (Crawford). A provisional key to the species of Schizophragma is presented.

This paper reviews the occurrence of the genus Chlorochroa Stål in Canada. It is shown that 10 species occur in this country, namely C. belfragii (Stål), C. faceta (Say), C. congrua Uhler, C. granulosa (Uhler), C. ligata (Say), C. opuntiae Esselbaugh, C. persimilis Horvath, C. rossiana Buxton and Thomas, C. uhleri (Stål), and C. viridicata (Walker). Chlorochroa sayi (Stål) does not occur in Canada. The published records of C. sayi as a pest of agricultural crops and ornamentals in Canada refer to C. uhleri.

Enhancement of virulence in entomogenous fungi has been a particularly neglected area of research (Roberts and Yendol 1971). It is generally believed that virulence increases following successive passage through a host and decreases following repeated subculturing on artificial media (see Aizawa 1971; Roberts and Yendol 1971). Using single-spore isolates (clones) of Beauveria bassiana (Bals.) Vuill., SamšiňSáková and Kálalová (1983) demonstrated spontaneous mutants with increased virulence. Enhancement of virulence using parasitic selection pressures has been accomplished by passage of fungal strains through a host (Daoust and Roberts 1982; references in Ignoffo et al. 1982). Such changes are thought to be due to gradual selection of genotypes.

Adults of the anthomyiid Coenosia tigrina (Fab.), which are predators of flying insects including pest Diptera such as the onion maggot fly, feed on earthworms in the larval stage. The bionomics of C. tigrina females were studied in the laboratory at 15, 20, and 25°C, under different mating regimes. Adult female longevity slightly exceeded 1 month at 25°C and was close to 2 months at 15°C. Oviposition started 1–3 weeks after emergence, the delay tending to decrease with increased male presence. Females laid eggs at intervals of 1 to several days, in batches averaging 10–30 eggs depending on temperature. Fecundity reached an average of 230 eggs at 25°C with the sustained presence of males. Egg hatch decreased with the mother’s age, except when males were present for most of the female’s lifetime. Females exhibited maximal daily rate of predation at 25°C, but maximal lifetime predation was observed at 20°C. Male predation was less than females’, and female predation decreased with age. The time to eclosion decreased from 11 to 5 days as the temperature of egg incubation increased from 15 to 25°C. Larval weight at eclosion decreased with mother’s age. Postembryonic development and larval growth were studied at 15, 20, and 25°C, larvae being fed on four lumbricids. Development times decreased with increasing temperature between 15 and 25°C: from 35 to 15 days for larval development, and 28 to 12 days for pupal development. Males developed at a slower rate than females, but females weighed more at emergence. Larval survival was 30–60% on worm sections, and dropped to 17% on live mature Eisenia foetida (Sav.); but survival reached 90% on live, immature E. foetida 1–2 cm long. The larvae of C. tigrina penetrate the epidermis of earthworms, and feed internally with a preference for circulatory and chlorogogonous tissues.

Relationships between temperature and development rates of eggs, overwintered second-instar larvae, and all larval stages of Choristoneura fumiferana (Clem.) fed on artificial diet were determined. Egg development was observed at eight constant temperatures between 7 and 32°C. It was fastest at 30°C, and showed relatively little variability. The rate of emergence of overwintered second-instar larvae was observed at 10 constant temperatures between 4 and 33°C. Maximum development rates occurred at 30°C. Variability in emergence rates was large, but unimodal. Development rates of the second to sixth larval instars were measured at 10 constant temperatures between 7 and 36°C, and maximum rates were observed, again, at 30°C. Variability in the development rates of the larvae was large, with no correlations between the development rates of the various larval instars. The results of computer simulations of the insect’s seasonal history are presented and discussed.

Comparison of type material and series of Ips cribricollis (Eich.) and I. grandicollis (Eich.) showed that the species are readily separated by external morphology, the pars stridens of the females, and, especially, the genitalia of the males. Earlier work showed that representatives of the two species were not able to interbreed and that their chromosomes were different. These data and the discovery of the two species at the same locality in Central America are compelling reasons for recognition of these entities as separate species.

Pissodes approximatus Hopkins (1911) is a junior subjective synonym of P. nemorensis Germar (1824). The conspecificity of these entities, traditionally considered distinct based only on distribution and slight morphological differences, is corroborated here with comparative studies of ecology, behavior, and morphology. When pheromone-baited traps were deployed during the spring (May–June) and fall (November–December) in several localities to examine seasonal activity, southern populations (P. nemorensis sensu Hopkins) responded only in the fall and northern populations only in the spring, but a population in Virginia responded during both seasons. Laboratory studies found that individuals from five southern populations became reproductively mature under 16:8, 12:12, and 8:16 (L:D) photoperiods but weevils in a New York population did not mature under the 8:16 photoperiod. A two-species model based on strict seasonal isolation between northern and southern populations is rejected. Morphometrics revealed significant differences in six body dimensions and three morphometric ratios among 13 populations, but there was no geographic pattern of differences to suggest the existence of two species. Sexual dimorphism in rostrum length was most pronounced in southern populations but occurred in all five populations in which it was investigated. Examination of male and female genitalia revealed similar variation in northern and southern populations and conflicted with previously reported diagnostic differences. Our study and the results of earlier work lead us to conclude that the populations previously represented by the names P. nemorensis and P. approximatus comprise one widely distributed species and display intraspecific variation in life history and morphological characters.

Laboratory bioassays showed the occurrence of 8.5-fold resistance to cyhexatin and ca. 15-fold resistance to dicofol in laboratory-selected populations of European red mite (Panonychus ulmi (Koch)). Surveys, in 1984, of 45 orchards, using field-collected mites exposed to discriminating concentrations of cyhexatin or dicofol, detected resistance to cyhexatin in ca. 29% of the populations. Resistance to dicofol was identified in 2 of 45 assays.

A key is given for 16 species in the genus Macrosiphoniella Del Guercio in America north of Mexico, including one new species from Manitoba, Macrosiphoniella paucisetosa sp.nov. from Artemisia spp. An annotated list is provided which includes tentative identification of M. oblonga (Mordvilko) intercepted on plants of Chrysanthemum imported into the United States of America from Europe.

The distribution of selected insect species among samples from empty farm granaries in the Prairie Provinces was determined as a guide to determining the number of samples that would have to be collected to obtain reliable estimates of the average number of these species. The number of pest and fungivorous species (adults) per sample followed a negative bionomial distribution for Manitoba data but the number of pest species adults from Sasktachewan followed a Poisson distribution. In Alberta, 39 granary samples contained only one pest species and 507 had none. The number of pests per sample from Manitoba and Saskatchewan and the number of fungivorous species from Manitoba also fitted logarithmic series.

The mean number of individuals of each species found in samples (adults or larvae) was always smaller than the variance and the distribution of insect counts followed the negative binomial distribution. Tribolium audax Halstead adults from Alberta also followed a Poisson distribution.

The numbers of samples required to provide a predetermined measure of precision for the numbers of species per sample (Manitoba data) and for the numbers of individuals per sample of 15 species (adults or larvae) for each of the three Prairie Provinces were calculated.

Eggs (24–28 h old) of Delia radicum (L.) were treated with the same doses of diflubenzuron, methoprene, juvenile hormone I, or precocene II. Diflubenzuron significantly reduced egg hatching compared with untreated and solvent-treated controls. Methoprene had a delayed effect, preventing eclosion of adults from pupae that subsequently developed from treated eggs. A commercial formulation of diflubenzuron, Dimilin®, significantly suppressed and delayed hatching of eggs treated when 3–7 h old but not of eggs treated when 24–48 h old. Diflubenzuron may be as effective as the commercial insecticide carbofuran in protecting rutabaga slices from damage, as all larvae that did hatch died shortly afterwards.

The sunflower stem weevil, Cylindrocopturus adspersus (LeConte), is a pest of cultivated sunflower in the major production areas of North and South Dakota, Minnesota, and Texas. Adults appeared in sunflower plots between 5 and 25 June in 1980–1985, when plants had 4–14 leaves. Oviposition began soon after adults were present and continued into late August. Peak densities of both eggs and adults occurred in mid-July. Larvae hatched between 6 and 11 July, when plants were in the early flower bud growth stages. Larvae fed in the sunflower stalk and moved to the stalk base or root crown to construct overwintering chambers. The seasonal patterns of the weevil’s life stages in 6 years were similar, but population densities varied. Regression equations were developed to predict larval numbers in stalks from number of adults to aid in making control decisions.