The anthomyiid fly Pegomya curticornis (Stein), introduced into Alberta from Europe for the biocontrol of leafy spurge (Euphorbia esula L.), normally induces simple galls on subterranean stems. Here we describe the anatomy of galls collected in Europe that had been induced by P. curticornis on horizontal roots of spurges. Four mature galls were found on the roots of E. virgata Waldst. and Kit. and 10 on the roots of E. esula. Tissues of the root galls were composed of gall parenchyma that had proliferated from feeding sites near the outside edge of secondary xylem. It is assumed that some larvae inadvertently tunnel beyond the base of stems into the roots and that similar galls will form on Alberta spurges.

The larvae, pupae, and adult males and females of Micropsectra dives (Johannsen), Micropsectra nigripila (Johannsen), Micropsectra polita (Malloch), and a new species Micropsectra geminata are described.

Individuals of Perilissus nudus sp.nov. of the Perilissus anatinus species group are described. This species, which occurs in the mountain ranges of southern Mexico and Costa Rica, is compared with the closely related species P. anatinus Barron. Locality data on additional specimens of P. anatinus, found in mountain ranges in Mexico, are included. Study of characteristics of P. nudus in relation to P. anatinus clarifies further the relationship of this species group with the other species groups of Perilissus.

A standardized, oil-free neem (Azadirachta indica A. Juss) seed extract (NSE) was tested for repellency to honey bees using a feeding-dish choice bioassay, and to honey bees and other pollinators in field applications on blooming canola. Foraging honey bee workers were able to discriminate between untainted sugar syrup and syrup containing formulated NSE at concentrations as low as 0.1 ppm azadirachtin, the principal active ingredient of NSE. However there were no significant differences in the numbers of foraging bees collected in neem-treated, solvent-treated, or untreated canola plots. Other pollinator. species present were similarly unaffected. Our results suggest that honey bees may be successfully utilized in blooming crops that have been treated with doses of NSE sufficient to control phytophagous insect pests. The results of this study also suggest that using feeding-dish bioassays to screen potential repellent compounds, although demonstrating the ability of honey bees to detect compounds, may not yield similar results in the field.

We monitored eclosion patterns of adult Coquillettidia perturbons (Walker) in the Minneapolis – St. Paul region of Minnesota directly using emergence traps (1983, 1984, and 1992), and indirectly using CO2-baited adult traps (1987–1992) and larval sampling (1988 and 1989). Most mosquitoes eclosed in a unimodal pulse during June although peak eclosion periods varied among years and sites. It required 26.6 ± 1.5 days for 90% of individual populations to eclose. Temporal abundances of host-seeking females also suggested unimodal eclosion with peaks typically occurring in June and July. Most larvae overwintered in the fourth instar and pupated in early summer, as expected from adult data. However, many larvae overwintered in the third instar and did not molt into the fourth until July, which was after most eclosion was completed. These individuals may eclose in autumn or may spend a second winter as larvae.

The pterin age-grading method was applied to natural populations of stable flies sampled for 3 years from diverse locations in Minnesota and Iowa. Significant differences were detected among years in mean degree-day ages per fly. Fly ages, in degree-day units, were exponentially distributed. A two-parameter Weibull distribution closely fit the fly survival distributions. Mean expectations of life did not differ significantly between males and females and were estimated to be 86.6 degree-days above a 6.5 °C threshold. Conventional age-grading techniques based on ovarian morphology applied to Iowa females showed that large fractions of the populations experienced delays in vitellogenesis. The reproductive rate, in terms of lifetime ovipositions, was less than the maximum sustainable rate suggested by ambient temperatures.

Four species of Cruciferae [canola species Brassica rapa L. and Brassica napus L., and mustard species Brassica juncea (L.) and Sinapis alba L.], and various cultivars of each species, were evaluated for susceptibilities to infestation by Delia spp. (Diptera: Anthomyiidae) under field conditions in central Alberta, Canada. Susceptibility was measured throughout the season by recording numbers of eggs of Delia spp. laid on or near individual plants, and at the end of the season by a semi-quantitative determination of injury inflicted by larvae on taproots. Differences in susceptibility occurred among and within canola and mustard species. Plants of B. rapa were most susceptible to Delia spp.; both mean eggs per plant and mean damage ratings per plant on B. rapa significantly exceeded those of all other species studied. Intermediate susceptibility was observed for plants of B. napus and B. juncea; plants of S. alba were least susceptible. In general, differences in susceptibility were greater among species than among cultivars within species. Root damage generally correlated with oviposition among and within species, suggesting that the mechanism of resistance by cruciferous species to infestation by Delia spp. is antixenosis or nonpreference. Results of this study indicate that canola growers in regions infested annually by high population densities of Delia spp. should seed B. napus or B. juncea rather than B. rapa. However, if a short growing season necessitates seeding B. rapa, then growers should select the more resistant cultivars of this species.

Cuticular damage of Spodoptera exigua (Hübner) pupae, caused by puncturing with a sterilized insect pin, resulted in enhanced susceptibility to the entomopathogenic nematode Steinernema carpocapsae (Weiser), but cold shock (5 °C for 24 h) did not alter susceptibility. The additional avenue of entry for the nematode probably accounted for the increased mortality of the damaged pupae. In all treatments, some dead pupae contained Xenorhabdus nematophilus (Poinar and Thomas), the symbiotic bacterium of S. carpocapsae, but no nematodes. More nematode-killed pupae containing X. nematophilus but no nematodes were found in the cold-shock treatment than in the room-temperature control (62.6 versus 46.9%). In contrast, fewer nematode-killed pupae containing X. nematophilus but no nematodes were found in the damaged pupae compared with the undamaged control (25.0 versus 45.1%). Moreover, mortality of nematodes within the cadavers of cold-shocked insects was higher than in the cadavers of non-cold-shocked insects. These results suggest that the stressors, cold shock and cuticular damage, produce fundamentally different responses in insects exposed to them, and that the physiological state of the insect greatly influences nematode survival in the host and hence nematode recycling in the environment.

The pine engraver, Ips pini Say, and Pityogenes knechteli Swaine often co-exist in lodgepole pine, Pinus contoita var. latifolia Engelmann. We tested the hypotheses that P. knechteli produces an attractive pheromone and that the attraction of P. knechteli and I. pint to conspecifics is inhibited by the presence of the other species. Pityogenes knechteli males and females were attracted to bolts infested with conspecific males and to bolts infested with I. pini males; however, there was no significant cross-attraction of I. pini males or females to bolts infested with P. knechteli males. Attraction of P. knechteli and I. pint males and females to bolts infested with conspecific males was not inhibited in the presence of bolts infested with males of the other bark beetle species. Pityogenes knechteli has no potential for competitive displacement of I. pini but may enhance the adverse effect of I. pini on the mountain pine beetle, Dendroctonus ponderosae Hopkins.

Following attack by Dendroctonus brevicomis LeConte, ponderosa pines were periodically sampled over 7 weeks. Xylem water conduction was assessed using a dye flow technique. Fungal isolations were made from functioning and occluded xylem. Neither Ophiostoma nigrocarpum (Davids.) de Hoog or other bluestain fungi were commonly found at the interface of the occluded and functioning xylem. Instead, blue-stain fungi appear to colonize already occluded xylem, not cause xylem occlusion by direct hyphal penetration of functioning sapwood. No evidence for a mutualistic association of D. brevicomis and its vectored bluestain fungi was found.

Sweep-net and sticky-trap data were used to examine the influence of time of day (morning, afternoon, evening), trapping location (pasture, bog, fen, regrowth, and mature forest), and meteorological factors (wind, temperature, saturation deficit, and light) on adult female fly catch for three species (species complex) of black flies — Simulium truncatum/venustum complex, Prosimulium mixtum, and Stegopterna mutata (triploid). Wind speed, light, temperature, saturation deficit, and time of day were all shown to have a significant effect on mean catch, although effects varied among species. After accounting for weather and time, trap location was shown to have a significant effect on mean catch. The effect of site on the mean fly catch of S. truncatum/venustum complex varied with season (June to July), which may have resulted from a seasonal shift in sibling-species composition. Mean catches of P. mixtum and St. mutata were lowest in traps located in open habitats.

Inundative release of Trichogramma brassicae Bezdenko for control of European corn borer was tested in experimental plots in 1991 and 1992 in southern Alberta, Canada, to determine its effectiveness as a potential method of control in sweet corn. The tests were conducted in 1-ha plots, in three different fields of irrigated sweet corn each year, at a release level of about 196 000 wasps per ha. The reduction in European corn borer damage in the release plots ranged from 85 to 87% in 1991 and from 45 to 95% in 1992. The reduction in damage was not significantly different in fields with 25 and 49 release points. General area degree-day accumulation for postdiapause development was not adequate to determine the timing of release for individual fields because European corn borer phenology varied among fields. Total moth catch in pheromone traps, however, was directly related to the number of plants damaged by European corn borer, and releases near the time of peak trap catch produced the greatest reduction in damage.

In the scope of a worldwide revision of the genus Myzocallis, a key of the following subgenera is presented: Agrioaphis Walker (type: Aphis myricae Kaltenbach), Californicallis subg.nov. (type: Myzocallis agrifolicola Richards), Castaneomyzocallis Quednau and Remaudière (type: Aphis castaneae Fitch), Globulicaudaphis Hille Ris Lambers (type: G. pakistanica H.R.L.), Lineomyzocallis Richards (type: Aphis bella Walsh), Myzocallis s.str. (type: Aphis coryli Goeze), Neodryomyzus subg.nov. (type: Myzocallis polychaetus David), Neomyzocallis Richards (type: Callipterus punctatus Monell), Paramyzocallis subg.nov. (type: Myzocallis tenochca Remaudière and Quednau), and Pasekia Aizenberg (type: Hoplocallis komareki Pasek). Four new species of Myzocallis living on various species of Quercus in southern Europe, Turkey, Iran, and Pakistan are described: M. (Neodryomyzus) naumanni sp.nov., M. (Pasekia) mediterraneus sp.nov., M. (P.) persicus sp.nov., and M. (P.) tauricus sp.nov., and a new subspecies, M. (Agrioaphis) castanicola leclanti ssp.nov., host-specific to Castanea in southern Europe. Keys are given for the species belonging to the palaearctic subgenera of Myzocallis.

Seven species of Nabicula Kirby occur in Canada: N. americolimbata (Carayon), N. flavomarginata (Scholtz), N. limbata (Dahlbom), N. nigrovittata nearctica (Kerzhner), N. propinqua (Reuter), N. subcoleoptrata Kirby, and N. vanduzeei (Kirkaldy), of which N. limbata is officially recorded for the first time for North America. A faunistic review of the species, key to all taxa, generic diagnosis, and characters distinguishing male and female last-instar nymphs are presented. As appropriate for each species, die following are provided: synonymy, description of adult, wing polymorphism, taxonomic comments, detailed geographical distribution, bioecology, and illustration of important structural characters and nymphal instars. The last-instar nymphs of N. americolimbata, N. nigrovittata nearctica, N. propinqua, N. subcoleoptrata, and N. vanduzeei are described and illustrated for the first time. The biogeography of Nabicula is considered with regard to species diversity patterns, ecological assemblages, species distribution patterns, and relationships between macroptery and geographical distribution.

Action thresholds for imported cabbageworm, Pieris rapae (L.), diamondback moth, Plutella xylostella (L.), and cabbage looper, Trichoplusia ni (Hübner), were evaluated on two cultivars of cabbage, Brassica oleracea var. capitata (L.), in Prince Edward Island. Thresholds were tested on plots of mid-season cabbage, cv. Minicole, and late-season cabbage, cv. Lennox, both grown for fresh market in 1991 and 1992. Management of larval populations at a threshold of 0.25 Cabbage Looper Equivalents (CLE) per plant resulted in yields equal to those obtained with bi-weekly applications or grower treatments. Higher thresholds of 0.50 and 1.0 CLE per plant were not as useful and did’ not consistently result in yields greater than untreated plots. Use of the threshold of 0.25 CLE per plant reduced the number of applications of insecticides by 30% compared with spraying insecticide at bi-weekly intervals from heading to harvest, and 43% compared with management by the grower without regard to insect populations or growth stage of the crop.

Behaviour of locally occurring adult females of seven species of coccinellids was assessed on wooden dowel and paper models that mimicked branching patterns and arrangements of leaf attachments to stems. Ambient temperature and hunger of the beetles were controlled. The movements up or down the main branch of the branch models when contacted from a side branch, duration of searching, and method of leaving leaf models were recorded for 20 beetles of each species.Each species responded to the seven models with different frequencies of behaviours that reflected species-specific modifications of the taxes that lead coccinellids to the tops and terminal parts of plants. Some beetles consistently modified the pattern of responses on die models that was displayed by die species as a whole. The individual modifications could be selected for. The differences in frequencies of behaviours were judged to be sufficient to result in differences in the efficiency with which plants with different architectures were searched.

Development of eggs of 35 species of Nearctic and Palearctic Pentatomoidea are described. Eggs are discussed in relation to the number of ovarioles of each species, characteristics of eggs, incubation time, diapause, embryonic development, embryonic orientation, hatch, and parasitism, and are classified into two groups in relation to then-form, position of egg-burster, and hatch. Emergence of first-instar larvae is described in representatives of five families.

Neomeoneurites dissitus sp.nov., the second known species of the genus, is described from Neuquén territory, Argentina. The generic diagnosis is revised to accommodate the species. The structure of the male postabdomen of Neomeoneurites is discussed and some errors in previous interpretations of the postabdomen are corrected. Synapomorphic characters of the male postabdomen in Neomeoneurites include extensive fusion of the hypandrium and sternite 8, loss of the phallic guide, well-developed posteroventral hypandrial projections, and surstyli that are completely fused with the epandrium.

In a recent revision of the genus Timema (Phasmatoptera: Timematodea) (Vickery 1993), an important reference inadvertently was omitted. It contained the following information on T. boharti Tinkham.

Rentz (1963) reported capturing a large series of T. boharti at Pinon Flats, Riverside County, California, during the latter part of April 1962. (The specimens were included in the revision of the genus.) The habitat is “xeric pinyon-juniper with chaparral intrusions”, at approximately 915 m. The series was taken at night. Rentz found mating pairs as well as last-instar numphs, some moulting. He noted that this species had previously been known only in a grey colour phase but there he found both greyish and green specimens with no intergrading. Mating pairs were segregated by colour. As noted in the revision (Vickery 1993), fading subsequent to death produced a brownish colour in all individuals so that detection of original colour is impossible.

The apple brown bug, Atractotomus mali (Meyer), is an economic pest of apple in the Annapolis Valley of Nova Scotia (Rogers 1990). Feeding on developing fruit of sensitive apple varieties induces persistent corky scar tissue that reduces the quality of affected fruit. Forty-five percent of Annapolis Valley apple orchards monitored in 1992 required chemical insecticide applications to control the pest complex of A. mali and the mullein bug, Campylomma verbasci (Meyer) (Craig 1992).

Female-produced sex pheromones occur in several mirid species, including the mullein bug (Smith et al. 1991) and Lygocoris communis (Knight) (Boivin and Stewart 1982). The sex pheromone of C. verbasci has been identified as a 16: 1 blend of butyl butyrate and crotyl butyrate (Smith et al. 1991). Our objective was to determine if a sex pheromone occurs in A. mali.