Diptera caught in malaise traps set in forests of Sitka spruce, Picea sitchensis (Bon.) Carrière, in the Carmanah Valley, on Vancouver Island, British Columbia, included two new species of Sphaeroceridae. Minilimosina sitka Marshall sp.nov. and Phthitia squamosa Marshall sp.nov. are described for the first time and compared with related species. Fourteen other sphaerocerid species caught with these species are listed.

In laboratory studies, suspensions of killed and live ice-nucleating microorganisms were used to decrease the supercooling capacity of the winter form of pear psylla, Cacopsylla pyricola (Foerster) (Hemiptera: Psyllidae). Dry, untreated adults supercooled extensively before they froze at −22.7 °C. Application of 1000 ppm of a preparation of the killed ice-nucleating bacterium, Pseudomonas syringae Van Hall 1902 (Pseudomonadaceae), significantly decreased the adults’ supercooling capacity causing some individuals to freeze at temperatures as high as −3.9 °C. Topical application of several live microorganisms also reduced the supercooling capacity of adults significantly; Pseudomonas putida (Trevisan 1989) was the most effective, causing more than 80% of C. pyricola adults to freeze at −15 °C or higher. Furthermore, the temperature of crystallization of adults treated with P. putida remained significantly higher than controls for at least lid post-treatment. Application of ice-nucleating microorganisms also reduced the capacity of adults to survive short-term exposure to high subzero temperatures comparable to a mild frost. Realization of this approach for biological control of pear psylla will require the development of methods for the delivery of microorganisms to overwintering adults under field conditions.

The spruce budworm Choristoneura fumiferana (Clem.) is the most damaging insect of the balsam fir Abies balsema (L.) Mill. (Pinaceae) and the white spruce Picea glauca (Moench) Voss (Pinaceae) throughout eastern North America. In outbreak conditions, close to 100% tree mortality can occur in untreated mature fir stands (MacLean 1980). Bacillus thuringiensis var. kurstaki (Bacillaceae) is currently used to reduce spruce budworm damage (Van Frankenhuyzen and Payne 1993). Other possible biological control agents, such as baculoviruses, are also investigated to complement the use of B. thuringiensis. Baculoviruses are advantageous because they occur naturally in several insect species and are generally host specific (Federici 1993).

The life history of pine false webworm, Acantholyda erythrocephala (L.), in three pine (Pinaceae) plantations in northern New York is similar to that reported for this species on red pine, Pinus resinosa Aiton, in Ontario. Adult emergence extended from early May to early June. The sex ratio of emerging adults favored males by as much as 2.7:1. Oviposition occurred from mid-May to early June. Significantly more eggs per fascicle were deposited on the distal third of branches and in the lower third of the crown. Larval feeding took place throughout June. The proportion of prepupae remaining in the soil for more than 1 year varied from 9% to 66% between two sites. There was no evidence of egg parasitism, and egg survival exceeded 95% in each of 2 years. A new species of nematode (Steinernema sp.) (Nematoda: Steinernematidae) was recovered from pronymphs. Homaspis interruptus (Provancher) (Hymenoptera: Ichneumonidae) parasitized larvae and emerged from 8.5% and 2.8% of the pronymphs in two populations.

In 1995, Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae), a commercially available pupal parasitoid of the house fly, Musca domestica L., and stable fly, Stomoxys calcitrans (L.) (Diptera: Muscidae), was purchased to examine the status of wasps being sold to Manitoba producers. Percentage of pupae parasitized, numbers of parasitoids per pupa, total parasitoids, and parasitoid sex ratio were determined for each shipment of parasitoids received. To determine the extent to which these wasps could successfully parasitize house flies and stable flies, parasitoids were released weekly in four Manitoba dairy barns and levels of parasitism estimated. In 10 622 freeze-killed sentinel house fly pupae, 2.2% were parasitized throughout the season by N. vitripennis, and 5.8% were parasitized by eight other species of parasitoids. Of 11 897 naturally occurring house fly and stable fly pupae, 0.6% were parasitized by N. vitripennis, and 3.4% by eight other species of parasitoids. In four barns where there were no releases of N. vitripennis, 1.1% of 11 779 sentinel pupae were parasitized by four species of parasitoids and 3.8% of 8384 naturally occurring house fly and stable fly pupae were parasitized by nine species. The release of an estimated 3 648 093 N. vitripennis did not result in substantial parasitism in either sentinel pupae or naturally occurring pupae. In 1996, live sentinel house fly pupae (n = 50 842) and house fly and stable fly pupae occurring naturally (n = 4691) were collected in two of the nonrelease barns from the 1995 study to examine the activity of endemic parasitoids. Of the sentinel and naturally occurring pupae sampled, 4.0% and 9.4% were parasitized, respectively. Phygadeuon fumator Gravenhörst (Hymenoptera: Ichneumonidae) was the most abundant parasitoid, accounting for 97.4% and 79.9% of parasitoids collected from sentinel pupae and naturally occurring pupae, respectively. Other parasitoids included Urolepis rufipes (Ashmead), Muscidifurax raptor Girault and Sanders, Muscidifurax zaraptor Kogan and Legner, Spalangia subpunctata Först, Spalangia cameroni Perkins, Spalangia nigra Latreille, and a species of Trichomalopsis Crawford (Hymenoptera: Pteromalidae).

We investigated pollen and nectar foraging of honey bees, Apis mellifera L., from pollen-poor and pollen-rich, small and large colonies in blooming highbush blueberry, Vaccinium corymbosum L. cv. Bluecrop fields. The proportion of pollen foragers differed significantly between pollen-rich and pollen-poor colonies after storage levels were manipulated, but foraging and pollen stores returned to similar levels within a week. No differences were found in small colonies, although the proportion of pollen foragers was high (46% and 45% from pollen-rich and pollen-poor colonies, respectively). Only 7.6% of pollen foragers carried Vaccinium sp. pollen in their loads independent of treatment, day, and colony size, whereas 60.8% of nectar foragers carried up to 100 tetrads of Vaccinium sp. pollen on their bodies. The average proportion of Vaccinium sp. pollen carried by nectar and pollen foragers per day and treatment was less than 10%. Our research indicates that when colonies are placed in fields of blooming blueberry flowers, pollen foraging is stimulated in large colonies with stores that are pollen poor, but predominantly for pollen types other than blueberry. This research indicates that nectar foragers are the major visitor of highbush blueberry cv. Bluecrop and suggests that increasing the number of nectar foragers rather than pollen foragers would result in more honey bees foraging on highbush blueberry, in particular cv. Bluecrop.

Monoctonus paulensis (Ashmead) was reared in the laboratory on the four nymphal instars of the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphidoidea: Aphididae). Females frequently laid clutches of two eggs during a single ovipositor probe; however, clutches of more than two eggs were rare. The time needed to capture and position an aphid for oviposition increased with aphid instar but was independent of the number of eggs laid. Oviposition time was proportional to egg number, which shows that eggs were laid one at a time rather than clumped together as a package. Intensity of parasitism (i.e., number of eggs per parasitized host) increased with host instar but declined with the number of hosts attacked in quick succession. Our results suggest that clutch size in M. paulensis is not accidental but controlled by the female.

A laboratory experiment was conducted to identify the overwintering stage of the fir coneworm, Dioryctria abietivorella (Grote), in eastern Canada and determine the influence of photoperiod on diapause induction. In another experiment, different developmental stages were exposed to field conditions to evaluate their capacity to survive the overwintering period. Insects were either placed in the duff or exposed to ambient (above ground) conditions to assess the importance of overwintering site on winter survival. Exposure of the fir coneworm to constant short-days or a daily decreasing photoperiod during larval development induced almost all insects to initiate diapause at the fifth instar. Third-, fourth-, and fifth-instar larvae survived the overwintering period when placed in the duff. Because the fir coneworm must leave its host tree and drop to the ground to avoid rigorous winter conditions, we concluded that only fifth-instar larvae could resume development in spring using such a strategy.

The parasitoid Sinophorus megalodontis Sanborne is a univoltine endoparasitoid that attacks larvae of the pine false webworm, Acantholyda erythrocephala (L.). The morphologies of the egg, instar 1, and cocoon are described. Adult-emergence and Malaise traps were used to examine the patterns of adult activity in Ontario. Adults emerged from the soil over 17 d, in late May and early June, and the median emergence of males preceded that of females by 3.5 d. The sex ratio of emerging adults was approximately 1:1. Malaise traps collected more adults than did emergence traps and also provided information on adult flight period, but collections were biased towards captures of males. Dissections indicated that S. megalodontis oviposited in all instars of the host and that temporal and spatial variations occurred in coincidence with host instars. Encapsulation and superparasitism limited effectiveness of the parasitoids in reducing host populations. At the end of the larval period, the parasitism rate was 17.1%, but encapsulation reduced the effective rate to 9.0%. Superparasitism was observed in 4.8% of the host larvae. There was some indication that parasitism resulted in retardation of host development. Later-dropping host larvae had a significantly greater incidence of parasitism. The host is an introduced insect from Europe, whereas the parasitoid is likely endemic to North America. Few North American parasitoids attack this introduced species, and S. megalodontis appears limited in its ability to reduce the size of pine false webworm populations. Consequently, pine false webworm is a suitable candidate for classical biological control attempts with introduced parasitoids from Europe.

The suitability of three potential host plants, Solidago canadensis L. var. canadensis (Asteraceae), Solidago graminifolia (L.) Salisb., and Aster lateriflorus L. (Asteraceae), for the goldenrod beetle, Trirhabda virgata LeConte was determined by measuring several fitness components during the T. virgata life cycle. Neonate larvae were collected from S. canadensis plants and transplanted onto S. canadensis, S. graminifolia, and A. lateriflorus and maintained in field enclosures until the last instar was reached. Once brought into the laboratory, larvae were fed their assigned host plant until pupation. Following emergence, adults were weighed and separated into mating pairs to record oviposition and longevity. Eggs were kept in the laboratory until the following spring, when first instar larvae were taken into the field and re-established on their assigned host, and the experiment was repeated for 2 years. Larval survival and rate of development was not affected by the host plant. Mean weight of adults at emergence was greater on S. canadensis than on either S. graminifolia or A. lateriflorus. Two components of adult fitness, postmating longevity and realized fecundity, were measured. Longevity of adult female T. virgata was not affected by the host plant. Fecundity of T. virgata reared on A. lateriflorus and S. graminifolia was lower than the fecundity of females reared on S. canadensis. These results are consistent with the hypothesis that both intrinsic plant quality and the mobility of the foraging stage are important in the evolution of host range in T. virgata. These experiments were repeated over a 3-year period, using offspring from the survivors of the previous year for the 2nd and 3rd years. Over this time, individuals experienced "laboratory adaptation," and both accepted and increased their performance on previously unacceptable food plants.

The spatio-temporal distribution of cotton plants, Gossypium hirsutum L., infested with Aphis gossypii (Glover) winged adults, is described in a plot located in Bangui, Central African Republic. Each cotton plant growing in the plot was examined visually for a short period of time to ascertain the presence or absence of A. gossypii and to construct weekly infestation maps. Tests of autocorrelation and dispersion were carried out at different spatial scales by means of Monte Carlo procedures on embedded counting grids. Edge effect tests were also carried out. The statistical analyses show significant overdispersion of the infested plants and positive spatial autocorrelation. Positive temporal autocorrelation and significant edge effect are detected intermittently throughout the season.

Lodgepole pines, Pinus contorta var. contorta Engelmann, killed by mountain pine beetle, Dendroctonus ponderosae Hopkins, are often subsequently infested by other scolytid species (Safranyik et al. 1996). Ips pini (Say) breeds in the phloem region of the main bole and larger branches in areas not occupied by mountain pine beetle. Adults emerge in the fall and drop to overwinter in the duff near the bases of their brood trees (Safranyik et al. 1996). Hylurgops porosus (LeConte) infests lodgepole pine (Keen 1952; Bright 1976) stumps or severely weakened trees near the root collar and in large roots (Wood 1982). We examined the pattern of emergence of I. pini and H. porosus from the duff around infested trees to describe changes in density over distance from the trees.

The flute-shaped leaves of the pitcher plant Sarracenia purpurea L. are a fluidfilled microhabitat rich in invertebrate diversity (Bradshaw 1983; Heard 1994; Hardwick and Giberson 1996; Harvey and Miller 1996; Miller et al. 1994). They are the obligate larval habitat for Fletcherimyia fletcheri (Aldrich) (Forsyth and Robertson 1975). Most literature reports of F. fletcheri present information only on larval life history and population dynamics (Fish and Hall 1978; Hardwick and Giberson 1996). Forsyth and Robertson (1975) state anecdotally that they observed adults feeding on flowers and other nectar sources within their study area. We believe that our observations represent the first report of adult F. fletcheri roosting within the flower heads of the pitcher plant.

Tree and site characteristics were compared between 19 groups of Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco (Pinaceae), infested by Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, and 19 uninfested groups to identify individual or combinations of characteristics associated with Douglas-fir beetle attacks. Of the tree characteristics, diameter, height, age, phloem thickness, bark thickness, and a standardized variable consisting of diameter divided by the last 10 years growth rate (DBHTYG) showed significant differences. None of the site characteristics showed significant differences between infested and uninfested areas. Two models, identified through discriminant analysis, placed 84 and 87% of the data in the correct infestation groups. These models included the variables diameter, height, phloem thickness, aspect, and DBHTYG in various combinations. The results were confirmed using a jackknifed cross-validation approach. These variables have potential for use in the development of a biological process model of tree and stand susceptibility to the Douglas-fir beetle.