p. 228, Figure 1. La frontière entre le Québec et la province de Terre-Neuve et Labrador est omise.

p. 705, Table 1, 3rd column, 2nd line, for 23 ± 1.7 read 98 ± 1.7.

Predation of the cabbage aphid, Brevicoryne brassicae (L.), by the cecidomyiid Aphidoletes aphidimyza (Rond.) was studied in the laboratory and the field. Predation was random with respect to aphid instar, and predation rate was constant with respect to aphid density. A. aphidimyza consumed 1.7 times more aphids in the laboratory than in the field during larval development. When aphid weight and age distribution were accounted for, it was found that the same biomass, 2.14 mg, was eaten in both cases.

The pupal developmental temperature threshold for A. aphidimyza was 9.2 °C. The developmental times of the egg, larval and pupal stages, and complete life cycle were 32°, 66°, 171°, and 283°D9.2. In the field, there was at least 5 times more food available on individual leaves than was necessary for larval development, suggesting that female A. aphidimyza took care to place their eggs where there was sufficient food for larval development.

The numerical response of A. aphidimyza to aphid density was calculated using sample data from three field plots. The response between plots was not statistically different.

The implications of using prey weight rather than number to measure predator consumption, and biological control of aphids by A. aphidimyza, are discussed.

Pheromone baited traps and trap trees attracted an aggregate of 29 scolytid species associated with white spruce in three localities in Alaska. Species diversity was higher in the Fairbanks (lat. 64°45′) area than in the Brooks Range (lat. 68°15′) or Kenai Peninsula (lat. 60°37′). Scolytids were found inhabiting all bark-producing areas of the tree from the roots to small branches with the highest density in the tree bole. The most abundant scolytids were Ips perturbatus (Eichhoff), Ips tridens tridens (Mannerheim), Polygraphus rufipennis (Kirby), Dryocoetes affaber (Mannerheim), Trypodendron lineatum (Olivier), and Scolytus piceae (Swaine).

The effect of selected constant temperatures (15.6°, 21.1°, 26.7°, 32.2°, 37.8 °C) on oviposition, feeding, and longevity of Liriomyza trifolii (Burgess) was examined in the laboratory with chrysanthemum, Chrysanthemum morifolium Ramat, as a host plant. There was no significant difference in total feeding at 21.1°, 26.7°, and 32.2 °C nor was there significant difference in egg deposition at these temperatures. The ratio egg deposition: feeding was significantly larger at 26.7 °C. Longevity was similar (12–16 days) at all temperatures except 37.8 °C where it was reduced to ca. 3 days. The effect of temperature was more pronounced when feeding and oviposition were analyzed per day. Maximum feeding occurred at 32.2 °C while significantly more oviposition was found at 26.7 °C. An estimate of the threshold temperature for oviposition was 12.2 °C which was higher than that observed experimentally (10 °C). Ninety percent of oviposition occurred with 550°D of adult female life (above base 10 °C).

Many instances of pest populations increasing following the application of pesticides to crops have been reported, with natural enemy destruction by the pesticide often cited as the cause (Putman and Heme 1959). Other explanations include a greater food supply available due to the death of competing pest species (Root and Gowan 1978), and direct stimulation of the enhanced species by sublethal doses of a pesticide, evidenced as increased fecundity (Leigh and Wynholds 1980; Boykin and Campbell 1982; Coombes 1983). In Ontario the use of the insecticide azinphosmethyl has been followed by population increases of the green peach aphid (Myzus persicae (Sulzer)) (Founk and McClanahan 1970; Ritcey et al. 1982). Our study was undertaken to determine the causes.

Populations of the citrus red mite, Panonychus citri (McGregor), reared on “rough lemon” seedlings (Citrus limon (L.) Burm.) in a greenhouse and treated with malathion or permethrin were significantly higher than those on untreated seedlings. Significant increases were demonstrated in age-specific fecundity (mx), mortality corrected mx (lx mx), and net reproductive rate (Ro) values for mites reared in the laboratory on leaves treated with malathion or permethrin when compared with those reared on untreated leaves. Mites reared on oxamyl-treated leaves exhibited significant reductions in age-specific survivorship (% lx), mx, lxmx, and Ro values compared with those reared on untreated leaves. The importance of reproductive stimulation in relation to other causes of pest resurgence is discussed.

Wheat treated with 2,4, or 8 ppm of insecticide, on a whole-seed basis, was bioassayed with Tribolium castaneum (Herbst) and Cryptolestes ferrugineus (Stephens) adults at 30 °C and 70% RH after 4 days, 2 weeks, and then at eleven 1-month intervals. Malathion was more toxic to C. ferrugineus than to T. castaneum whereas the reverse was true for pirimiphos-methyl; malathion showed little effectiveness after 2 weeks. The pyrethroids, cypermethrin and permethrin, were more toxic to T. castaneum than to C. ferrugineus. For malathion and pirimiphos-methyl, percentage knockdown of the insects following exposure for 24 h was similar to percentage mortality after a 3-day recovery period; for cypermethrin and permethrin under the same conditions, knockdown was consistently greater than mortality. Cypermethrin at 8 ppm on wheat gave 90% knockdown of T. castaneum after 1 year of storage. Pirimiphos-methyl gave nearly 100% control of both species for 9 months at 4 ppm and 11 months at 8 ppm, and of the grain mite Acarus siro (L.) for at least 4 weeks at 8 ppm. Seed germination did not change during 1 year of storage; the levels of Penicillium spp. infection observed were much greater (about 60%) on wheat treated with pirimiphos-methyl (2, 4, 8 ppm) or cypermethrin (2 ppm) than with malathion or permethrin.

Reproductive performance of Ips calligraphus (Germar) in typical slash pine, Pinus elliottii Engelm. var. elliottii, bark slabs with phloem thicknesses ranging from 0.5 to 4.0 mm was studied at 20°, 25°, and 30 °C during the fall (1981) and summer (1982) seasons by means of radiography and slab dissection. Oviposition rate (eggs/day) and egg density (eggs/cm) were positively correlated with both phloem thickness and temperature, being greatest with a combination of thick phloem (3–4 mm) and warm temperature (30 °C). Gallery construction rate (cm/day) was positively correlated, and length of initial egg-free gallery was negatively correlated, with temperature. Depth of xylem-etching was negatively correlated with phloem thickness. Reproductive performance, as measured by oviposition rate and egg density, was greater in the summer study than in the fall study under similar conditions of phloem thickness and temperature. Nutritional, physical, and seasonal characteristics of xylem, phloem, and outer bark are discussed in relation to the above findings.

Invertebrate predation of egg masses of the gypsy moth has been little studied in North America despite its reported impact on populations of this pest in Eurasia and North Africa (Nonveiller 1959; Stefanov and Keremidchiev 1961; Hérard 1979). There, on occasion, this feeding guild has regulated local gypsy moth outbreaks (DeLépiney 1933). The most important predators were dermestids of the genera Anthrenus, Dermestes, Megatoma, and Trogoderma.

An insecticide, diflubenzuron, suppressed 3rd- and 4th-instar larvae of the Colorado potato beetle, Leptinotarsa decemlineata (Say), with reduced effect on the tachinid parasite, Doryphorophaga doryphorae (Riley), developing within the larvae. Concentrations applied to potato foliage were 50, 100, 300, and 500 mg/L. In laboratory and greenhouse tests, parasite survival was not adversely affected when the 3rd instars were treated with 50 mg/L diflubenzuron but survival decreased to 0 and 4% at 300 and 500 mg/L. Survival and emergence of the parasite from treated 4th instars were not adversely affected at any concentration tested. Fourth-instar beetle larvae were much more tolerant of diflubenzuron than were the 3rd instars. Neither fertility nor the ability to parasitize beetle larvae was adversely affected in adult parasites emerging from treated 3rd or 4th instars. Adult beetles developing from treated larvae mated normally and laid fertile eggs. Foliage consumption by the beetle larvae decreased progressively as dosage of diflubenzuron increased but only slowly once the dosage increased beyond 100 mg/L.

Exploratory data analysis was employed to investigate the regional dynamics of managed budworm populations based upon survey data reporting spruce budworm egg-mass densities and damage to balsam fir. The Maine Forest Service collected these data annually from 1975 to 1980 at approximately 1000 different locations each year throughout Maine's spruce–fir forest regions. Although spraying was often associated with ‘better’ conditions in heavily defoliated or infested areas, it was generally associated with somewhat ‘poorer’ conditions in areas which had experienced only light defoliation or infestation in the previous year. The analysis also indicated that while insecticide application may reduce budworm larval populations immediately after application, the largest relative decrease in defoliation rates appeared the year after insecticide application. Insecticide treatments were not as effective as expected. In the year following application, the maximum reduction observed in average defoliation was 20% and in average egg-mass density the maximum reduction was 50%. In many cases the reduction was substantially less. Spraying was not associated with any substantial decline in hazard rating.

The impact of an experimental aerial application of carbaryl (Sevin-4-oil®) on the macroinvertebrate fauna of woodland ponds was studied in northern Maine. Carbaryl was applied at the rate of 840 g A.I./ha, the same rate as was used for control of spruce budworm, Choristoneura fumiferana (Clemens), damage. Four treated ponds and three untreated ponds were observed for up to 30 months following treatment. Maximum residue levels of 254 μg/L were found in the water and 53,793 μg/kg (dry weight) in the sediment. Residues were detectable in the water 14 months and in the sediment 16 months after treatment.

The most severe and persistent impact was on the Amphipoda with Hyallela azteca (Saussure) and Crangonyx richmondensis Ellis reduced to near 0/m2 and failing to recolonize in some of the ponds 30 months after treatment. Numbers of immature Ephemeroptera and Trichoptera were reduced immediately following spray application but this impact did not persist throughout the season nor into the following year. Immediate reduction in numbers of adult Ephemeroptera and Trichoptera emerging from the ponds was also found. Numbers of immature Odonata were reduced following treatment and remained low during the following year. The Chironomidae did not appear affected either as immatures or emerging adults.

A computer model was written to simulate the population dynamics of the cabbage aphid, Brevicoryne brassicae (L.), on the host Maris Kestrel kale, Brassica oleracea L., at Vancouver, British Columbia. The model incorporated the effects of temperature, morph determination, plant quality, predators, parasites, and leaf fall. Comparisons of simulated results with field observations indicated that although B. brassicae, Aphidoletes aphidimyza (Rond.), and Diaeretiella rapae (M'Intosh) were reasonably well understood, syrphid predation was not, and appropriate feed-back mechanisms which could prevent monotonic increase or decrease in the simulated population were lacking. A detailed study in which the population dynamics of the prey is accounted for in terms of the numerical and functional responses of syrphid predators is necessary to understand the population dynamics of B. brassicae on Maris Kestrel kale at Vancouver. Comparisons with other aphid systems suggest that a major change in one component of the system can be compensated for by changes in other components. An overview of the cabbage aphid system at Vancouver is given.

Adults of the new species Cubanotyphlus largo Frank, from Florida, U.S.A., are described, illustrated, and differentiated from adults of C. jimenezi Coiffait and Decou and of C. poeyi Decou, which are known only from Cuba. Distinguishing characteristics of Cubanotyphlus and of the 12 other described genera of New World Neotyphlini are given in a table, as are bibliographic citations and distribution of the 39 known species of New World Leptotyphlinae. The habitat of C. largo in the northern part of Key Largo, Monroe Co., Florida has been threatened by encroaching urban development but recently has been listed for acquisition and conservation by the government of Florida.

Wind tunnel experiments confirmed the optimum blend of the two major components of the sex pheromone of the spruce bud worm Choristoneura fumiferana (Clem.), (E)- and (Z)-11-tetradecenal, to be close to a ratio of 95(E):5(Z). The addition of two minor components, (E)-11-tetradecenyl acetate and the saturated tetradecanal, previously identified in the effluvia of calling virgin females, showed that the acetate alone reduced the level of some responses, while the addition of tetradecanal to the acetate:aldehyde blend restored response to previous levels. Addition of tetradecanal alone showed only minor effects on responses. Males responding to calling females showed higher levels of response and sustained flight longer than did males responding to the four-component blend, and this fact suggests that the blend is incomplete.

A sequential egg-mass sample system for Douglas-fir tussock moth, Orgyia pseudotsugata McDunnough (Lepidoptera: Lymantriidae), was designed, based on visual scanning of the lower branches of Douglas-fir trees, Pseudotsuga menziesii (Mirb.) Franco. A branch was removed from each quadrant from the upper, middle and lower crown level, and from the lowest whorl of a total of 59 non-defoliated trees in 10 areas. No consistent trend in egg-mass density per branch could be found between crown levels and no level proved superior as a representative of the tree. Therefore, the lower whorl of branches was selected for survey purposes because of sampling efficiency. Sample stop lines were determined from egg-mass density and variability data collected on 55 sites and subsequent defoliation estimates were related to these densities. The system is designed as an early detection tool to be used only in non-defoliated stands at the incipient stage of an impending outbreak.

A holidic diet which allowed the onion maggot, Delia antiqua (Meigen), to undergo complete development to the adult reproductive stage was developed. The effects of various concentrations of choline and salts on development were investigated. The amount of choline which gave optimal development was approximately 1/50 that used in most other artificial diets. It was found that the complex salt mixture (Wesson salts) normally used could be replaced by a solution of salts containing specific trace element ions (Fe, Mn, Cu, and Zn) and the two salts CaHPO4·H2O and KH2PO4.

Dans la toundra forestière, zone correspondant non seulement à la limite des forêts et des arbres (Payette 1983), mais aussi à celle de la plupart des espèces de tabanides (Chvála et al. 1972; Baribeau et Maire 1983), les tourbières constituent le principal type de milieux humides propice au développement des larves de tabanides (Miller 1951; Teskey 1969).

The male of the rare Bombus digressus (Milliron) is described based on new material from Costa Rica. Both male and worker castes display unusual combinations of structural characteristics and the unique male genitalia are considered to warrant the erection of a new monotypic subgenus, Digressobombus.

Bacillus thuringiensis var. kurstaki (B.t.) is the most widely used biological control agent against the spruce budworm, Choristoneura fumiferana (Clem.), a major defoliator of coniferous forests. The technology of applying the bacterium, however, is still not fully developed and the strategy of applying single or split applications of B.t. in unmixed stands is still in question. Double applications are generally accepted as necessary in mixed stands of white spruce, Picea glauca (Moench) Voss, red spruce, P. rubens Sarg., black spruce, P. mariana (Mill.) BSP, and balsam fir, Abies balsamea (L.) Mill., due to difference in the phenological development of the host trees and of the budworm infesting them. Field trials were conducted at Mine Centre, Ontario, to compare the efficacies of double and single applications of B.t. against the budwonn infesting balsam fir stands.