Parasitoid studies were conducted concurrently with a pilot control project to test the efficacy of Dipel® WP, a formulation of Bacillus thuringiensis Berliner, in reducing western spruce budworm, Choristoneura occidentalis Freeman, populations. Twenty-one species of parasitoids were recovered in rearings of the budworm and an associated defoliator, the spruce coneworm, Dioryctria reniculelloides Mutuura and Munroe. Parasitoid population alterations occurred following application. Parasitism by Apanteles fumiferanae Vier. and Glypta fumiferanae (Vier.), which attack prediapausing first-instar budworm, was significantly higher in treatment blocks following B.t. application. Parasitism by Phaeogenes hariolus (Cr.), Cermoasia auricaudata Tns., and Madremyia saundersii (Will), parasitoids of late instars and pupae, was significantly lower following treatment. Comparisons of parasitoid populations were made between pre- and post-spray sampling periods and between treatment and check blocks.

The principal developmental stages and the female reproductive system of Grypocentrus albipes Ruthe are briefly described and illustrated. The oviposition pattern is described. Females chew through the leaf tissue and gnaw on Fenusa pusilla (Lep.) larvae while the larvae are in their larval mines. The average fecundity in laboratory experiments was 3.2 eggs per day, and the maximum number of eggs deposited by one female was 96. Some observations are presented on egg and larval development as well as on pupation.

A temporary pond close to Calgary, Alberta, was studied for 2 years. In the spring of the first year (1974) the pond filled with water to a much higher level than normal and it did not dry and reflood until August. The first flooding hatched eggs of Aedes euedes, A. cataphylla, A. excrucians, A. fitchii, A. flavescens, and A. mercurator; the second flooding hatched eggs of A. vexans and A. cinereus. Estimates of larval population size were made for the latter two species and little larval mortality occurred until the pond was reduced to a few small puddles, when larvae became stranded. The pond dried completely before the pupal stage was attained. Fifty per cent of surviving A. vexans larvae attained instar II in 3.7 days, instar III in 6.6 days, and instar IV in 10.3 days. A. cinereus developed more slowly.

In the second year (1975) the pond contained water from the middle of April to the beginning of June, and did not refill in the summer. Estimates of larval population sizes were made for A. euedes and A. mercurator. These larvae shared a preference for the deeper water in the centre of the pond. Their numbers declined at rates of 9% per day for A. euedes and 7% per day for A. mercurator. Larvae in the second instar survived a period of 3 days when the water surface was covered with ice and snow, but A. euedes experienced a sharp drop in numbers at this time.

Fifty-three per cent of the eggs of A. vexans survived a period of 1 year in areas not flooded with water at appropriate temperatures for hatching.

Methods for sampling eggs, larvae, and pupae of Aedes spp. in a temporary pond are described. Changes in the area of the pond were mapped by reference to 8 transect lines and correlated with depth at the centre. These pond outlines at different centre depths were also used for the characterization of sampling strata. Samples were taken along the 8 transects only. Soil cores were taken from the dry pond bed, and the larvae that hatched after repeated floodings in the laboratory were used as estimates of the number of viable eggs present in the cores. The temperature of the water used for flooding was adjusted to hatch the ’spring’ species separately from Aedes vexans and Aedes cinereus. Samples were taken in the spring of 1974, in the autumn after the pond had been naturally reflooded, and in the spring of 1975. The estimated number of eggs in the pond decreased with time and the number estimated to have hatched in the summer of 1974 was similar to the estimated number of larvae. The standard errors were about 10% of the mean. Larvae and pupae were sampled with a Belleville sampler and population estimates were obtained for Aedes vexans and Aedes cinereus in August 1974 and for the ’spring’ species, Aedes euedes and Aedes mercurator, in April–May 1975. The efficiency of this program increased when the sample size exceeded 40, when the size of the sample unit was appropriate to the density of larvae, and when sufficient time was allowed for larvae (1 h for instar I) to become trapped. However, standard errors of less than 10% of the mean were obtained only at high mosquito densities.

The genus Syndyas Loew is revised for North America, and four of the six included species are described as new. A general description of the Nearctic species group is given, and keys are presented. All species but one are restricted to eastern North America. Three unplaced specimens that may represent additional species are discussed.

The pink bollworm (Pectinophora gossypiella (Saunders)) is an important pest of cotton in the desert areas of the United States and Mexico, as well as other areas of the world. The literature on this pest is quite extensive, and hence, beyond the scope of this paper. Work by McLaughlin (1974), Lukefahr (1962), Watson et al. (1973), Slosser and Watson (1972), Adkisson et al. (1963), and Westphal et al. (unpublished) have been extremely useful in providing a satisfactory data base for formulating a mathematical description of the biology of this pest species (i.e., a time varying life table model—Hughes (1963), see Southwood (1966)).

Storage of diapausing larvae of Choristoneura viridis and C. occidentalis at low temperature (2°C) appeared to be sufficient stimulus to terminate diapause. Reactivation at 25°C occurred sooner and was more synchronous with longer storage at 2°C. Highest survival was obtained after storage of 20 to 22 weeks for both C. viridis and C. occidentalis. Intraspecific and interspecific reactivation rates were compared by analysis of covariance, using the model ln Y = a + B ln X , where Y = larval emergence in days at 25°C and X = storage in weeks at 2°C. Intraspecific sex differences were not significant, indicating that protandry observed in this laboratory in both species must be due to some other factor. C. viridis had substantially less stringent thermal requirements for diapause termination than C. occidentalis. Diapause in the two species is discussed.

Anopheles stephensi Liston larvae were reared in food- and space-limited environments to which a mixture of penicillin G, chloramphenicol, and amphotericin B was added to suppress microbial populations. Under crowded conditions larvae took longer to develop, exhibited reduced survival, had an extended pupation period, and produced adults that were smaller. Under uncrowded conditions slightly more males than females emerged, whereas under crowded conditions proportionately fewer males than females emerged. Indirect evidence suggested that inhibitory compounds that slowed development and increased larval mortality were produced by crowded larvae. The addition of antibiotics did not suppress all microbial populations, but rather selected for resistant Pseudomonas-group bacteria which actually increased in number. The addition of antibiotics increased developmental rates at uncrowded, but not crowded densities, increased larval mortality, and increased the size of the emerging adults. Residual antibiotics increased development rates in a subsequent bioassay of the rearing media.

Experiments with caged populations of Anopheles stephensi Liston were performed to evaluate the effects of larval intraspecific competition on adult density and sex ratio. The changing of the water in continuous culture cages prevented the accumulation of larval competitive compounds and excretory products, and resulted in higher adult densities and the successful emergence of proportionately more males.

The effect of daily day-degrees C in relation to brood age was investigated to determine its influence on the induction of larval (prepupal) diapause in Dendroctonus rufipennis (Kirby). Daily day-degrees of less than about 9° above the development threshold (6.1°C) induced diapause in most of the broods while diapause was averted by daily day-degrees C of 10 or more above the threshold. Induction of diapause occurred no later than third larval instar; temperature changes during the fourth instar produced no change in aversion or induction of diapause. Laboratory results reveal that field temperatures during larval development determine whether most beetles have a 1- or 2-year life cycle.

Feeding by aphids during 11 days decreased plant weight between 4.7% at an initial density of 5 aphids/plant and 63.9% when the infestation began with 50 aphids/plant. At this infestation level, plant surface area was decreased by 54.3% after 10 days. Both soluble carbohydrate and total protein were reduced by aphid feeding but caloric equivalent of pea tissue was not significantly affected. Extraction by aphids of up to 3.5 cal/plant day was offset by a compensatory increase in production by the plant. Extraction of about 32.7 cal/plant day, equivalent to 0.46 adult aphids/cm2 of plant surface, completely eliminated pea net primary productivity. The relation between energy extracted by aphids, X, and % reduction of plant NPP, Y = 5.54 X−0.058 X2−19.17. Aphid consumption affected pea production directly by removing the amount actually ingested and indirectly because of lost production that would have resulted from the consumed material. Maximum sustainable efficiency of utilization of pea NPP by aphids was between 41% and 47% and maximum sustainable efficiency of transfer of pea NPP to aphid biomass was between 20% and 23%. These high utilization and transfer efficiencies probably would be reduced under field conditions by factors which limit aphid numbers.

The influence of temperature on the development of immature stages of Bracon mellitor Say, a braconid parasite of the boll weevil, Anthonomus grandis Boheman, was studied at a series of constant and variable temperatures. Resulting developmental rates and times were compatible with recent advances in the theory of thermal responses exhibited by poikilotherms. Mean development times recorded were in close agreement with predictions calculated from a previously derived absolute reaction rate development model.

Bracon mellitor cohort developmental data were also checked against a prototype stochastic cohort development model. In this comparison, observed and predicted probability distributions agreed for constant and variable day/night temperature regimes but showed some differences under sinusoidal temperature regimes.

Newly moulted sixth instar larvae of spruce budworm, Choristoneura fumiferana, were force fed graded dosages of preparations containing (1) purified crystals, (2) purified spores, and (3) mg/mg mixtures of purified spores and purified crystals. The LD50 for purified crystals was 0.094 μg/larva and for the mixture 0.096 μg/larva but the latter preparation had an LD50 of 0.048 μg/larva based on crystals indicating that the presence of 2.4 × 105 spores enhanced the toxicity of crystals twofold. The LD50 spore crystal corresponded to LD60 for crystals alone. The LD50 for spores treated with proteinase to remove residual crystals was 20 μg/larva, or 1,0 × 108 spores. The regression coefficients were not significantly different from each other in all three preparations indicating a common or similar mode of action. It is concluded that spores play little or no role in mortality of spruce budworm induced by Bacillus thuringiensis insecticides.

Geocoris bullatus (Say) adults were observed on two separate occasions dragging adult flea beetles over the soil surface, with one of the flea beetles being identified as Phyllotreta striolata (F). No predation was seen on other occasions when this predator and flea beetles were present together in the field, nor in laboratory confinement experiments. Under the latter circumstances G. bullatus readily attacked aphids, however. It seems likely that G. bullatus is only an incidental predator on adult flea beetles in western Canada.