The effects of the biologically derived insecticide spinosad on parasitoids of Mamestra configurata Walker were studied. Adult Trichogramma inyoense Pinto and Oatman (Hymenoptera: Trichogrammatidae), an egg parasitoid, were as susceptible to a dose of 0.125 μg/cm2 as they were to a high dose of 2.0 μg/cm2. Application of spinosad to host eggs at the time of oviposition resulted in significantly reduced T. inyoense parasitism and higher parasitoid mortality in parasitized eggs. Adult Microplitis mediator (Haliday) (Hymenoptera: Braconidae), a larval endoparasitoid, were highly susceptible at the highest dose tested, 1.0 μg/cm2. Spinosad at 2.0 μg/cm2 fed to larval M. configurata parasitized with M. mediator 1 and 7 d previous caused similar mortality to that for nonparasitized larvae. At a dose of 0.125 μg/cm2, only larvae parasitized 1 d previously showed mortalities similar to those of nonparasitized larvae, whereas larvae parasitized 7 d previously were not affected by this low dose. Larval M. mediator that egressed from hosts parasitized 7 d previously and treated with the low dose were unable to complete cocoon formation and died. This study suggests that integrated pest management programs for M. configurata in canola should include evaluating the presence and abundance of parasitoids.

Populations of leaf rollers on apple can be influenced by the proximity of alternative host plants, notably rose, privet, and antelope bush, in part because larval dispersal is common. Indications are that leaf roller population increases caused by parasite decreases are ultimate consequences of pesticide treatments, so that reductions in spray programs will not necessarily cause potential leaf roller pests to become actual pests. The composition of the leaf roller fauna on apple m the Okanagan Valley becomes increasingly complex as the environmental water balance is changed by cultivation and irrigation. There are indications that heavy vehicular traffic can be harmful to leaf rollers and their parasites nearby.

As part of a detailed study of the life system of the alfalfa weevil, Hypera postica (Gyll.), in southern Ontario, two methods were developed for estimating numbers of eggs in the spring growth of alfalfa. The first is based on direct counts of the eggs, which are laid in clusters and hence, aggregated in distribution; for moderate levels of infestation (ca. 8 eggs per bouquet), estimates with acceptable precision may be obtained by taking a single 3-stem bouquet of alfalfa from 80 randomly selected ft2 (.09 m2) quadrats within a field. The second is based on counts of the oviposition punctures which are randomly dispersed and consistent with the Poisson distribution. Although slightly less accurate, this method will provide a valid index of the number of eggs with less labour; acceptable precision may be obtained by taking a single bouquet from just 32 quadrats.

Cretonomyia pristina new genus and new species, a fossil fly in amber from Cedar Lake, Manitoba, is described and assigned to the Ironomyiidae. This fossil establishes that the family, heretofore known from a single Australian species, Ironomyia nigromaculata White, existed during Mesozoic times in North America. Comparison of the extinct species with the living species shows that the family appeared little different 73 million years ago than it does today. In points of difference, the fossil species usually shows the more primitive conditions. It is postulated that the family arose in North America in late Jurassic – early Cretaceous times, dispersed to South America late in the Cretaceous Period and thence to Australia via Antarctica while the latter three were contiguous — 43 million years ago.

The dispersal of the pine needle scale has long been a problem to entomologists. Although its transfer on nursery stock has been accepted as a means of dispersal, the method of its spread from tree to tree in a localized area has not been investigated previously. There are two stages in its development when it is able to move about by its own volition: the crawler or first instar nymphs wander for short distances on the twigs of the host tree and the adult males move about freely. Effective spread of this scale occurs only in the crawler stage. Phoresy is unlikely because nymphs have extreme difficulty in crossing small gaps such as would be encountered in transferring from a needle to an insect or bird and parent scales do not secrete substances attractive to carriers as described by Mahdihassan (1933) for some lac-insects. Because of the limited motility of the first instar nymphs, dissemination by wind required investigation.

Mixed colonies of adults of Lytta nuttalli Say and L. viridana Le Conte, and of L. cyanipennis (Le Conte) and nuttalli, and colonies containing only one of these three species have been seen in various parts of the Canadian prairies, usually in aggregations and most commonly near bodies of water. The flight period of nuttalli extends from early June to early August, of viridana from late May to late June, and of cyanipennis from mid-June to early July. The natural food plants of these three species are a variety of wild legumes, though they prefer certain cultivated legumes when present. Nuttalli and viridana will eat some non-leguminous plants, including species of Iris, Delphinium, and Brassica, and such crops as sugar beets, oats, barley, and wheat. In captivity, males and females of nuttalli and viridana mated more than once and females deposited more than one batch of eggs. Egg batches of nuttalli, viridana, and cyanipennis contained an average of 320, 340, and 390 eggs each, respectively. Cross-mating between nuttalli and viridana and nuttalli–viridana hybrids were observed in the field. Four nuttalli females were seen ovipositing in an area that contained the remains of nesting cells of leafcutter bees (Megachile sp.); these are the first recorded observations of Lytta species ovipositing in the field. The beetles preferred moist, firm soil for oviposition, and the eggs desiccated very quickly when not in contact with moisture. The eggs of these three species developed fairly uniformly at temperatures from 15° to 30 °C, and it appeared to take about 2 to 3 weeks to complete embryological development at temperatures normally encountered during June through August. Relationships among these three species suggested by their behaviour and biology are discussed.

In this study, survival to adult stage, duration of development of the immature stages, egg micromorphology, DNA polymorphism, and reproductive compatibility were measured for early- and late-emerging phenotypes of Delia radicum Linneaus to determine whether both phenotypes had evolved differences other than the duration of puparial development and to find the most likely genetic system controlling the expression of both phenotypes. Survival to adult stage was not significantly different between the early- and late-emerging phenotypes. Random amplified polymorphic DNA (RAPD) primers tested suggest that it is possible to distinguish an early-emerging fly from a late-emerging fly. Furthermore, the results suggest that the early- and late-emerging phenotypes differ not only in the timing of adult emergence but also in their egg structure (egg micromorphology) and in their larval and puparial mortality. These two phenotypes are not reproductively or ecologically isolated. The genetic system controlling the expression of early and late emergers in a population of D. radicum is probably an adaptive strategy reducing predator and parasitoid pressures, optimizing resource utilization, and ensuring survival of D. radicum during atypical winters. This strategy could eventually lead to temporal sympatric speciation if there are changes in a few key loci responsible for host plant selection and fitness on a new host.

Triglycerides of Nigrospora sphaerica which elicit aggregation of adult confused flour beetles were separated according to their degree of unsaturation by chromatographic methods. Several fractions showed activity. The largest and most active fraction consisted of monounsaturated triglycerides of which the major component was oleodipalmitin. Triglycerides from three other fungi showed varied levels of activity.

In laboratory studies with the codling moth, Cydia pomonella (L.), TH 6043 and TH 6044, new benzoylphenylurea chitin-synthesis inhibitors, were more effective than TH 6045 and diflubenzuron in reducing hatch of eggs from treated adults. With TH 6043 and TH 6044, egg hatch was reduced only when the female of each mating pair was treated. Topical application of diflubenzuron to adults moderately reduced egg hatch while TH 6045 had no effect. Diflubenzuron also reduced oviposition by females. None of these compounds adversely affected mortality, longevity, or mating propensity of adults.

The spatial distribution of adult Ooencyrtus kuvanae (Howard) (Hymenoptera: Encyrtidae) was examined in central Pennsylvania during 1978–1980. Data were gathered over a wide range of gypsy moth (Lymantria dispar (L.) (Lepidoptera: Lymantriidae)) densities and from all phases of population growth. There was a linear relationship between the log variance and log mean, fitting Taylor's Power Law with a power of 1.27. The degree of aggregation in O. kuvanae populations, as measured by the variance-to-mean ratio, was correlated positively with the abundance of the parasite, and was independent of host density. Aggregation was believed to result from the habit of the female parasite ovipositing repeatedly on the same egg mass, and the resultant progeny emerging synchronously. Behavior and density of O. kuvanae populations were found to depend upon the gypsy moth population condition, i.e., low, rising, high stable, outbreak, or collapsed. The frequency distribution of O. kuvanae populations fit the Poisson at densities less than 0.2 parasite adult per egg mass, a condition which occurred early and late (July, November) in the season, and the negative binomial above this density; a few distributions fit the log normal. The data were also analyzed using analyses of variance (multivariate and univariate), correlation, and regression techniques. All main effects, i.e., study area, host egg mass volume, egg mass height from the ground (within the 0–2 m sampling universe), aspect of the egg mass on the tree, and tree species, were important in explaining the variance in parasite abundance; study area differences were the most important. The effects of aspect and tree species were explained on the basis of small sample sizes, and not studied further. There was a positive correlation between host egg mass volume (= size) and parasite abundance. There was also a positive correlation between the height of the egg mass and parasite abundance during the summer; however, this relationship became negative by late fall. This seasonal change in vertical distribution was attributed to the tendency of O. kuvanae to be closer to the ground where they overwinter. Variation in adult abundance was generally greater among gypsy moth egg masses on different trees than among egg masses on the same tree, except at low parasite densities. This was attributed to the parasites searching for egg masses on one tree before dispersing to another.

The effect on insect populations of the widespread use of plant growth regulators and herbicides is a neglected field. Fox (1948) reported on a relationship between the use of 2,4-D and wireworm damage to wheat. Putnam (1949) suggested that 2,4-D could be an environmental factor in the ecology of grasshoppers. A recent report (Maxwell and Harwood, 1958) indicates that even slight dosages of 2,4-D increase the rate of reproduction of pea aphids on broad beans. This note is a preliminary report on similar investigations with the pea aphid, Acyrthosiphon pisum (Harris), and broad bean, Vicia faba L.

An analysis of the times to emergence in three sparse populations of Choristoneura spp. in western North America indicates that there was considerable variation in the calculated threshold of development among populations. Also, the number of heat units required to effect the emergence of any specified proportion of the population varied considerably among populations. The pattern of intra-population variation in times to emergence is such that the within-family variation was much larger than the among-family variation in the two populations from areas in which white fir is the only host. In the other population, from an area with a mixed stand of Douglas-fir and white fir, the pattern is reversed. This pattern remains even after an accounting is made for the parental host and larval color morph. It is hypothesized that the pattern of variation in the times to emergence may be due to the presence, in the latter population, of physiological morphs which cannot be recognized either by their appearance or their host of origin. These results have clear implications for pest management procedures which attempt to schedule activities related to the emergence of these insects in the spring.

The demise of the American bison, Bison bison (L.), following European settlement has given rise to two hypotheses regarding the fate of their dung-associated insects. The “extant” hypothesis proposes that all of these taxa now persist in the dung of cattle, Bos taurus L. The “extinction” hypothesis proposes that a subset of these taxa were unable to make this transition and have gone extinct. We examined these hypotheses by comparing the response of coprophilous insects to dung of bison versus cattle on similar diets and versus dung of cattle on different diets. Results showed insects to be more responsive to changes in diet than to changes in host species and, therefore, were supportive of the extant hypothesis. To our knowledge, these data provide the first experimental comparisons of bison dung versus cattle dung as habitat for coprophilous insects.

Mechanistic species niche models were used to map the seasonal spatio-temporal dynamics of biological control pressure. Future climate scenarios were applied to these models to identify potential future trends in the patterns of biological control pressure through space and time during an annual seasonal cycle. Peristenus digoneutis Loan (Hymenoptera: Braconidae) is a parasitoid of Lygus Hahn (Hemiptera: Miridae) species, important pests of glasshouse and field crops throughout Europe and North America. Consistent with theoretical expectations, the modelled potential range of P. digoneutis expanded polewards and contracted from its southern temperature range limits. However, its distribution did not change consistently across continents or countries. Locations near the outer limits of the current modelled distribution were more sensitive to changes in future climates than locations near the central core. Weekly climate suitability and stress maps were developed to provide insight into seasonal adjustments that accompany changes in the potential range of pest species and their natural enemies. Climate change may increase the number of Lygus generations in western Canada allowing P. digoneutis to establish in areas, where biological control attempts had failed in the past.

Using regression analysis on data compiled from the literature, I compared relationships (forewing versus body length) of mayfly imagoes, as a measure of dispersal, between suborders (Schistonota and Pannota) and among habitat type (lotic, lentic, and mixed). There were no significant differences in slopes or intercepts of the regression lines between sexes. Forewing length changed less markedly with body size for species within the ancestral Schistonota than the Pannota. Regression lines for lake and river forms intersect at 7.85 mm (wing length) and 7.30 mm (body length). Small (body length < 7.3 mm) lentic mayflies have proportionately longer wings than small riverine forms. Large (body length > 7.3 mm) riverine mayflies have proportionately longer wings than lentic forms. Based on these relationships, small lake-dwelling mayflies and large riverine mayflies are best able to disperse. Mayfly species occurring in mixed (both rivers and lakes) habitats exhibited allometric relationships similar to mayflies restricted to rivers.

Of the fruits grown in the Kootenay Valley of British Columbia, pears are third in importance; in the more arid Okanagan Valley 300 miles to the wrest they are second. During 1959 the pear psylla, Psylla pyricola Foerster, caused severe losses for fruit growers in the Okanagan Valley. The damage was much greater than had occurred during the previous 17 years. It became clear that the insect was a major economic pest, and that it was not being adequately controlled by the recommended insecticides. Obviously, more information was needed on the biological aspects of the situation. The roie of climatic conditions was particularly in question. In 1960 a start was made on a biological study of the pear psylla at Creston in the Kootenay Valley. This paper deals with observations thnf were made there.

In view of the background of information on Bacillus popilliae Dutky (Beard, 1945) and the reported success of this bacterium in reducing populations of Popillia japonica Newm. (White and McCabe, 1950) and in view of the discovery of a similar bacterium attacking Odontria grubs in New Zealand (Dumbleton, 1945), a survey of microparasites and their possible pathogenicity in scarabaeid larvae was undertaken in Australia as a project supported by a Fulbright award.

The Poisson and the negative binomial series, Taylor’s power law, and Morisita’s Iδ-index were used to interpret the dispersion of field counts of the immature stages of Hypera postica (Gyll.) on alfalfa. The data conformed consistently to an overdispersed distribution. Transformations are offered for stabilizing the variance of field counts.

Prepupae of three species of Diplolepis (D. nebulosa (Bassett) a leaf-gall-former, an undescribed stem-gall-former, and D. radicum (Osten Sacken), a root-gall-former) were overwintered at various heights above the ground. Most prepupae of all three species buried beneath the snow survived the winter, while only stem-gall-formers survived at a height subject to fluctuating snow depths. All specimens of the three species that overwintered above the snow were killed.

Several host–parasitoid models were examined to assess the feasibility of parasitoid inundation as a means of pest control or eradication. The approach is comparative, to assess independently the effects of various ecological factors on the ease of control by this means. For most of the models, there exists a critical inundation rate, I*, above which the host population is eradicated, provided inundative releases continue beyond the time of eradication. The existence of density-dependent mortality in the hosts reduces the time to eradication but does not affect I*. Density dependence in the parasitoids, however, usually increases I*. The existence of hyperparasitoids appears to have no effect on the ease of host eradication.