An analysis of the primary setae and pores (campaniform sensilla) of first instars of 32 species of Colymbetinae, 61 species belonging to other dytiscid subfamilies, and seven species belonging to other families of Hydradephaga was performed to deduce the ancestral system of primary setae and pores of the head capsule and head appendages of Colymbetinae. Sixty-one setae and 46 pores have been assigned to the ground-plan pattern of the colymbetine larva, 27 setae and 20 pores on the head capsule and 34 setae and 26 pores on the cephalic appendages. The pattern proposed for the Colymbetinae is remarkably consistent and similar to the condition observed within the Carabidae. However, members of the Colymbetinae differ strongly from those of Hydroporinae which are characterized by several secondary losses. A preliminary phylogenetic reconstruction of the relationships of colymbetine genera studied based on 41 larval features suggests that the Nearctic fauna includes two monophyletic lineages: (1) (Agabus Leach + Ilybius Erichson) + Agabinus Crotch, and (2) {[Colymbetes Clairville + (Rhantus Dejean + Neoscutopterus Balfour-Browne)] + Matus Aubé}.

A soil-dwelling predatory mite, Geolaelaps sp. nr. aculeifer (Canestrini), introduced inundatively at a rate of 6000 mites per plant to the sawdust substrate of hydroponically grown, greenhouse cucumbers significantly reduced numbers of fungus gnat, Bradysia spp., larvae and adults over a 10-week period. Inundative introductions of 1600 mites per plant reduced emergence of western flower thrips, Frankliniella occidentalis (Pergande), adults to about 30% of that in the controls over a 40-day trial. An inoculative introduction of 125 mites per plant to cucumber plants in selected rows in a commercial greenhouse reduced peak fungus gnat numbers to about 20% of those in untreated rows. These results suggest that a single inoculative introduction of Geolaelaps sp. nr. aculeifer, early in the crop cycle, would maintain control of fungus gnat populations in greenhouse cucumber crops at an acceptable level. This predator would also contribute to biological control of western flower thrips by reducing emergence of adults.

We investigated changes in a wild bee community by repeating a detailed historical study of bee biodiversity in Ontario. In 1968 and 1969 (period 1), an inventory of bee species was taken from an old field habitat in southern Ontario. We resampled the bee fauna in 2002 and 2003 (period 2), following the same methods. Bee species richness, diversity, and evenness were significantly greater in period 2, and this was observed in all functional guilds except wood-nesting, pollen specialist, and nonnative bees. In period 2, a total of 150 bee species were found (2002, 98 species; 2003, 143 species), whereas in period 1, a total of 105 species were found (1968, 98 species; 1969, 76 species). Although 90 bee species collected in period 1 were re-collected in period 2, bee community composition was remarkably different between periods, with an estimated community similarity of only 7.5%. Changes in the bee fauna, specifically the increase in the proportions of pollen specialist and wood-nesting bees, might be best explained by changes in the habitat as a result of succession over the intervening 34 years. We compare and contrast our findings of bee community change with the published literature and discuss the possible factors driving the change.

Larvae of Pseudosarcophaga affinis auct. nec Fallén readily discriminated between synthetic diets satisfactory for growth and those that had nutritionally important faults. The faults were lack of an essential amino acid, unsatisfactory ratios of essential and nonessential amino acids, and unsatisfactory proportions of the best amino acid mixture relative to glucose levels. Some of these were made to resemble the proportions of amino acids and glucose found by other workers in tissues of aphid-resistant and -susceptible varieties of peas. All the experiments showed that the diets chosen by larvae were those on which they grew and developed best. That larvae can relate the chemical composition of the selected foodstuff with their nutritional requirements may cast some light on varietal resistance of plants or other foodstuff to insects.

The light brown apple moth, Epiphyas postvittana Walker, is a highly polyphagous native pest of Australia that has recently caused widespread damage to pome, citrus, and vine crops in Victoria and Tasmania. Populations of the pest were followed in a young pesticide-free orchard for two seasons and showed a survival trend of less than 1% of the total eggs laid in each season. An evaluation of its natural enemies by numerical, serological, and forced feeding techniques showed that spiders, particularly the theridiid Achaearanea veruculata (Urquhart), were valuable predators and that they were supported by chrysopids and mirids for short periods of time. Egg, larval, and pupal parasites also contributed to mortality. Brief biological notes on some of the predators are given.

Spring wheats, Triticum aestivum L., previously identified as being lightly infested by eggs or larvae of wheat midge, Sitodiplosis mosellana (Géhin), were tested to determine if reduced infestation was the result of oviposition deterrence. Oviposition deterrence was measured as the number of eggs deposited on a wheat line relative to that on a check. Egg densities on some of these lines were 10% or less compared with the susceptible commercial cultivar 'Roblin' in choice tests and 20% or less in no-choice tests in the laboratory. These lines also deterred oviposition in the field, reducing egg densities by at least 50% in single-row and multi-row field plots. Other experimental lines showed levels of oviposition deterrence intermediate between the most deterrent lines and 'Roblin'. One of 12 commercial cultivars tested, 'AC Superb', also had low egg densities in the laboratory and in single-row field tests, but this possible oviposition deterrence was not consistently present in large plots or commercial fields. The most deterrent experimental lines showed a level of oviposition deterrence that would be agriculturally useful and desirable in combination with a previously described antibiotic resistance.

Two bioassays were used to study the effects of the various life stages of a Temperate Zone ambrosia beetle, Xyleborus dispar (F.) (Coleoptera: Scolytidae), on the induction of the ambrosial form of its symbiotic fungus, Ambrosiella hartigii Batra (Fungi Imperfecti).Postdiapause adults and pupae of X. dispar cause a change from the mycelial to the ambrosial form of A. hartigii in culture.

Larvae feed on the mycelial form in vitro, but ambrosia is required by larvae to develop and pupate. One of the main factors inducing the ambrosial form of A. hartigii is probably a secretory product of X. dispar.

Using bioclimatic chambers to provide diurnally fluctuating temperature and humidity conditions, the relationship between fecundity of females of the aphid parasite, Praon exsoletum (Nees), and different host densities, was examined over a wide range of mean temperatures. At each temperature level the number of eggs laid by females was found to vary with host density in accordance with the functional response curve (disc equation) of Holling. Superparasitism was common at all temperature levels studied, and, irrespective of host density, eggs were found laid at random with respect to hosts present. The functional response equation was thus modified so that number of hosts attacked was determined by both number of hosts present and number of eggs laid. Using this modified disc equation, the bioclimatic characteristics of parasite oviposition were examined from rhc standpoint of varying temperature levels. Oviposition was limited to mean temperatures between 8° and 29°C; near these limits the maximum number of eggs laid and the maximum number of hosts attacked were low. At medial mean temperatures (13°–24°) the number of eggs laid per parasite was high, averaging between 70 and 110 each 12-hour day. At these same medial temperatures, according to the modified disc equation, the average "handling" time per oviposition attack was shortest, and the parasite effective searching rate fastest. Averaged over a 12-hour day (this parasite does not oviposit in darkness), females of P. exsoletum were capable of laying from seven to nine eggs per hour at temperatures between 15° and 24° respectively. In all cases, the number of hosts attacked varied with numbers of eggs laid in accordance with Thompson’s superparasitism formula.

The forest tent caterpillar, Malacosoma disstria Hbn., and the eastern and western tent caterpillars, M. americanum (Fab.) and M. pluviale (Dyar), are common pests of several species of deciduous trees in Canada. All are colonial during the larval stage, but M. disstria differs from the others in one respect: it does not construct a communal tent. This difference in habit merits special consideration in any comparative study of larval behaviour, particularly in one concerned with the effects of physical factors upon the insects, since a tent modifies the effects of the physical environment considerably. Recently, a series of such studies was carried out, and one part of the work consisted of laboratory and field observations on the light reactions of larvae. The results obtained have raised a number of new questions which unfortunately cannot be answered now, hecause two of the species have been difficult to obtain in quantity since 1950. Nevertheless, the findings are presented here without additional delay, since they are of general interest, and other workers may wish to use them.

Pseudaletia unipuncta (Haworth) was reared at eight constant temperatures from 5° to 31 °C. The eggs hatched at all temperatures except 5 °C. Development was completed at 13°, 17°, 21°, 25°, and 29 °C but at 10° and 31 °C none survived beyond the final larval instar.The duration of each stage decreased with rise in temperature up to 29 °C; but a further rise brought no further change, or even an increase. Developmental rates plotted against temperature gave shallow sigmoid curves with the maximum development rate near 29 °C for all stages except for the final instar larva where it was between 25° and 29 °C. Various alternating temperature regimes had no special influence on the rate of the development of eggs or larvae.There was a significant linear increase in larval head width with rise in temperature for all instars except the first. For larvae with six instars, the mean head width in the last instar ranged from 3.15 mm at 13 °C to 3.38 mm at 29 °C. At 13 °C some larvae required an additional moult to reach the apparent minimum size (about 3 mm) to complete development.

Larval growth in B. terricola Kirby was measured from daily photographs of the combs of colonies. The growth rate of well-fed larvae was exponential until the commencement of cocoon spinning. No difference between the instantaneous growth rates of physiologically determined workers and queens developing in the same larval clump could be detected. Queen morphogenesis consisted principally of an extended stadial duration as compared with workers. Larvae which were starved regained their former growth rates once they were again fed plentifully. As a general feature of larval growth in Bombus it is suggested that the capacity to resume growth at an invariant maximal rate is retained under widely varying trophic regimes. Thus larval growth in bumble bees is interpreted as a succession of bursts of maximum proportional increase separated by periods of temporary starvation induced both by irregularities in colony food intake and the inherent stochasticity of worker feeding behaviour.

A resumé of the North American literature concerned with hymenopterous parasites of bark beetles is presented. Morphology, seasonal history, host-tree selection, hyperparasitism, importation and colonization and their influence upon control of the host are briefly discussed.

Parasites of a given host or hosts of a known parasite can easily be found in two different lists. Parasites are listed below in an alphabetical list of bark beetle species. Hosts, including some species other than bark beetles, are listed under a separate list of parasite families and genera. Host-parasite associations in each list are supported by a numerical reference to the literature cited.

The process of resource utilization by Dendroctonus frontalis Zimmerman attacking loblolly pine, Pinus taeda L., was investigated. The quantitative relationship of attacking parent adult D. frontalis as a function of the normalized infested bole height is described by the model y = Ax(1−x)eBx. Greatest attack density occurs at the mid-bole of the tree and tapers toward the top and bottom. Gallery length (and hence eggs)/100 cm2 was independent of attack density. The relationship between gallery length (or eggs) per parent adult and parent adult density is described by the exponential decay curve y = AeBx, indicating that gallery length and egg population density are controlled by a density dependent compensatory feedback process operating instantaneously. Further support for the mechanism was obtained by analyzing the gallery length per parent adult at different locations on the infested bole. The relationship is described by the model y = [AeBx]/[x(1−x)] and indicates that gallery construction and egg population per attacking beetle increase in the upper and basal portion of the bole. The result is a uniform amount of food and space per individual of the developing population.

The spruce beetle, Dendroctonus rufipennis (Kirby), has described life cycles of 1–3 years. Although temperature has been shown to be strongly associated with flexible voltinism in the spruce beetle, the physiological basis for this phenomenon is not clear. Two competing hypotheses were tested under laboratory conditions. First, we tested the hypothesis that larval diapause, induced by cool temperatures during or before instar III, initiates prolonged life cycles while larvae not diapausing complete development to adults before the first winter. We compared development times at constant temperature (12 °C) and field-simulated thermoperiod treatments against development times in a reference (21 °C) treatment for which there is no indication of diapause induction. The constant temperature treatment was not significantly different than the reference treatment, although there were a few outliers. The thermoperiod treatment was significantly longer than the reference treatment, but only by a few days. These results provide little support for the hypothesis of larval diapause induction during or before instar III. Second, we investigated the hypothesis of life-cycle regulation through life stage specific developmental temperature thresholds, particularly, a relatively high threshold for pupation that might prevent development beyond the prepupal life stage under cool conditions. We found little evidence of distinct differences in low-temperature thresholds between life stages. Instar-IV larvae held at ≤ 15 °C, however, did not pupate for 125–300 days, a developmental arrest that suggests diapause. Based on all present and previous investigations, the induction-sensitive phase appears to be late in the instar-IV or early in the prepupal stages. For semivoltine spruce beetles, this life stage occurs late in the growing season, after most temperature-dependent development has been completed. It is our conclusion that spruce beetle voltinism is primarily under direct temperature control and that prepupal diapause is the default overwintering strategy for individuals not completing development to maturity by fall.

Bees of the genus Osmia Panzer (Hymenoptera: Megachilidae) are among the contenders to replace honey bees, Apis mellifera L. (Apidae), for pollinating tree-fruit crops. One species, Osmia lignaria Say, has shown great potential in western North America and was recently introduced into Nova Scotia for evaluation as a pollinator of apple, Malus Mill. (Rosaceae). A major component of that study was to develop management options for O. lignaria, including methods of sustaining nesting females following crop flowering to maximize population recovery for pollination in subsequent seasons. The objective of this study was to evaluate bigleaf lupine, Lupinus polyphyllus Lindl. (Fabaceae), as a secondary food plant for nesting female O. lignaria by investigating nesting activity, pollen-use patterns, and fecundity. During 2002–2003, female O. lignaria collected high proportions of apple pollen (>70%) during mid and late flowering; after then, most pollen (>90%) was collected from bigleaf lupine. The flowering period of lupine in Nova Scotia (late May to early July) slightly overlapped that of apple, so there was no scarcity of pollen resources during the life-span of O. lignaria. Most nests typically showed high levels (≤200%) of population growth, but recorded levels varied among nest types and locations. In 2004, nests closer to lupine plots exhibited significantly greater population recovery than nests located farther away (i.e., approximately 600 m). Bigleaf lupine is a suitable plant species for meeting the pollen requirements of nesting populations of O. lignaria following apple flowering, thus promoting the recovery of populations to meet apple pollination requirements in subsequent seasons.

Larvae of Leptinotarsa decemlineata (Say) reared on tomato fed longer, consumed more foliage, and had a lower survival rate than when reared on potato, its principal host. On both plants, a direct linear relationship was obtained between food consumption and larval growth. Potato was the more efficient of the two plants in terms of food conversion to body matter. This was reflected by increased weight gain of the larvae and greater pupal size.

Adults from larvae reared on tomato were smaller and less fecund than those from larvae reared on potato. Half of them rejected tomato as food. However, egg-laying increased when they were transferred to potato after 50 days. The present investigation indicates that L. decemlineata can survive and attain maturity on tomato in the absence of its principal host plant. However, when potato is once again available, it is able to increase growth, accelerate development, and achieve a greater reproductive potential.

There is a correlation between the amount of blood ingested by Aedes aegypti (L.) and the trypsin activity (but not the chymotrypsin activity) in the midgut 16 and 24 hr after feeding. Puromycin and Dactinomycin ingested with a blood meal depress the level of midgut trypsin. Trypsin purified from the midguts of A. aegypti fed upon defibrinated blood containing 14C-amino acids contains radioactivity. Midguts from blood-fed mosquitoes did not produce significant amounts of trypsin when dissected from mosquitoes and maintained in a tissue culture medium for up to 50 hr.

As of summer 2014, the invasive emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), has become established in 24 states in the United States of America and has killed tens of millions of ash trees since its introduction into Michigan in the 1990s. Considerable research has been conducted on many aspects of EAB life history, natural history, ecology, and management strategies in an attempt to contain this devastating pest. In this article, we review the life history, mating behaviours, and host plant selection by EAB in North America as well as host resistance to EAB attack.

The parasite and predator component of within-tree southern pine beetle, Dendroctonus frontalis Zimmermann, mortality was investigated by mechanically excluding insect parasites and predators from the bark surface of naturally infested shortleaf, Pinus echinata Mill., and loblolly, P. taeda L., pines. Mortality caused by insect parasites and predators was determined by comparisons of five treatments that differed only in the duration of natural enemy exclusion. These natural enemies were responsible for 28.04% and 23.85% of the within-tree beetle mortality in 1978 in Arkansas and in 1979 in Georgia, respectively. Natural enemy species that arrived on the tree during the first week following mass attack by beetles caused the greatest amount of mortality.

Predator density was greater than parasite density at both locations. The majority of the predator complex arrived during the first week following mass attack by beetles, while the parasite complex arrived throughout the entire period of beetle brood development.

A linear response was found between the number of southern pine beetle prey and the number of prey destroyed per predator. A mean (± S.E.) of 4.79 ± 0.64 southern pine beetle immatures were destroyed by each individual predator.

The threshold temperature of development, life table, and innate capacity for increase of the twospotted spider mite, Tetranychus urticae Koch, were established from life stage development studies at constant temperatures. The threshold for development was determined to be 10.0°C. The durations in degree-days above 10°C from the beginning of the egg stage to adult for females were 141.3, 152.3, and 139.8; for males 134.2, 144.7, and 135.2 at 15°, 18°, and 21°C, respectively. Life tables were constructed and innate capacity for increase was .069, .156, and .372; net reproduction rate 20.8, 38.4, and 58.1; and mean generation time 44.0, 23.4, and 10.9 at 15°, 18°, and 21°C, respectively.