Laricobius nigrinus Fender is being reared for release as a biological control agent for hemlock woolly adelgid (HWA), Adelges tsugae Annand. HWA is an introduced insect lethal to hemlock trees (Tsuga canadensis (L.) Carr. and T. caroliniana Engelm.) in the eastern United States. In nature, the predator (Laricobius nigrinus) and its prey (HWA) undergo a dormant period in the summer (aestivation). In the laboratory, the aestivation of L. nigrinus has not been synchronized with that of HWA, resulting in significant predator mortality. Four factors (genetics, temperature, photoperiod, and moisture) were investigated for their effects on aestivation in L. nigrinus. Both the number of individuals and the time at which they emerged from aestivation were measured in response to these factors. Temperature was the most important cue for termination of aestivation, and photoperiod was a modifying factor. High temperature and long day length delayed emergence and high moisture levels resulted in greater emergence but did not affect emergence time. Genetics, as represented by broods, was not a major factor in aestivation termination. These results have led to improvement in rearing L. nigrinus, since emergence from aestivation can now be synchronized with the active period of HWA. Increased success in rearing has expedited field releases of L. nigrinus in the eastern United States.

A field study was carried out to determine the intracrown distribution of the balsam fir sawfly, Neodiprion abietis Harris (Hymenoptera: Diprionidae), throughout the season on balsam fir, Abies balsamea L. (Pinaceae), during the first 2 years of an outbreak in western Newfoundland. Eggs were usually laid one per needle on current-year shoots, and the following year, newly emerged larvae usually initiated feeding on the same shoots. Balsam fir sawfly larvae were gregarious on needle and shoot levels in the early instars but gradually became solitary as larvae developed. The process of becoming solitary was not due to the increased physical area required for the growing larvae as some older individuals, in mainly solitary stages, were seen feeding together. Unlike the continuous change from gregarious to solitary at the needle and shoot levels, the seasonal variation in larval density among whorls varied in an inconsistent manner. The majority of early-instar larvae were found in the middle crown, but on at least one date in both years the majority of late instars were in the lower crown. Seventy-five percent of crawling larvae trapped within the crown were third and fourth instars, suggesting that changes in the intra-tree distribution are due to larval movement.

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.

There have been few quantitative studies on the role of woodpeckers in control of insect pests. Hutchison (1951) and Wygant (1958) pointed out the importance of these predators in reducing outbreaks of the Engelmann spruce beetle and Knight (1958) established a means of assessing the value of woodpeckers by correlating their activity with beetle survival but made no attempt to measure the numbers of woodpeckers in an area.

The angiosperm bark volatile, conophthorin, was tested at release rates of 3.0 and 0.3 mg/24 h against the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, the spruce beetle, Dendroctonus rufipennis (Kirby), the pine engraver, Ips pint (Say), and the western balsam bark beetle, Dryocoetes confusus Swaine (all Coleoptera: Scolytidae). The responses of D. pseudotsugae, I. pini, and (in one of two experiments) female D. confusus to attractant-baited traps were disrupted by conophthorin in a dose-dependent manner. Dendroctonus rufipennis was not disrupted by conophthorin. Our results extend the repellent bioactivity of conophthorin to Ips DeGeer spp. and confirm earlier experiments with D. pseudotsugae. Conophthorin may have some utility in protecting susceptible timber from bark beetle attack.

The concept of degree-day summation was employed in three models of malthusian growth predictive over a range of temperatures. When supplied input data from life table studies conducted at five constant temperatures, the models were able to predict the magnitude and pattern of growth of populations of Tribolium confusum Duval reared under malthusian conditions. The stochastic model, moreover, revealed that the series of chance events found in the course of population growth could explain differences between one population and the next. When computer experiments on the importance of various life table parameters were run, the models revealed the overwhelming importance of time taken to mature on the rate of population growth. The level of fecundity was next in order of importance while population growth was least sensitive to changes in survivorship.

Five controlled-release granular formulations were developed that eluted 3-methyl-2-cyclohexen-1-one (MCH) in the laboratory at a rate ≥ 0.5µg/h for 60 days. Elution rate was determined by trapping gaseous radioactive MCH followed by scintillation counting. The inert components of these formulations consisted either of a wax-coated molecular sieve, polyethylene emulsion-coated ground corncob, or dimer acid polyamide beads. These formulations and a liquid standard were applied 9 May just prior to Douglas-fir beetle (Dendroctonus pseudotsugae Hopk.) flight to plots containing single, freshly felled Douglas-fir (Pseudotsuga menziesii var. glauca) trees. Three months later, infestation by Douglas-fir beetle and other insects was evaluated. All treatments except coated corncobs and certain applications of the molecular sieve significantly reduced Douglas-fir beetle attacks. Douglas-fir beetle brood in three treatments was significantly less than in controls. Abundance of entomophagous insects was proportional to density of host beetle attacks. Douglas-fir beetle attack density was negatively correlated with degree of infestation by the scolytid Pseudohylesinus nebulosus (Lee).

Wild bee pollinators were collected in tree-fruit orchards and uncultivated habitats in the Okanagan Valley. Higher abundance and diversity of wild bee pollinators were found at uncultivated sites than on tree-fruit crops. Wild bees were not abundant enough in orchard habitats to provide adequate tree-fruit pollination. Variable flower visitation patterns by polylectic bees in orchard and uncultivated habitats make it difficult to predict floral visitation patterns. Therefore, orchardists cannot rely on a substantial and predictable contribution to pollination of fruit crops by wild bee species. Research into the use of wild bees as managed pollinators for tree-fruit crops in the Okanagan Valley may have potential. Future studies should consider three wild bee species collected in Okanagan Valley orchards, Bombus terricola occidentalis Greene, Bombus bifarius nearcticus Handlirsch, and Osmia lignaria propinqua Cresson, for pollination management.

Conspecific host discrimination and larval competition in two aphid parasitoid species were studied in the laboratory using the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae), as a host. Aphidius ervi Haliday (Hymenoptera: Aphidiidae) used internal host cues to discriminate between unparasitized and conspecific parasitized hosts. When only parasitized hosts were available, females oviposited into recently parasitized ones where their progeny had a good chance to survive, but rejected those parasitized ≥24 h earlier where their offspring normally died. Competitions occurred only after both eggs had hatched. Larvae eliminated supernumeraries by means of physical combat and physiological suppression. In Aphelinus asychis Walker (Hymenoptera: Aphelinidae), factors, or changes in host internal condition, associated with hatching of the first egg resulted in suppression of conspecific competitors which could be in either larval or egg stage. The older larvae always won competitions through physiological means. A wasp’s oviposition decision is shown to be influenced by the probability of its progeny’s survival. Species that have different reproductive strategies may respond differently to identical host conditions.

The effect of interplanting collards with a mixture of herbs on oviposition of the imported cabbageworm, Pieris rapae (L.), was investigated at Chesterfield Co., Virginia during 1981 and 1982. Analysis of the dispersion indices of the insect using Taylor's power law and Iwao's model revealed that P. rapae eggs were significantly — m (P < 0.001) clumped (b > 1) on collards interplanted with herbs. However, insect counts on control collards conformed to the Poisson distribution (b = 1, P > 0.05). Pieris rapae laid significantly (P < 0.01) more eggs on collards hidden between sage than on collards hidden between other companion plants. Also, P. rapae laid significantly (P < 0.005) more eggs on collards bordered by companion plants than on non-bordered control. These data suggest that companion herbs did not repel P. rapae but instead significantly encouraged colonization of the insect and produced an aggregated distribution.

Southern pine beetles (Dendroctonus frontalis) carrying phoretic Trichouropoda australis deutonymphs were caught in bucket traps baited with frontalin-alpha pinene at heights of 3, 6, and 9 m on the boles of loblolly pines. Of 8475 beetles collected, 36.3% carried uropodids or their pedicels. Beetles trapped at 3 m carried more pedicels than those trapped at 6 or 9 m, indicating that the flight of beetles is influenced by the presence of phoretic mites. Re-emerging parent beetles can be differentiated from brood adults by the color of the mite pedicels.

In the 1960s, the prediction that synthetic juvenile hormones (JHs) and their analogs would form the basis of a new generation of insecticides with enhanced target specificity greatly stimulated research on this hormone. Although JH-based insecticides were found to be effective against certain groups of insect pests, their shortcomings soon became apparent; however, current JH research provides new opportunities and ideas for the development of innovative integrated pest management (IPM) tools and strategies aimed at disrupting JH functions. Interfering with JH endocrinology requires that we either artificially increase JH titers at stages of development when titers are normally low or artificially reduce JH titers at stages of development when titers are normally high. Our discussion is organized around these two conceptual approaches and covers such areas as (i) the isolation and cloning of JH receptors; (ii) the characterization of polydnavirus and entomopoxvirus gene products responsible for the inhibition of host metamorphosis; (iii) the isolation and molecular cloning of allatostatins and the design of allatostatic pseudopeptides; (iv) the characterization of JH biosynthetic enzymes specific to the Lepidoptera; (v) the characterization of regulatory material originating from parasitic wasps of the genus Chelonus Panzer (Hymenoptera: Braconidae), which induce precocious metamorphosis in their hosts; (vi) a tree resistance mechanism involving anti-JH effects resulting in the failure of female insects to produce and lay eggs; and (vii) the cloning of JH esterase and epoxide hydrolase cDNAs and the production of recombinant baculoviruses that overexpress these JH-degradative enzymes.

Residue analysis of apple foliage obtained from an orchard treated with the insecticides cypermethrin, fenvalerate, deltamethrin, permethrin, and azinphos-methyl revealed detectable residues on the leaves 8–9 weeks after the last treatment. Laboratory studies of foliage showed that of the synthetic pyrethroids, permethrin was initially as toxic as the other synthetic pyrethroids; however, its toxicity decreased considerably by the 5th and 6th week post-treatment. Azinphos-methyl was the least persistent and toxic insecticide evaluated. Unless new pest-management strategies are developed, the use of synthetic pyrethroids post-bloom in an integrated-pest-management program would not be desirable where Amblyseius fallacis (Garman) is the principal predator of phytophagous mites.

Sixteen species of parasitoids were found attacking outbreak and collapsing populations of the jack pine budworm, Choristoneura pinus pinus Free. (Lepidoptera: Tortricidae), in several plots in northeastern and northwestern Ontario. The patterns of parasitism were similar among widely separated plots with only a few species consistently dominating the parasitoid fauna. The greatest difference in the pattern of parasitism was between sustained and collapsing infestations. Collapsing populations of jack pine bud-worm were associated with relatively high levels of parasitism by Meteorus trachynotus Vier. (Hymenoptera: Braconidae) and Lypha setifacies (West.) (Diptera: Tachinidae) which attacked the late larval stages of the budworm. The results are discussed in comparison with other jack pine budworm studies and with spruce budworm population studies.

The Engelmann spruce weevil, Pissodes engelmanni Hopkins, is an indigenous pest of spruce regeneration in western Canada and the adjacent United States. It is univoltine, overwintering as an adult in the duff beneath the host trees. Eggs are deposited in feeding punctures in the terminal leader. Larvae feed downward in the phloem causing two or more years loss of height growth. Deformities incurred by three or more consecutive years of weevil attacks produce a tree of no commercial value. The incidence of weevilling is most numerous in open grown, even-aged, young stands. Of 14 insect parasites and one predator, Dolichomitus terebrans nubilipennis (Viereck), Eurytoma pissodis Girault and Lonchaea corticis Taylor are considered principal natural control agents.

In recent years there have been marked increases in populations of a pine weevil, Pissodes approximatus Hopk., in southern Ontario, especially in areas where pine trees, particularly Scots pine, Pinus sylvestris L., are grown in pure stands for the Christmas tree market. In several such areas where large weevil populations have built up in the stumps of the previous year's cutting, damage to remaining trees by adults feeding on the twigs and small branches has been heavy. Not only has the quality and value of the trees been reduced by this damage, but in some instances the trees have been killed (5).

Cytoplasmic polyhedrosis viruses are, in general, more infectious to spruce budworm, Choristoneura fumiferana (Clemens), and forest tent caterpillar, Malacosoma disstria (Hübner), than the nuclear polyhedrosis viruses which affect these insects. The cytoplasmic polyhedrosis viruses interfere with and retard development of the nuclear polyhedrosis viruses.Larvae of both insects, as they grow older, develop resistance to both viruses. Resistance develops more rapidly and to a greater degree against the nuclear polyhedrosis than against the cytoplasmic polyhedrosis viruses.The nuclear polyhedrosis viruses are more lethal than the cytoplasmic polyhedrosis viruses, and all larvae infected with the nuclear polyhedrosis viruses die except those infected so late in larval development that they are able to pupate. Most young larvae infected with the cytoplasmic polyhedrosis virus die or are seriously affected, but infection has progressively less effect as the larvae mature.

Methods are presented for sampling and constructing life tables for Scolytus ventralis LeConte with the objective of comparing the histories of populations inhabiting individual trees. A bark area of 72 sq. in. was an effective sample unit. Within-tree variation was minimized by taking two sample units from two vertical strata at each sampling date. Trees were serially sampled several times during development of the insect.

Population tables were constructed for each sampling date and life tables were developed from the complete series of population tables. The precision of the life table estimates varied between 10% and 40% of the mean and generally decreased as population density diminished during development. A sampling design is presented for increasing the precision of life tables, and methods are given for determining the number of trees required for estimating the mean density when studying populations occupying large areas.

The embryonic development of the bertha armyworm is traced from the time of oviposition until blastokinesis. The following are described: the egg; fertilization and cleavage; formation of blastoderm, serosa, and amnion; the germ band; formation and differentiation of the lower layer; germ layers and derivatives; blastokinesis.

Fourteen species of parasitoids (13 hymenopterans, 1 dipteran) were reared from larvae or pupae of the obliquebanded leafroller, Choristoneura rosaceana (Harris), collected from commercial raspberry fields in the Fraser Valley, British Columbia, Canada, over 3 years. Levels of parasitism ranged from 5 to 15%. Among these 14 species, five represent new host records. A polyembryonic wasp, Macrocentrus nigridorsis Viereck (Hymenoptera: Braconidae), was the most abundant parasitoid. External feeding on the final host instar is obligatory for M. nigridorsis to complete development. On average, each parasitized host larva produced about 36 M. nigridorsis, in either unisexual or mixed-gender groups. Overall male to female sex ratio was 1:4. Head capsules of mature parasitized host larvae were significantly larger than those of unparasitized ones, suggesting that C. rosaceana larvae parasitized by M. nigridorsis might have an extra larval stage.