Deutonymphs, and male and female adults, of Stygameracarus cooki sp.nov., and a male adult of S. canadensis sp.nov., are described from interstitial habitats associated with small streams in temperate North America. The genus Stygameracarus and the monobasic subfamily Stygameracarinae are proposed and diagnosed, based primarily on the shape of the capitulum and the highly modified structure of the pedipalps in both deutonymphs and adults, and the distinctive structure of the genital field region in adults. Possible relationships between members of the new genus and other Athienemanniidae are discussed, and a new key to the subfamilies of Athienemanniidae is presented.

The Nearctic species of the genus Homaspis Foerster, parasites of various species of sawflies on coniferous and deciduous trees and shrubs, were revised. There are 10 species of which seven were described as new. These were placed in three species groups as follows: the areolatus group including H. areolatus and H. petiolatus spp.nov.; the cristatus group including H. cristatus and H. pectinatus spp.nov.; and the interruptus group, including H. interruptus (Provancher), H. slossonae Cushman, H. brevis sp.nov., H. cephalciae sp.nov., H. albipes Davis, and H. cavatus sp.nov. Relationships of the species groups were discussed.

Ips grandicollis (Eichhoff) was first recorded from Jamaica in 1978 and has become a potential pest in Pinus plantations in the island. Its distribution there is determined by the occurrence of suitable food, but not by altitude or rainfall. Developmental mortality due to predators, parasites, and resin did not limit population numbers within logs: control resulted ultimately from competition among egg-laying females and among larvae for space in suitable logs. However, when the entire Jamaican population was considered, dispersive loss of adults played a major part in the limitation of numbers. A cyclic budget revealed that a minimum of 44% of the population was lost during dispersal. Dispersive loss in the males (77.3%) was higher than that in the females (35.4%), and this difference may be related to the primary role of the males in finding suitable logs.

The family Nudomideopsidae fam.nov. is proposed on the basis of an analysis of morphological characters of larvae and adults of species of Nudomideopsis and related genera, and consideration of the zoogeography of the group. The systematics and distribution of North American species are reviewed, and adults of Nudomideopsis (Allomideopsis) wichitaensis subgen.nov., sp.nov. are described.

Annual spruce budworm, Choristoneura fumiferana (Clemens), survey data were subjected to multiple and logistic regression analyses to examine the relationship between egg mass density in the fall and resultant defoliation the next season. Egg mass density was the most important variable associated with resultant defoliation, followed by current defoliation, regional population trends, host species, and sprays. Together, these accounted for 60% of the variation in resultant defoliation. Balsam fir [Abies balsamea (L.) Miller] suffered greater levels of defoliation than white spruce [Picea glauca (Moench) Voss] at a given egg mass density. Resultant defoliation of balsam fir also showed a steeper response to egg mass density than resultant defoliation of white spruce. Levels of current defoliation increased susceptibility to defoliation in a similar manner between species, as did regional population trends. Sprays were more effective at reducing resultant defoliation on balsam fir than on white spruce but, overall, did not confer a high level of foliage protection. Predictions of resultant defoliation using the multiple regression models had confidence limits averaging 75%, which are too large to be useful for predictive purposes. The logistic regression equations could be used to predict the probability of a stand receiving light or severe defoliation.

The behavioral responses of male spruce budworm moths to a wide range of loadings of synthetic sex pheromone on filter paper and rubber septa were investigated in a wind tunnel. The highest proportion of males flying upwind and reaching filter-paper dispensers occurred at pheromone loadings of between 0.1 and 10 μg. Above these loadings, males were activated but upwind flight was arrested before the moths reached the pheromone source. No such arrestment occurred with rubber septa up to the maximum loading assayed, 1 mg. Up to 72% of the males that reached a septum attempted to copulate with it, but even this response was less than that to a septum in the presence of pheromone emitted by females. This confirms previous conclusions that the synthetic pheromone blend used here, 95:5 (E:Z-11-tetradecenal) is incomplete.

Reproductive and survival patterns of the heteropteran predator Podisus maculiventris (Say) (Heteroptera: Pentatomidae) were measured under low prey inputs. A single prey, mealworm larva (Tenebrio molitor L.), of one of two sizes (120 or 30 mg), was given to predators for a 24-h period every 1, 2, 4, 8, or 16 days. Additional treatments included: predators provided prey in excess of attack rates; predators given no food; and predators given green bean slices only. Results showed that predators provided with prey survived regardless of feeding interval. When given large prey, predators showed reproductive patterns that were not clearly reflective of feeding interval; only predators fed at 8- and 16-day intervals showed reduced fecundity. When given small prey, the reproductive patterns of predators clearly reflected the feeding intervals. Predators that were fed less frequently laid fewer eggs, less often, and later in life.

Body weights were measured for Podisus maculiventris (Say) (Heteroptera: Pentatomidae) given low prey inputs. Predators were fed green bean slices ad lib and a single mealworm larva (Tenebrio molitor L.) of one of two size classes, for a 24-h period every 1, 2, 4, 8, or 16 days. Other treatments included predators fed to excess of daily attacks, predators given only green bean slices, and predators given no food. Results showed that predators fed bean slices maintained body weight after an initial decline, whereas predators given no food lost weight continually until death. Predators maintained weight when fed prey ad lib, and when fed prey of either size daily. Those fed at longer intervals lost weight between feedings, and weight fluctuations increased as the interfeeding interval increased. Slopes of weight change between feedings did not differ significantly for predators fed at 2- through 16-day intervals. During oviposition, predators lost about 15 mg of body weight. Egg clutches comprised about 60% of the weight lost. Egg weights did not differ among treatments. The results suggest that P. maculiventris can survive long periods without prey, and adjusts its weight loss by reducing reproductive effort when prey become scarce. The importance of these adaptations for P. maculiventris to sustain populations in agricultural systems is discussed.

The structure, distribution, and type of sensory hairs on the palptarsus of female Varroa jacobsoni Oudemans were examined by scanning electron and phase contrast microscopy. The two large, peg-like setae with apical pores are chemoreceptor sensilla chaetica. The seven slender, round tipped setae, stained with crystal violet at the hair cuticle, are considered to be the chemoreceptor sensilla trichodea. A number of long hairs that did not stain with crystal violet are trichoid tactile setae. The possible functions of these sensilla were discussed.

The responses of Ips latidens (LeConte) to multiple-funnel traps baited with various monoterpenes were determined in stands of lodgepole pine in British Columbia. β-Phellandrene was attractive to I. latidens in the absence of the pheromone ipsenol. β-Phellandrene increased the attraction of I. latidens to ipsenol-baited traps while α-pinene, 3-carene, terpinolene, and myrcene reduced trap catches. Differential responses by males and females to sources of ipsenol with or without β-phellandrene suggest that the information conveyed to males differs from that conveyed to females. Species-specific responses to monoterpenes by I. latidens and three sympatric species of scolytids suggest that unique combinations of kairomones could be important in facilitating matings with conspecifics. Pheromones need not be the sole constituent of species-specific chemical messages.

Nine entomopathogenic nematode–bacteria complexes were screened for their virulence against larvae of six noctuids, a geometrid, and a pyralid. Ninety-six-hour LD50’s of steinernematids (and heterorhabditids) ranged from 1 to 3 (1–8) infective juveniles in Galleria mellonella (L.), 1–71 (2) in Peridroma soucia (Hbn.), 1–10 (1–3) in Mamestra configurata (Wlk.), 1–28 (3–7) in Euxoa ochrogaster (Gn.), 19 in Lacanobia radix (Wlk.), 22–60 (4) in Pseudaletia unipuncta (Haw.), 2–95 (111) in Agrotis ipsilon (Hufn.), and 3–28 in Paleacrita vernata (Peck). The nematode, Steinernema feltiae LIC, a cold-hardy strain isolated in Newfoundland, was highly virulent for G. mellonella and M. configurata, but not for P. soucia and E. ochrogaster. The number of nematodes invading larvae and the number produced were greater in G. mellonella than in other insects tested. Nematode–bacteria complexes that showed potential for controlling cutworms included S. feltiae, S. glaseri, S. bibionis, Heterorhabditis bacteriophora, and H. heliothidis.

Although the role of phytoseiid mites as predators of the European red mite, Panonychus ulmi (Koch), on apple is well established, the role of another family of European red mite predators, the stigmaeids, is not as clearly understood. We compared predatory behavior and prey-stage preferences of the stigmaeid Zetzellia mali (Ewing) and the phytoseiid Typhlodromus caudiglans (Schuster) in the laboratory. The only predator–predator interaction we found to be potentially important was consumption of phytoseiid eggs by stigmaeids. Given a choice of equal numbers of both European red mite eggs and phytoseiid eggs, Z. mali consumed 38% phytoseiid eggs. Eggs and quiescent larval stages of European red mite were preferred by Z. mali, but active larval stages also were consumed. By contrast T. caudiglans preferred active forms to quiescent forms and eggs, and was able to consume adult forms. Although Z. mali was found to be slower, less active, and less voracious than T. caudiglans, Z. mali produced more eggs for a given number of prey consumed than did T. caudiglans. These behavioral and prey-stage preference differences should enable phytoseiids and stigmaeids to be compatible in the short term (within one generation).

Relationships between temperature and development rates of eggs and larvae of Winthemia fumiferanae Toth. were experimentally determined, using the spruce budworm as host. Hatching of parasitoid eggs was triggered by host pupation. The median time required to complete egg development at different temperatures was estimated from distributions of percentage development success of the parasitoid over time between egg deposition and host pupation. For parasitoid eggs that had sufficient time to hatch, detachment from the host before pupation was the most important cause of mortality at 15 °C or higher, but was negligible below this temperature. A curvilinear model describing egg development rate as a function of temperature was used to simulate the development of W. fumiferanae eggs in the field. The relationship between larval development rate and temperature also was modelled, and the variability described. Simulations initiated by host pupation-driven egg hatching, and terminated with prepupal drop to the ground, are presented and discussed with respect to the appropriateness of using host pupation as an indicator of parasitoid egg hatching in the field.

Incidence of the western pine shoot borer, Eucosma sonomana Kearfott, and tree growth measurements from 5687 ponderosa pines, Pinus ponderosa Dougl. ex Laws., were recorded in the Calf Pen plantation Payette National Forest, ID. The percentage of trees infested by shoot borer generally increased as tree height increased.

Infestation of the tree’s leader usually resulted in reduced height growth especially where needle length was shortened in the leader. Height growth of infested leaders was less than uninfested leaders. This difference in height growth increased with the total height of the tree as measured in the previous year.

The solitary aphid parasitoid Ephedrus californicus Baker is able to discriminate between unparasitized and parasitized third-instar nymphs of the pea aphid, Acyrthosiphon pisum (Harris). Superparasitism varied with the number of mature eggs (which is age-dependent) present in the ovaries as well as with the number and the quality of any hosts encountered. Conspecific superparasitism varied with wasp age; older females, with a large egg supply, accepted hosts parasitized by a conspecific female if unparasitized aphids were unavailable. Self superparasitism occurred at all ages; it was the least likely behaviour compared with egg deposition in unparasitized and conspecific-parasitized hosts. Prior experience (learning) was not necessary for host discrimination, but it did influence the search rate, which was higher in inexperienced than experienced females. In choice experiments, wasps preferred conspecific- over self-parasitized aphids and thus were able to distinguish between them. It is suggested that oviposition markers vary among conspecific females. The data are discussed with reference to theories about oviposition decisions and progeny allocation in solitary hymenopteran parasitoids.

Females of the solitary parasitoid Aphelinus asychis Walker discriminated between unparasitized and parasitized second-instar nymphs of the pea aphid, Acyrthosiphon pisum (Harris). Wasps normally avoided superparasitism, except when they were confined with few hosts for a long time. Parasitoid females did not need previous experience with unparasitized aphids (learning) in order to discriminate. They probed with the ovipositor any aphids encountered, a behaviour suggesting that host acceptance and rejection were determined by internal cues. Prolonged ovipositor insertion (>80 s) was correlated with host acceptance and egg deposition, but short insertion times (≤80 s) generally indicated host rejection. Females tended to reject both self- and conspecific-parasitized aphids when provided with two of each kind. We consider hypotheses mat conspecific superparasitism may be adaptive and give examples to show exceptions. We propose that, in egg-limited parasitoid species such as A. asychis, a reproductive strategy based on the regulation of egg production and on oosorption can explain the equal avoidance of self and conspecific superparasitism.

A two by two factorial experiment in a randomized complete block design tested single and combined effects of tree felling and semiochemical baiting on the attractiveness of spruce (Picea spp.) trees treated with monosodium methanearsenate (MSMA) to Dendroctonus rufipennis (Kirby) in British Columbia and Alaska. In British Columbia, tree felling and semiochemical baiting had significant effects on attack density, but in Alaska only tree felling had a significant effect. Semiochemical baiting had a significant effect on within-tree attack distribution in British Columbia but cot in Alaska, regardless of the felling treatment. The felled treatment captured more beetles than the not-felled treatment regardless of the baiting treatment in British Columbia, but only in the absence of a semiochemical bait in Alaska. The differences between the two locations may have been caused by lower temperatures and beetle population density in Alaska. Effective spruce beetle management with MSMA-treated trees requires tree felling, and beetle capture can be improved with the use of a semiochemical bait.

The immature stages of Panzeria ampelus (Walker) are described and illustrated.

The sunflower stem weevil, Cylindrocopturus adspersus (LeConte), infests wild and cultivated sunflowers in Colorado, Texas, North Dakota, South Dakota, and Minnesota (Schulz 1978; Charlet 1983). It was first observed in Saskatchewan in a sunflower test plot near Carnduff, in August 1984 (unpublished data). Its abundance and distribution in the major Saskatchewan sunflower growing area, in the Carnduff, Estevan, and Weyburn areas, had not previously been studied.