A fossil mayfly nymph Caenoephemera shangyuanensis, gen.nov., sp.nov., discovered in the lower part of the Upper Jurassic – Lower Cretaceous Yixian Formation of Jianshangou, Beipiao district, West Liaoning, China, is described. It has several archaic features typical of Paleozoic mayfly nymphs, such as 5 tarsal segments and hind wing pads not covered by fore wing pads, but also exhibits specialized modern features, such as a short metathorax, abdominal tracheal gills, and cerci. It appears to be intermediate in structure between Paleozoic and extant mayfly nymphs.

Three new species of oribatid mites in two genera of Mycobatidae are recorded from canopy habitats of coniferous temperate rainforest and montane forest in the Pacific Northwest of North America. These species, Mycobates acuspidatussp.nov., M. corticeussp.nov., and Zachvatkinibates epiphytossp.nov., are described on the basis of adults and immatures. The previous key for adult Mycobates species of America north of Mexico is modified to include these new species, and a key for adults is given for the three species of Zachvatkinibates now known from North America.

The genus Holocephalus Hope is revised and now contains five species: H. cristatus (Gillet), H. eridanus (Olivier), H. julienisp.nov., H. sculptus (Gillet), and H. simonisp.nov. All taxa are described and illustrated. A key to species of Holocephalus is included. Lectotypes are designated for H. eridanus and H. sculptus. Scarabaeus eridanus Olivier is designated as the type species for the generic name Atrichius Gillet (a junior synonym of Holocephalus).

We evaluated the resistance to tracheal mites, Acarapis woodi (Rennie) (Acari: Tarsonemidae), of colonies of honey bees, Apis mellifera L. (Hymenoptera: Apidae), headed by daughters of three queens from each of three honey bee stocks: (i) British Columbia "mite-resistant stock, (ii) Buckfast "mite-resistant" stock, and (iii) Canadian unselected stock. Colonies of all nine families were distributed among four apiaries; half of the colonies in each apiary were treated with formic acid to attempt to control tracheal mites. The study documented significant differences in resistance to tracheal mites among the families of bees, even within each of the three stocks. After the first 4 months of study (by November 1993), differences in mite infestations had developed among the nine families. Formic acid treatments had either short-lived effectiveness (1993) or no effect (1994) on tracheal mite infestations, thereby eliminating the opportunity to evaluate colony performance in the absence of mites. Mite infestations varied significantly among apiary sites. This study highlights the value of evaluating sets of colonies headed by sister queens when identifying mite-resistant stock for breeding purposes.

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.

We assessed the effects of microencapsulation on the toxicity of chlorpyrifos, cypermethrin, and lambda-cyhalothrin to larvae of the Oriental fruit moth, Grapholita molesta (Busck), in the laboratory and the field. We also compared the toxicity of microencapsulated and traditional formulations to pyrethroid-susceptible and pyrethroid-resistant populations of the predaceous mite Typhlodromus pyri Scheuten in the laboratory. In laboratory bioassays with neonate larvae of G. molesta, the microencapsulated formulations of chlorpyrifos and cypermethrin were less toxic than the wettable-powder and emulsifiable-concentrate formulations. The emulsifiable-concentrate and microencapsulated formulations of lambda-cyhalothrin were equally toxic. In the field, all trees in insecticide-treated plots contained less damage by first generation G. molesta larvae than unsprayed controls. In the second generation, the microencapsulated formulations of cypermethrin and chlorpyrifos were generally less effective than the emulsifiable-concentrate formulation of cypermethrin. The microencapsulated formulation of lambda-cyhalothrin was as effective as the emulsifiable-concentrate formulation. The microencapsulated formulation of cypermethrin was less toxic than the emulsifiable-concentrate formulation to both pyrethroid-susceptible and pyrethroid-resistant populations of T. pyri. Both populations were highly resistant to chlorpyrifos and unaffected by either formulation. The microencapsulated formulation of lambda-cyhalothrin affected the two populations of T. pyri differently; the microencapsulated formulation was approximately fivefold more toxic than the emulsifiable-concentrate formulation to the pyrethroid-susceptible population, but sixfold less toxic than the emulsifiable-concentrate formulation to the pyrethroid-resistant population. Much of the selectivity reported for the microencapsulated formulations of cypermethrin and chlorpyrifos appeared related to a general reduction in toxicity to both target insects and beneficial mites. The microencapsulated lambda-cyhalothrin was as toxic as the emulsifiable-concentrate formulation to the target insect but was less toxic than the emulsifiable concentrate to pyrethroid-resistant predator mites. This limited increased selectivity may be useful where resistant populations of predators occur.

The spruce beetle, Dendroctonus rufipennis (Kirby), has possible life cycles of 1 or 2 years. Empirical and experimental evidence suggest that temperature is the primary regulator of these life-history pathways. These different life cycles potentially result in substantial differences in population dynamics and subsequent spruce mortality. A multiyear field study was conducted in Utah, Colorado, and Alaska, to monitor spruce beetle development under a variety of field conditions with concurrent air temperature measurements. This information was used to model the tree- or stand-level proportion of univoltine beetles as a function of air temperature. Temperatures were summarized as averages, cumulative time, and accumulated heat units above specified thresholds over various seasonal intervals. Sampled proportions of univoltine insects were regressed against the summarized temperature values in logistic models. The best predictive variable, as evaluated by Akaike’s Information Criterion, was found to be cumulative hours above a threshold of 17 °C elapsed from 40 to 90 days following peak adult funnel-trap captures. Because the model can be used to forecast trends in spruce beetle populations and associated spruce mortality, it is a tool for forest planning.

The objectives of this study were to determine whether the spatial distribution of Melanoplus sanguinipes F., the most abundant species of grasshopper on rangeland in southern Idaho, varied annually in response to changing patterns of grazing and to investigate how vegetation affects the spatial distribution of low-density populations of M. sanguinipes at scales relevant to most rangeland-management activities. A lattice of 72 sites was established across nine pastures, covering approximately 5000 ha. At each site, densities of M. sanguinipes, percent canopy coverage by plant species, and percent forage utilization by livestock were estimated twice per year, in June when M. sanguinipes was in the nymphal stage and in August during the adult stage, for 4 years, 1991–1994. Spatial analyses of variance were used to evaluate the influence of grazing and vegetation type on densities of M. sanguinipes. In August of each year, densities of M. sanguinipes were lower on heavily grazed sites than on lightly grazed sites, except in 1993, when the opposite trend was observed. Above-normal precipitation in 1993 resulted in abundant growth of annual forbs and regrowth of grazed plants. The distribution of nymphs in June of 1993 and 1994 reflected the grazing patterns of the previous summer. Densities of M. sanguinipes were lower on crested wheatgrass habitats than on annual grasslands for every sampling period from June 1991 to June 1993, after which no differences were observed. We interpret the results to suggest that grazing effects on low-density populations of M. sanguinipes were contingent on weather conditions; under dry conditions, grazed habitats were less favorable to M. sanguinipes but, during relatively cool wet summers, grazing created conditions that were more favorable to M. sanguinipes.

Low seed set is a serious problem in seed orchards of lodgepole pine (Pinus contorta var. latifolia Engelmann) in the southern interior of British Columbia. We tested the hypothesis that Leptoglossus occidentalis Heidemann is responsible for the low seed set. Cones enclosed in insect exclusion bags as part of a pollination experiment produced significantly more filled seeds per cone than cones that were not bagged. In a separate bagging experiment, cones that were enclosed with a L. occidentalis female and her progeny produced only about one filled seed per cone, compared with about 28 seeds in bagged control cones. Changes in microclimate associated with the use of bags did not appear to be responsible for the observed increase in seed set in bagged cones. Leptoglossus occidentalis was also excluded from trees using the insecticide fenvalerate. Cones on fenvalerate-treated trees produced > 11 filled seeds per cone, whereas water-treated (control) cones produced < 1.7 filled seeds. These data suggest that L. occidentalis should be considered a serious pest in lodgepole pine seed orchards.

The pheromone communication systems of azinphosmethyl-susceptible (susceptible) and azinphosmethyl-resistant (resistant) obliquebanded leafrollers, Choristoneura rosaceana (Harris), from the Niagara Peninsula of Ontario, were compared in the laboratory and field. The pheromone glands of resistant females contained approximately one-half as much (Z)-11-tetradecenyl acetate (Z11-14:Ac), (Z)-11-tetradecenol (Z11-14:OH), and (Z)-11-tetradecenal (Z11-14:Al) as the glands of susceptible females. A similar amount of (E)-11-tetradecenyl acetate (E11-14:Ac) was found in the glands of the two types of females. The pheromone effluvium from resistant females contained approximately one-half as much Z11-14:Ac, E11-14:Ac, Z11-14:OH, and Z11-14:Al as the effluvium from susceptible females. The onset and duration of female calling and the effect of age on calling were similar in susceptible and resistant C. rosaceana. In an apple orchard, traps baited with resistant females captured approximately one-half as many marked and released susceptible and resistant males as traps baited with susceptible females. There was no difference in the response of antennae from susceptible and resistant males to synthetic Z11-14:Ac and E11-14:Ac. The antennae of resistant males were less sensitive to Z11-14:OH and Z11-14:Al than the antennae of susceptible males. In a flight tunnel, pheromone-gland extracts from susceptible and resistant females, and calling susceptible and resistant females, were equally attractive to both susceptible and resistant males. In an apple orchard, the rate of capture of marked and released susceptible males was greater than that of resistant males in traps baited with susceptible females, but not in traps baited with resistant females or in traps baited with synthetic pheromone. The reduced ability to locate virgin females suggests that the presence of resistant males in an apple orchard may result in a reduction in the capture of moths in pheromone-baited traps. The reduction in trap catch was likely not caused by resistant females because they were less attractive to males than susceptible females and would therefore, in theory, compete less with traps for males than susceptible females. The differences observed in the pheromone communication systems of susceptible and resistant C. rosaceana are likely pleotropic effects associated with the selection for insecticide resistance.

Activity of bumble bees, Bombus impatiens Cresson, was examined in commercial tomato, Lycopersicon esculentum Mill. (Solanaceae), greenhouses in relation to greenhouse covering type, solar radiation, greenhouse temperature and humidity. Bumble bee activity was measured by photodiode monitors inserted into the entrance of the colonies. Colony sizes were monitored as an indicator of bee loss through gutter ventilation systems in relation to covering. Activity monitors were found to be a good predictor of actual bumble bee entrances and exits (r2 = 0.85). Bumble bee activity was 94.0% greater under the ultravioltet (UV)-transmitting covering than under ones that transmitted less UV light. No relationship was found between bee activity and the amount of solar radiation or internal greenhouse humidity. Bee activity was weakly positively correlated with internal greenhouse temperature (r2 = 0.18). Bee activity was not different during three periods of the day: morning, midday, and evening. The mean ± SE colony size under the UV-transmitting covering was 86.0 ± 2 bees per colony after 10 days within the greenhouses, compared with 36.4 ± 5.8 bees per colony under the other three types of covering. Our results suggest that bee activity is greatest and bee loss through gutter ventilation systems lowest in greenhouses made with coverings that transmit high levels of UV light.

In volume 133, issue 5, the first line on p 722, the duration was from “egg to adult” and not “egg hatch to adult”. In context, it shoud read: Duration from egg to adult was 217.1 ± 0.1°d above 11.6°C.