A method of assessing susceptibility of white fir, Abies concolor (Gord. and Glend.) Lindl., by fungal inoculation was tested during an outbreak of the fir engraver beetle, Scolytus ventralis LeC., at Lake Tahoe, California, in 1987 through 1989. A total of 592 firs growing in six forest stands containing trees infested by the beetle were inoculated with the mutualistic fungus, Trichosporium symbioticum Wright. Six weeks later, reaction wounds were characterized by vertical length and resin concentration. After 2 years, 196 (33.1%) of the test firs had been killed by the beetle. Reaction lengths tended to be greater and resin concentrations lower in test firs that died than in those that survived, but predictive accuracy of the wound variables was inadequate on either an individual tree or a stand basis. On an individual tree basis, discriminant functions using either or both of these reaction wound variables as predictors produced overall percentages of correct classification little higher than would be obtained by predicting that all test firs would survive. On a stand basis, regression models using stand means for the wound variables and white fir basal area as predictors statistically explained more than 95% of observed variation in basal area of white fir killed, but another model using only basal area of white fir as a predictor performed nearly as well.

Laboratory observations on the biology of Ceranthia samarensis (Villeneuve), a tachinid parasitoid of the gypsy moth, were carried out in the laboratory at 22 °C day/15 °C night, 85–90% RH, and a 12L:12D photoperiod. Older (5–6 days post-eclosion) males mated readily with newly emerged females. Mating success was 60%. The gestation period of the mated females was 10–12 days. Laboratory-reared (on diet) second- and third-instar gypsy moth larvae feeding on newly grown foliage of Quercus rubra L. were exposed to gravid females of the parasitoid. Ceranthia samarensis ovolarviposited on the body of the host. The first-instar larva penetrated the host cuticle and developed internally, forming a respiratory funnel that caused a dark circular scar on the lateral side of the caterpillar. The average number of progeny (puparia) produced over the lifetime of a C. samarensis female was 55.0 ± 5.0 (SE) and average longevity was 4.1 ± 1.7 (SE) days. Diapause of the puparia was facultative and induced by temperatures below 20 °C combined with a 12L:12D photoperiod. In nondiapause individuals, total generation time was 22–40 days. To obtain diapause insects, puparia were stored for2monthsat 15 °C, 100% RH, and 12L:12D photoperiod for development of pharate adults. Cold storage at 2–4 °C and 100% RH for at least 5 months was required to obtain up to 75% eclosion after 5–9 days the following year.

The need to exploit new sources of energy has recently led France to encourage several research programs toward the cultivation of crops for biomass production to extract alcohol, glucides, and chips for burning. To produce large quantities of biomass rapidly, several species of Populus have been selectively tested in short rotation coppices on about 400 ha in several parts of the country.

Among the practical consequences of this policy, one appears to be harmful, namely the spatial extension of several pests, mainly leaf eaters or polyphagous insects. These insects previously were located in poplar nurseries. Among the leaf eaters, larvae and adults of the poplar leaf beetles Chrysomela (= Melasoma) populi L. and Chrysomela tremulae F. feed on many poplar species in central France (e.g. Populus tremula L., Populus trichocarpa Torrey and Gray, Populus deltoides Bartram, Populus lasiocarpa Oliver).

Ninety-nine primary types of mostly North American Crambinae (Lepidoptera: Pyralidae) which are, or were supposed to be, in the collections of the Natural History Museum (NHM), London, are listed. For the 87 types that were located in the NHM, the sex and information on each label are given. Thirty-eight lectotypes are designated. Fissicrambus hospition Bleszynski is moved to Loxocrambus.

Workers of social insects are members of colonies that survive and reproduce together. Therefore, the behavioral activities of individual workers should be integrated with colony state. We here summarize and discuss the relationship between colony state and foraging behavior of individual workers under the provisional assumption that the colony is a unit. We argue that colony state can be described by a number of variables that should relate to fitness components in order to be meaningful. Among the possible candidates, colony population size seems to have an overriding importance in many respects, as shown by its relation to fitness components such as survival probability and reproductive performance. Other important variables include colony demography, i.e. caste or size distributions, nutritional status, or queen number. Each of these variables has been shown to affect fitness components; however, the evidence is rather scanty. We also discuss the evidence that variation in colony state variables relates to variation in individual worker behavior. Nutritional status (i.e. low or high levels of food stores) and colony size have been shown repeatedly to affect individual behavior. However, most of the evidence comes from the honey bee. Some studies suggest that behavioral responses are hierarchically structured. More work needs to be done to investigate the actual mechanisms of integration of individual behavior with colony state. Some knowledge has accumulated about the processes that govern recruitment to food sources. We conclude this review by discussing some concepts and problems for further research. These include the concept of a preferred colony state to which the colony should return after disturbance through the behavioral activities of the workers. Further theoretical elaboration and empirical investigations may help to elucidate whether this concept is useful and necessary. A largely neglected issue concerns the number versus effort problem, i.e. whether individuals should work harder or more workers should be allocated to a task that is in demand. We propose a simple scenario that suggests testable predictions. Finally, we discuss how colony state, individual work load, and the dependence of worker mortality rate on activity level may interact to generate different short-term foraging strategies that workers should adopt.

A double application of 1.25 × 1012 (total 2.5 × 1012) polyhedral inclusion bodies (PIB) of Disparvirus (nuclear polyhedrosis virus) in an emitted volume of 10.0 L per ha gave acceptable control of gypsy moth, Lymantria dispar (L.), larvae in 1988. More aerial spray trials were conducted in 1989 and 1990 to test a reduced dosage and volume of Disparvirus. Dosage on all plots, applied when larvae were mainly in their first instar, was a double treatment of 5 × 1011 PIB per ha, 3–5 days apart, giving a total of 1012 PIB per ha. The aqueous tank mix contained 25% (v/v) molasses, 10% (w/v) Orzan LS, and 2% (v/v) Rhoplex B60A sticker. Emitted volumes of 10.0 L per ha and 5.0 L per ha were each tested on three replicated plots in 1989, and 5.0 L per ha and 2.5 L per ha were each tested on three replicated plots in 1990. In both 1989 and 1990, three untreated check plots were paired with treated plots on the basis of pre-spray egg-mass densities.The treatments were assessed by counts of pupae in burlap traps, estimates of defoliation, and change in numbers of egg masses in the treated and check plots. Better control was obtained with the reduced dosage at 10.0 L per ha and 5.0 L per ha than at 2.5 L per ha. Using the aqueous formulation described above, a double application of 5 × 1011 PIB per ha at 5.0 L per ha applied at the peak of the first larval instar is the current recommendation for control of gypsy moth in Ontario using nuclear polyhedrosis virus.

An extensive survey of black spruce, Picea mariana (Mill.) B.S.P., in Newfoundland in 1978 disclosed that up to 50% of the old cones remaining on the trees were damaged by the deathwatch cone beetle, Ernobius bicolor White (Schooley 1983; White 1983). This beetle infests black spruce cones produced in the previous year's growing season and also damages cones in storage. Eggs are deposited between the scales and larvae feed within the cone and pupate in the fall or the following spring; their feeding can reduce extracted seed yields by one-half (Schooley 1983).

Diumal patterns in yellow sticky trap catch of pear psylla, Cacopsylla pyricola Foerster, are described for the spring (reproductive) winterform generation, summerforms, and the fall (diapausing/dispersing) winterform generation. For each life stage, trap catch of the two sexes is also compared, and sex ratios on sticky traps are contrasted with independent estimates of population sex ratio obtained by beat tray samples. Beat tray estimates of sex ratio showed a slight male bias for both winterform generations (although P = 0.09 for spring winterforms), and a female bias for the summerform samples. Sticky trap catches were significantly male biased for the reproductive generations (i.e. spring winterforms and summerforms). Trap catches of fall winterforms were not different from a 1:1 ratio. The male bias for the reproductive generations may be due to mate-seeking activities of males or to a decrease in activity by egg-laden females. Peak catch for summerforms occurred in the morning, and that of both winter-form generations occurred at midday. There was no evidence that trapping depleted local densities of psylla during a 24-h period.

The taxonomy and phylogeny of two related species groups of Mexican and Central American Onthophagus are considered. The dicranius group is composed of four species, including two new species, O. asperodorsatus and O. petenensis. The mirabilis group contains three species, one of these new, O. solisi. A fourth new species, O. quetzalis, shares characters with both species groups. All species in these groups are described and illustrated. A suggested phylogeny is presented. Our analysis indicates that these groups, including O. quetzalis, may be more closely related to Indo-Malaysian species than to other New World groups of Onthophagus.

The predatory gall midge, Aphidoletes aphidimyza (Rondani 1847), is a biological control agent used worldwide to control aphids. Mass-production methods are well established in Canada, the Netherlands, England, Germany, Finland, and the former U.S.S.R. (cf. van Leiburg and Ramakers 1984). In early March 1991, after 6 years of massproduction of A. aphidimyza on a rapidly increasing scale, two minute adult hymenopterous parasitoids were observed eclosing from a sample of pupae at a commercial insectary in British Columbia. It is likely that the founding parasitoid individual(s) entered the greenhouse before winter, as parasitoids appeared too early in the year to have entered from outdoors at that time.

Laboratory experiments were conducted to determine the effect of wounding the cotyledons of Sinapis alba L. cv. Ochre, Brassica napus L. cv. Westar, B. rapa L. cv. Tobin, and C8711, a selection from Tobin, on subsequent feeding damage by the flea beetle, Phyllotreta cruciferae (Goeze). Cotyledons of 7-day-old seedlings were wounded either by puncturing them with needles (mechanical wounding) or by exposing them to flea beetles. One, 2, or 9 days following wounding, the wounded and unwounded seedlings were exposed to flea beetles and the feeding damage was estimated as a measure of antixenosis. Mechanical wounding of one of the cotyledons with 96 needle punctures induced a significant reduction in the damage of the unwounded cotyledons of S. alba, 1 or 2 days following wounding. True leaves of the wounded seedlings also showed consistently less damage than unwounded controls, 9 days following wounding. In S. alba, all three levels of mechanical wounding (i.e. 6, 24, or 96 punctures per cotyledon) reduced subsequent flea beetle damage to a similar extent. Wrapping a cotyledon of S. alba with a plastic film produced an effect similar to wounding it with needles. As with mechanical wounding, flea beetle wounding also reduced subsequent flea beetle damage in S. alba. Other plant species (B. napus and B. rapa) tested showed no measurable induced effects on subsequent feeding damage.

The pine false webworm, Acantholyda erythrocephala (L.) (Hymenoptera: Pamphiliidae), is an introduced sawfly that is becoming increasingly important as a pest of pine plantations in Ontario. Laboratory bioassays of 10 insecticides, applied to excised pine branches containing eggs immediately prior to hatching, indicated that carbaryl and permethrin at low dosages were efficacious in controlling larvae. Neither carbaryl nor permethrin affected egg hatch, and field trials at various dosages indicated that 500 g AI per ha of carbaryl significantly reduced larval numbers and mitigated defoliation of 1-year-old and current-year foliage. Comparisons of single early (during egg hatch), single late (mean instar about 3.8), and combinations of early and late applications of lower concentrations of both chemicals suggested that the late application better reduced webworm populations. All tested application rates of permethrin and carbaryl provided significant foliar protection, particularly to current-year foliage. Dosages as low as 35 g AI per ha of permethrin and 125 g AI per ha of carbaryl in mistblower applications of third- and fourth-instar larvae may provide suitable protection, depending on management objectives. Ground applications using a mistblower resulted in no differences in efficacy on branches from different vertical strata, but reduced efficacy was observed on branches on the sides of the trees opposite where sprays were applied. Spray drift tests with carbaryl at 500 g AI per ha indicated that some population reduction occurred in trees up to two 2.1-m-spaced rows downwind from treated trees. Thus, each row would not need to be sprayed in operational programs.

The last-instar nymph of the nabid Lasiomerus annulatus (Reuter) is described for the first time and a diagnosis of the adult is presented. Its geographical distribution is detailed and the northern limit of its range in North America is established at 45 °37′N latitude. New phenological and ecological information is provided based on collections made in Québec from 1979 to 1985 and the bioecology is discussed, especially with regard to habitat preferences and phenological cycle.

Hypselistes kolymensis sp.nov. and Hypselistes basarukini sp.nov. are described from the Yakutia and the Magadan areas of Siberia, and Sakhalin Island, respectively. Distribution extensions for two other species known previously from Siberia, Hypselistes jacksoni (O. Pickard-Cambridge, 1902) and Hypselistes semiflavus (L. Koch, 1879), are included. The name Hypselistes reducens Chamberlin and Ivie, 1935, is synonymized with Hypselistes jacksoni (O. Pickard-Cambridge, 1902), NEW SYNONYMY.

The discovery of the European dandelion leaf-gall midge, Cystiphora taraxaci (Kieffer, 1888) (Diptera: Cecidomyiidae), in north-central Saskatchewan, Canada, on dandelion, Taraxacum officinale Weber (Asteraceae), is reported. This is the first record of this insect in North America. Cystiphora taraxaci is similar to Cystiphora canadensis Felt which produces galls on rattlesnake-root, Prenanthes spp., and is known only from females. Separation of the two species was achieved by demonstrating that C. taraxaci produced galls on dandelion but not on Prenanthes spp. The identity of C. taraxaci was confirmed by comparison of specimens collected in Saskatchewan with those in Europe. In Saskatchewan, C. taraxaci occurs over at least 12 000 km2 and is parasitized by Aprostocetus sp. near atticus Graham and Crysonotomyia spp. (Hymenoptera: Eulophidae).

Azadirachtin (AZA) is the principal insecticidal compound occurring in the oil of neem [Azadirachta indica (Juss.)] seed. Although many studies have been published (Schmutterer 1990) regarding the effects of AZA on herbivorous insects, little is known of the impact of this compound on the natural enemies of herbivores. Beckage et al. (1988) investigated the effects of injected AZA on Cotesia congregata (FAY) (Braconidae), a parasitoid of Manduca sexta (L.). Parasitoid development was retarded when injections of 2.5–10 μg AZA were administered to the host larva prior to the wasp's first larval ecdysis. The development of new neem-based insecticides in North America (Isman et al. 1991) has prompted the investigation of the effects of AZA on the natural enemies of pest insects that have ingested sublethal doses of the active compound. Our laboratory study was carried out with the ichneumonid parasitoid, Diadegma terebrans (Gravenhorst), and its host, the European corn borer, Ostrinia nubilalis (Hubner). AZA (>95% purity) for this study was extracted as described previously (Xie et al. 1991) from seeds collected in India.

Larvae and adults of Mamersellides costenius sp.nov., from Mexico and Florida, USA, are described. The resulting new morphological data are incorporated into revised diagnoses for the genus Mamersellides, the subfamily Anisitsiellinae, and the family Anisitsiellidae. Preliminary assessment of character states exhibited by larvae and adults of Mamersellides and other genera of Lebertioidea, and by those of genera of the family Limnesiidae, suggests that a comprehensive cladistic analysis would provide a phylogenetic basis for extensive revision of the classification of these mites.

The zebra caterpillar, Melanchra picta (Harris), has been reported as a minor pest of corn (Philip 1990) and some small fruits (Belton 1988; Fitzpatrick and Troubridge 1991) in British Columbia. This pest also infests various vegetables, blueberries, and currants, and has become more and more abundant lately in the Fraser Valley (unpublished data). The larval parasitoid Limneria annulipes Harris (Hymenoptera: Ichneumonidae) has been reported to parasitize zebra caterpillar populations in eastern Canada (Maxson 1948). Fitzpatrick (pers. comm.) found Winthemia quadripustulata (Fab.) (Hymenoptera: Tachinidae) from zebra caterpillars in British Columbia. Here we report the occurrence of another larval parasitoid reared from natural populations of M. picta collected from commercial high bush blueberry fields in Delta, British Columbia, during June of 1992.

Grasshoppers are responsible for considerable agricultural losses in different parts of Argentina (C.O.P.R. 1982). Most of the pest species in Argentina belong to the subfamily Melanoplinae. It is generally accepted that South American melanoplines are derived from a nearctic stock that crossed the Panamanian land bridge (Carbonell 1977). The genus Dichroplus Stål is one of the largest genera within the South American Melanoplinae (Ronderos and Cigliano 1990). Dichroplus contains several economically important species and is believed to be closely related to the nearctic genus Melanoplus Stål (Vickery 1989).

Large infestations of the mountain pine beetle, Dendroctonus ponderosae Hopkins (Coleoptera: Scolytidae), reportedly arise from small, spot infestations that expand, multiply, and eventually coalesce (Safranyik et al. 1974). If these spot infestations can be located and eradicated, the development of outbreaks may be delayed, or even precluded. The principal means of eradication of such spots in forests of lodgepole pine, Pinus contorta var. latifolia Engelmann, in British Columbia is single tree disposal (B.C. Ministry of Forests 1987). This may be accomplished by treating with an arsenical herbicide within 3–4 weeks after attack, cutting, bucking, piling, and burning trees before brood emergence, or extraction and processing of brood trees before emergence.