The hispidus species group is formed for four new species from East Asia of the genus Plagiophorus Motschulsky: P. hispidussp. nov., P. hlavacisp. nov., P. serratussp. nov., and P. grandoculatussp. nov. Uncoated specimens were examined using field-emission scanning electron microscopy, and micrographs of the holotypes are presented. Keys to the species groups of the genus occurring in East Asia and to the species of the hispidus group are given. The hispidus group is probably monophyletic, having peculiar spinous setae on the male metasternum. The chaetotaxy of the labrum and clypeus is useful for distinguishing species of Plagiophorus.

The aphid parasitoid Aphidius rhopalosiphi is the most abundant species of Aphidiinae in cereal fields in northern Europe. Although the larval morphology of other Aphidiinae has been described, the morphology and immature development of A. rhopalosiphi remain unknown. Our goal is to relate growth and larval developmental stages to morphological changes during parasitoid development, using light and scanning electron microscopy. Aphidius rhopalosiphi develops through three larval stages with clear differences in the morphology of the mouthparts, tegument sculpturing, and respiratory features that can be related to the different constraints that the larvae have to face. In the first instar, adaptations to physical combat with competitors take the form of strong mandibles, active caudae, and dorsal spines that allow crawling motion. In the third instar, the larva is adapted to tear tissues with short hooked mandibles and to face aerial respiration. All instars possess sensory structures. The "three instars" hypothesis is supported here by the observation of larvae in exuviation. No differences were found between our observations and descriptions of other Aphidius species, supporting the idea that species of this genus cannot be distinguished by larval morphology but only by morphometric analysis. Some new features of the genus are presented for the first and second instars.

Fauna of the genus Pandeleteius Schoenherr of Colombia, Venezuela, Trinidad, and the Lesser Antilles are revised in part. Six new species of Pandeleteius are described: P. trinidadensissp. nov. (P. angustirostris species group); P. sabanaensissp. nov. and P. bolivarisp. nov. (P. campestris species group, new concept); P. guriensissp. nov. and P. ductilissp. nov. (P. candidus species group, new concept); and P. clarkisp. nov. (P. modestus species group). The P. kirschi species group (new concept) is redefined based on male and female genitalia, and P. testaceipes Hustache is added to the species group. The other sex is described for three species formerly known from only one sex: the male of P. candidus Howden, male of P. arcanus Howden, and female of P. liberalis Howden. New findings on the post-pupal growth and morphology of the male and female genitalia are applied to the group- and species-level taxonomy. The key to the Pandeleteius species of Venezuela and Colombia is revised to include all the original species groups and subsequent changes, as well as all new taxa.

The first fully documented North American records of the Palearctic Ceutorhynchinae weevil species Amalorrhynchus melanarius (Stephens, 1831), Microplontus campestris (Gyllenhal, 1837), Pelenomus waltoni (Boheman, 1843), and Rhinoncus perpendicularis (Reiche, 1797) are presented. Characters providing for their recognition, as well as keys and habitus photographs facilitating their identification, are provided. It is likely that all four species have recently been introduced unintentionally by human activities.

This study characterized the spatial distribution of adult western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), released at the centres of greenhouses stocked with either cucumber (Cucumis sativus L. (Cucurbitaceae)) or chrysanthemum (Dendranthema grandiflora (Tzelev) (Asteraceae)) plants. Experiments conducted using either adults marked with fluorescent powder or unmarked adults revealed that the density of females per plant decreased as an inverse function of the distance from the release point. Inverse regression models with steep decreases in density over small distances may commonly describe the dispersal behaviour of insects that have limited flight capacity and settle on the first plants that they encounter. Females were found on plants farther from the release point as time elapsed, dispersing throughout the greenhouse at an average rate of 0.18 to 0.29 m per day. Distinct sex ratios for adults captured on sticky cards or sampled on host plants suggested that males and females exhibit different dispersal behaviours. The spatial distribution of F. occidentalis varied across generations, with females exhibiting a lower level of aggregation around the release site than their nymphal progeny. The average rate of spread between consecutive generations fluctuated between 0.05 and 0.17 m per day. Considering the limited dispersal of F. occidentalis, outbreaks may be effectively suppressed by applying insecticides or releasing natural enemies in relatively small concentric areas surrounding heavily infested plants, as well as near the edges of greenhouses.

Outbreak and declining populations of spruce budworm (Choristoneura fumiferana (Clem.)) were sampled extensively at three locations in New Brunswick, Canada, between 1982 and 1992 and were examined for the prevalence of granulosis and nuclear polyhedrosis viruses (Baculoviridae). Larvae, pupae, and adults were collected using a variety of methods. Spruce budworm nuclear polyhedrosis virus (CfMNPV) genomic DNA probes and wet-mount light microscopy were used to determine CfMNPV prevalence in 50 274 juvenile spruce budworms. Spruce budworm granulosis virus (ChfuGV) genomic DNA probes were used to determine the prevalence of ChfuGV in 25 703 of these same samples. The prevalence of both viruses was low, with ChfuGV and CfMNPV not found in more than 15% and 2%, respectively, of samples in any collection in a given year. Prevalence of ChfuGV was greatest in mid- to late June in sixth-instar larvae. Each virus was detected in only two of 2177 female moths and in none of the 420 male moths examined. In the entire collection, cytoplasmic polyhedrosis virus (Reoviridae) was detected in only two budworm larvae and entomopoxvirus (Poxviridae) was not detected in any.

Various genotypes of seven species of Brassicaceae (Brassica rapa L., B. napus L., B. juncea (L.) Czern., B. nigra (L.) Koch, B. tournefortii Gouan, Sinapis alba L., Crambe abyssinica Hochst. ex R.E. Fries, and B. napus × S. alba) were evaluated for susceptibility to infestation by the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham). In the field, weevils were counted by excising and dissecting pod samples weekly for the presence of eggs, larvae, and larval exit holes. In the laboratory, excised pods from potted plants were exposed to gravid female weevils for 24 or 48 h and then the numbers of eggs and (or) feeding punctures were assessed. Differences in susceptibility of Brassicaceae species to the cabbage seedpod weevil were relatively consistent in both field and laboratory studies. Brassica rapa was the most susceptible. Intermediate susceptibility was observed for B. napus, B. napus × S. alba, B. tournefortii, and B. juncea, although the last species displayed some antixenotic resistance. Sinapis alba, B. nigra, and C. abyssinica were least susceptible. Pods of some species more frequently contained single, rather than multiple, larvae and this may have important implications for total yield loss, particularly in areas where opportunistic pests utilize weevil exit holes to gain access to seeds. New-generation adults fed on all Brassicaceae, and therefore all species may be susceptible to some yield loss. Canola growers in regions infested with C. obstrictus at high population densities can reduce losses by seeding S. alba, B. juncea, or a less susceptible genotype of B. napus.

Cereal leaf beetle, Oulema melanopus L., is an invasive pest insect of small grain cereal crops, particularly oat, wheat, and barley. The first report of cereal leaf beetle populations in North America came from Michigan in 1962. Surveys indicate that populations have become established throughout eastern North America from Ontario to Alabama and in northwestern North America from Utah to southern British Columbia. The establishment of O. melanopus in western North America has raised concern that its presence is a potential risk to the Canadian cereal industry, especially in the prairie ecozone of western Canada, where up to 10 million hectares of cereal crops are grown annually. Field surveys to date have indicated that O. melanopus has not yet become established in this region. A CLIMEX™ model for O. melanopus in North America was developed, based on climate and ecological parameters, and validated with actual distribution records. The actual distribution of O. melanopus in eastern North America matched the predicted distribution well. The model predicts that, once introduced, O. melanopus would readily survive in the cereal-growing areas of western Canada and present a significant risk to cereal production. The potential for establishment of O. melanopus in the prairie ecozone of western Canada substantiates the efforts by regulatory agencies to prevent accidental introduction of this pest species.

A hypothetical parasitoid mass rearing facility is used to unite principles from behavioral ecology and biological control. The key to the problem is variation in the tendency of solitary parasitoids to superparasitize. Superparasitism affects individual and population parasitoid productivity, though not necessarily to the same degree. Herein, the interest is in determining conditions that will maximize parasitoid population productivity when superparasitism varies. To accomplish this, a combination of graphical marginal analysis (to provide an economic context), dynamic optimization models (to determine individual parasitoid superparasitism tendency), and functional response models (to determine parasitoid population productivity) has been used. Marginal analysis shows that marginal returns decrease with an increase in the number of parasitoids released but that the slope of the marginal returns curve depends upon the sensitivity of superparasitism to environmental conditions. In addition, results show that parasitoid responses can be highly nonlinear and, as such, can greatly affect optimal numbers of parasitoids released in a nonintuitive manner. This behavioral ecology approach greatly increases efficiency and predictability of parasitoid production.