We describe the morphology of the alimentary canal in adult Acalymma vittata (F.), the vector of Erwinia tracheiphila (Smith) Bergey et al. emend. Hauben et al. (Enterobacteriaceae), the causal agent of bacterial wilt in cucurbits (Cucurbitaceae). The foregut includes a pre-oral cavity, pharynx, oesophagus, and crop but lacks a well-developed proventriculus. The midgut occupies approximately 65% of the length of the gut, has distinctive ventricular crypts throughout its length, and is lined with a peritrophic membrane, but lacks caeca for harboring symbionts. The hindgut comprises the colon and rectum and four Malpighian tubules. The cuticular intima of both foregut and hindgut bears rows of spines and is thrown into numerous folds. Transmission electron microscopy showed bacteria resembling E. tracheiphila within the hindgut 1 and 30 d after the beetles fed on E. tracheiphila spread between cotyledons of cucumber, Cucumis sativus L. (Cucurbitaceae). Our observations suggest that the midgut is not appropriate for long-term retention of E. tracheiphila because of the absence of caeca and the presence of a peritrophic membrane. Temporary and long-term pathogen retention may be associated with rows of spines and numerous folds within the foregut and hindgut.

Descriptions are provided for larvae of nine species of Ceratophyllus Curtis for which swallows in North America, north of Mexico, are recorded hosts. A detailed description is provided for the larva of Ceratophyllus celsus celsus Jordan and for other species only where there are significant differences from C. c. celsus. Ceratophyllus celsus celsus, Ceratophyllus scopulorum Holland, and Ceratophyllus petrochelidoni Wagner are characterized by a large number of anal comb (25–42) and anal mound (13–23) setae, but among themselves have not proved separable; Ceratophyllus styx riparius Jordan and Rothschild is remarkable in having two ventral plate setae on all thoracic segments as well as on the eighth and occasionally the ninth abdominal segments; Ceratophyllus idius Jordan and Rothschild and Ceratophyllus niger C. Fox characteristically display stout ventral plate setae on the thoracic segments, as seen in C. c. celsus, but have fewer anal comb and mound setae. We are unable to separate larvae of C. idius and C. niger from each other. Ceratophyllus gallinae (Schrank) also has few comb and mound setae, but the ventral plate setae are more slender than evident in other species treated here. Ceratophyllus diffinis Jordan and Ceratophyllus garei Rothschild, the sole Nearctic representatives of the subgenus Emmareus Smit, are characterized by their short, slender, thoracic ventral plate setae, but have not been separated from each other here. Redescriptions are provided for larvae of C. gallinae and C. garei. Descriptions for all other taxa are provided for the first time. A key is provided to the known larvae of species associated with swallows in North America, north of Mexico.

The new species Neurocordulia michaelisp.nov. from New Brunswick and Maine differs from other northeastern species in the genus in its short mesotibial keel and from all congeners in the great width of its abdomen. The species is obligate crepuscular and can be locally abundant at its riverine habitat. Larvae of the species have the lowest dorsal spines in the genus and cling to the underside of rocks in rapids.

A survey of nine populations of the European earwig, Forficula auricularia L., species complex from eastern North America revealed the presence of the two sibling species recently identified as species A and B. A mitochondrial analysis, based on restriction polymorphism observed on the 16S rRNA and the cytochrome oxydase regions, proved to be a rapid method to identify and distinguish these two species. Furthermore, consistency between these mitochondrial data and a biological diagnosis, based on the dates and number of oviposition periods in each population, revealed that species A and B occupy different habitats. These observations are consistent with the hypothesis of multiple introductions of the two species on the Atlantic coast of North America, followed by a selection of the most adapted species to each habitat.

The aim of this study was to characterize polypeptide components of the capture net spun by trichopteran larvae Hydropsyche slossonae (Banks) (Trichoptera: Hydropsychidae). Thirty-one polypeptide bands were identified by SDS – polyacrylamide gel electrophoresis (SDS–PAGE) from extracted net material, with molecular weights ranging from 8500 to 179 000. Comparison with published data on Bombyx mori (L.) (Lepidoptera: Bombycidae) silk, treated under similar denaturing conditions, shows that six low molecular weight polypeptides ranging between 8500 and 18 800 in the silk of H. slossonae are absent from that of B. mori; furthermore, two high molecular weight polypeptides (210 000 and 220 000) detected in the silk of B. mori are not present in that of H. slossonae. Differences between both groups are probably related to their mode of living and to the specific use of silk (in air versus under water). Our findings are consistent with the current trend in the literature that silk spun by aquatic and terrestrial insects, as well as those spun by different species, is apparently made of different biopolymers according to the protein constituents. Hence, the polypeptide characterization of silk, combined with sequence data and (or) antibodies cross-reactivity data, could represent a potential tool for taxonomic classification improvement of aquatic insects. These results could eventually be used to characterize hydropsychid capture net anomalies induced by environmental pollution.

The toxicity of dicofol, pyridaben, formetanate HCl, and abamectin to European red mite, Panonychus ulmi (Koch), was determined using either a Petri dish or leaf dip bioassay (as potential field assay procedures) and was compared with results from a standard laboratory procedure that requires a Potter spray tower to treat leaf disks. Abamectin and pyridaben were the most toxic acaricides tested, and dicofol and pyridaben were more toxic when applied to Petri dishes than to leaf disks. Formetanate HCl was the least toxic acaricide tested by either leaf disk or leaf dip procedures. Diagnostic concentrations of pyridaben were determined as 5 mg active ingredient per litre (a.i./L) with the Petri dish assay and 15 mg a.i./L with the leaf disk assay. Mortality of European red mites to pyridaben at diagnostic concentrations was consistently 100% with the leaf disk assay and > 90% with the Petri dish assay. Residues of pyridaben on Petri dishes stored at 4 °C in a refrigerator were stable for at least 21 d. For dicofol, both leaf disk and Petri dish assays gave similar results, and 25 mg a.i./L, previously used as the diagnostic concentration in the Petri dish assay, resulted in > 99% mortality of the standard susceptible strain. This technique identified resistant individuals in all of the field populations tested. Abamectin applied at 2 mg a.i./L to leaf disks consistently gave 98–100% mortality, but results at 2 mg a.i./L with the Petri dish assay gave variable results and this was not a reliable technique for monitoring resistance. Concentrations of formetanate HCl required for the leaf dip assay were too high to be useful in field assays; however, all populations of European red mite tested using the leaf disk assay appeared susceptible. For the ovicide, clofentezine, mortality of eggs tested by the leaf disk assay at 100 or 500 mg a.i./L ranged from 89 to 100%. Results with the leaf dip procedure, using a 350 mg a.i./L suspension consistently resulted in > 96% mortality of eggs from susceptible field populations. These procedures are a useful tool in the development of resistance management programs for acaricides used in integrated pest management (IPM) systems for tree fruits.

A two-choice feeding bioassay was used to investigate the effects of larval source (colony versus wild larvae) and rearing medium (artificial versus foliar diet) on the feeding-deterrent activity of the oral exudate of the spruce budworm and the western spruce budworm, Choristoneura fumiferana (Clem.) and Choristoneura occidentalis Free., respectively. Feeding by both wild and colony larvae was deterred by conspecific oral exudate. Larvae reared on artificial diet responded to exudate from both diet- and foliage-reared larvae, whereas the foliage-reared larvae responded only to exudate from other foliage-reared larvae. These results suggest that differences exist between artificial diet- and foliage-reared larvae in the composition of oral exudate, in the concentrations of its biologically active constituents, or in differential sensitivity of diet- and foliage-reared larvae to exudate from foliage-reared larvae.

In laboratory experiments adults and nymphs of the western conifer seed bug, Leptoglossus occidentalis Heidemann, were allowed to feed on mature seeds of Douglas-fir, Pseudotsuga menziesii (Mirbel) Franco. Weight-loss measurements and scanning electron microscopy provided strong supporting evidence for the use of simple radiographic diagnosis as a method of classifying feeding damage to seeds into four categories: light (greater than two thirds of seed contents remaining), moderate (one third to two thirds of seed contents remaining), severe (less than one third of seed contents remaining), and extreme (seed empty). Scanning electron micrographs showed the apparent depletion of lipid and protein storage reserves which was verified by quantitative analyses that showed significant loss of lipid and buffer-insoluble (crystalloid) storage protein from seeds in all damage categories. The amount of buffer-soluble (matrix) protein was reduced in seeds from the severe and extreme damage categories. The increase in buffer-soluble protein observed in lightly damaged seeds was likely due to the solubilization of crystalloid storage protein, as a result of its breakdown into smaller peptides. Our results suggest that through the action of both lipases and proteases, L. occidentalis can have a serious impact on the major storage reserves of conifer seeds. Moreover, our data suggest that L. occidentalis feeds in a different manner than the laceration and flushing method found in other seed-feeding Hemiptera.

The Colorado potato beetle, Leptinotarsa decemlineata (Say), overwinters in the soil as a diapausing adult. Large numbers of adult beetles fly and walk from potato, Solanum tuberosum L. (Solanaceae), fields to the surrounding forested edges late in the summer (Voss and Ferro 1990). This movement can result in higher densities of diapausing adults in the soil along these edges than in potato fields (Weber and Ferro 1993). Beetles that overwinter in these woody borders show lower levels of overwintering mortality (Weber et al. 1994). Survivorship of overwintering Colorado potato beetle adults was positively correlated with soil depth for studies conducted adjacent to potato fields in New Jersey (Lashomb et al. 1984) and Massachusetts (Weber and Ferro 1993). Lashomb et al. (1984) reported that a 10-cm increase in soil depth decreased winter mortality by 32%.

The potential for using synthetic sex pheromone to disrupt mating of spotted tentiform leafminers, Phyllonorycter blancardella (F.), was evaluated in four experimental and two commercial apple, Malus domestica (Borkh) (Rosaceae), orchards in Ontario during 1992 and 1993. The average disruption index [i.e., (total number of moths trapped in control plot – total number of moths trapped in pheromone-treated plot)/total number of moths trapped in control plot × 100] was 80.7% when leafminer pheromone, (E)-10-dodecen-1-yl-acetate, was evaporated into square, approximately 400-m2 plots. During the 2-year study, pheromone was evaporated into the pheromone-treated plots at an average hourly rate of 39.6 mg/ha. There was no relationship between the estimated release rate of pheromone and average temperature. There was a negative linear relationship between the disruption index and leafminer density, as measured by the number of moths trapped in the control plot. There was no relationship between the disruption index and the estimated release rate of pheromone. Our results suggest that it may be possible to control the spotted tentiform leafminer using sex-pheromone-mediated mating disruption.

The Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins, attacks Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco (Pinaceae), throughout western North America. Periodic outbreaks cause increased mortality of its host. Land managers and forest health specialists often need to determine population trends of this insect. Bark samples were obtained from 326 trees distributed over 21 stands during a 2-year period in late winter to early spring of 1997 and 1998 in the Colorado Front Range. The variance to mean relationship of brood adults was examined using the Taylor power law, and a fixed-precision sampling plan was developed using Green’s method. Stop lines and minimum number of samples required to estimate brood adult density per 0.046 m2 with precision levels of 0.1, 0.2, and 0.3 were calculated. A resampling simulation conducted with an independent data set indicated that desired precision levels were not met. Theoretical precision levels were adjusted until desired precision levels were achieved. Average number of samples needed to estimate brood adult densities up to 25.1 adults per 0.046 m2 with precision levels of 0.09, 0.2, and 0.3 were 91, 20, and 8, respectively. For densities greater than 25.1 brood adults per 0.046 m2, conservative estimates are obtained with 72, 15, and 6 samples for precision levels of 0.09, 0.2, and 0.3, respectively. An emergence ratio can be obtained by dividing the estimated density of brood adults by twice the number of gallery starts. This system provides the user with an immediate assessment of the population trend of Douglas-fir beetle. The data collected compare favorably with data from other Douglas-fir beetle outbreaks reported in the literature. The use of this plan outside the Colorado Front Range, or by sampling at a different height, should be cautioned until additional data from other locations and sampling heights are examined.