The occurrence and distribution of resistance to insecticides in populations of the obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), from apple, Malus × domestica Borkhauser (Rosaceae), and pear, Pyrus communis L. (Rosaceae), orchards in the various production areas of southern Ontario were assessed in the laboratory and field from 1993 to 1999. Laboratory bioassays were conducted with neonate larvae from the first laboratory generation. Responses of populations from commercial orchards where control failures had occurred or where populations were large or damaging were compared with populations from unsprayed wild hosts. Resistance to azinphosmethyl and to pyrethroids and methomyl was identified in populations from all areas. Resistance levels ranged from 4- to 27-fold for azinphosmethyl, 4- to 8-fold for cypermethrin (a representative pyrethroid), and 3- to 5-fold for methomyl. In the field, deltamethrin was more effective than azinphosmethyl against a population resistant to both insecticides. Resistance to azinphosmethyl was unstable and rapidly declined in a population newly established in the laboratory and not selected with azinphosmethyl. After selection for nine generations, resistance declined only slowly when selection pressure was removed for four generations. This instability may be exploited in the management of resistance, but the possible cross-resistance between azinphosmethyl and pyrethroids needs clarification.

Celisaltica ruwenzorica, gen.nov., sp.nov., a flea beetle found at high elevations from Central Africa (Ruwenzori) is described. This new genus is closely related to the genus Manobia Jacoby, 1885 but is easily distinguishable mainly by the pronotal antebasal sulcus being almost completely absent, pronotum basally weakly narrowed, antennal segments 9–10 subglobose, and antennal segment 11 subglobose–asymmetric. Line drawings of male and female genitalia and scanning electronic micrographs of particular morphological aspects of Celisaltica ruwenzorica are provided. The genus Afroalytus Scherer, 1961 is synonymized with the genus Manobia Jacoby, 1885 (syn.nov.).

The growth (increase in body mass) and development (progression to specific instar) of the bertha armyworm, Mamestra configurata Walker, were examined using up to 14 plant lines from five species of brassicaceous plants. Varietal and breeding lines of Brassica napus L., B. juncea L., B. rapa L., B. carinata L., and Sinapis alba L. were selected on the basis of differing seed and foliar glucosinolate levels. No-choice feeding experiments were conducted with larvae isolated on leaf discs, individual leaves, or entire plants of each line. The no-choice tests showed that M. configurata weight gain and development varied significantly among host plants tested. Two B. juncea lines (AC Vulcan and H-Allyl) and the S. alba lines (AC Pennant and L-GS) were the poorest hosts in terms of larval weight gain, and the two B. juncea lines also significantly slowed development relative to the other lines tested. Mamestra configurata feeding preference, which was examined using a series of paired leaf disc choice tests, was also significantly different among the lines examined. Two B. juncea lines (AC Vulcan and H-Allyl) were significantly less preferred than all the other lines examined. The data extends previous work indicating that specific foliar glucosinolates, such as sinigrin, which is predominant in B. juncea, and sinalbin, which is abundant in S. alba, may provide brassicaceous crops with some protection from M. configurata. Thus, it may be possible to use foliar glucosinolate levels as predictors of M. configurata feeding damage in the development of breeding lines for the genus Brassica.

In North America, the black carpet beetle, Attagenus unicolor (Brahm) (Coleoptera: Dermestidae), is a common household insect pest that feeds on many animal-origin and grain products. It overwinters as a larva, and the entire life cycle generally takes about 1 year. No information exists on its overwintering biology or cold hardiness (Fields 1992). In this experiment, the supercooling point (SCP) and survival rate of initially overwintering A. unicolor larvae collected in the nests of tree swallows, Tachycineta bicolor (Vieillot) (Aves: Hirundinidae), were measured. Changes in SCP and cold hardiness were determined for larvae held at 15 and –15°C. The cold hardiness of A. unicolor larvae collected from a feed mill in British Columbia was also measured.

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.

A key stage in the development of an insect epizootic, either natural or induced, is the transmission of a pathogen from an infected to an uninfected host (Andreadis 1987). The establishment of secondary infections can augment long-term control by increasing the amount of inoculum present within the environment (Thomas et al. 1995). The ease of disease transmission from an infected to a healthy host is an important consideration in evaluating the potential of an entomopathogen as a microbial control agent. Currently, we are field-testing the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin (Moniliaceae), for the suppression of adult western corn rootworm, Diabrotica virgifera virgifera LeConte, which is a key pest of corn, Zea mays L. (Gramineae), throughout the north-central United States and eastern Canada (Mulock and Chandler 2000). During our investigations we have often observed sporulating cadavers on corn plants, particularly within the leaf collars, following fungal application. In this study, we estimated the effect of the density of infected cadavers and the length of exposure time on disease transmission in adult western corn rootworm.

The emergence patterns of Diptera breeding in small-sized and buried carrion were studied in rearing experiments with field-exposed baits. Development times are reported for 52 species in the families Phoridae, Sphaeroceridae, Sepsidae, Heleomyzidae, Anthomyiidae, Fanniidae, Muscidae, Sarcophagidae, Psychodidae, and Sciaridae. Most species showed a synchronous emergence of males and females. Protandry was detected in Hydrotaea ignava (Harris) (Muscidae), H. palaestrica (Meigen), and Psychoda minuta (Banks) (Psychodidae). Protogyny was found in several species of Phoridae, namely Conicera similis (Haliday), C. schnittmanni Schmitz, Anevrina unispinosa (Zetterstedt), and Triphleba dudai (Schmitz). Conicera schnittmanni and T. dudai showed two discrete emergence periods for each sex, which is due to a delayed emergence of some specimens. Protogyny is a rare phenomenon in Diptera and insects in general, and has never been reported before in Phoridae. The significance of protogyny could not be ascertained in the examined species, because of insufficient information on their mating systems and female receptivity patterns.

Based on external structural features and on those of male and female genitalia, the monobasic carabid genus Chalteniagen.nov. is described and illustrated, along with Chaltenia patagonicasp.nov. A parsimony analysis of tribe-level taxa supports a position of this new genus within the supertribe TrecFhitae. Based on the analysis of fittest trees, the genus Chaltenia is most closely related to the tribe Zolini. Several characters, such as head with three supraorbital setae, two rows of squamosetae on ventral surface of male protarsomeres 1–2, elytral interval 8 not carinate, and glossal sclerite quadrisetose, differentiate the genus Chaltenia from the three subtribes of Zolini. Because of the large degree of difference from the previously known genera of Zolini, a new monogeneric subtribe, Chalteniina, is described in order to hold the new genus Chaltenia. The biogeographical pattern exhibited by the tribe Zolini is congruent with the biogeographical patterns of other carabids, such as the tribe Broscini, that show an amphitropical distribution.

Optical brighteners were recently discovered to function as UV protectants for baculoviruses of insects (Shapiro 1992) and, also, to enhance entomopathogenic activity of these viruses (Hamm and Shapiro 1992; Li and Otvos 1999a). Enhancement of viral activity by brighteners varied greatly from one virus–host system to another: for example, from 1500-fold in LdMNPV against Lymantria dispar (L.) (Lepidoptera: Lymantriidae) (Argauer and Shapiro 1997) to 2- to 13-fold in a multicapsid nuclear polyhedrosis virus of Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae) (CfMNPV) against Choristoneura occidentalis Freeman (Li and Otvos 1999a). The reason for this variation in enhancement of viral activity is still unknown. In this study, we used CfMNPV to compare the levels of viral enhancement by an optical brightener between C. occidentalis and C. fumiferana.

The effect of delayed mating on the reproductive biology of females of the Oriental fruit moth, Grapholita molesta (Busck), was studied in the laboratory. Expected reproduction, defined as t-th day survival rate × percent successful mating × total viable eggs, was reduced by 13, 36, and 74%, respectively, after a 2-, 5-, and 10-d delay in pairing with a male compared with females that were paired with a male on their day of emergence. Female fertility (percentage of females laying fertile eggs), fecundity (total number of eggs laid), egg fertility (percentage of eggs developing to black head stage), and egg hatch (percentage of eggs hatching) were reduced by delays in mating. The pre-oviposition period of females mated within 24 h of emergence was longer than that of females mated 2, 5, or 10 d after emergence. The duration of the oviposition period declined with delays in mating. Female longevity increased with delays in mating and was greatest in virgin females. The number of eggs laid per day was similar in females paired with a male 2, 5, and 10 d after their emergence. Commencing 2 d after pairing, females paired on their day of emergence exhibited a daily oviposition rate similar to that of females paired 2–10 d after emergence. These observations suggest that the successful control of the Oriental fruit moth using sex-pheromone-mediated orientation disruption (mating disruption) is more likely accomplished by preventing mating than by delaying mating.

Studies were conducted to document the oviposition biology of female white pine weevil, Pissodes strobi Peck. Data were recorded on female fecundity and daily feeding and oviposition activities. In addition, we compared fecundity of 1- and 2-year-old females. Female white pine weevils laid a mean ± SE total number of 132.3 ± 7.5 eggs (range 40–344 eggs) during an average oviposition period of 5.8 ± 0.4 weeks. It is during the first 5 weeks that white pine weevils lay the most eggs, with an egg-laying peak in the second week of the oviposition period. For a few females, egg production did not cease until the 22nd week. There was no difference between the number of eggs laid in the photophase and in the scotophase, but higher numbers of feeding punctures were observed during the night than during the day. The oviposition and feeding results for 2-year-old female white pine weevils were similar to those for 1-year-old females. This information contributes to the management of white pine weevils by providing a better understanding of some of the mechanisms of its population dynamics.

To confirm patterns of diversity and differentiation found with isozymes and mitochondrial DNA, we surveyed 10 populations of the white pine weevil, Pissodes strobi (Peck), for randomly amplified polymorphic DNA (RAPD) markers. Four weevil populations were sampled from Sitka spruce, Picea sitchensis (Bong.) Carr (Pinaceae), five from the "interior" spruce of British Columbia [admixtures of white spruce, Picea glauca (Moench) Voss, and Engelmann spruce, Picea engelmanni (Parry)], and one from Jack pine, Pinus banksiana Lamb. (Pinaceae), in Ontario. In each population, 30–60 weevils were assayed with 10 RAPD primers, yielding 74 RAPD markers. Genetic analyses showed that populations from interior spruce and Jack pine formed a distinct complex; as well, Vancouver Island populations formed a distinct group within the Sitka populations. Levels of diversity, both in terms of polymorphic loci and expected heterozygosity, declined from east to west, supporting the contention that P. strobi originated in eastern North America and migrated west, and suggesting that biocontrol methods may be more effective on populations from Sitka spruce, owing to their reduced diversity. These results parallel an earlier isozyme study but, in contrast, the diversity differences and population relationships are demonstrated to be statistically significant, owing to both the much larger number of loci sampled and the attachment of statistical confidence intervals to estimates of diversity and differentiation.

The influence of male and female body size on copulation duration and probability of insemination was determined for Anthocoris whitei Reuter allowed to mate at two temperatures. Copulation duration decreased significantly with increasing male length or increasing relative size (male length divided by female length). Female length had no effect on copulation duration. We interrupted copulation at 20 or 40 min at both 25 and 15 °C to determine the interacting effects of male size, temperature, and copulation duration on probability of insemination. Insemination probabilities increased with increasing male size, increasing temperature, and increased duration of copulation. Large males were more successful than small males at inseminating females at cool temperatures and for severely shortened copulations. Results are consistent with the hypothesis that males of this species experience physical difficulties either in achieving intromission or in forcing sperm through the aedeagus, and that larger body size in males lessens these difficulties.

Factors that might contribute to variability in the densities of wheat midge eggs, Sitodiplosis mosellana (Géhin), on common and durum wheats, Triticum aestivum L. and Triticum durum Desf., were investigated to improve the quantification of oviposition preferences in relation to crop resistance. Egg densities on wheat spikes were highly variable, with a similar contagious distribution in the laboratory and field, although variance was highest in the laboratory. Females laid eggs in small groups, usually of one to six eggs; most infested spikes had more than one egg group. Females showed no preference for ovipositing on different parts of a spike, although spikelets on one side and at the base often received fewer eggs because these spikelets were covered by the flag leaf and inaccessible for longer than others. Oviposition rates varied from night to night, probably related to the weather. Females showed no preference for spikes at different growth stages, from the time spikes began to emerge until at least flowering. Spike size did not affect egg density, and spike height was a factor only for spikes deep within or protruding above the canopy. Sources of environmental variation such as effects of weather on oviposition rates in the field or spatial phenomena in cages were measurable but of secondary importance. In the field, comparisons among spikes which emerged on the same day could reduce variation in egg density. In the laboratory, variation in egg density could be reduced by using arrays of excised spikes arranged at the same height, leaving the central portion of the array empty. The primary cause of high variability in egg density among spikes was variation in egg-group size and the presence of multiple egg groups on a single spike, factors which cannot be experimentally controlled because they are the result of oviposition behaviour rather than environmental heterogeneity.

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 lily leaf beetle, Lilioceris lilii Scopoli, was first found in North America near Montreal, Canada, in 1943 (LeSage 1992). It was recovered in Boston, Massachusetts, in 1992 (Livingston 1996), and now occurs throughout all of the New England states and in the Canadian provinces of Quebec, Ontario, Nova Scotia, and Manitoba. It is a serious pest of native and cultivated lilies (Liliaceae) (Livingston 1996). This univoltine insect overwinters as an adult and after initiating feeding in the spring, oviposits in rows on the undersides of lily leaves. Larvae, which carry a fecal shield, pass through four instars before pupating in the soil. In North America, larval feeding often results in complete plant defoliation. Lilioceris lilii apparently originated in Asia (Berti and Rapilly 1976), and now exists throughout Eurasia from Siberia to Morocco and from the United Kingdom to China (Labeyrie 1963; Lu and Casagrande 1998). Based on its Eurasian distribution, L. lilii will likely increase its distribution in North America.

Females of Monoctonus paulensis (Ashmead), a solitary parasitoid of aphids, generally select the relatively smaller over equally available larger instars of the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphidoidea: Aphididae). Large hosts contain more resources for parasitoid development and hence have presumably higher quality; however, they require more time to subdue and are more likely to escape. We tested the hypothesis that a female’s choice among first (L1), second (L2), third (L3), and fourth (L4) instars of the pea aphid is based on the optimal balance between fitness costs in terms of time and fitness gains in terms of offspring number and size. Prepupal mortality did not vary with host instar, but pupal mortality was greater among parasitoids developing in L4 than in any younger instars. Offspring mortality was not influenced by clutch size in that mortality risk did not differ between parasitoids developing alone and counterparts developing in a clutch. The sex ratio, measured as proportion of daughters among offspring, was female-biased on all four host instars; the degree of bias increased from 0.70 (in L1) to 0.92 (in L4). Parasitoid body size was a function of aphid size at parasitism. Females were larger than males; the magnitude of the difference in body size was constant and independent of host and hence parasitoid size. A female’s potential fecundity as measured by the number of ovarial eggs at eclosion varied with her size and larval ontogeny. The four instars of the pea aphid were ranked in the order L1 > L2 > L3 > L4 both in terms of the number of offspring produced per encountered host and in terms of a female’s time costs; first instars are easier to handle and are more abundant in the field than older instars. The four host types were ranked in the order L2 > L3 > L1 > L4 in terms of the proportion and potential fecundity of daughters among offspring. The observed preference pattern (L1 > L2 > L3 > L4) suggests that, in choosing hosts, females of M. paulensis maximize the number of offspring per unit of search time rather than simply offspring quality.

Two stands of intensively managed balsam fir [Abies balsamea (L.) Mill. (Pinaceae)] in western Newfoundland, located within an area infested by the balsam fir sawfly, Neodiprion abietis (Harr.) (Hymenoptera: Diprionidae) complex, were selected to study growth loss and recovery following severe defoliation by the balsam fir sawfly in the early 1990s. Four years after the start of the outbreak, volume increments were reduced by 78–81%. The decreased volume increment and recovery coincided well with the balsam fir sawfly outbreak and decline. The growth recovery rates following severe balsam fir sawfly defoliation were slow due to the absence of bud destruction, which triggers the release of suppressed buds, and thus increases foliage production. It is imperative that the severe losses in volume growth caused by balsam fir sawfly defoliation are incorporated into wood supply analyses so that future annual allowable cuts may be adjusted. In addition, to ensure maximum recovery rates at the end of an outbreak, future populations must be kept at a minimum to avoid additional foliage loss.

Host preference of the pine shoot beetle, Tomicus piniperda (L.), was investigated in two laboratory choice test studies using red pine (Pinus resinosa Ait.) (Pinaceae), jack pine (Pinus banksiana Lamb.), and Scotch pine (Pinus sylvestris L.). Host preference of parent adult beetles was evaluated using freshly cut, similarly sized logs in a wind tunnel. Parent beetles colonized Scotch pine logs significantly more often when given a choice of Scotch pine and either red pine or jack pine logs, but did not show a preference when presented with red pine and jack pine logs. Host preference of progeny adults was tested in a laboratory bioassay using current-year pine shoots. Shoot-feeding progeny adults initiated tunnels in jack pine shoots significantly more often than in Scotch pine and red pine shoots, and preferred Scotch pine over red pine shoots. Shoots with diameters of 0.4–0.5 cm were attacked most frequently, regardless of species. Results suggest that the two North American pines are suitable hosts, but T. piniperda may be most likely to colonize Scotch pine, a European species. Efforts to detect or monitor T. piniperda populations in the Great Lakes and northeastern regions should focus on areas with abundant Scotch pine brood material. Progeny that emerge from brood material, however, may be as likely to shoot-feed in jack pine as in Scotch pine.

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.