Potato plants (Solanum tuberosum, cv. Russet Burbank) genetically altered to produce the CryIIIA protein from Bacillus thuringiensis var tenebrionis were tested for susceptibility to attack by the potato flea beetle, Epitrix cucumeris (Harris), on Prince Edward Island, Canada, from 1993 to 1996. Average weekly damage to the fourth terminal leaf of transgenic potato plants was 31% lower in 1993 and 20% lower in 1994 compared with nontransgenic plants. Transgenic plants had 29% fewer potato flea beetle adults when compared with nontransgenic plants in 1994, although no difference was detected between the two plant types in 1993. Recovery of potato flea beetle pupae in the soil was noticeably lower from transgenic plants expressing the CryIIIA protein in all parts of the plant (Construct No. RBBT02-10Y1) than from either the transgenic plants that expressed the CryIIIA protein primarily in the green foliage (Construct No. RBBT04-01) or the nontransgenic plants. Adult potato flea beetles, when given a choice between transgenic and nontransgenic leaf material, fed preferentially on nontransgenic material. In contrast, when adults were not given a choice, feeding damage was similar between treatments. These results suggest that the reason for reduced feeding on transgenic potato plants by the potato flea beetle is, at least in part, due to some toxicity of the plants to immature growth stages and a preference for adults to feed on nontransgenic material when it is available.

Investigations were conducted to quantify the effects of treatment of cracked wheat, Triticum aestivum L. (Gramineae), kernels with sublethal and median-lethal concentrations of Bacillus thuringiensis Berliner 1915 (Eubacteriales: Bacillaceae) on the energy use by Plodia interpunctella (Hübner) 1813 and Tribolium castaneum (Herbst) 1797 larvae. Cumulative food consumption and egestion during insect development and the weight and energy values of adult insects were determined and oxygen consumption was estimated. At sublethal (4 μg/g wheat for P. interpunctella, 250 μg/g wheat for T. castaneum) and median-lethal (18 μg/g wheat for P. interpunctella, 1950 μg/g wheat for T. castaneum) concentrations, food consumption during development decreased from controls by 9.1% and 47.1%, respectively, for P. interpunctella and 14.4% and 38.2%, respectively, for T. castaneum. Egestion decreased by 9.5% and 61.5% for P. interpunctella and 19.4% and 47.3% for T. castaneum at these respective concentrations. Increasing B. thuringiensis had negative effects on food consumption and energy use by the insects. Levels of B. thuringiensis lower than required for complete control may assist in protecting grain from stored-product insects.

Development of resistance to organophosphorus and carbamate insecticides by the Oriental fruit moth, Grapholita molesta (Busck), has caused great concern regarding the sustainability of peach production in Ontario, Canada. Thus, a resistance management program was implemented and a procedure was developed to monitor for resistance to insecticides in adult moths. Diagnostic concentrations needed to distinguish susceptible genotypes from resistant individuals were determined to be carbofuran (0.1 μg per vial), carbaryl (1.0 μg per vial), malathion (0.5 μg per vial), and cypermethrin (2.5 μg per vial). Significant survival of field-collected moths to diagnostic concentrations of cypermethrin suggested that resistance to pyrethroids might be widespread. The seasonal patterns of resistance of several Oriental fruit moth populations from the Niagara Peninsula of Ontario indicated a decrease in frequencies of resistance to all insecticides tested from 1996 through 1998. Resistance levels were unstable, thus suggesting that resistance could be successfully managed. Our data confirmed the usefulness of the vial test to monitor for resistance to insecticides in the adult Oriental fruit moth, and provided the basis for the development of a resistance management strategy designed to extend the efficacy of all classes of insecticides used for control.

Additions of feeding stimulants have been reported to increase the efficacy of Bacillus thuringiensis based insecticides (Bartelt et al. 1990). pheast™ (Miller Chemical and Fertilizer Corp., Hanover, Pennsylvania), which derives its trade name from yeast constituents, is one of the most effective feeding stimulants (Farrar and Ridgway 1994). Li and Fitzpatrick (1997) found that the addition of 5% Pheast to B. thuringiensis based insecticides increased the mortality of Choristoneura rosaceana (Harris) larvae fed leaves of raspberry plants, Rubus idaeus L. (Rosaceae), treated with these insecticides in the laboratory. We report results from a test of the effectiveness of Pheast when exposed to field conditions and fed to larvae in the laboratory.

The influence of defoliation type (artificial versus natural), timing (early versus late), and intensity (25%, 50%, and 75% of needle mass removed) on leader growth of Scots pine, Pinus sylvestris (Linnaeus), was assessed for 2 years after treatment on an even-aged stand located in southeastern Finland. Trees were defoliated simultaneously, either artificially with a pair of scissors or naturally with larvae of Neodiprion sertifer (Geoffroy) and Diprion pini (Linnaeus) for the early- and late-season treatments, respectively. After 1 year, early-season artificial defoliation generally caused greater growth reduction than natural defoliation. Late-season defoliation yielded opposite results. Trees defoliated artificially in early-season treatments were significantly shorter than control trees irrespective of defoliation intensity, whereas those defoliated late in the season did not differ from controls, except at the highest intensity. Trees defoliated by sawflies, either early or late in the season, were significantly shorter than control trees only at the highest defoliation intensity. The pattern of growth loss in the second year appeared similar to that in the first year. The impact of defoliation was either prolonged neutral or negative, as no compensatory responses on height growth in Scots pine were observed. Timing of the treatment in relation to completion of leader growth, differences in defoliation types, alteration of the photosynthetic capacity due to biomass loss, and the functional role of plant parts defoliated may explain the results observed.

A survey of larval and pupal populations of the spruce bud moth, Zeiraphera canadensis Mutuura and Freeman (Lepidoptera: Tortricidae), conducted from 1994 to 1996 in eastern Newfoundland, disclosed that the incidence of endemic parasitism by Hymenoptera was up to 50% for Tycherus osculator (Thünberg) (Ichneumonidae), up to 15% for Earinus zeirapherae (Walley), under 3% for Ascogaster (Wesmael 1835) sp. and Clinocentrus (Haliday 1833) sp. (Braconidae), and under 1% for Lamachus (Foerster 1868) sp. and Triclistus (Foerster 1868) sp. (Ichneumonidae). Tycherus osculator, E. zeirapherae, Ascogaster sp., and Clinocentrus sp. represent new distributional range extensions to Newfoundland, and to the nearctic region in the case of T. osculator. The biology of European populations of T. osculator was studied on a natural host, Zeiraphera diniana (Guenée). Only females overwintered and ovarian maturation did not occur until after several months of exposure to near-freezing temperatures. Tycherus osculator successfully parasitized prepupae and pupae of Z. diniana of all ages but, in the laboratory, appeared to prefer pupae. Host feeding by T. osculator was common but not necessary for ovarian maturation. Tycherus osculator imported from Europe attacked and successfully developed within the spruce bud moth host in laboratory screenings. Morphological comparisons indicated that T. osculator reared from Z. canadensis were smaller than those reared from Z. diniana. Tycherus osculator obtained from either Newfoundland or Europe may have potential as a biological control of Z. canadensis in mainland Canada, where it is presently absent.

The wheat midge, Sitodiplosis mosellana (Géhin), infests wheat, Triticum aestivum L., heads only up to anthesis when pollination occurs. The termination of infestation might be due to a deterrence of oviposition or to a suppression of larval growth on developing seeds. These hypotheses were tested in the laboratory by measuring oviposition preference, larval development, and larval preference for plants at different growth stages. Females showed no preference for ovipositing on heads at any stage from the onset of heading up to and including anthesis, and continued to lay eggs at a reduced rate 10 days after anthesis. Survival of newly hatched larvae was reduced on seeds 3–1 days after anthesis and survival and development was greatly reduced on seeds 5 or 6 days after anthesis. Larvae moved away from older seeds and fed on younger seeds in a choice test. Given a hatching time of 5–6 days, a failure to infest wheat after anthesis is not due to oviposition deterrence at anthesis, but to suppression of larval growth and development which begins soon after anthesis.

A 2-year field study was carried out to determine densities and stage-specific survival of eggs, second- and third-instar larvae, prepupae, pupae, and adults of Strobilomyia appalachensis Michelsen in a black spruce, Picea mariana (Mill.) B.S.P. (Pinaceae), seed orchard located in New Brunswick, Canada. Trends in stage-specific survival were similar for both years. Most individuals died during the second-instar stage, we suspect mostly because of failure to establish. The lowest stage survival occurred during the prepupal and pupal stages, due primarily to predation by ground-dwelling invertebrates.

Dendrocerus carpenteri (Curtis) was reared in the laboratory on prepupae of Aphidius ervi Haliday (Hymenoptera: Braconidae, Aphidiinae) developing in pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae). To test alternative hypotheses about host-marking behaviour and discrimination, we transferred unparasitized and previously parasitized A. ervi prepupae from donor to recipient mummies, which were either "unparasitized" or "parasitized." Females accepted already parasitized hosts within unparasitized mummies, but they rejected unparasitized hosts within previously parasitized mummies. Host discrimination was not influenced by self and conspecific parasitism. Eggs were frequently placed directly on the mummy shell, rather than on the primary parasitoid, or on dummies made from dental wax. Prepupae removed from their mummy shell were not accepted for oviposition. We propose that the "search template" of D. carpenteri is defined, primarily, by the aphid mummy, which is being marked with a contact pheromone after oviposition.

Natural mortality of gypsy moth [Lymantria dispar (L.) (Lepidoptera: Lymantriidae)] eggs, larvae, and pupae was examined at several locations along a gradient of infestation in Ontario, Canada. Most mortality of eggs was the result of exposure to winter weather. This mortality was mitigated in egg masses located near ground level where they benefited from snow cover. At least six species of parasitoids were found attacking gypsy moth larvae and pupae. The most common species were present in the same rank order of abundance at all sites. Identified pathogens were also present in most sites but their relative abundance varied greatly. The mycopathogen Entomophaga maimaiga Humber, Shimazu & Soper (Zygomycetes: Entomophthorales) was found at all sites and usually was responsible for the highest levels of observed, single-source mortality at the site.

Pitfall and screen traps were used around potato Solanum tuberosum L. (Solanaceae) plots to detect directional patterns of prediapause (two seasons) and postdiapause (one season) movement in a univoltine population of the Colorado potato beetle, Leptinotarsa decemlineata (Say), from Quebec. Prediapause beetles were sampled for diapause readiness using a feeding–digging test. In 1994, a plot left unprotected from the beetle (moderately defoliated) was monitored. In 1995, movement around a plot left unprotected from the beetle (severely defoliated) was compared to that from a plot protected (only lightly defoliated) by inundative release of the potato beetle predator Perillus bioculatus Say (Hemiptera: Pentatomidae). Movement frequency by postdiapause beetles in spring 1995 was low compared with 1994 prediapause movement, especially on the ground. Low-frequency flying persisted over several weeks of postdiapause beetle oviposition, with only a brief period of directionality. Flight movement by satiated prediapause beetles in August 1994 and 1995 was strongly directional, being oriented toward the closest forest border east of the plots, where sampling confirmed overwintering. In both years, satiated prediapause beetles also emigrated by walking, but mostly from densely populated and defoliated plots. Newly emerged (unsatiated) prediapause beetles emigrated en masse from severely defoliated plants, and did so exclusively by walking. Directional walking contrasted with directional flying in being predominantly oriented south-westward to northwestward, suggesting cueing on the sun position during warm hours of the day.

Colorado potato beetle, Leptinotarsa decemlineata (Say), is an important pest of potatoes Solanum tuberosum L. worldwide. To control this insect, commercial growers in North America may increasingly rely on planting transgenic potatoes that express the Bacillus thuringiensis (Berliner) subsp. tenebrionis Cry3A toxin in their foliage (Whalon and Ferro 1998). Because persistence and distribution of the toxin in these plants are maximized (Perlak et al. 1993), there is strong selection pressure towards development of resistance to the Cry3A toxin in beetle populations (Ferro 1993). One strategy proposed to delay development of resistance is to provide spatial refugia of nontransgenic potatoes to support populations of susceptible individuals sufficient to curtail matings between resistant individuals (Whalon and Ferro 1998). Therefore, it is important that susceptible beetles moving into the transgenic crop from refugia can successfully mate with local resistant beetles. Wierenga et al. (1996) reported that adult beetles that fed continuously on transgenic potatoes since eclosion from pupae did not display any reproductive activity, but that successful reproduction was eventually observed if beetles fed on nontransgenic foliage later. Under field conditions, however, it is more likely that susceptible beetles emerging from pupae in refugia will feed on nontransgenic potatoes before, not after, moving onto transgenic plants. We have recently discovered that under such circumstances female beetles remain reproductive, but with significantly reduced fecundity relative to control females continuously fed on nontransgenic foliage (Alyokhin and Ferro 1999). No such data are currently available for male beetles.

A European gall mite, Aceria malherbae Nuzzaci, was released and established in southern Alberta and Montana as a biological control agent for field bindweed, Convolvulus arvensis L. (Convolvulaceae). Populations of the mite survived for up to 4 years at some sites and caused slight to severe damage to the weed. The establishment of A. malherbae in these areas suggests that it could be established throughout the North American range of field bindweed.

Blueberry maggot, Rhagoletis mendax Curran, eggs and larvae infesting highbush ’Bluecrop’ and ’Elizabeth’ blueberries, Vaccinium corymbosum L. (Ericaceae), were treated with 4–1200 Gy of gamma radiation. The treatment reduced the number of immature stages that pupated and the number of adults that emerged from puparia. The lethal dose for 99.9968% mortality (LD 99.9968%) [lower and upper fiducial limits (FL)] estimated by linear regression analysis to stop pupariation was 1486 (1400–1585) Gy, at the 95% confidence level. The LD 99.99968% (lower and upper FL) estimated to stop flies emerging from puparia irradiated as immature stages was 88 (83–93) Gy, at the 95% confidence level as estimated by regression analysis. An estimated 100 762 larvae were killed, with no survivors, by irradiating 853 918 ’Bluecrop’ blueberries in bulk quantities with 71–776 Gy with a commercial irradiator. No flies or parasites emerged from puparia irradiated as larvae with ≥ 71 and > 80 Gy using commercial and research irradiators, respectively. Infestation rate of blueberry maggot larvae in nonirradiated ’Bluecrop’ and ’Elizabeth’ blueberries averaged 11.1 ± 1.2% and 14.3 ± 2.4%, respectively; the range of infestation rate was from 6.3% to 14.8% and 9.8% to 18%, respectively. Parasitism of blueberry maggot larvae by the larval–puparial parasite, Diachasmimorpha (Opius) mellea (Gahan) (Hymenoptera: Braconidae), averaged 10.1 ± 2.4% (range 3–13.3%).

For the last 50 years, populations of the Bruce spanworm, Operophtera bruceata Hulst, and other wingless geometrid species have been sampled using sticky bands placed around host-tree trunks to catch wingless females in search of oviposition sites. This method is tedious and, because of trap saturation by males, may underestimate female populations at moderate to high levels. A standard oviposition trap was developed to sample eggs of the Bruce spanworm and other wingless geometrid species. A small polyurethane foam band placed on a post covered by a Multi-Pher® plate detected low populations and was almost unsaturable during outbreaks. Sub-sampling can be easily done in such situations. Egg density on oviposition traps was higher than female density on sticky bands for both the Bruce spanworm and the fall cankerworm, Alsophila pometaria Harris. This suggests that the oviposition trap might be useful to sample other wingless geometrid species. Operating this system was easy and could involve woodlot owners and companies to reduce the traveling costs necessary to collect samples.

The efficacy of an extruded plastic trap placed on the ground was measured against plastic-lined trenches used to prevent the colonization of potato fields by walking overwintered Leptinotarsa decemlineata (Say). Laboratory comparisons showed that the original standard extruded trap did not capture as many adult beetles as the plastic-lined trench but that this could be corrected by abrading its surface. Beetles took longer to be trapped by the extruded trap than by the trench and walked away more frequently. The efficacy of the two barriers was unaffected by light simulated rain. Field tests in 1996 and 1997 confirmed that plastic-lined trenches can reduce adult abundance and egg deposition within field even when beetle populations were low. The original extruded trap did not significantly reduce egg deposition. However, it is suggested that a modified extruded trap could be used together with the plastic-lined trench to provide temporary closure of untrenched field sections used for farm equipment access or to surround small fields.