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AbstractDusky wireworms, Agriotes obscurus(L.), aggregated in similar numbers at wheat [Triticum aestivumL. (Gramineae) ?Max?], oat [Avena sativaL. (Gramineae) ?Walderen?], barley [Hordeum vulgareL. (Gramineae) ?Verdin?], and fall rye [Secale cerealeL. (Gramineae) ?Wheeler? and ?Prima?] cultivar bait stations containing 100 seeds planted 3 cm deep in 127-cm2circular bait stations. Similar levels of aggregation also occurred at 11 varieties of wheat planted at 100 seeds/127 cm2. When wheat, oat, barley, and the fall rye cultivars were planted at increasing density (0?180 seeds per bait station), aggregation by A. obscurusincreased initially, but reached a plateau at numbers and at seeding rates specific to each grain variety as determined using the asymptotic equation y= B0(1 ? e?B1x). Except for barley, this equation predicted wireworm densities within 11% of the densities actually observed at bait stations with 100 seeds/127 cm2. It was concluded that any of the wheat, oat, barley, or fall rye varieties would be suitable for monitoring A. obscuruswireworm populations if planted in bait stations at 100 seeds/127 cm2, as well as for aggregating wireworms by means of a trap crop.

AbstractDusky wireworms, Agriotes obscurus(L.), aggregated at rows of wheat, Triticum aestivumL., spaced 1 m apart within 6 d of seeding. Wireworms also aggregated at rows of newly planted strawberries, Fragaria× ananassaDuchesne, resulting in 43% plant mortality. Wheat rows planted 8 d in advance of intercropped rows of strawberries aggregated wireworms at the wheat rows rather than at the strawberry rows. Mortality of strawberry plants protected by the previously planted wheat rows was only 5.3%. Strawberry seedlings planted 14 d before intercropping with wheat rows incurred 29.6% mortality. These data show that trap crops of wheat planted 1 week in advance of planting strawberries can effectively reduce wireworm feeding and plant mortality and can be used as an inexpensive pest management method.

AbstractYellow water pan traps and yellow sticky traps were used to collect Deliaspp. flies in plots of canola, var. Tobin, for an entire growing season in the Peace River region of Alberta. At one or more times during the growing season, pan traps and sticky traps captured Delia radicum(L.), Delia floralis(Fallen), Delia planipalpis(Stein), or Delia platura(Meigen). Numbers of males and females caught varied dramatically between the two trap styles, both within and between the various species. Prior to the onset of flowering, cumulative captures of each of the four Deliaspp. in pan traps were all significantly lower than on sticky traps for females and males. From the onset of flowering until trapping ended on 17 August, cumulative captures of D. radicum, D. floralis, and D. planipalpisfemales were similar in pan traps and sticky traps. Sticky traps, however, remained significantly better than pan traps for trapping all Deliaspp. males, as well as D. platurafemales. Pan traps were more suitable than sticky traps for collecting intact specimens for positive identifications. Results indicate that a combination of sticky traps and pan traps should be used over an entire growing season when conducting initial surveys for Deliaspecies in crops such as canola. In routine monitoring programs for Deliaspp., sticky traps would be more efficacious early in the growing season and more practical than pan traps. The level of expertise required to accurately identify the Deliaspp. complex in canola would be higher for sticky traps than for pan traps.

AbstractThe responses of adult cabbage maggot [Delia radicum(L.)], turnip maggot [D. floralis(Fallén)], radish maggot [D. planipalpis(Stein)], and seedcorn maggot [D. platura(Meigen)] to sticky traps painted blue, yellow, green, non-UV-reflecting white, or UV-reflecting white, were determined in a field of canola (Brassica rapacv. Tobin) at the rosette and flowering stages. Traps colored white, blue, or yellow generally caught higher numbers of D. radicum, D. floralis, and D. planipalpisthan did traps colored green or UV-reflecting white. Depending on the crop developmental stage and its background color, response to color sometimes differed both within and between the sexes. This was most pronounced for D. floralis, for which blue and white traps were preferred by males at the rosette stage but not die flowering stage, and for which white, but not blue, traps were preferred by females at the rosette siage. White and blue, but not yellow, were the colors preferred by male and female D. platurain our study, with UV-reflecting white also being preferred by males during the flowering stage. It was observed dial catches on white and yellow traps were often significantly different and [hat white versus yellow preferences could be reversed within or between males and females of certain species during the rosette or flowering stages. The data suggest dial the concurrent use of white and yellow sticky traps should be considered when conducting relative abundance surveys of Deliaspp. in canola fields.

AbstractWe propose a sequential sampling plan for adult tuber flea beetles, Epitrix tuberisGent., in potato fields, which is based on a confidence interval calculated around a critical density value (Iwao 1975) and which uses Taylor’s Power Law (Taylor 1961) to estimate the variance. Because of the highly edge-biased gradients of density displayed by this insect, separate sequential expressions have been calculated for densities at the edges and centers of fields.In a survey of 12 commercial potato fields, spring-generation E. tuberisdensities in centers of fields were always far below the threshold level of one beetle per 10 plants employed at the time of sampling. The survey also indicated that fields that have been sown with potatoes for 2 consecutive years have higher beetle densities than fields sown with potatoes for a 1st year. Edge:center density ratios, however, were the same for the two categories of fields.

AbstractMean weekly catch of adult Psila rosae(F.) on sticky, yellow-painted cardboard traps from 93 commercial carrot fields provided seasonal records of their activity during 1980–1983 in the lower Fraser Valley, British Columbia. When monitoring extended from April through November in 1982 and 1983, 3 distinct periods of adult activity were observed that probably reflect the occurrence of 3 adult generations per year. Trap catch first peaked in mid- to late-May, followed by a second peak in late-July to early-August, and a third peak in mid-October. Of the temperature summations calculated, those commencing 1 February provided the most accurate degree-day (DD) indices for predicting seasonal activity of overwintering and 1st-generation adults. Four-year means for cumulative DD above 3 °C (air temperature) after 1 February for first, 10%, maximum, and 90% trap catch of the overwintering generation were 326, 435, 557, and 838 DD, respectively.

Early season infestations of adult tuber flea beetles, Epitrix tuberisGentner, usually are concentrated at the edges of potato fields, and it generally has been assumed that they move into potato fields from the outside inward. This edge-effect suggests that tuber flea beetles overwinter outside potato fields, and other species of flea beetles have been reported to behave similarly (Wolfenbarger 1940; Dominick 1971; Burgess 1981). This may not be true of E. tuberis, however. Hoerner and Gillette (1928), in Colorado, noted that potatoinfesting flea beetles [probably E. cucurneris(Harris), E. subcrinata(Lec.), or E. tuberis] often congregated under piles of old potato vines in potato fields, and Hill and Tate (1942) observed flea beetles feeding on cull tubers in a potato field after harvest. These observations suggest, but do not confirm, that some flea beetles including E. tuberismay remain in harvested potato fields during winter.