To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Mean 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.
We propose a sequential sampling plan for adult tuber flea beetles, Epitrix tuberis Gent., 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. tuberis densities 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.
Yellow water pan traps and yellow sticky traps were used to collect Delia spp. 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 Delia spp. 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. planipalpis females were similar in pan traps and sticky traps. Sticky traps, however, remained significantly better than pan traps for trapping all Delia spp. males, as well as D. platura females. 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 Delia species in crops such as canola. In routine monitoring programs for Delia spp., 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 Delia spp. complex in canola would be higher for sticky traps than for pan traps.
Dusky wireworms, Agriotes obscurus (L.), aggregated at rows of wheat, Triticum aestivum L., spaced 1 m apart within 6 d of seeding. Wireworms also aggregated at rows of newly planted strawberries, Fragaria × ananassa Duchesne, 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.
The 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 rapa cv. Tobin) at the rosette and flowering stages. Traps colored white, blue, or yellow generally caught higher numbers of D. radicum, D. floralis, and D. planipalpis than 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. platura in 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 Delia spp. in canola fields.
A specially constructed fence was developed to exclude cabbage flies, Delia radicum (L.), from plantings of rutabaga. The number of first-flight female D. radicum caught on traps inside fenced enclosures declined linearly with fence height from 0 to 90 cm. Females caught in plots surrounded by a 90 cm high fence were 80.6 and 82.8% fewer than in open check plots in 1991 and 1992, respectively. The percentage of transplanted rutabagas killed by cabbage maggot in the 90 cm high enclosures was 1.4% in 1991 and 25.5% in 1992, compared with 11.8 and 84.5% in the open check plots, respectively. The mean damage index rating for rutabagas was severe in the open check plots but slight in the 90 cm high enclosures in 1991. Only 1.2% of rutabagas in the open check plots would have been of marketable grade in 1991, compared with 54% in the 90-cm enclosures. The mean damage rating was highest in the open check plots in 1992, but damage was also severe in all fenced plots due to the heavy infestation levels that year. The potential of exclusion fences for use in pest-management programs for rutabagas and other brassica crops is discussed.
Early season infestations of adult tuber flea beetles, Epitrix tuberis Gentner, 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. tuberis may remain in harvested potato fields during winter.
Dusky wireworms, Agriotes obscurus (L.), aggregated in similar numbers at wheat [Triticum aestivum L. (Gramineae) ‘Max’], oat [Avena sativa L. (Gramineae) ‘Walderen’], barley [Hordeum vulgare L. (Gramineae) ‘Verdin’], and fall rye [Secale cereale L. (Gramineae) ‘Wheeler’ and ‘Prima’] cultivar bait stations containing 100 seeds planted 3 cm deep in 127-cm2 circular 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. obscurus increased 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. obscurus wireworm populations if planted in bait stations at 100 seeds/127 cm2, as well as for aggregating wireworms by means of a trap crop.
The goal of the Copenhagen Consensus project was to set priorities among a series of proposals for confronting ten great global challenges. These challenges, selected from a wider set of issues identified by the United Nations, were: climate change; communicable diseases; conflicts and arms proliferation; access to education; financial instability; governance and corruption; malnutrition and hunger; migration; sanitation and access to clean water; and subsidies and trade barriers.
A panel of economic experts, comprising eight of the world's most distinguished economists, was invited to consider these issues. The members were Jagdish N. Bhagwati of Columbia University, Robert S. Fogel of the University of Chicago (Nobel Laureate), Bruno S. Frey of the University of Zurich, Justin Yifu Lin of Peking University, Douglass C. North of Washington University in St Louis (Nobel Laureate), Thomas Schelling of the University of Maryland, Vernon L. Smith of George Mason University (Nobel Laureate) and Nancy Stokey of the University of Chicago.
The panel was asked to address the ten challenge areas and to answer the question: ‘What would be the best ways of advancing global welfare, and particularly the welfare of developing countries, supposing that an additional $50 bn of resources were at governments' disposal?' Ten challenge papers (chapters 1–10 in this volume), commissioned from acknowledged authorities in each area of policy, set out more than thirty proposals for the panel's consideration. During the conference, the panel examined these proposals in detail.
Email your librarian or administrator to recommend adding this to your organisation's collection.