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Can. Ent. 107: 1233-1252 (1975) Several species of wireworms were attracted to germinating wheat, air from flasks of germinating wheat, decomposing oatmeal, commercial CO, and, in addition, germinating seeds of eight other cultivated plant species. Larvae located a biological or experimental source of CO, by a directed movement along CO, gradients, from distances up to 20 cm.Methods and apparatus for measuring small CO, gradients, using gas chromatography and mass spectrometry, are described. Ctenicera destructor (Brown) larvae apparently responded to CO, gradients between glass plates, that ascended on the average by 0.0028 (soil) and 0.0058 (agar)/cm over a distance of from 12 to 16 cm. The "sensitivity threshold" was calculated as being 1-2 ppm over the distance involved in one deflection of the head during klinotactic orientation. Attractancy was observed within a range of CO, concentration from about 0.0368 to 1.5%. Repellent effects did not appear to be only related to concentration, but possibly were due to steepness of the gradient and(or) previous exposure to CO,.Passing an air stream from germinating grain over a KOH solution eliminated the attractancy of the grain by removing the CO, and possibly other undetected attractants. A small percentage of C. destructor larvae apparently oriented to an ethylene source, but it was concluded the CO, was the most important if not the only attractant from germinating wheat seeds. General MethodsThe wireworms used for the majority of the experiments were Ctenicera destructor (Brown) and Agriotes obscurus-lineatus (L.). Observations were also made on Limonius californicus (Mannerheim) and Hypolithus bicolor Eschscholtz. The Agriotes larvae were collected from pastures in Switzerland, near Wadenswil and Horgen in the autumn and near Egnach in the spring. The remaining species mentioned above were collected near Saskatoon, Sask.The A. obscurus-lineatus, L. californicus, and H . bicolor larvae were brought to room temperature (22-25°C) 24-48 h before being used in experiments. The C . destructor larvae were put in individual dishes at 15OC for at least 2 weeks and then transferred to room temperature (ca. 25°C) for testing. None of the larvae was fed before any of the experiments.The response of larvae to the stimulus offered by a germinating seed or a source of CO, was observed and recorded following the general method of Klingler (1958). A thin layer of soil was sprinkled on a 3 0 x 30 cm glass plate on which a germinating seed or seeds had been placed. The soil and seed were then covered by a second glass plate held 2.4 mm above the bottom plate by supports in each comer. If CO, was used as the stimulus, a No. 22 hypodermic needle 15 cm long was taped to the bottom of the top plate at any desired point between the plates before the soil was applied. The hypodermic needle was connected to a 125-or a 50-ml flask filled with COZ4 and with an automatic syringe which allowed injection speeds ranging from 0.2 to 60 mllh.Larvae to be tested for a response were introduce...

Losses in yield of spring wheat due to infestations of Sitodiplosis mosellana (Géhin) were determined for 700 000 ha of arable land in northeast Saskatchewan, Canada in 1983. The proportion of kernels infested (y) was a power function of the number of wheat-midge larvae (x) (y = 35.3x0.725). One, 2, 3, and 4 larvae per kernel resulted in a level of infestation of 38, 58, 78, and 96%, respectively. There was no significant difference between infestation levels from fields sampled at the heading stage of crop growth and the estimates of infestation levels for these fields at harvest time. Yield of grain (y) was negatively exponential to an increase in level of infestation (x) (ln y = 5.7−0.017x). Infestations of 30, 60, and 90% reduced yields of spring wheat by 40, 65, and 79%, respectively. The average decrease in crop yield in the study area was about 30%, which resulted in estimated losses in total gross revenue of about $30 million.

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The Crystalens AT-45 accommodating IOL provided good uncorrected near, intermediate, and distance vision in pseudophakic patients. Contrast sensitivity with the Crystalens AT-45 was not diminished relative to standard monofocal IOLs, and near and intermediate visual performance was significantly better than with standard IOLs.

No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

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