Lygus species were sampled from alfalfa and canola fields in Manitoba from 1988 to 1990. Lygus lineolaris (Palisot de Beauvois), L. borealis (Knight), and L. elisus (Van Duzee) were found consistently throughout the agricultural area. The relative abundance of these species varied among crops, physiographic regions, years, and date of collection. The most abundant species in alfalfa and canola fields tended to be L. borealis in the north and west, L. elisus in the south, and L. lineolaris in the east. Each of the species was the most abundant in some collections, however L. borealis tended to be more abundant in alfalfa and L. lineolaris and L. elisus in canola. First-generation nymphs of Lygus species were found on alfalfa and those of the second generation on canola.

Pods of canola plants (Brassica napus L., mostly cv. Westar) were sampled annually from 11–40 canola fields in Manitoba in 1985–1991. The effects of temperature, precipitation, and lygus bug density (in 1989 and 1990) on seed classes (normal, aborted, and collapsed) were determined. In 1991, all pods from 10 racemes sampled from each of 11 canola fields in Manitoba were examined, and the collapsed seeds were classified as injured by lygus bugs or not. The proportion of aborted seeds was not related to lygus bug densities or to weather conditions. The proportion of collapsed seeds varied from 2 to 53% among fields and was related to the number of lygus bugs in the field at the time the pods were collected. Collapsed seeds increased by 1.5% for each lygus bug per sweep. In 2 yr, the proportion of collapsed seeds increased with the mean monthly temperature and decreased with the total precipitation in July, but these weather factors accounted for little of the variation in the proportion of collapsed seed in most years. Collapsed seeds occurred at low frequency in many pods at all canopy levels, but they were most common in small pods in the upper part of the canopy. The proportion of seeds injured by lygus bugs was estimated to be 3–5%, on average, and in some fields, 20%. In addition, lygus bug feeding on other parts of the host plant may induce seed collapse. Key words: Insecta, Lygus, Brassica napus, seed damage, canola

The cabbage root maggot, Delia radicum (L.), was the only Delia species capable of attacking undamaged roots of canola [oilseed rape, Brassica napus (L.)] that was found in commercial fields in Manitoba. Adults of the overwintering generation infest canola. Their progeny, adults of the first generation, left the maturing plants after completing a single generation. Root maggot damage occurred in fields in all agricultural regions of the province. The mean percentage of the roots with damage was higher in the more northerly agricultural regions (15.8%) than in the south (8.0%). Most of the damage was light and the damage did not visibly affect the growth or vigour of the plants. Foot rot fungi were not associated with the feeding damage. In cage experiments, the seed yield of canola did not decrease with increasing proportions of plants damaged by D. radicum. The percentage of plants with root maggot damage (DAM) was best described in a polynomial by the mean daily air temperature (TEMP) and the total precipitation (RAIN) for June and July:log(DAM + 1)=–12.3 + 0.66 TEMP + 0.09 RAIN – 0.004(TEMP × RAIN).The level of damage caused by the larvae of D. radicum to canola in commercial fields during the years 1985 through 1988 did not appear to have caused yield losses. However, the level of damage increased with increasing precipitation and temperature during June and July so a series of favourable years could lead to increased damage and possibly to significant yield losses.

. 2002. A rapid method to detect Cryptolestes ferrugineus (Coleoptera: Cucujidae) larvae in stored grain. Can. J. Plant Sci. 82: 591-597. Modifications of three detection methods, based on the heat-gradient principle employed by the Berlese funnel method were investigated to extract larvae of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), developing under the seed coats of infested kernels in grain samples. Onekilogram samples of wheat, barley and corn were artificially infested with rusty grain beetle eggs, resulting in survival rates (to larval stage) of 71.1 ± 14.4, 58.9 ± 14.3, and 24.7 ± 11.8%, respectively. Sets of 10 infested kernels containing different-aged larvae (10 individuals ¥ 4 instars) were added to 1-kg samples of hydrated grain, then heated on screens beneath heat sources (lights) at several heights in three different containers (Berlese funnel, with a 7-cm-deep grain layer, or square and rectangular screened boxes with a grain layer several kernels deep). There were no significantly different extraction rates between the rectangular and square containers for all heating trials. A larval extraction rate of 31% was produced by 1-h trials with wheat (15% moisture content wet basis) 5.5 cm below the lamp bank with a thermostat set at 50°C. This matched the efficiency of the Berlese funnel method (36% extraction in 6 h), but in much less time. Similar results were found for barley, but for corn the square and rectangle gave significantly better extraction than the Berlese funnel, although extraction efficiency was half that of wheat and barley. Considerably lower extraction rates were obtained from trials that did not use a thermostat. The results from this experiment show that there is a potential alternative detection method with the thermostatically controlled heating of a thin layer of grain that should be faster than the conventional 6-h Berlese funnel method. Cette méthode s'avère aussi efficace que l'appareil de Berlèse (taux d'extraction de 36 % au bout de 6 heures), mais est beaucoup plus rapide. Des résultats analogues ont été obtenus avec l'orge, mais les récipients carré et rectangulaire donnent un taux d'extraction significativement supérieur à celui de l'appareil de Berlèse pour le maïs, même si l'extraction est deux fois moins efficace qu'avec l'orge ou le blé. Sans thermostat, les essais entraînent un taux d'extraction considérablement plus faible. Les résultats indiquent que le chauffage d'une mince couche de grains avec réglage thermostatique pourrait constituer une méthode de dépistage plus rapide que la technique traditionnelle avec l'appareil de Berlèse.

Can. Ent. 122: 1201-1210 (1990) Pea aphids, Acyrthosiphon pisum (Hams), were sampled weekly or biweekly over the summers of 1985 and 1986 in a total of 15 commercial plantings of Century, Trapper, or Triumph field peas across Manitoba. Pea aphid populations rose more quickly in fields of Trapper than in Century or Triumph fields. The owners of all Trapper fields sampled initiated aerial application of insecticide for pea aphid control; at the time of THE CANADIAN ENTOMOLOGIST NovemberIDecember 1990 du pois en apogee a 48,5 & 9,2 (ETM) (erreur-type du moyen) par pointe de la plante pendant la formation et le remplissage des cosses. Les pertes significatives ont aussi kt15 demontrees dans les lotissements non-arrosks d'un champ de Triumph, ayant une apogee de pucerons de 4,8 ? 1,6 par tige de plante a la maturation de la cosse.