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The potential for pheromone-based mating disruption of the Brassica pest Contarinia nasturtii was tested, both in small-scale plots with Brussels sprouts and in commercial-scale fields with either broccoli or cauliflower. Experiments in the small-scale plots used laboratory-reared insects released into a previously uninfested area, whereas large-scale experiments used a high natural population of C. nasturtii. Effectiveness of mating disruption was evaluated by the reduction of male captures in pheromone traps, and by reduction of crop damage caused by C. nasturtii. Dental cotton rolls (small-scale experiment) and polyethylene caps (large-scale experiment), containing 50 μg (2S, 9S)-diacetoxyundecane, 100 μg (2S,10S)-diacetoxyundecane, and 1 μg (2S)-acetoxyundecane, spaced 2 m apart, served as dispensers in the test plots. In both experiments, mean catches of C. nasturtii males in pheromone traps were reduced to near zero in treated plots, with control plots averaging 71 males/trap. In the large-scale experiments, no males were caught in pheromone traps over a period of 41 days after mating disruption was applied; one male was caught from days 42-60. In the small-scale trials, crop damage was reduced by 59 %, compared to the untreated control plot. In the large-scale experiments, damage was reduced on average by 91 %. This study shows successful field application of the mating disruption technique for control of a member of the dipteran family Cecidomyiidae, and demonstrates that pheromone-based mating disruption has potential for management of C. nasturtii populations.

The walnut husk fly, Rhagoletis completa Cresson (Diptera: Tephritidae), has recently invaded Switzerland, Austria, Germany, and France, probably crossing the alpine divide after its initial introduction into Italy. Here, the susceptibility of 36 walnut [ Juglans regia L. (Juglandaceae)] cultivars to attack by R. completa was studied in an experimental orchard in Switzerland. Walnut cultivars differed significantly in infestation rates; cultivars that produced large, heavy fruit harboured significantly more larvae than cultivars that produced smaller fruit. Pupal weight was significantly influenced by cultivar, but not by any of the physical properties that we measured. For individual fruit within a cultivar, pupal weight was weakly related to fruit weight and infestation level. Adult longevity was correlated with pupal weight and appeared to be favoured in flies that developed in large-fruit cultivars. The longevities of adults recovered from different cultivars differed significantly. The shortest longevity was recorded for flies recovered from Geisenheim 1049 (39.2 ± 2.80 days) and the longest for flies recovered from Sheinovo (68.8 ± 21.75 days). Differences in diapause length were also highly significant and varied between 167 ± 5.1 (Esterhazy III) and 257.4 ± 8.21 days (Mayette). These results suggest that (1) across and within cultivars, walnut husk flies prefer to infest (i.e., they develop better in) large, heavy fruit, and (2) offspring that develop in large fruit are likely to accrue fitness advantages over the offspring of females using smaller fruit. Our results provide the basis for subsequent studies on resource defence by males, as they enable a prediction of which type of fruit males should defend more vigorously. [ABSTRACT FROM AUTHOR]