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Abstract. A Y-tube olfactometer and a still-air olfactometer were developed to determine the attractiveness of several host plants for the vine weevil (Otiorhynchus sulcatus (F.); Coleoptera: Curculionidae). Odours of weevil-damaged yew (Taxus baccata) and spindle trees (Euonymus fortunei) are attractive to the vine weevil, but Rhododendron and strawberry (Fragaria  ananassa) are not. Undamaged Euonymus is attractive to the weevils in springtime but not in late summer. When clean air or undamaged Euonymus is the alternative, weevils strongly prefer weevil-damaged Euonymus foliage, and this preference is retained throughout the year. Hence, plant damage plays a role in attraction of the vine weevil. In contrast to the permanent attractiveness of weevil-damaged Euonymus, mechanically damaged plants gradually lose the attractiveness that they have early in the growing season. This suggests that emission of volatiles, produced by the plants in response to weevil damage, is important for attraction of the weevils because the weevils may use these plant odours to find suitable food plants throughout the season. Apart from weevil-damage-related plant volatiles, green leaf volatiles must also play a significant role, as indicated by the fact that weevils prefer: early season, undamaged Euonymus over clean air; early season, mechanically damaged Euonymus over undamaged Euonymus; and, throughout the season, had no preference when mechanically damaged Euonymus is tested against weevil-damaged Euonymus. Thus, monitoring traps may be developed by the use of green leaf volatiles and/or herbivore-induced volatiles, as attractants.

Root weevils in the genus Otiorhynchus are cited as one of the most important pests in the major nursery and small fruit production areas throughout the United States, western Canada, and northern Europe. A major problem in combating weevil attack is monitoring and timing of control measures. Because of the night-activity of the adult weevils growers do not observe the emerging weevils in a timely manner and oviposition often starts before effective control measures are taken. Several vine weevil electroantennogram-active plant volatiles were identified from a preferred host plant, Euonymus fortunei. Main compounds evoking antennal responses on the weevils' antennae were (Z)-2-pentenol, (E)-2-hexenol, (Z)-3-hexenol, methyl benzoate, linalool, (E)-4,8-dimethyl-1,3,7-nonatriene, methyl eugenol, and (E, E)-alpha-farnesene. Several of these compounds were tested alone and in mixtures on attractiveness for the vine weevil Otiorhynchus sulcatus (F.) in field-grown strawberry in Oregon. O. sulcatus were attracted to (Z)-2-pentenol (approximately 3 x more than control) and a 1:1 ratio mixture of (Z)-2-pentenol and methyl eugenol (4.5 x more than control). This is the first report of field-active attractants for O. sulcatus which holds promise for the development of new monitoring strategies for growers in the near future.

We compared the efficacy of four plant essential oils to repel onion thrips, Thrips tabaci (Lindeman) (Thysanoptera: Thripidae), in the presence of an attractive odour, ethyl iso -nicotinate in a pasture field. Four horizontal white sticky plates were placed adjacent to (directions: N, S, E, W) a central horizontal white plate (C). After 24 h, in the treatment combination where the four plates were sprayed with essential oil surrounding a central sticky plate sprayed with ethyl iso -nicotinate, fewer onion thrips were found on the plates treated with sweet marjoram [ Origanum majorana L. (Labiatae)] or clove basil [ Ocimum gratissimum L. (Labiatae)] (87 and 71% less, respectively) compared to the control treatment of four water-sprayed plates surrounding a central plate with ethyl iso -nicotinate. We also compared the distribution of onion thrips on the plates. Relative thrips numbers on each plate were compared with similar (N, S, E, W, and C) plates in the control treatment. There were relatively lower thrips numbers on the south (23% reduction) and west (26% reduction) O. majorana -treated plates and higher numbers (37% increase) on the central attractant-treated plate indicating a shortdistance push-pull effect. When four plates were sprayed with the thrips attractant surrounding a central sticky plate sprayed with an essential oil or water (control), only O. majorana reduced the number of thrips on the attractant-sprayed plates (62% reduction). The distribution of thrips on the different plates within this treatment combination did not change substantially when compared to the distribution in the water-control treatment. Other essential oils tested (wormwood [ Artemisia arborescens L. (Compositae)]) and tea tree [ Melaleuca alternifolia (Maiden. & Betche.) Cheel. (Myrtaceae)]) were not effective in any of the treatments. It appears that O. majorana is a promising thrips repellent which could be used for further testing in a push-pull system with the attractant ethyl iso -nicotinate. The field setup used also proved to be a valuable tool for evaluating the potential of repellents to control onion thrips.