Entomologia Experimentalis et Applicata (1999) 90, 141-148

J. Bligaard, R. Meadow, O. Nielsen and A. Percy-Smith (1999)
Evaluation of felt traps to estimate egg numbers of cabbage root fly, Delia radicum, and turnip root fly, Delia floralis in commercial crops
Entomologia Experimentalis et Applicata 90 (2), 141-148
Abstract: The use of felt traps to estimate oviposition by the cabbage root fly, Delia radicum (L.), and turnip root fly, Delia floralis (Fall.), was compared with soil sampling at seven localities between 1992 and 1994 in Denmark and Norway. In all, 281 comparisons were made, based on 6800 samples. In 4.6% of these comparisons no eggs were found by either method. In 16% of the comparisons, 2.0±0.41 (±S.E.) eggs were found per soil sample and no eggs were found in felt traps, whereas in 0.7% of the comparisons 0.10±0.03 eggs were found per felt trap and no eggs in soil samples. When eggs were found using both methods, the ratio between soil sampling and felt traps varied from 13.1±3.2 when the egg laying rate was very low to 1.8±0.2 at high egg laying rates. Regression analysis showed significant correlation between felt trap catches and soil sampling (P<0.001), whereas locality did not influence felt trap efficiency (P=0.096). The influence of the physical conditions of felt traps, i.e., whether they were clean and dry, were analysed in a single year. Tentative action thresholds for control measures against cabbage root flies and turnip root flies were developed for cauliflower, Brassica oleracea, convar. botrytis (L.) Alef., var. botrytis, based on data from the literature and the present results.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Jens Bligaard, Otto Nielsen, Richard Meadow

Research topic(s) for pests/diseases/weeds:
pheromones/attractants/traps
damage/losses/economics

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Delia radicum	Cabbage (Brassica oleracea)	Denmark
	Delia radicum	Cabbage (Brassica oleracea)	Norway
	Delia floralis	Cabbage (Brassica oleracea)	Denmark
	Delia floralis	Cabbage (Brassica oleracea)	Norway