Carrot psyllid (Trioza apicalis) winter habitats - insights in shelter plant preference and migratory capacity

In English The carrot psyllid (Trioza apicalis) is a serious pest in carrot-growing areas in northern and parts of central Europe. The psyllids overwinter as adults on conifers and during summer feed and lay eggs on carrot plants (Daucus carota ssp. sativus), thereby destroying the crop. To investigate the migratory capabilities and preferences for different shelter plant species of the carrot psyllid, we made an inventory study of its winter habitats in three carrot-growing regions in southern Sweden. Norway spruce (Picea abies) was the preferred conifer over Scots pine (Pinus sylvestris) and juniper (Juniperus communis). We found psyllids on trees up to 1 km from the carrot fields, which was the largest distance sampled. The regression of catch numbers over distance was non-significant, however all samples containing more than seven psyllids were collected within 250m distance from the fields. There was no obvious pattern between catch directions and the prevailing wind directions of the preceding migratory period. Our study did not show any differences between males and females with respect to migration or shelter species preferences.