Trioza apicalis

Fig. 1. Adult carrot psyllid. Photo: Bioforsk
The carrot psyllid also has a strong preference concerning its summer host. Studies have
shown that it chose carrot over other host plants (Rygg 1977; Nehlin et al. 1996). Rygg
also found that the carrot psyllid could not complete its development on other hosts he
investigated. In other studies, where the females were not given a choice of host plants,
they layed eggs on several species related to carrot and the larvae were able to develop on
most of these (Valterová et al. 1997).
When the adults have settled on the carrot plants they begin feeding. They feed by
inserting a stylet into the plant tissue (Hodkinson 1974) and suck nutrients from the
phloem. Feeding by carrot psyllid causes curling of the youngest leaves (fig. 2), not
necessarily directly at the feeding site. This is assumed to be the result of a toxin that is
transported systemically in the plant causing other symptoms, including wilting and death
of the plants (Markkula & Laurema 1971). The toxin is unknown, but recent studies have
shown an association between the carrot psyllid and the plant pathogenic bacterium
Candidatus Liberibacter solanacearum (Munyaneza et al. 2010). In a Norwegian study, a
trained test panel conducted sensory tests of carrots with different levels of carrot psyllid
damage (Seljåsen et al. 2006). They found that plants with heavy attack early in the
growth period yielded carrots that had negative taste characteristics, including bitterness
and astringency, and that the carrots were tough and lacking crispness.
Meadow. Bioforsk Rapport vol. 5 nr. 151 2010
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