Integrated control of aphids on organic celery – from the glasshouse to the field

Abstract: Aphids are serious pests of field-grown organic celery. Willow-carrot aphid
(Cavariella aegopodii), peach-potato aphid (Myzus persicae), and black bean aphid (Aphis
fabae) all cause feeding damage and are contaminants on the harvested crop. Cavariella
aegopodii can also transmit celery mosaic virus which is very damaging. Options for the use of plant protection products (PPPs) on organic celery are very limited. Available integrated pest management (IPM) methods include use of insect-proof mesh over the crop, use of contactacting PPPs such as fatty acids and the release of biological control agents including aphid parasitoids, both in the glasshouse at the propagation stage and after transplanting into the field. Although Aphidius colemani is known to parasitise M. persicae and A. fabae, little was previously known about the efficacy of commercially available parasitoids against C.
aegopodii. In laboratory bioassays using celery leaves, Aphidius colemani and Aphidius
matricariae were equally effective against M. persicae and both species parasitised A. fabae.
In laboratory bioassays and a pilot cage experiment, both A. colemani and A. matricariae
parasitised C. aegopodii on celery, with A. matricariae potentially being a better candidate. In a field trial on a commercial organic celery crop under bird netting, using increased parasitoid release points and barley banker plants infested with bird cherry-oat aphids (Rhopalosiphum padi) to augment numbers of both A. matricariae and A. colemani gave promising results, leading to better control of C. aegopodii than the grower’s standard IPM strategy of using aphid parasitoids at less frequent release points under insect-proof mesh. The grower is now adopting the use of banker plants to boost natural enemies, to improve aphid control in organic celery.