Developing a bait for asparagus miner (Diptera: Agromyzidae) monitoring in commercial asparagus fields

Globally, asparagus production is in decline due to increased pest pressure, despite increasing consumer demand. The asparagus miner, Ophiomyia simplex (Diptera: Agromyzidae) is an important pest because it is a potential vector of Fusarium crown and root rot and because it causes direct damage to stems. Asparagus growers are lacking a monitoring method and management tool for this insect pest. Because the asparagus miner is a specialist, it is likely that it uses chemical cues from the plant to locate asparagus, and if these cues were better understood they may be used as part of a monitoring tool.  The goals of the current research project were 1) to compare healthy and damaged asparagus headspace, 2) to identify individual volatiles in the asparagus headspace, and 3) to test volatile baits in a field experiment. Asparagus headspace composition was different among intact, mechanically-damaged, and herbivore-damaged plants, but some volatiles were expressed constitutively. In particular, hexadecyl acetate is associated with mechanically-damaged plants, whereas pentadecane and 1-hexadecene is associated with herbivore-induced plants and hexanoic acid was constitutively expressed. Six volatiles that were identified from damaged and healthy plants were used in baits attached to yellow sticky traps in a field experiment. Baits were deployed in a randomized complete block design in three commercial asparagus fields. Certain baits attracted (e.g. methyl salicylate), while others repelled the asparagus miner (decanal) under field conditions relative to the control. This information can be used to help tailor management of the asparagus miner through monitoring or reducing its populations.