"Attract and reward" for syrphid flies using methyl salicylate and sweet alyssum

“Attract and reward” is an ecologically-based pest management technique for improving biological control. A predator attractant, such as an herbivore-induced plant volatile (HIPV) is used to “attract” the biological control agent. The predator is sustained and nourished by an insectary plant which acts as a “reward”. The “attract” and “reward” effects are expected to act synergistically in enhancing the effectiveness of the predator. Here we tested methyl salicylate (MeSA) to attract syrphid flies, and sweet alyssum (Lobularia maritima L. Desv.) to reward them in a kale (Brassica rapa L.) field in north Florida, USA. We found sweet alyssum in kale showed higher incidence of syrphid fly visitations compared to untreated control fields. The most abundant syrphid fly species was identified as Toxomerus marginatus. In another field study, we compared syrphid fly counts using MeSA, sweet alyssum, MeSA + sweet alyssum, and an untreated control. Sweet alyssum was found to increase incidence of T. marginatus. However, the addition of MeSA did not increase syrphid fly counts in either the sweet alyssum or untreated controls.  In attract and reward for syrphid flies, sweet alyssum has shown potential as a reward component, but MeSA proved ineffective as an attractant when used alone or did not have an additive effect when combined with sweet alyssum. Other HIPVs should be evaluated to develop an effective attract and reward system for syrphid flies.