"Attract and reward” for syrphid flies using methyl salicylate and sweet alyssum in kale in north Florida

Authors: Legaspi, Jesusa; Miller, Neil; KANGA, LAMBERT - Florida A & M University; HASEEB, MUHAMMAD - Florida A & M University; ZANUNCIO, JOSE - Universidade Federal De Viçosa

Submitted to: Subtropical Agriculture and Environments
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/26/2020
Publication Date: 7/8/2020
Citation: Legaspi, J.C., Miller, N.W., Kanga, L.H., Haseeb, M., Zanuncio, J.C. 2020. "Attract and reward” for syrphid flies using methyl salicylate and sweet alyssum in kale in north Florida. Subtropical Agriculture and Environments. 71:49-52.

Interpretive Summary: Hoverflies are important generalist insect predators of whitefly and aphid insect pests in vegetable crops. Plants are known to produce odors when fed on by insect pests which in turn attracts the generalist predators (known as the attract component). Flowering plants are known to provide nectar as a source of nourishment to these predators (known as the reward component). Scientists at the USDA, ARS, Center for Medical, Agricultural and Veterinary Entomology in Tallahassee, Florida, in collaboration with researchers from Florida A&M University and Universidad Federal de Vicosa conducted studies to test a plant volatile methyl salicylate as a reward in attracting hoverflies. The test was conducted in kale and broccoli crops in north Florida with sweet alyssum flowering plants as a natural reward for the hoverflies. We found that sweet alyssum attracted the most numbers of hoverflies while, methyl salicylate alone was not an effective attractant of hoverflies. Even though methyl salicylate was not an effective attractant, other plant volatiles will be studied that may contribute as an effective component in an attract and reward system for hoverflies.

Technical Abstract: “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. 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 hoverflies, and sweet alyssum (Lobularia maritima L. Desv. (Bassicales: Brassicaceae)) to reward them in kale and broccoli fields in north Florida. In spring 2014, sweet alyssum in kale showed higher incidence of hoverfly visitations compared to untreated control fields. The most dominant species found was Toxomerus marginatus (Say). Fall 2014 experiments in broccoli compared hoverfly counts using MeSA, sweet alyssum, MeSA + sweet alyssum, and an untreated control. Analysis was possible only for T. marginatus, although the following species of syrphids were recorded: Pseudodoros clavata F., Syritta pipiens (L.), Eristalis spp., Chalcosyrphus spp., T. boscii Macquart, T. geminatus (Say), Ocyptamus fuscipennis (Say), Eupeodes americanus Wiedemann, and Allograpta obliqua (Say). Sweet alyssum was found to increase incidence of T. marginatus. However, the addition of MeSA did not increase hoverfly counts in either the sweet alyssum or untreated controls. The pattern was repeated in spring 2015, but did not attain statistical significance (P = 0.07). In attract and reward for hoverflies in kale and broccoli, sweet alyssum has shown potential as a reward component, but MeSA proved ineffective as an attractant. Other HIPVs should be evaluated to develop an effective attract and reward system for hoverflies.