Abundance of adult hoverflies (Diptera: Syrphidae) on different flowering plants

Author

Dept. of Plant Protection, Ferdowsi University of Mashhad

Abstract

Encouraging natural enemies by growing attractive plants is considered an effective method of pest control in organic farming. However, it is important to identify which flowers best attract beneficial insects. In this study, relative attractiveness of 16 species of flowering plants to adult hoverflies was assessed by conducting timed observations of feeding-visit frequencies. The experiments were conducted at two sites, at FUM Research Farm and FUM Campus in a completely randomized design with 3 replications. At both sites, there were significant differences between the mean numbers of feeding-visits to selected flowers by hoverflies. At the Research Farm Fennel, Chamomile, Hypericum, Yarrow, Lavender and Bishop's weed had higher visit rates than Marigold, Spider ivy, Sage, Dill and Dwarf Lark Spur. At this site, Fennel followed by Hypericum and Yarrow attracted more hoverflies than other flowers throughout the season. Lavender and Bishop?s weed that were less attractive on early sampling dates received more hoverflies toward the end of the season. At the FUM Campus, Petunia, Chamomile and Cosmos were the most attractive flowers, whereas Ageratum, Yarrow and Coreopsis were of intermediate visit status and Pot marigold was relatively under visited. On the whole, Cosmos, Petunia and Chamomile were visited more frequently than other floral sources, but their attractiveness were not constant throughout the season. On the first two sampling dates, Chamomile was the most preferred flower, but on the last two dates of sampling Cosmos was highly attractive to hoverflies. The hoverflies found in the study sites were: Sphaerophoria scripta (L.), Episyrphus balteatus (DeGeer), Eupeodes corollae (Fab.), Syrphus ribesii (L.), Eupeodes nuba (Wied.), Syrphus vitripennis (Meigen), Paragus bicolor (Fabr.), Sphaerophoria ruppellii (Wied.), Paragus tibialis (Fallen), Eristalis spp., Syritta pipiens. Sphaerophoria scripta, Episyrphus balteatus and Eupeodes corollae , which were the most abundant aphidophagous species.

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