Tachinidae (Diptera) associated with flowering plants: Estimating floral attractiveness

Non-agricultural flowering plants in agricultural settings provide ecological services, such as nectar-food for adult parasitic flies. In order to determine the attractiveness of flowers to Tachinidae, 12 species of cultivated, introduced/established and native potted plants-in-flower were individually placed beneath interception traps erected along the wooded margins of fields planted seasonally with either feed-corn or rye. Simultaneous controls consisted of traps associated with the same species of plant without flowers, a pot without plants or both. In two additional instances where flowering-plants grew in situ it was necessary to compare initial trap captures to those following the removal of the plants. Of the 14 plant species tested five captured more Tachinidae at the family level than controls (Agastache hybrid, Ageratina aromatica (L.), Aloysia virgata (Lopez & Pavon), Daucus carota L. and Stelleria media (L.)). At the tachinid subfamily and genera/species levels traps associated with Buddleia davidii Franch., Galium aparine L., Agastache hybrid, A. aromatica, A. virgata and D. carota caught significantly more flies than controls. Over all taxonomic levels, half (7) of the plant species-in-flower were associated with trap-catches greater than those associated with plants out-of-flower and/or without plants. There was no relationship between the ratios of flies captured in flowering plant-baited traps relative to those captured in controls and flower widths, flower depths, flower densities, numbers of flowers or floral areas (flower area * number of flowers). However particular plants were identified that might be incorporated into regional conservation biological control programs.

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► Of 14 flowering plant species seven captured significantly more Tachinidae than controls.
► Species of Dexiinae, Exoristinae and Tachininae, but not Phasiinae, were collected.
► The magnitude of attraction was not related to flower width, depth or density.
► Specific plants may be means of concentrating Tachinidae for biocontrol.