Research Reports: Life History and Parasites of Asphondylia Borrichiae (Diptera: Cecidomyiidae), a Gall Maker on Borrichia Frutescens

Peter Stilin, Anthony M. Rossi, Donald R. Strong, Derek M. Johnson

Abstract


We studied the life history, seasonal and spatial abundance, and parasites of Asphondylia borrichiae Rossi and Strong (Diptera: Cecidomyiidae), a newly described gall maker on sea oxeye daisy, Borrichia frutescens (L.) DC. Galls are located on the apical meristem of the host plant, are usually solitary, often prevent flowering, and can kill the host stem. Individual galls may contain from one to eight fly larvae, most commonly one to three. Gall size is greatest in spring. Galls can be found year round, and there are several generations, of which the largest occurs in the summer. Gall densities differ consistently between sites, but the seasonal variation of galls within sites is very similar. Fly larvae in galls are attacked by four species of Hymenoptera, Rileya cecidomyiae and Tenuipetiolus teredon (Eurytomidae), Torymus umbilicatus (Torymidae), and Galeopsomyia haemon (Eulophidae), of which G. haemon causes the most mortality. At least two of the parasites are facultatively hyperparasitic. Parasitism levels are low in the spring but rise quickly to reach 100% in the early summer and late fall.

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