Introducing Phorid Fly Parasitoids of Red Imported Fire Ant Workers from South America to Texas: Outcomes Vary by Region and by Pseudacteon Species Released
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Since the first report on introductions to Texas of Pseudacteon decapitating flies, a variety of participants have released flies in a range of sites. The expansions of Pseudacteon populations have been systematically and widely monitored. Before 2002, the widely released initial species P. tricuspis Borgmeier did not become established. Severe drought in 1996-2001 and host-size-dependent sex ratio were proposed constraints in establishing this species. In recent years, however, these limitations have been lifted in some areas by favorable weather, irrigation of release sites, and/or by use of a smaller Pseudacteon species, P. curvatus Borgmeier, not reliant on larger fire ant workers to produce females. Beginning in 2002, the USDA-APHIS collaboration with USDA-ARS and Texas Cooperative Extension programs began to supplement release sites in Texas beyond those initiated by the University of Texas, Austin phorid fly project. In 2005, private citizens began to participate in the spread of Pseudacteon to new sites. By fall 2006, P. tricuspis, expanding from releases between 1999 and 2001, was found on more than 3 million hectares of Central and Coastal Texas, while P. curvatus, with its later start, is only now beginning to expand at some sites. Pseudacteon that established more easily in mesic and moderate climates has difficulty surviving unfavorable weather in South Texas. However, two sites where flies "failed" to become established were revealed to be false negatives after the record rains of summer 2007. Starting in late 2006, the first releases of P. obtusus Borgmeier in North America established, and three to five additional species are being released.
author list (cited authors)
Gilbert, L. E., Barr, C. L., Calixto, A. A., Cook, J. L., Drees, B. M., Lebrun, E. G., ... Puckett, R. T.