Associations of Fire Ant Phorids and Microhabitats

Abstract

We examined flight activity patterns for a guild of fire ant parasitoids in western Argentina in relationship to their host's location (mound/foraging trail) and light condition (full sun/partial sun/full shade) at different scales, from the individually sampled mound to the full day's summation for each species. We asked first whether taxa showed preferences among these conditions, and second, whether certain species and sexes might be found together more frequently than expected to by chance. All species, except the P. obtusus species complex, were significantly more likely to be found attacking ants at disturbed mounds than at paired foraging trails. The P. nocens complex and P. litoralis were more likely to be in the shade when temperatures were above the overall mean of the study (28.3 degrees C), whereas others, such as the P. obtusus complex and P. tricuspis, were more likely to be in full sun under these same conditions. Our analyses indicated that a limited set of species, particularly P. nocens with P. litoralis, and males with female P. obtusus and P. tricuspis, were more likely to be found together than expected. We also found decreasing proportions of males with increasing time of analysis. We discuss the implications of host location, metereological conditions, and sex ratios in relationship to ongoing classical biological control efforts using species of these phorids.

Efeito da estrutura de habitat sobre a abundância de parasitóides Pseudacteon Coquillett (Diptera, Phoridae) em ninhos de Solenopsis invicta Buren (Hymenoptera, Formicidae)

“…Pseudacteon tricuspis Borgmeier foi introduzida em oito locais no norte da Flórida, obtendo-se êxito em seis deles (Porter et al 2004). Outros estudos sobre comunidades de Pseudacteon foram realizados em países vizinhos, como a Argentina, Bolivia e Paraguai (Folgarait et al 2003;Calcaterra et al 2005;Folgarait et al 2007a), sendo que 18 espécies desse gênero já foram identificadas como parasitóides de Solenopsis na América do Sul (Porter & Pesquero 2001).…”

“…Diversos são os fatores bióticos e abióticos que exercem influência sobre a dinâmica populacional dos forídeos (Folgarait et al 2007a;Folgarait et al 2007b). Pseudacteon comatus Borgmeier, por exemplo, está associada às épocas de maior temperatura e baixa umidade relativa, enquanto que P. nudicornis Borgmeier possui padrão oposto (Folgarait et al 2003).…”

Parasitoids of the endangered leafcutter ant Atta robusta Borgmeier in urban and natural areas

“…Habitat structure seems to be an important factor for the understanding of the spatial distribution of ant parasitoids (Folgarait et al 2007;Elizalde & Folgarait 2010; but see Reese & Philpott 2012). For example, phorid fly species that attack Solenopsis invicta in agroecosystems are associated with annual open crops or closed perennial crops (Almeida & Queiroz 2009).…”

“…The phorid flies that parasitize ants use the host's body to complete their life cycle, and their occurrence is restricted by certain conditions, such as habitat structure, temperature and relative humidity (Folgarait et al 2007;Almeida et al 2008;Elizalde & Folgarait 2010). In addition, parasitoid abundance may depend on host foraging activity (Tonhasca Jr. 1996), and the form of attack or oviposition site (such as nest entrance holes or foraging trails) vary among phorid species (Erthal Jr. & Tonhasca Jr. 2000;Bragança & Medeiros 2006;Gazal et al 2009;Elizalde & Folgarait 2011, 2012.…”

Geographical transition zone of Solenopsis fire ants (Hymenoptera: Formicidae) and Pseudacteon fly parasitoids (Diptera: Phoridae) in the state of São Paulo, Brazil

“…Due to the high species richness of fire ants and the natural occurrence of parasitoids in South America, the host specificity is an important aspect to be considered when selecting natural enemies for fire ant biological control in the US (Vazquez et al 2004, Folgarait et al 2005b. Moreover, the ecological differentiation among parasitoid species such as daily activity (Pesquero et al 1996, Folgarait et al 2007a, attack place (Pesquero et al 1993, Orr et al 1997, Folgarait et al 2007b and host size (Williams & Banks 1987, Campiolo et al 1994, Morrison et al 1997 has also been demonstrated to be important in species composition of local communities.…”