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

Abstract

Solenopsis saevissima (Smith) and Solenopsis invicta Buren are the most abundant and widely distributed fire ants in Brazil. The occurrence of the two fire ant species and of their parasitoids Pseudacteon spp. is described for a climatic and phytophysiognomic transition area in the state of São Paulo. Both fire ant species have a parapatric distribution, apparently determined by the climate: S. saevissima predominates in the north part of São Paulo (Aw climate), while S. invicta in the south (Cfa climate). A sympatric area is observed between the latitudes 21ºS and 23ºS. Two different communities of parasitic decapitating flies were associated with S. saevissima in the north and with S. invicta in the south, with a sympatric area in the municipality of São Carlos (21º58'S 47º53'W). The possible causes of this biogeographic pattern are discussed. Preference tests with Pseudacteon flies challenge the association of P. litoralis Borgmeier, P. curvatus Borgmeier, P. wasmanni Schmitz, P. pradei Borgmeier and P. obtusus Borgmeier with S. saevissima, and P. dentiger Borgmeier, P. disneyi Pesquero and P. lenkoi Borgmeier & Prado with S. invicta.

A Species delimitation approach to uncover cryptic species in the South American fire ant decapitating flies (Diptera: Phoridae: Pseudacteon)

“…The fact that one species of fire ant decapitating fly can attack multiple species of fire ants along its range of distribution has already been mentioned [22,25,63]. It is known that that distribution of these parasitoid flies is mainly determined by its host specificity [64], that those with wider geographical ranges which often attack multiple species of fire ants (usually, too, with wide ranges) [63] and, in this sense, the broader the ranges seems to be the result of parasitoid fly species using multiple host [56]. But particularly, is also known that in a single location multiple Pseudacteon species may coexist and parasitize the same host species [2,9,23].…”

Pseudacteon Phorid Flies: Host Specificity and Impacts on Solenopsis Fire Ants

“…There is limited information about the host preferences of the different species and biotypes of phorid flies. Field assays for host selection demonstrated the preference of the Pseudacteon fly communities for the local fire ant species (89). Laboratory no-choice and pair-wise choice bioassays demonstrated that the Las Flores (Argentina) biotype of P. curvatus obtained from S. richteri populations preferred S. richteri and hybrid fire ants over S. invicta, and the strong preference for S. richteri was retained even after it was successfully reared for many generations on S. invicta (13,42,98).…”

Biology of Pseudacteon Decapitating Flies (Diptera: Phoridae) That Parasitize Ants of the Solenopsis saevissima Complex (Hymenoptera: Formicidae) in South America

“…Solenopsis saevissima (north climate) and S. invicta (south climate) have a parapatric distribution in the state of São Paulo, Brazil, apparently determined by the climate. Two different communities of decapitating flies were associated with S. saevissima in the north and with S. invicta in the south [51]. The most abundant species in the northern community were Pseudacteon affinis, P. cultellatus, Pseudacteon dentiger, Pseudacteon disneyi, and Pseudacteon fowleri, and in the southern community were P. litoralis, P. pradei, P. tricuspis, and P. wasmanni.…”