Oviposition Behavior and Development of Pseudacteon Flies (Diptera: Phoridae), Parasitoids of Solenopsis Fire Ants (Hymenoptera: Formicidae)

Abstract

We studied the oviposition behavior and larval development of Pseudacteon phorid flies, which are parasitoids of Solenopsis fire ants. Four South American Pseudacteon spp., P. litoralis Borgmeier, P. tricuspis Borgmeier, P. wasmanni (Schmitz) and P. curvatus Borgmeier (which attack S. invicta Buren), and 2 North American Pseudacteon spp., P. browni Disney and P. crawfordi Coquillett (which attack S. geminata [F.]), were evaluated. In laboratory tests, larger Pseudacteon spp. attacked larger Solenopsis workers. The mean worker size preferred was significantly larger than the colony mean worker size for all but the smallest phorid species, P. curvatus , which preferred workers significantly smaller than the colony mean. Within Pseudacteon spp., larger females preferred larger workers, but this relationship was significant only for the 2 North American species. Natural parasitism rates of Solenopsis workers by the 2 North American Pseudacteon spp. in the field were low (0–2.42% per colony), but >90% of the overall size range of worker ants showed evidence of parasitism. Between 11.8 and 31.0% of apparent oviposition attempts resulted in successful parasitism. Mean larval development times ranged from 13.0 to 18.4 d at 30°C and were shorter for North American species. Larval stages required 24.8–36.5% longer to develop at 25°C than at 30°C. Mean pupal development times ranged from 15.6 to 18.7 d at 30°C. In general, larger Pseudacteon spp. had longer larval and pupal development times. Overall, North and South American Pseudacteon spp. were similar in terms of oviposition behavior and development.