Survey of Neodohrniphora spp. (Diptera: Phoridae) at colonies of Atta sexdens rubropilosa (FOREL) and specificity of attack behaviour in relation to their hosts

Abstract

Atta sexdens rubropilosa is a leaf-cutting ant that is a significant agricultural and forestry pest in the Neotropical region. This ant is parasitized by flies from the genera Neodohrniphora spp., Apocephalus spp. and Myrmosicarius spp. This study was carried out to determine which species of Neodohrniphora spp. are found near foraging trails of Atta sexdens rubropilosa and to evaluate the specificity of attack behaviour of these parasitoids. From May 2002 to April 2004, we sampled Neodohrniphora spp. hovering over foraging trails of Atta sexdens rubropilosa between 8:00 and 11:00 h and between 15:00 and 18:00 h. To investigate the attacking behaviour against the ants, flies were released individually inside an observation chamber containing a single leaf-cutting ant worker. Each parasitoid was confronted successively with a worker ant of A. sexdens rubropilosa, Atta laevigata Smith, Acromyrmex crassispinus Forel and Acromyrmex subterraneus molestans Santschi. Phorids of three species were identified: Neodohrniphora elongata Brown, Neodohrniphora declinata Borgmeier and Neodohrniphora tonhascai Brown. The three phorid species were active throughout the year and often along the same foraging trails, but N. elongata was the most frequent species. In the laboratory assay, N. elongata, N. declinata and N. tonhascai attacked workers of A. sexdens rubropilosa, A. laevigata and A. crassispinus, but not of A. subterraneus molestans.

Behavioral Strategies of Phorid Parasitoids and Responses of Their Hosts, the Leaf-Cutting Ants

“…striatus Roger). Based on previous observations, and on those of Feener and Brown (1993), four host-related behaviors displayed by phorids were defined, and were the main activities performed: (1) perching: when the phorid was sitting on the side of the foraging trail, nest, or refuse pile, with the head directed towards the ants; (2) flying: when the phorid was flying to get close to an ant, came back to the perching site, went from perch to perch, or moved along the foraging trail; (3) attacking: when the phorid touched an ant for at least one second, so as to deposit an egg (as defined previously for other phorids, Tonhasca et al 2001; Silva et al 2008; Bragança et al 2009) (this behavior is not referred to as oviposition because we did not confirm the presence of eggs); (4) landing on a leaf: when the phorid landed on the leaf transported by an ant, usually prior to an attack.…”

Current Understanding and Future Prospects of Host Selection, Acceptance, Discrimination, and Regulation of Phorid Fly Parasitoids That Attack Ants

“…Movement of target ants is a common visual cue frequently used by the Pseudacteon spp. phorid flies that attack both A. instabilis and ants in the Solenopsis saevissima complex as well as by N. elongata phorid flies attacking A. sexdens [16][17][18][19]. A. paraponerae attacking P. clavata, however, prefer stationary ant hosts [5].…”

“…Once a phorid parasitoid has located a potential host through long-range cues, the parasitoid requires host acceptance cues to trigger the parasitoid's oviposition behavior. Short-range cues such as movement, host size, and contact chemical cues have all been implicated in triggering phorid fly oviposition [7,[16][17][18][19][20][21][22][23][24][25][26].…”

Trait-Mediated Indirect Effects of Phorid Flies on Ants

“…Phorid parasitoids also influence the size of foragers (Table 1). The pattern of worker size selection by ovipositing female phorid flies has been described for a few species of Pseudacteon on Solenopsis [12,[41][42][43], and Neodohrniphora on Atta [44,45]. Mathis and Philpott [15] discuss ant size as a factor in host acceptance by phorid species.…”