Parasite Lost: Chemical and Visual Cues Used by Pseudacteon in Search of Azteca instabilis

Abstract

An undescribed species of phorid fly (genus: Pseudacteon) parasitizes the ant Azteca instabilis F Smith, by first locating these ants through the use of both chemical and visual cues. Experiments were performed in Chiapas, Mexico to examine a) the anatomical source of phorid attractants, b) the specific chemicals produced that attract phorids, and c) the nature of the visual cues used by phorids to locate the ants. We determined that phorid-attracting chemicals were present within the dorsal section of the abdomen, the location of the pygidial gland. Further experiments indicate that a pygidial gland compound, 1-acetyl-2-methylcyclopentane, is at least partially responsible for attracting phorid flies to their host. Finally, although visual cues such as movement were important for host location, size and color of objects did not influence the frequency with which phorids attacked moving targets.

Dead ant walking: a myrmecophilous beetle predator uses parasitoid host location cues to selectively prey on parasitized ants

“…This study also demonstrates that M. xipe uses A. sericeasur alarm pheromone as a cue to locate prey. Although phorid flies also use the alarm pheromone to locate A. sericeasur hosts, they are attracted to 1-acetyl-2-methylcyclopentane, a less abundant compound within the alarm pheromone blend that is only found in Azteca species ants [23,32,33]. The compound that attracts M. xipe, 2-heptanone, is relatively common in the alarm pheromone of dolichoderine ants.…”

“…Ants in the genus Azteca are known for their pungent alarm pheromone that they disperse liberally from large pygidial gland sacs when disturbed. A suite of Pseudacteon phorid fly species uses this alarm pheromone to locate and parasitize A. sericeasur [23]. Pseudacteon lasciniosus is the largest of the three species and the most abundant at our field sites and Pseudacteon planidorsalis is a smaller species and the second most abundant [24].…”

Cuticular Hydrocarbon Cues Are Used for Host Acceptance by Pseudacteon spp. Phorid Flies that Attack Azteca sericeasur Ants

“…Previous work has shown that phorid flies that parasitize A. sericeasur are attracted to the ant's alarm pheromone, which is produced in their pygidial gland. The phorid flies then use movement of an individual ant to home in on a host (Mathis et al 2011). Here, we show that the phorid flies are attracted to the pygidial gland contents and to movement of both A. sericeasur and A. JTL020.…”

“…This likely is due to the relatively lower abundance of this species in the field (Reese and Philpott 2012) and the subsequent overall scarcity of P. planidorsalis attacks. Previous work has shown that these species of Pseudacteon phorid flies also use the ant's alarm pheromone (originating from their pygidial gland) to locate hosts at a distance, and use movement to home in on individual ants (Mathis et al 2011).…”

PseudacteonParasitoids ofAzteca instabilisAnts in Southern Mexico (Diptera: Phoridae; Hymenoptera: Formicidae)

“…Males of the three species have not been collected or identified. As a group, the flies are attracted to the host ant by an alarm pheromone (1-acetyl-2-methylcyclopentane) released from the dorsal section of the ant gaster, but they do not attempt to oviposit without ant movement [16]. Work is underway to determine whether visual and similar chemical cues are used by each species in host location and host selection processes.…”