Bioacoustics of Neoponera apicalis

Biology: Pachycondyla apicalis is a common and conspicuous insect in many Neotropical forests. Most observations and collection records are of single foragers on the ground or on low vegetation. According to the collection data associated with museum specimens, P. apicalis occurs from sea level to 1600 meters (n = 40, median = 380 meters, mean = 642 meters). 14 collections were from primary or secondary rainforest or other kind of tall, moist forest. Two records were from rainforest edges and clearings, three from coffee plantations, one from cloud forest, and one from second growth thorn forest. This species has been observed nesting in rotting wood on or near the ground (Levings & Franks 1982, Dietemann & Peeters 2000, Longino 2004), in the ground (Levings & Franks 1982), and in the root mass of large Ficus trees within one meter of the ground (Fresneau 1985). One Colombian record in MCZC is from a Guadua sp. Colonies are small, containing fewer than 200 workers (Fresneau 1985, Goss et al 1989, Dietemann & Peeters 2000), and monogynous (Dietemann & Peeters 2000). Dietemann and Peeters (2000) investigated the interactions between queens and workers, finding that workers can lay both trophic eggs and reproductive male eggs, some switching to reproductive male eggs in the absence of physical contact with the queen. Workers are apparently incapable of mating (Dietemann & Peeters 2000) and exhibit overt dominance interactions as well as egg-policing (Oliveira & Hoelldobler 1990). Age polyethism in P. apicalis is described by Fresneau and Dupuy (1988). The formation of colony odor was studied by Soroker et al (1998), who tagged lipid precursors with radioactive tracers, injected them into ants, and conducted a series of experiments demonstrating that the molecules were spread through the colony by allogrooming of nestmates and not by trophallaxis. Fresneau (1985) describes foraging behavior in a field population in Chiapas, Mexico. He found apicalis to be generalist predators and scavengers, collecting “20%… fruit debris and vertebrate carcasses and the remaining 80%…an assortment of 12 arthropod orders half of which were dead, and other half of which were living Lepidoptera and Coleoptera larvae.”(Fresneau 1985, pg 110.) Longino (2004) observed that foragers readily take crushed tabanid flies and lepidopteran larvae. A collection by E. O. Wilson from Veracruz, Mexico, records P. apicalis preying on termites, and two apicalis workers in the MCZC collection were found at a tuna bait in Guanacaste, Costa Rica. Foraging is done individually, without recruitment, and individual foragers over time show strong fidelity to a particular area (Fresneau 1985). Tandem-running has been observed during nest relocation (Fresneau 1985). Orientation is probably visual (Fresneau 1985). Goss et al (1989) test an optimal foraging model using P. apicalis , concluding that foraging in the observed colonies is sub-optimal. Interestingly, a group of computer scientists have used the foraging behavior of P. apicalis as a model for creating an internet search algorithm ( Monmarche et al 2000). Pachycondyla apicalis , as in other ponerine ants, subdues its prey by injecting venom through a sting. The venom may also have a defensive purpose and is described as tasting “bitter and burning” (Schmidt 1986). Cruz and Morgan (1997) investigate venom chemistry, Schmidt (1980) looks at venom toxicity, and Schmidt et al (1984) score P. apicalis sting-induced pain in humans as a “two” on a standardized ascending scale of one to four. Pavan et al (1997) report on the auditory emissions of P. apicalis . As in most stridulating ants, the stridulatory organ is composed of a file on the fourth abdominal tergite and a scraper on the preceding tergite (Giovannotti 1996, Pavan et al 1997). Abdominal glands in the male are described by Hoelldobler and Engel-Siegel (1982). In Panama, P. apicalis serves as a model for the ant-mimic spider Castianeira memnonia(Koch) (Reiskind 1977). Reiskind (1977) reports the identity of the model as P. obscuricornis , but the voucher specimen at LACM is clearly P. apicalis . Additionally, his description of the yellow antennal apices and the photographs in the article unambiguously identify the ant as P. apicalis . There is one record in MCZC of Pachycondyla apicalis in the gut contents of a leptodactylid frog, Eleutherodactylus biporcatus (Peters) , in Nicaragua.