Necrophagy by Neotropical Swarm-Founding Wasps (Hymenoptera: Vespidae, Epiponini)1
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BIOTROPICA 27(1): 133-136 1995 NOTES Necrophagy by Neotropical Swarm-Founding Wasps (Hymenoptera: Vespidae, Epiponini)1 Key words: Agelaia; Angiopolybia; Epiponini; mandibular modification; necrophagy; Vespidae. IN THIS PAPER I PRESENT OBSERVATIONS of necrophagy, the consumption of flesh from vertebrate and large invertebrate carcasses, by Neotropical swarm founding wasps (Hymenoptera: Vespidae, Epiponini) collected in Costa Rica, Peru, and Venezuela; I also review earlier records of this phenomenon in the Neotropics. Most eusocial bees and wasps rely primarily on pollen and live insect prey, respectively, as sources of protein for developing brood (Michener 1974, Hunt 1991). However, nectophagy appears to have evolved independently in swarm-founding Neotropical bees and wasps. Among stingless bees (Apidae, Meliponinae), three species in the Trigona hypogea group are obligately necrophagous. These bees have mandibles modified for carrion feeding and collect flesh from diverse types of carrion (Roubik 1982, Camargo & Roubik 1991). Nectophagy has also been noted in Neotropical swarm-founding wasps. Bertoni (1912) recorded swarm-founding wasps of several genera coming to and collecting meat "exposed to the sun" in Paraguay (Table 1); the same author found an active nest of Parachartergus apicalis that smelled of rorting meat. Probably the best known nectophagous wasps are in the genus Agelaia (formerly Stelopolybia; Carpenter & Day 1988). Meat eating by these wasps is familiar to residents of Spanish speaking South American countries, where they are widely known as "camiceras" (butchers). Ducke (1910) noted the common name "caba de peixe" (fish wasp) for A. fulvofasciata in Brazil, where large numbers of these wasps came to fish bound for market. Below I report observations from Central and South America on nectophagy by swarm-founding wasps of the genera Agelaia and Angiopolybia. On 15 March 1993 in wet, lowland forest in Loreto Province, Peru (Explorama Lodge, approximately 200 m elevation), I discovered foragers of three species of epiponine wasps (Agelaia testacea, A. hamiltoni, and Angiopolybia pal/ens) simultaneously collecting flesh from a large katydid (Orthoptera: Tertingoniidae) carcass in a seasonally flooded area. Foragers of the different wasp species displaced each other from the carcass but tolerated conspecifics, with larger bodied species always displacing smaller. An active colony of A. hamiltoni was located inside a large arboreal ant nest (Azteca sp.) approximately 70 m from the katydid carcass. At 1500 hr on 19 March, I placed four 0.1-0.2 kg pieces of fresh catfish flesh at 25 m intervals on the ground in an area of second growth terra firme forest along the Bushmaster trail at Explorama Lodge. I surveyed the baits for wasp foragers collecting flesh at 5-15 min intervals for the next 2.5 hr. All four baits were quickly discovered by ants, which reauited large numbers of foragers within 10 min. Each of the baits was visited within 5 to 13 5 min by Angiopolybia pallens foragers. One bait was also visited within 135 min by Agelaia testacea foragers, which displaced the smaller bodied A. pal/ens workers. Wasp foragers collecting flesh landed on the bait and chewed at small projections on the surface with their mandibles. Foragers tore a strip of flesh from the bait and used their mandibles and fore legs to form it into a ball for transport while slowly walking backwards; the actions of foragers collecting fish flesh closely resemble those of nest material foragers I have observed collecting pulp from weathered wood surfaces. Some flesh foragers had difficulty flying off with their loads. Wasps hovered over ants they contacted at the baits, occasionally darting downwards, and often caused the ants to flee. Wasps landed in spaces thus cleared of ants and collected flesh with their wings raised over their backs, often fanning their wings and darting forward at ants. Similar responses to invading ants are seen in some swarm founding wasps at their nests (Chadab 1979, O'Donnell & Jeanne 1990). I observed Agelaia testacea foragers taking flesh from a partially decayed tayra (Eira barbara) pelt in a nearby area of flooded forest the previous week; the pelt was suspended 2 m above the ground in a tree and was being visited by large numbers of ants. In the same area, several Agelaia hamiltoni foragers arrived at live catfish within 2 min of their bei!Jg removed from the water and placed in a dugout canoe. These foragers ran over the surface of the fish buzzing their wings, then repeatedly bit at the eyes. 1 Received 27 May 1993; revision accepted 15 February 1994. 133 134 O'Donnell TABLE 1. Records of necrophagy by epiponine wasps.• Species Source(s) Species Source(s) Agelaia angulata 2,3,6 Angiopolybia pal/ens 7 A. areata 4, 5, 7 A. obidensis 3 A. fulvofasciata 1, 3, 6 A. paraensis 6 A. hamiltoni 7 Brachygastra augusti 2 A. multipicta 7 Parachartergus apicalis 2 A. pallipes 3, 5 Polybia ignobilis 2 A. pallidipes 2 P. minarum 2 A. panamensis 4, 7 P. occidentalis 2 A. testacea 7 Protonectarina sylveirae 2 A. yepocapa 7 Synoeca cyanea 2 Sources: 1. Ducke (1910) 2. Benoni (1912) 3. Richards and Richards (1951) 4. Cornaby (1974) 5. Forsyth (1978) 6. Richards (1978) 7. This paper; pers. obs. Voucher specimens of Agelaia areata, A. hamiltoni, A. multipicta, A. panamensis, A. testacea, A. yepocapa, and Angiopolybia pal/ens were deposited in the University of California Davis Entomological Museum. a All records refer to observations of foragers visiting flesh, except that for Parachartergus apicalis, which refers to a nest that smelled of rotting meat. Similarly, A. multipicta foragers in the seasonally dry Venezuelan llanos (near Corozo Pando, Guarico State) arrived at a freshly road-killed snake within several minutes and began removing flesh. In July 1992, foragers of a large-bodied wasp (possibly Agelaia panamensis) were abundant at Casa Menco Research Station on Volcan Cacao, in wet, premontane forest in Northwestern Costa Rica at an elevation of approximately 1100 m. These wasps collected flesh from a partly decayed opossum (Didelphis sp.) carcass, and visited tuna fish baits placed to attract leaf litter ants. Near San Luis, Puntarenas Province, Costa Rica, at a similar elevation, a farmer reported that large, dark colored wasps removed flesh from botfly wounds on his livestock, but I was unable to confirm this report. In October 1993, Agelaia areata, A. panamensis, and A. yepocapa foragers simultaneously collected flesh from cooked and uncooked chicken baits at approximately 1300 m elevation in Monteverde, Puntarenas Province, Costa Rica. The manner of removing flesh and responses to ants were similar to those observed in other epiponine wasps in Peru. The phylogenetic distribution of necrophagy in Neotropical swarm-founding wasps is difficult to assess given the scanty data on its occurrence (Table 1). Presumably necrophagy was derived from the use of live insect prey for larval protein. Necrophagy appears to be widespread if not chatacteristic in the sister genera Agelaia and Angiopolyhia (Richards & Richards 1951, Richards 1978, Carpenter 1991). Within the genus Polyhia, the necrophagous species P. minarum and P. ignohilis are dose relatives in the subgenus Trichinothorax with similar biologies and nesting habits (Richards 1978, Carpenter & Day 1988). Records of necrophagy occur in several more distantly related species and genera (Table 1; see Carpenter (1991) on phylogeny of Vespidae). At least some swarm-founding wasps are apparently facultatively necrophagous, harvesting such alternative sources of protein as frog embryos and live insect prey (Bertoni 1912, Richards 1978, Lacey 1979, S. O'Donnell, pers. obs.). Necrophagous swarm-founding wasps collect flesh from a wide diversity and size range of carcasses, although Cornaby (1974) recorded Agelaia areata and A. panamensis on iguanid lizard, but not toad (Bufo marinus), carcasses in Costa Rica. The importance of necrophagy in colony nutrition is unknown, but the pest status of meat-collecting Agelaia spp. in South America, and their ability to discover carrion rapidly (Ducke 1910, Comaby 1974, this study), suggest that flesh is a major source of protein for these wasps. In addition to decaying flesh, foragers of necrophagic wasps are attracted to freshly killed carcasses and, at least occasionally, to live vertebrates. Therefore the cues used in locating flesh resources are not exclusively produced during the decay process. Recently discovered antibiotic properties of larval saliva in necrophagous temperate zone vespine wasps (Gambino 1993) may represent an adaptation to utilization of decomposing protein sources and should be investigated in necrophagous epiponines. Workers of three closely related genera (Apoica, Agelaia, and Angiopolyhia; Carpenter 1991) share a srrqctural modification of the mandibles that may be associated with necrophagy: the dorsal tooth on Notes 135 DORSAL MT 1mm FIGURE 1. Oblique view of the inner (mesal) surface of the left mandible of an Agelaia testacea worker, with dorsal and distal edges labelled to show orientation. Line from MT indicates the dorsal mesal tooth, which forms an elongated, knife-like ridge in all species examined of the genera Agelaia, Angiopolybia, and Apoica. This ridge is absent, reduced, or blunt in other epiponine wasp species examined (Appendix 1). the mesal (inner) surface of the mandibles is elongated into an acute, blade-like ridge that spans the length of the mandible (Fig. 1). In other epiponine