DOI: 10.17151/bccm.2016.20.2.17

* FR: 10-V-2016. FA: 30-IX-2016.
¹ GEBIOME (Genética, biodiversidad y manejo de ecosistemas), Manizales, Colombia.
² GEDAR (Grupo de Ecología y Diversidad de Anfibios y Reptiles) Departamento de Ciencias Biológicas, Universidad de Caldas, Manizales, Caldas, Colombia.
** E-mail: sebastian.escobar@ucaldas.edu.co

It is known that there are a considerable number of interactions established between amphibians and dipterans. Among these, there is the predator-prey interaction in which amphibians ingest flies from a broad variety of families (DURÉ & KEHR, 2004). On the other hand, there have been reports of cases of flies parasitizing anurans (BOLEK & JANOY, 2004; Gosá et al. 2009; Gómez-Hoyos et al., 2012). In these cases, the diversity of fly families involved is lower, represented by four families (Gosá et al., 2009), and, in the new world, parasitism has been reported in adult anurans by species of Calliphoridae and Sarcophagidae (BOLEK & JANOY, 2004; Gosá et al., 2009; Medina et al., 2009).

In this work, we present the first record of a flesh fly (Diptera: Sarcophagidae) depositing its eggs on the body of a leaf litter frog, Pristimatis achatinus (Boulenger, 1998; Anura: Craugastoridae; Fig. 1). The frog was sampled at the botanical garden of the Universidad de Caldas (JBUC; 5°4'12'' N, 75°31'14'' W, 2150 m of elevation), which is located in the central Andes of Colombia, municipality of Manizales, department of Caldas. With the aim of evaluating the bacterial richness of the posterior gut of this species, eight individuals, with an average of snout vent length (SVL) 27.6 ± 7.77 mm, were captured and analyzed. For sampling, approximately 5 mm of an empty micropipette (100 uL) were introduced in the cloaca of each animal. Suction of the material was performed and the tip was washed with peptone broth. After the procedure, all frogs were released and samples of peptone broth were incubated for 48 hours at 28°C, and the material was inoculated in petri dishes with Crystal Violet agar (Bacto®); subsequently, these were incubated at the same temperature. After three days, bacterial growth was registered in six of the eight petri dishes and, in one of them, 12 dipteran larvae were found, reaching an average of 0.8 mm in length approximately (Fig. 2). Manipulation of the petri dish was minimal to avoid contamination with exogenous microorganisms and to record the development of the flies.

Unfortunately, after 15 days, 100% of the flies had died, some of them at the stage of pupa. These were immediately preserved in 70% alcohol for their taxonomic identification at the lowest taxonomical level possible. It was determined that larvae belong to the family Sarcophagidae (Coto, 1998).

Hoyos-Hoyos et al., (2012) indicate that the main components of the diet of P. achatinus are coleopterans and hymenopterans. However, it has been demonstrated that this species is highly generalist, choosing its prey depending on the availability of resources (Lynch & Duellman, 1997). For this reason, we would suggest that the frog could have ingested a female fly with eggs, and these survived the digestion through the gut, finally reaching the cloaca. However, despite being generalist, until now there are no known reports of Sarcophagidae fly ingestion by P. achatinus.

On the other hand, there are other features suggesting that this is not a case of survivorship to predation. Some species of Sarcophagidae have been categorized as parasites, found in different anuran families (see Gosá et al., 2009; Medina et al., 2009; Gómez-Hoyos et al., 2012). Also, the location of the fly eggs in the cloaca of the frog makes it more feasible that these eggs had been deposited by a parasite. Gómez-Hoyos et al., (2012) made the first report of myasis in frogs from the Cordillera Central of Colombia, in which an individual of Pristimantis thectopternus (Lynch, 1965) was parasitized by a larvae of a Sarcophagid species. This observation was made approximately at 50 km to the southeast of the location of the present record. Despite the information collected, it is not possible to conclude with total certainty whether this is a case of predation or parasitism, even when the evidence and external information allow us to suppose that this is a case of parasitism. Moreover, we can suggest that parasites in adult frogs are more common than have been reported, as it is known for larval stages of anurans (Villa, 1977; Rojas-Morales & Escobar-Lasso, 2013).

We thank Daniel Ricardo Toro for letting us use the Applied Microbiology Laboratory, Lucimar Gomes Diaz and Professor Luciano Fiuza for their careful observations on the taxonomy of the dipterans. We thank Prof. Viviana Andrea Ramírez, Gustavo González, and Julian Andrés Rojas for their valuable comments to the manuscript, and Diego Gomez Hoyos for the taxonomic confirmation of the anuran.

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