Toledo, Luís Felipe

Phyllomedusa Journal of Herpetology

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Luís Felipe Toledo

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		Predation on seven South American anuran speciesby water bugs (Belostomatidae)Luís Felipe ToledoDepartamento de Zoologia, Instituto de Biociências, Universidade Estadual Paulista, Caixa Postal 199, 13500-970,Rio Claro, SP, Brazil. E-mail: toledolf@hotmail.com.		 !""#$$%		Keywords: Anura, predation, water bugs, Belostomatidae, Belostoma elongatum.The risk of predation is one of the manycosts related to reproduction in frogs (Howard1981, Ryan 1985, Pough et al. 1992). Althoughamphibians exhibit a great diversity of defensivestrategies (reviews in Duellman and Trueb 1994,Stebbins and Cohen 1997, Pough et al. 1998),anurans, in particular, are preyed upon by agreat variety of arthropods, such as ants, beetles,water bugs, spiders and crabs, as well asvertebrates (fishes, other amphibians, reptiles,birds, and mammals), and even carnivorousplants (Duellman and Trueb 1994, Pough et al.1998). A considerable amount of informationhas recently been collected on invertebratepredators of adult anurans (Formanowicz et al.1981, Hinshaw and Sullivan 1990, Schiesari etal. 1995, Del-Grande and Moura 1997, Haddadand Bastos 1997, Owen and Johnson 1997, Zuffi2001, Pramuk and Almillo 2002). Water bugs(Belostomatidae) eat tadpoles (Martins et al.1993, Eterovick and Sazima 2000) and adultfrogs (Smith 1980, Hinshaw and Sullivan 1990,Bastos et al. 1994, Haddad and Bastos 1997,Mijares-Urrutia et al. 1997). Little informationis available about predation on adult frogs byBelostomatidae. Here I present newobservations of predation by water bugs,Belostoma elongatum, on adult frogs.Field observations were made at threetemporary ponds at the Estação Ecológica deItirapina (22º13’30”S, 47º54’19”W; 725 m),Municipality of Itirapina, São Paulo state,Brazil, between November 2002 and March2003. The ponds were no deeper than 15 cm andsurrounded by grass and small bushes. A straighttransect, 400 m long by 4 m wide was used inone of the ponds, both during the day (from09:00 to 12:00 h) and at night (from 19:00 to02:00 h), between 16 and 19 December.Occasional observations were also made at othertimes. Animals that were being preyed upon, orrecently released by the bug on the watersurface, identified by the characteristic circularpunctures (approximately 1.5 mm in diameter)in the frog’s skin caused by the insect’sproboscis, were measured with a digital caliperto the nearest 0.01 mm and preserved in 70%alcohol solution. Specimens are deposited atCélio F. B. Haddad collection (CFBH 5937,5950-60, 5962-68), Departamento de Zoologia,Universidade Estadual Paulista, Rio Claro, SãoPaulo state, Brazil. The belostomatids aredeposited at the entomological collection of theMuseu de Zoologia of the Universidade de SãoPaulo, Brazil (without voucher numbers).During the study, 15 anuran species werefound calling at breeding sites: Hyla		Toledoalbopunctata, H. jimi, H. minuta, Scinaxfuscomarginatus, Scinax sp. (aff. similis), S.squalirostris, Leptodactylus furnarius, L. fuscus,L. labyrinthicus, L. ocellatus, Physalaemuscentralis, P. cuvieri, P. fuscomaculatus, P.nattereri, and Elachistocleis cf. ovalis. The 19predation events by adult and nymphal waterbugs (Belostoma elongatum) involved sevendifferent species of frogs (Table 1).Whole predation sequences upon a juvenileLeptodactylus labyrinthicus and two adult ma-les of Scinax sp. (aff. similis) were observed. Allthree events were similar: the frogs were initiallyat the edge of the pond and, when they jumpedinto the water, they were immediately capturedby a bug. One of the males of Scinax sp. (aff.similis) tried to escape by jumping out of thewater, after being grasped by an adult B.elongatum. However, the water bug was firmlyattached to the anuran and did not release it. Thethree individuals remained alive, but almostimmobile, from 25 to 35 minutes after capture.On the other occasions, the frogs were foundbeing preyed upon or just after having beenkilled by water bugs. All predation eventsoccurred on the water surface and the frogs werestrongly held by the forelimbs of the water bugs.The bugs did not hold the frog in any specificpart of the body. B. elongatum individuals werefound throughout the night and predation eventsoccurred between 21:15 and 00:05 h, coincidingwith the peak of calling activity of the frogs.During the day, four dead frogs [two Scinax sp.(aff. similis) and two P. cuvieri] were foundfloating on the water surface with leptodactylidtadpoles feeding on their internal organs.Males of the genus Physalaemus found atthe study site called while floating on the watersurface on the edges of temporary ponds. Hence,the production of waves may have attractedaquatic predators such as water bugs (Pough etal. 1992) (Figure 1A). Moreover, the proportionof females, in relation to males, in the site wasvery low (pers. obs.), suggesting why only ma-les were preyed upon. The only Leptodactylussp. preyed upon was a juvenile L. labyrinthicusthat jumped into the water (Figure 1B). Theother species of the genus were observed callingon the ground, strongly reducing the risk ofpredation by these insects. Hylid frogs havebeen also observed calling at dry sites, on theground [(Scinax sp. (aff. similis)] or from shrubs 	 ±	  	  	  	  ±	 	 ±	  	     ±  Table 1 - Anuran species preyed upon by Belostoma elongatum at the Estação Ecológica de Itirapina between November2002 and March 2003. SVL, snout-vent length; X ± SD, mean ± standard deviation.~~		Predation on South American anurans by water bugsabove the ground or the water (all hylidspecies). However, being highly dependent onwater bodies for reproduction, all observedspecies must have direct contact with water atleast during oviposition (Lutz 1973).Water bugs appear to be the majorinvertebrate predators of adult frogs in EstaçãoEcológica de Itirapina as no other predationevent was observed during the entirereproductive season at the temporary ponds Istudied or other breeding sites I visitedoccasionally.AcknowledgementsI thank Célio F. B. Haddad, Anne d’Heursel,Günter Gollmann, Jaime Bertoluci, and twoanonymous referees for revising the manuscriptand making helpful suggestions, CarlosCampaner for identifying the water bugs, Débo-ra Campos and Juliana Zina for helping in thefield. The author is also grateful to CNPq forfinancial support, Idea Wild for equipmentdonation, IBAMA, IF, and Denise Zancheta forthe permissions conferred.Figure 1 - Adult male Physalaemus cuvieri (A) and juvenile Leptodactylus labyrinthicus (B) being preyed upon by waterbug Belostoma elongatum in temporary ponds at Estação Ecológica de Itirapina, São Paulo state, Brazil.ReferencesBastos, R. P., O. C. Oliveira and J. P. Pombal Jr. 1994.Hyla minuta (NCN). Predation. Herpetological Review25: 118.Del-Grande, M. L. and G. Moura. 1997. Hyla sanborni(NCN). Predation. Herpetological Review 28: 147.Duellman, W. E. and L. Trueb. 1994. Biology ofAmphibians. 2nd ed. Baltimore and London. The JohnHopkins University Press. 670 pp.Eterovick, P. C. and I. Sazima. 2000. Structure of ananuran community in a montane meadow insoutheastern Brazil: effects of seasonality, habitat, andpredation. Amphibia-Reptilia 21: 439-461.Formanowicz Jr., D. R., M. M. Srewart, K. Townsend, F.H. Pough, and P. F. Brussard. 1981. Predation by giantcrab spiders on the Puerto Rican frog Eleuterodactyluscoqui. Herpetologica 37: 125-129.Haddad, C. F. B. and R. P. Bastos. 1997. Predation on thetoad Bufo crucifer during reproduction (Anura:Bufonidae). Amphibia-Reptilia 18: 295-298.Hinshaw, S. H. and B. K. Sullivan. 1990. Predation onHyla versicolor and Pseudacris crucifer duringreproduction. Journal of Herpetology 24: 196-197.Howard, R. D. 1981. Sexual dimorphism in bullfrogs.Ecology 62: 303-310.Lutz, B. 1973. Brazilian Species of Hyla. Austin.University of Texas Press. 260 pp.~~		Martins, M., I. Sazima and S. G. Egler. 1993. Predatorsof the nest building gladiator frog, Hyla faber, insoutheastern Brazil. Amphibia-Reptilia 14: 307-309.Mijares-Urrutia, A., A. Arends and J. M. Hero. 1997. Hylacrepitans (NCN). Predation. Herpetological Review28: 84.Owen, R. D. and S. A. Johnson. 1997. Pseudacris ocularis(Little Grass Frog). Predation. Herpetological Review28: 200.Pough, F. H., R. M. Andrews, J. E. Cadle, A. H. Savitzky,and K. D. Wells. 1998. Herpetology. New Jersey.Prentice Hall. 577 pp.Pough, F. H., W. E. Magnusson, M. J. Ryan, K. D. Wells,and T. L. Taigen. 1992. Behavioral energetics. Pp. 395-436 in M. E. Feder and W. W. Burggren (eds.),Environmental Physiology of the Amphibians. Chica-go. University of Chicago Press.Pramuk, J. B. and H. Almillo. 2002. Hyla nana. Predation.Herpetological Review 33: 46-47.Ryan, M. J. 1985. The Tungara Frog. Chicago. Universityof Chicago Press. 230 pp.Schiesari, L. C., F. A. Juncá and G. M. Accacio. 1995.Hylodes phyllodes (NCN). Predation. HerpetologicalReview 26: 30-31.Smith, R. L. 1980. Daddy water bug. Natural History 89:56-63.Stebbins, R. C. and N. W. Cohen. 1997. A Natural Historyof Amphibians. New Jersey. Princeton UniversityPress. 316 pp.Zuffi, M. A. 2001. Bufo bufo (European Common Toad).Red ant predation. Herpetological Review 32: 100-101.Toledo

Predation on seven South American anuran species by water bugs (Belostomatidae)

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