Some characteristics of anuran amphibians vary among Neotropical communities, such as abundance, biomass and body-size. Anurans also go through vulnerable periods in their life cycle, which makes them a fundamental group in trophic webs (Wilbur, 1997; Whiles et al., 2006).

In addition to preying on many types of organisms, anurans also serve as prey to a wide variety of potential predators on land or water, including vertebrates and invertebrates (Toledo, 2005). Among invertebrate predators, the hemipteran family Belostomatidae Leach, 1815 (Hemiptera Linnaeus, 1754) includes species of giant water bugs, a group of carnivorous insects that are distributed widely throughout the world (Ribeiro, 2005). These insects vary in size from medium to large (55 to 85 mm) and act as regulators in aquatic communities through predation (Ribeiro, 2005; Ohba, 2019). Predation by belostomatid insects upon adult bufonids is rare, with two known records for Brazil: one of an adult Rhinella ornata (Spix, 1824) being preyed upon by a Lethocerus grandis Linnaeus, 1758 on the north coast of the state of São Paulo (Haddad & Bastos, 1997), and one of an adult Rhinella mirandariberoi (Gallardo, 1965) preyed upon by a Letocherus annulipes (Herrich Schaeffer, 1845) in the municipality of João Pinheiro, state of Minas Gerais (Valencia-Zuleta et al., 2020).

Seeking to expand knowledge of such interactions, herein we report a new predation record of a Lethocerus grandis preying upon an adult Rhinella crucifer (Wied-Neuwied, 1821). We also provide a list of anuran species predated by giant water bugs of the family Belostomatidae in Brazil. We compiled the list by performing searches of the Google Scholar database (https://scholar.google.com/), using as keywords “Lethocerus grandis AND predat AND Rhinella crucifer” OR “Belostomatidae AND predat AND anuran AND Brazil”. We then checked the references of the recovered manuscripts, looking for additional records of predation events.

The predation event (Fig. 1) reported here was seen at 18:10 h during field work on 23 July 2019, when one of us (CLA) observed an adult Rhinella crucifer with snout-vent length (SVL) of 70 mm, being preyed upon by a Lethocerus grandis (99.2 mm). This interaction took place in a small artificial pond used for fish farming in the municipality of São Francisco do Glória, Minas Gerais, southeastern Brazil (20°48’20” S, 42°19’35” W; 515 m; Datum WGS 84). The site is located in a highly anthropized landscape within the Atlantic Forest biome, with a predominantly pasture matrix. At the observation moment, the air and water temperature were 14ºC and 17ºC, respectively. The toad was alive and struggling at the water surface near the edge of the pond. The giant water bug was positioned on the dorsum of the toad, with the limbs fixed on its ventral region, and the proboscis inserted in its left eye (Fig. 1A). After approximately 20 minutes of observation, both specimens (insect and anuran) were collected. The toad died during transport, and was fixed in formalin 10%, stored in ethanol 70%, and housed at Coleção Herpetológica do Museu de Zoologia João Moojen, of Universidade Federal de Viçosa, Minas Gerais, Brazil (MZUFV 19511). The anuran was identified as R. crucifer by the presence of a fringe on the ventral surface of the tarsus (Baldissera Jr et al., 2004). The giant water bug was identified as L. grandis due to its large body size (total length greater than 85 mm), large anterior tarsal claws as long or longer than the sum of the lengths of both anterior tarsal segments measured externally, and anterior femur slightly longer than the posterior femur (Ribeiro, 2005). There has been no previous record of predation on R. crucifer by a giant water bug, making this the first. Some “reptiles” are the main predators of the genus Rhinella, while records of predation by invertebrates are rare (Oliveira et al., 2017). Our search returned 294 articles, of which 16 were used on this study. Our data show that most of the reported predation events by giant water bugs in Brazil involved small-sized anurans (Appendix 1). It seems likely that the larger size of adult Rhinella may be difficult for these invertebrates to capture and subjugate (Toledo et al., 2007). In the present case, however, the individual Lethocerus grandis was 41.7% larger than its prey. The present observation suggests that the hemipteran large size combined with its anesthetic saliva (Menke, 1979), was sufficient for the hemipteran to subjugate the toad.