Comparative vulnerability of Indosylvirana temporalis and Clinotarsus curtipes (Anura: Ranidae) tadpoles to water scorpions: importance of refugia and swimming speed in predator avoidance

Abstract

The comparative vulnerability of two co-existing tadpole species (Indosylvirana temporalis and Clinotarsus curtipes) to their common predator, water scorpions (Laccotrephes sp.; Hemiptera: Nepidae), and the importance of refugia in predator avoidance were studied in the laboratory. In a total of 60 experimental trials, 10 tadpoles each of I. temporalis and C. curtipes of comparable body sizes were exposed to water scorpions (starved for 48 h). Thirty trials included refugia while 30 did not. The results of this study showed that in both the absence and the presence of refugia C. curtipes tadpoles fell prey to water scorpions more frequently than I. temporalis tadpoles. A main difference between the two species is the speed of swimming; Vmax of C. curtipes (24.73 cm/s) tadpoles is lower than that of I. temporalis (30.78 cm/s) tadpoles. This is likely to be the reason why more C. curtipes tadpoles were preyed upon than were I. temporalis tadpoles. Predation risk of tadpoles of both species was affected significantly by the presence of refuge sites. The vulnerability of both tadpole species was lower where refuge sites were available. The present study clearly shows that I. temporalis tadpoles avoid predation by water scorpions more effectively than do C. curtipes tadpoles.

Relative susceptibility of tadpoles of Uperodon taprobanicus (Anura: Microhylidae) and Duttaphrynus melanostictus (Anura: Bufonidae) to predacious Hoplobatrachus tigerinus (Anura: Dicroglossidae) tadpoles: significance of refugia and swimming speed in pre

“…Alternatively, it is also possible that better spatial avoidance by U. taprobanicus tadpoles or a preference of H. tigerinus to consume U. taprobanicus tadpoles over D. melanostictus. Our results conform to those of earlier studies (Van Buskirk and McCollum 2000, Dayton et al 2005, Mogali et al 2021. From the results of the present study it is clear that the V max of predator, H. tigerinus tadpoles (60.21 cm/s) is much higher than both prey species hence it could capture both prey tadpole species easily.…”

Predatory influence of dragonfly larvae and water scorpions on eggs and tadpoles of Indosylvirana temporalis (Anura: Ranidae)

“…are non-gape-limited and use a segmented beak to pierce I. temporalis and suck their body fluids. They are able to capture small to large tadpoles by quickly grabbing and immobilizing the tadpoles by using the front pair of raptorial legs (Mogali et al 2020b). Even though starved for 48 h, the water scorpions did not eat eggs of I. temporalis.…”

“…(N = 60) were collected from the same location as the eggs and tadpoles. Because both insects are highly cannibalistic in nature (Mogali et al 2020a(Mogali et al , 2021, they were reared individually in plastic tubs (14 cm diameter and 7 cm depth) with 500 mL of aged tap water to avoid cannibalism. All predators were fed each day with 5-8 tadpoles of I. temporalis.…”

“…Anurans usually deposit their eggs either in temporary or permanent ponds or streams with continuous or intermittent flowing water (Hiragond and Saidapur 1999, Eterovick and Barata 2006, Mogali et al 2016, 2017, resulting in early developmental stages being highly vulnerable to predation (Alford, 1999). As a consequence of this predation stress, larval anurans have developed various kinds of defensive mechanisms such as secretion of toxic substances that make eggs or larvae unpalatable or toxic to predators (Gunzburger and Travis 2005), a drastic reduction in activity levels to avoid being detected (Chovanec 1992, Mogali et al 2011, Gómez 2019, increased use of refuges (Kopp et al 2006, Hossie and Murray 2010, Sanders et al 2015, Mogali et al 2019, increased activity in order escape predators (Mogali et al 2021), or aggregation and formation of schools (Waldman and Adler 1979, Watt et al 1997, Spieler and Linsenmair 1999, depending upon the species or perceived predation threat.…”

Effects of abiotic and biotic drivers on tadpoles in seasonal rock pools of Western Ghats rock outcrops, India

“…(2022). The observer enumerated tadpoles of the three species and their potential invertebrate predators: fishing spiders (Araneae), crabs (Decapoda), dragonfly larvae (Odonata), and water beetles (Coleoptera) (Skelly, 1997;Valdez, 2020;Mogali et al, 2022), by counting them using head and hand-held torch lights. Pool volume (cm 3 ) was calculated by multiplying the mean depth, maximum length (longest axis) and maximum width (longest axis perpendicular to length).…”