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FOOD AND FEEDING HABITS OF RANA HEXADACTYLA LESSON5 IN KUTTANAD, KERALA 1 Sanil George and M.I. Andrews2 Key words: Rana hexadactyla, food, feeding habits The food and feeding habits ofRana hexadactyla were studied at Kuttanad, Kerala. Arthropods formed the majorfooditemsofthe species, with insects which wereofeconomic importancebeingthe primary food. Introduction Adult frogs were collected from the paddy fields of The stomach contents of many species of Kuttanad during night and killed immediately in anura have been examined to determine their role the laboratory. Their body weight was recorded and in an ecosystem. The food ofdifferent anuran species the stomachs removed and preserved in 10% inhabiting temperate regions have been studied by formalin. Stomach contents were taken in a petri several workers (Needham 1905, Drake 1914, Smith dish after incising the stomach longitudinally. The 1953, Tyler 1958, Brooks 1959, Berry 1965, 1970; stomach and stomach contents were weighed, and Jensen and Klimstra 1966, Blackith and Speight the contents examined under a binocular dissecting 1974). However, the food and feeding habits ofonly microscope. a few tropical species have been investigated (Khera Table 1 1975, Issac and Rege 1975, Nigam 1979, Battish STOMACH CONTENTS OFR. hexadactylaEXPRESSED AS PERCENTAGEOFTOTAL BODYWEIGHTWITH and Sandhu 1988, Battish et al 1989, Sreelatha et RESPECTTO SEX AND MONTH al. 1990). Rana tigerina is known to play a Sex significant role in controlling agricultural pests Month (Abdulali 1985). The food and feeding habits of Male Female Rana hexadactyla are not fully known (Chacko and Krishnamurthy 1951, Mondal 1970, Andrews January 2.03 1.76 February 0.50 0.44 1979). March 0.94 0.15 Kuttanad, a natural wetland in Kerala, is an April 3.46 1.29 ideal habitat for frogs, especiallyRana hexadactyla. May 1.07 1.11 June 0.45 0.74 This region being the ‘rice bowl’ ofKeralaproduces July 2.11 1.49 one-third of the total rice cultivated in the State. August 0.71 0.48 The present study is an effort directed not only September 0.30 2.61 towards collecting data on the natural diet of the October 0.82 0.44 Indian green frogRana hexadactylabul also towards November 0.96 0.90 December 2.14 1.49 determining the role it plays in the Kuttanad Results ecosystem. Material and methods The monthly distribution ofstomach contents The stomach content analysis of Rana expressed as percentage of total body weight with hexadactyla was carried out from January 1988 to respect to sex and month is shown in Table 1. Males December 1989. A total of 408 frogs (102 males seem to consume more food than females, except in and 306 females) were used in the present study. the months of May, June and September. The frog ‘AcceptedJune 1994. 'Rana hexadactylais presentlyOccidozygahexadactyla (Lesson, •^DepartmentofZoology, MarThomaCollege,Tiruvalla-689103, 1834).Theclassificationof IndianAmphibiahasundergoneseveral KeralaState. changes, fordetails.?^ S.K. Dutta(1992),Hamadryad, pp. 1-13. 9 FOODANDFEEDINGHABITSOERANA HEXADACTYLALESSON 221 Tabie2 ClassifiedFoodItem No. of No. of Economic FOOD SPECTRUM OFRana hexadactylaLESSON stomachs individuals Importance ClassifiedFoodItem No. of No. of Economic Family: Jassidaf. stomachs individuals Importance Nephotettixsp. 9 18 Harmfultocrops Annelida Family: Gerridae Class: Oligochaeta Gerrissp. 19 36 Waterskaters Order: Opisthopora Family: Hydrometidae 2 Family: Mkgascolhcidah 1 Megascolex sp. 18 36 Order: Lepidoptera Noctuid larva 18 27 Croppest Arthropoda ” Caterpillar 18 39 Class: Insecta Hesperidlarva 7 11 55 Order: Anisoptera Dragonfly 61 74 Carnivorous, Order: Blattaria predator Family: Beattidae Dragonflynymph 74 83 Periplaneta americana 9 12 Householdpest Order: Dermaptera Order: Diptera Family: Labiduridae Family: Culicidae Labidura riparia 18 22 Carnivorous Anopheles sp. 47 189 Vector Anisolabissp. 14 18 Family: Chironomidae Family: Forficulidae Chironomus larva 11 18 Fish food Forficulasp. 24 33 Family: Muscidae Family: Carcinophoridae Musca sp. 3 8 Householdpest Euborellia sp. 19 27 Rootpest Family: Sarcophagidae Order: Orthoptera Parasarcophaga sp. 1 1 Family: Gryllotalpidae Gryllotalpafosser 209 281 Paddypest Order: Hymenoptera Gryllopsissp. 43 59 Family: Formicidae Diacamma vagans 5 8 Harmful totrees Family: Tridactylidaf, 2 1 Odontomachus sp. 59 I 1 Family: Gryujdae Camponautus compressus8 174 59 Gymnogryllus sp. 97 1 1 1 Omnivorous Megachilla sp. 24 69 59 Gryllussp. 237 296 Order: Coleoptera Family: Carabidae Family: Acrididae Anoplogenius sp. 39 74 Paddypest Oxya hyla hyla 132 184 Harmfultopaddy Bembidion soborium 28 61 Spathosternum Chlaenius sp. 1 3 calignosum 4 12 Dioryche sp. 2 6 Hieroglyphus banian 81 158 Siagona sp. 4 8 Tryxalissp. 6 18 Scarites sp. 43 58 59 Scelimena sp. 12 19 Pheropsopheus catorei 1 1 Clivina sp. 1 1 Order: Hemiptera Systolocranius sp. 17 23 95 Family: Belostomatidae Gnathophorus sp. * 1 2 Spherodema rusticum 43 79 Carnivorous waterbugs Kareya sp. 1 1 S. annulatum 212 369 Abacetus sp. 1 3 Diplonyctus sp. 1 1 Pachytrachelus sp. 1 1 1 222 JOURNAL BOMBAYNATURALHIST. SOCIETY, Vol. 92 (1995) ClassifiedFood Item No. of No. of Economic ClassifiedFoodItem No. of No. of Economic stomachs individuals Importance stomachs individuals Importance Family: Dystichmh Class: Arachnida Cybisterlarva 12 18 Predacious Order: Lycosidae Paradosa songosa 83 147 Biologicalcontrol Family: Scarabaeidap; agent Anomaila dussumieri 13 29 Rootpest Paradosa bursantiensis 79 116 99 Anomaila chlorocarpa 16 37 PestofCashew Paradosasp. 22 48 Autoserica insanabilis 3 8 99 Hippassa sp. 20 43 Anserica sp. 1 1 Lycosa iranii 3 12 99 Mimela sp. 1 2 Lycosa sumatrana 6 18 99 Onthophagus sp. 22 43 Crop pest Lycosa bistriata 6 19 99 Onitissp. 1 2 Catharsius sagax Family: Tetrognathidae 1 1 Chiloloba sp. 2 2 Tetrognatha sp. 12 21 99 Allisonotumsp. 2 3 Tetrognatha Sisyphus sp. 3 4 andamanensis 94 167 99 Hybosorus sp. 6 8 Tetrognatha mandibulata 7 18 99 Holotrichiasp. 4 6 Family: Araneidae Heteronychus sp. 5 18 Paddy pest Neoscona legubris 31 69 Popilia sp. 12 16 Family: Hetropodidae Family: Hydrophilidae Heteropoda sp. 10 21 Sternolophus 6 21 Peststoredfood Class: Myriapoda brachyacanthus grain Family: Scoeopendridae Hydrophilid sp. 2 8 Larva Otostigmussp. 4 7 predacious Millipede 16 1 Family: Elateridae Mollusca Melanotus hirticornis 2 2 Pestofstored Class: Gastropoda food grain Order: Basommatophora Heteroderis sp. 1 1 Lema Family: Pi.ANORBroAE sp. 1 1 Indoplanorbis exustus 16 22 Attica sp. 1 1 Family: Pilidae Family: Curcul.ionidae Pitasp. I 1 Useful Odioporus sp. 2 2 Order: Systellommatophora Plococerussp. 1 1 Family: Veronicellidae Sipalus sp. 2 2 Croppest Laevicaulissp. 1 1 Xanthoprocliilus sp. 4 4 Pisces Family: Tenebrionidaf. Family: Cypriniixjntlformes Gonocephalum sp. 18 36 Paddy pest Haplochilus puncliax 11 18 Larvivorous, Scleron sp. 1 1 biologicalcontrol Mesomorphus sp. 1 1 agent Hematismussp. 1 1 Family: Cypriniformes Family: Coccineli.idae Rasbora daniconius 3 6 Ediblefish Coelophora sp. 8 18 Family: Perciformes Class: Crustacea Etroplus sp. 1 1 99 Order: Decapoda Amphibia Palaemonsp. 17 36 Useful Order: Anura Paratelphusa Family: Ranidae bouvieri 43 67 Seriouspaddypest Rana cyanophlyctis 2 3 Useful P. hydrodwmus 18 24 99 Rana hexadactyla 1 1 Ediblefrog FOODAND FEEDINGHABITSOFRANA HEXADACTYLALESSON 223 Discussion ClassifiedFoodItem No. of No. of Economic stomachs individuals Importance The food spectrum obtained in the present investigation indicates that insects form the main Reptilia diet. From the observations recorded in the present Order: Opidia study, it is noticed that insects, spiders and crabs Typhlopssp. 6 Predator 1 are the major food items of R. hexadactyla. Order: Squamata Ccilotes sp. —3 4 Predator Arthropods thus form the bulk ofthe diet. Amongst Stones, leavesanddebris Many the arthropods, insects appear to be the most feeds on a variety ofanimals belonging to 20 orders. favoured food, some ofthe insects being ofeconomic The most predominant insect orders were importance. Issac and Rege (1975) and Abdulali Orthoptera, Coleoptera and Hemiptera (Table 2). (1985) have reported that R. tigerina played a Other than the insects, spiders and crabs were the significant role in controlling agricultural and other main food items. Vegetable matter, stones and other pests in the field. Crabs were found in large numbers debris were also found in most of the stomachs in the diet ofR. hexadactyla. They are often seen in examined during the present study. the paddy fields and cause damage to the bunds in The economic importance ofsome ofthe food the fields by boring holes in them. Crabs are considered as one of the major pests of paddy items is represented in Table 2. It is evident that R. hexadactyla is a natural predator of many of the (Kadam and Patel 1960) and are known at certain agricultural pests, especially paddy pests found in stages of their life to feed on rice seedlings both Kuttanad. Many of the serious paddy pests like before and after transplanting. The frog is thus Gryllotalpa fosser. Oxya hyla hyla, Hieroglyphus useful in controlling the crab population harmful banian, Anoplogenius sp., Gonocephalum sp., to agriculture. Some gastropods were also recorded from the stomachs ofa few frogs. Vertebrate groups Paratelphusa bouvieri and P. hydrodromus and such as fishes, amphibians and and reptiles were other crop pests such as Nephotettix sp., Euborellia also recorded but there was no reason to believe sp., Nectuid larva, Bombidion soborium, Scarites that they formed regular items of the diet (see sp. and Sipalus sp. were present in the stomachs. Andrews 1976). Anopheles sp. is also an important food item of this frog. Pests of stored food grains like Sternolophus The presence of stones, leaves and debris brachyacanthus. Melanotus hiriticornis and among the gut contents of R. hexadactyla may be Anomaila chlorocarpa, an importantpestofcashew, the result of accidental ingestion. Vegetable matter were also found in the food spectrum. Other species occurred in many guts, but the quantity was small; found in the stomachs of R. hexadactyla included it might have been inadvertently ingested with the fish food organisms, prawns, fishes and some frogs. food. The intake of pebbles and plant matter may However, their numbers were very low. be important in providing roughage as well as R hexadactyla is usually found in water and increasing grinding capacity for the total mass . ingested. The presence of stones and vegetable its aquatic habit is reflected by the large proportion ofaquatic insects eaten by it. Movement ofthe prey matter in the guts of anurans has also been reported attracts the attention ofthis frog, whose first reaction by earlier workers (Battish et al. 1989, Sreelatha et is tojump upon and swallow its prey, all in a single al. 1990, George et al. 1992). movement. The frog may detect the prey from some Mondal (1970) observed that the “northern distance and then approach it in a series of bounds, race” of R. hexadactyla was a herbivore while the the last leap being made onto its prey. The forelegs “southern race” preferred animal food. The present are used to push into the mouth any item which the study indicates that R. hexadactyla in Kuttanad is frog may not be able to swallow completely. carnivorous, as noted by Andrews (1979). . . 224 JOURNAL, BOMBAYNATURALHIST. SOCIETY, Vol. 92 (1995) The present study reaffirms that frogs are The decline in the population of frogs in useful as control agents for various insect pests Kuttanad due to commercial capture for their legs especially those which are considered as serious crop and the effect of pesticide residues in the area may pests. Though frogs are opportunistic feeders, their be detrimental to crops, especially paddy. feeding on many phytophagous insect pests does Acknowledgements support their usefulness as biocontrol agents. This fact has been stressed by several earlier workers We are grateful to the State Committee on (Abdulali 1985, Battish et al. 1989, Sreelatha et al. Science, Technology and Environment, Govt, of 1990, Sally et al 1992). 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