Report on Food and Feeding Habit of Common Garden Lizard

INTRODUCTION:

Reptiles are some of the most fascinating animals on Earth. Reptiles are vertebrates of the taxonomic class Reptilian – that have a backbone while they share characteristics common to other vertebrates: fish, amphibians, birds, and mammals; reptiles display a unique combination of characteristics that distinguishes them from other vertebrates.

A reptile is an animal with tough, dry skin covered with horny scales. Reptiles are commonly called “cold-blooded”; exothermic  meaning they are unable to regulate their own body temperature and are instead influenced by the temperature of their surroundings.

Many reptiles and all snakes are carnivores. A majority of lizards eat insects, while most snakes eat smaller vertebrates, including birds, rodents, fish, amphibians, and other reptiles.

Reptiles can go for days, even months without food, and the food that they do eat is used in making more reptiles. Most reptiles are able to raise their body temperature rapidly above that of the air temperature on sunny days. They achieve this by choosing basking sites, which are sheltered from the wind and exposed not only to direct sunlight but to the warmth reflected off rocks or logs. If the substrate has been warmed by the sun they will often flatten themselves against it to absorb as much heat as they can.

The characteristic dry, scaly skin protects reptiles’ internal tissues from drying out, and in many species, it also plays a role in defense and mating.

Color changes may enable reptiles to escape notice by predators by blending with their environment, but these color changes may be more important in communicating with other reptiles, for instance, to attract a mate or warn a rival.

Reptiles rely on their keen senses to find food and evade predators. Among   species that hunt for food, the eyes are often located at the front of the head to provide binocular vision, the ability to see objects from slightly different angles to create a sense of depth. Many lizards, such as chameleons, can move their two eyes independently of one another to look in different directions at the same time. In some lizards and all snakes, a transparent scale, called a spectacle, covers each eye, providing a protective covering that keeps dust out and moisture in. Reptiles with spectacles do not have eyelids that open and close, giving the eerie impression that these animals stare relentlessly.

Reptiles play an important role in ecosystems as both consumers and as prey items.  Reptiles can regulate plant growth as well. Reptiles such as snakes, lizards, and turtles are a food source for many larger predators.

There are over 7,000 species of wide spread living reptiles, all of which belong to one of four main groups: turtles and tortoises; lizards; worm lizards; snakes; crocodiles and their relatives.

With over 4,300 individual species, the lizards are the most abundant and diverse group of reptiles alive today. In Bangladesh, 124 species of reptiles are found. Among them only 18 species are lizards and skinks (Khan, 2004). According to IUCN (2000), a total of 109 species of reptiles are found in Bangladesh. Typical lizards have long, slender bodies that taper to a narrow, pointed tail. Most have four legs ending in dexterous, clawed toes.

Most lizards are small, agile insectivores that live in trees or shrubs or in rocky places. Records of prey and other food items of Calotes versicolor, most of them based on observations in India. It would is predominantly insectivorous (according to Diong et al. 1994, “analysis of stomach contents [in Singapore] reveals a diet comprising mainly ants, larval and adult insects, and other small invertebrates”), but it is clearly an opportunistic omnivore that can prey on small vertebrates and feed on plant material as well.

They are good at keeping insect populations in check. In Bangladesh, Agamemnon are much-neglected group in the point of view of research. No detail study has yet been done on the food and feeding habit of Calotes versicolor. The study was, therefore, aimed to determine the food and feeding habit of Calotes varicolored and its role in biological pest control, which could be used for the management plan as well as the conservation of the species.

From the economic point of view, the insects which were consumed by C. varicolored  seemed to be economically important because most of them were crop pests, agricultural pests or injurious to trees, fruits and vegetation  Some are disease vectors; however, some species are beneficial to the human being.

Study species:

Following species was selected for the study:

Calotes versicolor, Common Garden Lizard

Systematic position:

 Kingdom: Animalia

       Phylum: Chordata

              Class: Reptilia

                  Order: Squamata

                         Suborder: Sauria

                               Family: Agamidae

                                      Genus: Calotes

                                             Species: versicolor

Family Agamidae includes the common garden lizard (C. versicolor ) or bloodsucker, commonly known as “Roctochosha” in Bangladesh. It is a medium-sized, arboreal lizard with oval head and laterally compressed body.

Some species under the genus Calotes are cited here:

Green Garden Lizard, Calotes calotes

Painted-lip Lizard, Calotes ceylonensis

Forest Crested Lizard, Calotes emma

Crestless Lizard, Calotes liocephalus

Whistling Lizard, Calotes liolepis

Black Cheeked Lizard, Calotes nigrigularis

General information:

The Common Garden Lizard (Calotes versicolor) is widely distributed throughout the Indian Sub-continent most of South East Asia.

Medium sized about 37 cm in length. Females are considerably smaller than males.

The species is identified by the short crest above the neck, the presence of small spines above the tympanum and by the lack of a shoulder fold .Generally broad brown bands across the back, interrupted by a yellowish lateral band. Black streaks radiate from the eye, and some of them are continued over the throat, running obliquely backwards, belly frequently with greyish longitudinal stripes, one along the median line being the most distinct; young and half-grown specimens have a dark, black-edged band across the inter-orbital region. The male has muscular and swollen cheeks.

The coloration is very variable, sometimes uniform brownish, greyish-olive, or yellowish a dark, black-edged band across the inter-orbital region. The ventral side is generally a light brownish olive, but the lizard can change it to bright red, to black, and to a mixture of both. This change is sometimes confined to the head, at other times diffused over the whole body and tail. The male gets a bright red throat in the breeding season leading to a common incorrect name of Bloodsucker.

Being a semi-arboreal, sun-loving lizard that spends a lot of time on tree-trunks and rocks, Calotes  versicolor has a predilection for open scrubland, wasteland.

The crested tree lizard is predominantly insectivorous Diet comprising mainly ants, larval and adult insects, and other small invertebrates.

Males become highly territorial during breeding season. They discourage intruding males by brightening their red heads and doing “push-ups”. Each tries to attract a female by inflating his throat and drawing attention to his handsomely colored head. They are able to breed at about 1 year old.

Plate 1.1 (a) & (b) Showing the species Calotes versicolor

Literature review:

Various types of research work had been done on different aspect of Calotes versicolor in different parts of the world.

In other countries different author worked on food and feeding habit of garden lizard. Some of these observations are on the field observation and some are based on examination of gut contents.

Some research and publications related to lizard are mentioned below:

Aengals R. (2000) worked on a strange food habit of the garden lizard (Calotes versicolor).

Ahmed S. worked on Myriapods as the food of the common garden lizard Calotes versicolor.

Bhatti U.S. (1988) studied on wasps in the stomach contents of the garden gigit, Calotes versicolor.

Bhatti U.S., Batti S.K. and Batti S.S. (1988) worked on vegetation in the food contents of the garden lizard (girgit), Calotes versicolor.

Chandra H. (1983) studied on the feeding capacity of the bush lizard (Calotes versicolor) on the surface grasshopper (Chrotogonus sp.).

Devasahayam S. and Devasahayam A. (1989) worked on a peculiar food habit of the garden lizard Calotes versicolor.

Manakadan R. (1993) worked on the common toad Bufo melanosticus and the garden lizard Calotes versicolor feeding on swarming termites.

Mitra A. (1996) worked on dragonfly predation by the garden lizard, Calotes versicolor.

Rajarathinam R. and Kalaiarasan V. (1999) worked on a strange feeding habit of Calotes versicolor.

Rao S.M.V. (1975) studied on the food and feeding behavior of the agamid garden lizards Calotes versicolor.

Saratchandra B. and Ramesh Babu P. (1982) worked on a new flagellate, Proteromonas krishnamurtyi n. sp., from the rectum of Calotes versicolor.

Sekar A.G. (1988) studied on a note on the food habit of the garden lizard Calotes versicolor.

Sharma S.K. (1992) worked on Common garden lizard Calotes versicolor preying on Brook’s gecko Hemidactylus brooki.

Sharma S.K. (1994) worked on the common garden lizard Calotes versicolor feeding on germinating seeds of Feronia limonia Swingle.

Sharma S.K. (1998) worked on a garden lizard (Calotes versicolor) feeding on a dry mango (Mangifera indica) leaf.

Sharma S.K. (1999) worked on Calotes versicolor feeding on Lycodon aulicus.

Sharma S.K. (2002.) worked on Indian garden lizard Calotes versicolor feeding on earthworms at Akyawad Forest Nursery, Udaipur District, Rajasthan.

Sunderasan S.R. and Daniels R.J.R. (1994) worked on distribution and abundance of the common garden lizard Calotes versicolor in the Madras Crocodile Bank.

Tiwari M. and Schiavina A. (1990) worked on Biology of the Indian garden lizard Calotes versicolor.

Aims and objectives:

The activities are designed to reach the following aims and objectives:

1. To identify the relationship between different body parts, which is an important tool for food adaptation.

2. To find the correct information about the food and feeding habit of Calotes versicolor.

3. To identify food materials taken by Calotes versicolor.

4. To ensure the percentage of their feeding preference, like insects, plant materials, mollusks, miscellaneous matter.

5. To identify different insect species taken by Calotes versicolor.

STUDY AREA:

Study area:

The study was conducted at Jahangirnagar university campus, Savar, Dhaka, Bangladesh. The common garden lizard occuring a wide variety of habitats troughout the J. U. The J. U. contains bushy areas and grasslands that are good habitat for the common garden lizards. The J.U. campus is geographically situated in the central part, if the country, which have the suitable vegetation for reptiles with its panoramic natural beauty. Thus, it has become the important residential area for the study of reptiles fauna.

Geographiacal location:

Jahangirnagar University Campus is situated in 32 km north from the Dhaka city and located between 21⁰24′ and 21⁰36′ N Latitudes and between 91⁰59′ and 92⁰08’E longitudes. It is bounded on the north by the army camp and National Smrity Saudha , on the east by  the largest animal farm “Savar  Dairy  Firm “, on the south by Bangladesh Public Administration Training Center (BPATC) And the Bangladesh radio broadcasting center on the west by Kolabagan, Islamnagar and Gerua etc.

Area:

Jahangirnagar University Campus occupies on area of 697.56 acre (20.48 hectares) including 195 acre water bodies (lakes, ponds and ditches) and 502 acre land surface.

 Soil condition:

The soil of Jahangirnagar University Campus is deep brown to yellowish red in color. The soil consist high amount of iron. In dry condition, the soil is very hard but in moist condition, it become very soft and clayed. The soil texture is slightly-clay, slightly-clay-loam and clayey. This area is part of Madhupur Pleistocene Originally, it is oxidized. Topographically the present areas covered by broad flattened and low-lying baids. The deeper baids are regularly flooded during the rainy season and rest of the lands remains flood-free.

The soil type of J.U. campus is laterite and its moisture contents are high particularly during the rainy season .The soil is acidic in nature (acidity 5.5).Nitrogen is high but phosphorus is very low. Sodium content is high and other nutrients (macro-micro) are also within normal range.

Vegetation:

The campus comprises a very good vegetation of different trees, herbs and shrubs. Undergrowth is very prominent. The ground vegetation includes bushes, many other shrubs, herbs and ferns. Open field with green small grasses was observed. The lake and ditches and its surrounding banks are characterized by aquatic and emergent vegetation and is home of many resident and migratory bird species. The campus contains various plants species of which the jackfruit trees (Artocarpus heterophyllus) are dominant.

Some relative dominant trees of the campus are Akashmoni (Acacia moniliformes), Mehgani (Swetenia mahagoni), Debdaru (Polyalthia longifolia), Shisu (Dulbergia sissoo), Kolkasunda (Cassia oblusifolia) etc. Some trees like Arjun (Terminalia arjuna), Krishnachura (Alonix regia), Kalokoroi (Albegia odoratissimuss), Sadakoroi (Albegia procera), Guava (Psidium guajava) and Kadam (Anthocephalas kadamba) are more common. It is clearly seen that the campus have too many exotic plants and for this reason, the local plants and wild fauna are being threatened. Such as Akashmoni, an exotic plant is hampered the local fauna. The birds cannot build their nest on these Akashmoni trees and the pollen grain of these trees are also harmful for health which may cause asthma in human being. If this species alter with Mango trees, Kathal and other local plants, it would become more friendly to the environment and will give us fruits, timbers and also a healthy atmosphere.

Climatic condition:

JahangirnagarUniversity enjoys a moderate climate. The monthly minimum and maximum temperatures range varies from 13.00 to 27.58 ⁰C and 20.10 to 32.67 ⁰C respectively and average temperature range was 72.39 to 90.68. The average monthly humidity was 81.94%. The average pH of the lake water was 7.2.

Table 2.1 Average Temperature, Humidity and Rainfall in different month of the

                    study period (November 2007 – March 2008)

MATERIALS AND METHODS:

Materials

Equipments and chemicals:

During study period the following equipments were used:

A. Collection

1. Sweep net – Sometimes it was used to collect the lizard;

2. Hand – Mainly free hand was used to collect the lizard;

3. Plastic bottles – It was used both for keeping and preserving the collected specimen.

B. Preservation

1. Chloroform – was used to anaesthetized the specimen;

2. Formalin – 10% formalin to preserve the caught specimen and 5% formalin to preserve the alimentary canal from those specimen;

3. Glass jar – were used to preserve the collected specimen;

4. Vials – were used to preserve the food items collected from the dissected alimentary canal.

C. Measurement

1. Balance – to measure the weight of lizards, their alimentary canals and food item a two battery balance was used;

2. Slide calipers – was used to measure various length of the body;

3. Centimeter scale – it was used to measure the length of alimentary canal of those collected specimen. 

Plate 3.1 (a) & (b) Showing the equipments used in dissection and

  measurement

   (c) Showing the vials used in preservation of analyzed food

D. Dissection

1. Tray – was used to attach the specimen in wax for dissection;

2. Scissors – a pair (fine for dissecting the alimentary canal and normal for dissection of the body) were used;

3. Scalpels – used to separate the skin from body muscles;

4. Forceps – both small and large forceps were used to pickup the food materials;

5. Petridish, watch glass and brushes – used during the separation of mixed food items;

6. Surgical gloves – were used during dissection to avoid the contamination of disease;

7. Cotton – were used to anaesthetize the specimen with chloroform and other different purposes.

E. Identification

1. Microscope – used to identify various undigested and semi-digested foods collected from the alimentary canal of the lizard.

Methods

 Specimen collection:

During the study period, the lizards were collected from the different sites of J.U. campus (Table 3.1).

For specimen collection 15-20 days in each month were spent to survey the area from November 2007 to March 2008. 35 individuals of C. versicolor were collected from the study area.

After capturing the lizards were anaesthetize immediately by chloroform and were took the measurement of different parts of the body.

During the study period, the specimens were collected at 11:00 to 16:00 from different habitat types and the specimens were collected by hand picking.

During specimen collection the date, time, locality, habitat type etc. and the length, weight of each specimen were measured and recorded on data sheet.

Table 3.1 Different collecting points of studied species

Map 3.1 Showing different collecting sites of Calotes versicolor at Jahangirnagar

                  University Campus

Preservation of collected specimens:

To prevent further breakdown of the stomach contents, the collected specimens were instantly anaesthetized by chloroform and preserved in 10% formalin. Then dissections were taken carefully to open the digestive tracts for the qualitative and quantitative analysis of food, consumed by the lizard. The weight and length of the alimentary canal were taken with food contents and without food content with the help of centimeter scales and battery balance and recorded on data sheet. The foods were separated item wise and preserved in 5% formalin in vials. The consumed food items were primarily categories into undigested, semi-digested, and digested. Then food items were identified with the help of books, literatures and sometimes with the help of Teacher.

Measurement of alimentary canal

 Alimentary canal length

It was measured after cutting the mesentery, as a straight line from esophagus to    cloacal aperture in cm by a measuring tape.

Alimentary canal weight

It was measured by a digital balance in gm and recorded in data sheet.

 Esophagus to stomach length and weight (with food)

Length and weight were measured separately by measuring tape in cm and digital balance in gm and recorded in data sheet.

 Esophagus to Stomach food weight

Food weight were measured by a digital balance in gm and recorded in data sheet.

 Intestine to Rectum length and weight (with food)

Length and weight were measured separately by measuring tape in cm and digital balance in gm and recorded in data sheet.

Intestine to Rectum food weight

Food weight were measured by a digital balance in gm and recorded in data sheet.

 (a) Showing the alimentary canal in the dissected specimen Calotes

                            versicolor ( Kotpal, 1999)

                    (b) Showing measurement of alimentary canal length separated from

                             the body

                       (c) Showing weight of alimentary canal

Plate 3.3 (a) Showing measurement of esophagus-stomach length of Calotes

                             versicolor

                       (b) Showing weight of esophagus-stomach

                      (c) Showing semi-digested food separated from the esophagus-stomach

                       (d) Showing weight of semi-digested food

Plate 3.3 (a) Showing measurement of intestine-rectum length of Calotes

                               versicolor

                          (b) Showing weight of intestine-rectum

                        (c) Showing semi-digested food separated from the intestine-rectum

                          (d) Showing weight of semi-digested food

Measurement of food:

Both qualitative and quantitative study of food was done by the following way:

Qualitative ] and SPSS.

RESULTS:

General:

A total of 35 individual of Calotes versicolor were analyzed for their food habit and gut measurement. Most of the species were collected from different tree trunks and bushy areas of J.U. campus. The average body weight (BWt) of male was 12.92 and female was 11.6 gm and the average food weight (FWt) of male was 0.63 gm and the female was 0.6 gm. A positive correlations were found among snout-vent length (SVL) and alimentary canal length (ACL), alimentary canal length (ACL) and esophagus-stomach length (E-StL), body weight (BWt) and alimentary canal weight (ACWt), alimentary canal weight (ACWt) and esophagus-stomach weight (E-StWt), esophagus-stomach weight (E-StWt) and esophagus-stomach food weight (E-StFWt), body weight (BWt) and food weight (FWt). A total of 35 food items were found in the alimentary canal of Calotes versicolor of which 29 animal matters, 2 plant matters, 1 mollusk and 3 miscellaneous. This species consumed different food items, which were beneficial and harmful for agriculture, plants, and household and as vectors of disease. There were considerable variations between male and female in SVL, BWt, ACL, ACWt etc.

Habitat preference:

Calotes versicolor often seen during day sitting on tree branches usually sidles to the back of the bole or branch, shrubs or bushy areas and hedges of which are most preferable habitat of them. In the present study, it was collected from various tree trunks (3-4 feet), bole or branch and some from bushy areas.    

Plate 4.1 Showing different habitat of Calotes versicolor

                                       (a) woodland with undergrowth

                                       (b) woodland without undergrowth

                                       (c) & (d) bushy area

                                       (e) & (f) tree trunk

Gut analysis:

 Relationship between Snout-Vent Length (SVL) and Alimentary Canal                 

         Length (ACL):

The average snout-vent length (SVL) of male was 7.59 cm (range=4-9.4cm, sd±1.10, n=29) and the female was 7.65cm (range=6.8-8.7 cm, sd±0.83, n=6) and the average alimentary canal length (ACL) of male was 16.24 cm  (range=10.2-22.7 cm, sd±3.42, n=29) and the female was 14.88 cm (range=11.8-16.8cm, sd±1.73, n=6) were measured. A positive correlation between snout-vent length (SVL) and alimentary canal length (ACL) was found. In this case, the Pearson correlation between SVL and ACL 0.69 and 0.71 respectively in male and female. Here in male, the correlation is significant at the 0.01 level.

In relation to male snout-vent length and alimentary canal length, the value of R² is 0.477. So the relationship is weak. In relation to female snout-vent length and alimentary canal length, the value of R² is 0.505. In this case, the relationship is not so strong (Fig.4.1 & 4.2).

Both the relationships between male and female snout-vent length and alimentary canal length are not so strong.

In comparison, the relationship of male snout-vent length and alimentary canal length is weaker than female snout-vent length and alimentary canal length.

Relationship between Alimentary Canal Length (ACL) and Esophagus-

         Stomach Length (E-StL):

The average alimentary canal length(ACL) of male was 16.24 cm  (range=10.2-22.7 cm, sd±3.42, n=29) and the female was 14.88 cm (range=11.8-16.8cm, sd±1.73, n=6)and the average esophagus-stomach length (E-StL) was 4.34 cm  (range=2.7-8 cm, sd±1.12, n=29) and the female was 3.81 cm (range=3.1-5.1 cm, sd±0.77, n=6) were measured. A positive correlation between alimentary canal length (ACL) and esophagus-stomach length (E-StL) was found. In this case, the Pearson correlation between ACL and E-StL was 0.68 and 0.58 respectively in male and female. Here in male, correlation is significant at the 0.01 level.

In relation to male alimentary canal length and esophagus-stomach length, the value of R² is 0.462. So, the relationship is weak. In relation to female alimentary canal length and esophagus-stomach length, the value of R² is 0.346. In this case, the relationship is also weak (Fig. 4.3 & 4.4).

Both the relationships between male and female alimentary canal length and esophagus-stomach length are weak.

In comparison, the relationship of male alimentary canal length and esophagus-stomach length is stronger than female alimentary canal length and esophagus-stomach length.

Relationship between Body Weight (BWt) and Alimentary Canal Weight

 (ACWt):

The average body weight (BWt) of male was 12.92 gm (range=5.2-22.9 gm, sd±4.53, n=29) and the female was 11.6 gm (range=7.8-17.9 gm, sd±4.09, n=6) and the average alimentary canal weight (ACWt) of male was 1.10 gm (range=0.5-2.5 gm, sd±0.58, n=29) and the female was 1.25gm (range=0.8-1.5gm, sd±0.25, n=6) were measured. A positive correlation between body weight (BWt) and alimentary canal weight (ACWt) was found in both male and female. In this case, the Pearson correlation between BWt and ACWt was 0.64 and 0.84 respectively in male and female, where correlation is significant at the 0.01 and 0.05 levels.

In relation to male body weight and alimentary canal weight, the value of R² is 0.412. So, the relationship is weak. In relation to female body weight and alimentary canal weight, the value of R² is 0.707. In this case, the relationship is strong (Fig. 4.5& 4.6).

In comparison, the relationship of male body weight and alimentary canal weight is weaker than female body weight and alimentary canal weight.

Relationship between Alimentary Canal Weight (ACWt) and Esophagus-    

        Stomach Weight (E-StWt)  :

The average alimentary canal weight (ACWt) of male was 1.10 gm (range=0.5-2.5 gm, sd±0.58, n=29) and the female was 1.25gm (range=0.8-1.5gm, sd±0.25, n=6) and the average esophagus-stomach weight (E-StWt) of male was 0.56 gm (range=0-1.8 gm, sd±0.41, n=29) and the female was 0.6 gm (range=0.3-0.8 gm, sd±0.17, n=6) were measured. A positive correlation between Alimentary canal weight (ACWt) and Esophagus-Stomach weight (E-StWt) was found in both male and female. In this case, the Pearson correlation between ACWt and E-StWt was 0.90 and 0.51 respectively in male and female. Here in male, the correlation is significant at the 0.01 level.

In relation to male alimentary canal weight and esophagus-stomach weight, the value of R² is 0.815. So, the relationship is strong. In relation to female alimentary canal weight and esophagus-stomach weight, the value of R² is 0.269. In this case, the relationship is weak (Fig. 4.7& 4.8).

In comparison, the relationship of male alimentary canal weight and esophagus-stomach weight is stronger than female alimentary canal weight and esophagus-stomach weight.

 Relationship between Esophagus-Stomach Weight (E-StWt) and Esophagus-

 Stomach Food Weight (E-StFWt):

The average esophagus-stomach weight (E-StWt) of male was 0.56 gm (range=0-1.8 gm, sd±0.41, n=29) and the female was 0.6 gm (range=0.3-0.8 gm, sd±0.17, n=6) and the average esophagus-stomach food weight (E-StFWt) of male was 0.37 gm (range=0-1.7 gm, sd±0.37, n=29) and the female was 0.36 gm (range=0-0.6 gm, sd±0.20, n=6) were measured. A positive correlation between esophagus-stomach weight (E-StWt) and esophagus-stomach food weight (E-StFWt) was found. In this case, the Pearson correlation between E-StWt and E-StFWt was 0.95 and0.92 respectively in male and female, where correlation is significant at the 0.01 level.

In relation to male esophagus-stomach weight and esophagus-stomach food weight, the value of R² is 0.915. So the relationship is strong. In relation to female esophagus-stomach weight and esophagus-stomach food weight, the value of R² is 0.847. In this case, the relationship is strong (Fig. 4.9 & 4.10).

Both the relationships between male and female esophagus-stomach weight and esophagus-stomach food weight are strong.

In comparison, the relationship of male esophagus-stomach weight and esophagus-stomach food weight is stronger than female esophagus-stomach weight and esophagus-stomach food weight.

 Relationship between Body Weight (BWt) and Food Weight (FWt):

The average body weight (BWt) of male was 12.92 gm (range=5.2-22.9 gm, sd±4.53, n=29) and the female was 11.6 gm (range=7.8-17.9 gm, sd±4.09, n=6) and the average food weight (FWt) of male was 0.63 gm (range=0-1.9 gm, sd±0.46, n=29) and the female was 0.6 gm (range=0-0.8 gm, sd±0.29, n=6) were measured. A positive correlation between Body weight (BWt) and Food weight (FWt) was found. In this case, the Pearson correlation between BWt and FWt was 0.47 and 0.39 respectively in male and female. Here in male, the correlation is significant at the 0.01 level.

In relation to male body weight and food weight, the value of R² is 0.229. So the relationship is weak. In relation to female body weight and food weight, the value of R² is 0.157. In this case, the relationship is weak (Fig. 4.11 & 4.12).

Both the relationships between male and female body weight and food weight are weak.

In comparison, the relationship of male body weight and food weight is stronger than female body weight and food weight.

Sex differences:

There was considerable variation between male and female among their snout-vent length (SVL), body weight (BWt), alimentary canal length (ACL) and alimentary canal weight (ACWt), esophagus-stomach length (E-StL) and esophagus-stomach weight (E-StWt), intestine- rectum length (I-RL) and intestine- rectum weight (I-RWt), food weight (FWt). The following table shows the differences between male and female. There were relationship between body weight and food weight in male and female.

Calotes versicolor (length units in cm and weight units in gm):

Food and Feeding habit:

General:

Food is essential for animal to survive, continue all metabolic activities and for maintaining breeding activities. Therefore, Calotes versicolor also require their food for to live and to adapt in the environment. They take nutrition by eating food from the ground level; found in natural dry habitats. They prefer sandy or rocky soil, short grass, thin woods, dusty roadsides, etc. to collect their food. They prefer mainly insects; occasionally they consumed worms, mollusks, plant materials, miscellaneous etc.

For the analysis of food, 35 individuals alimentary canal were dissected and analyzed. For this purpose first Calotes were collected during study period (November 2007-March, 2008) from 11:00-16:00 from different habitat of J. U. campus.

The species were collected by handpicking. Collected species were preserved in 10% formalin.

For getting food, alimentary canals were dissected and analyzed. After dissection the food found from alimentary canal were preserved in 5% formalin for their identification.

A total of 35 food items were found in the alimentary canal of Calotes versicolor, of which 28 families include 29 animal matters, 2 plant matters, 1 mollusk and 3 miscellaneous. In their food composition order- Hymenoptera occupied the first position followed as Hymenopterans 37.9%, Coleoptera 13.8%, Ephemeroptera 10.3%, Orthoptera 10.3%, Lepidoptera 6.9%, Isopteran 3.4%, Plecoptera 3.4%, Hemiptera 3.4%, Homoptera 3.4%, Trichoptera 3.4%, Dipterans 3.4%, Mollusks 2.9%, Plant matter 5.7% and Miscellaneous 8.6%.

Plate 4.2 Showing different food items consumed by Calotes versicolor

                           (a) larva of Papilio (b) & (c) larva

                           (d)sawfly larva, Neodiprion lectontei

                           (e) white grubs, Phyllophaga sp. (f) grubs

                           (i) & (j) grasshopper

Plate 4.3 Showing different food items consumed by Calotes versicolor

                           (k) leafhopper (l) winged termite (m) fungus beetle

                           (n) mount building red ant, Formica esecterdes

                           (o) mollusk (p) plant matter

                           (q) & (r) miscellaneous & stone

 Table 4.2 The food items found in the alimentary canal of C. versicolor

Economic importance on the basis of food habit:

From economic point of view, the insects which as consumed by Calotes versicolor seemed to be economically important because most of them were crop pests, agricultural pests, house hold pests or injurious to trees, fruits and vegetations. Some are disease vectors and some are carnivorous. Some are beneficial also. The insects consumed by Calotes are grouped according to their economic importance.

Table 4.3: Different types of insect family consumed by Calotes versicolor according

                   to their economic importance

Conclusion:

Any works on food and feeding habit of Calotes versicolor has not been attended in our country. Even no detail study has yet been done on the food and feeding habit of this species. The study was therefore, to find out the correct information about food and feeding habit of Calotes versicolor by analyzing their alimentary canal and their role in biological pest control. In the present study, it was found that this species is predominantly insectivorous.

After analyzing the alimentary canals of 35 individuals of Calotes versicolor, a total of 35 types of food items were found in the alimentary canal of Calotes versicolor, of which 29 were animal matters (insects), 2 were plant matters, 1 was mollusk and 3 were miscellaneous matter, which they eat accidentally or occasionally. After analyzing the alimentary canals, it is observed that the average consumed food weight by male and female was 0.63 gm and 0.6 gm respectively. Among the food items, animal matters (insects) were 82.9%, plant matters 5.7%, miscellaneous 8.6%, mollusk 2.9%. The identified insect species included 28 families of 11 orders belong to Class- Insecta of Phylum- Arthropoda. In their food composition order- Hymenoptera occupied the first position followed as Hymenopterans 37.9%, Coleoptera 13.8%, Ephemeroptera 10.3%, Orthoptera 10.3%, Lepidoptera 6.9%, Isopteran 3.4%, Plecoptera 3.4%, Hemiptera 3.4%, Homoptera 3.4%, Trichoptera 3.4%, Dipterans 3.4%.

Maknun (2007) and Hossain (2006) studied on food and feeding habit of different species of frogs and toads, which are compared here with the present study of Calotes versicolor.

After analyzing the alimentary canal of Limnonectes limnocharis, it was found that this species mainly insectivorous and consumed more insect species from the order Hymenoptera (33.95%), where as less from Lepidoptera, Arachnids and Scolopendromorpha (1.89%), (Maknun, 2007).

After analyzing the alimentary canal of the alimentary canals of Bufo melanostictus and Hoplobatrachus tigerinus, it was found that both the species insectivorous. Bufo melanostictus consumed highest insects from the order Coleopteran (29%) and lowest from Dermaptera, Homoptera, Isoptera (3%). Miscellaneous 8%. In case of Hoplobatrachus tigerinus, they consumed more insect species from the order Hemiptera 21% and less from Diptera and Odonata (5%), (Hossain, 2006).

In the present study, I found that Calotes versicolor consumed more insect species from the order Hymenoptera (37.9%) and less from Isopteran, Plecoptera, Hemiptera, Homoptera, Trichoptera and Dipterans (3.4%).

Though Calotes versicolor consumed less percentages insect species from different families which are important in the pollination of plants, production of commercial silk and also serve as an ecological indicator. But in the study, it was also found that they  consumed highest percentages of harmful insect species most of which were injurious to crops, fruits and vegetation, injurious to trees, household pest, disease vector, etc. They also feed on carnivorous, control their population, and keep the environment clean. They play an important role in the biological control of pests and in the food chain and the ecosystem of nature by their food habits.

Among Hymenoptera family- Formicidae were available in the alimentary canals of Calotes versicolor. Formicidae (mount building red ant) was one of the well-known household pests, which was nuisance on trees, leaves, clothes, houses, etc., and some of them create pain in the human skin.

In the present study, it was also found that there was a positive correlation between body weight (BWt) and food weight (FWt) respectively in male and female of Calotes versicolor. The mean consumed food weight was 0.63 gm. In case of male, it was 0.63 gm and in female, it was 0.6 gm.