ANT GENERA DISTRIBUTION ACROSS PUNE CITY

Tejaswini Pachpor1 and Yogita Ghodke2

1:- Anand, 6/10, Krutarth Society, Pune 411 037.
2:- Flat 103, Shishir Apartments, Lane 3, Happy Colony, Kothrud, Pune, 411 029.


Introduction

Ants deserve a special place in the study of ecology, including behaviour; given their species richness, social habits and high densities contributing much of the animal biomass on earth (Gadagkar et al, 1993). Unfortunately, studies and publications on ecology of ants are scarse compared to other animals, especially in India (Rastogi et al, 1997). As ants can be studied virtually everywhere from forest interiors or below ground right up to the kitchen, we tried to explore their distribution across variety of habitat types around Pune city.

Methodology

We sampled ants from various localities in and around Pune city, within 10 km of the city centre. The ecological habitats distinguished for sampling included forests, scrub and grasslands in the wilderness zone while tree plantations, agriculture and human habitations in the zone with pronounced human influence. We employed all out search for about two hours in the morning (Rastogi et al, 1997). Ants were collected during summer and early monsoon, when they are reportedly found in peak abundance. A few individuals from each trail or congregation of apparent recognisable taxonomic units (RTU) were collected and preserved at the Abasaheb Garware College, with careful notes of their locality, habitat and relative visual abundance. We identified the collection up to the genus level based on literature (Holldobler and Wilson, 1990).

Results and Discussion

Our ant sampling yielded 13 genera belonging to 4 sub-families depicted in the annexure. Table 1 reveals this to be less than half the genera (33 from 6 subfamilies) recorded for Bangalore city (Sunil Kumar et al, 1997) or even a single locality therein (Rastogi et al, 1997). This could be primarily attributed to much greater sampling efforts at Bangalore, where researchers could add about quarter species by using other techniques like pitfall and scented traps besides all out search. Preliminery calculations based on probability theory using methods adopted by Gadgil et al (2000), we expect Pune city environs to harbour about two dozen genera. Applying the genera to species ratios in above studies at Bangalore, we estimate ant fauna of Pune city to harbour about two dozen genera.

Table 1 indicates that tree plantations are most diverse, while the rest harbour about half the generic richness, with habitations equalling the agriculture and grasslands. Thus, residential area alongside tree plantations is richest in ant fauna, as evident from the fact that eleven out of total thirteen genera were collected Kothrud, where tree clad housing colonies are fringed by earstwhile scrub, grassland and agricultural area, including remnant groves of fruit trees like Mango. Thus, mosaic of habitats here harbours nearly twice the diversity as compered to even areas with low human impact such as Bhamburda and Pachgaon hill forests or banks of Pashan lake. These trends resemble the pattern for Bangalore city where Sunil Kumar et al (1997) report highest diversity from a public garden amidst habitation and lowest from an industrial estate devoid of trees. Indian Institute of Science campus (Rastogi et al, 1997), the other Bangalore landscape harbouring a mosaic of habitat types including the remnant wilderness habitats such as scrub and grasslands amidst extensive tree plantations supports the second highest diversity amongst Bangalore localities.

Few ant genera as Myrmicaria, Crematogaster, Leptogenys and Camponotus are most ubiquitous, commonly found in all the habitats and most localities. Few genera are confined to few localities or habitat types, such as Pheidole and Cryptopone recorded only from hill forests and thus more vulnerable. Our abundance estimates need verification to account for seasonal changes and the fact that many surface ants often reflect unknown proportion of their population, mostly housed beneath ground. Even Crematogaster ants reported to build nests of dried leaves and mud in tree canopy (Rastogi et al, 1997) showed no such nest in Pune but were seen to emerge from ground inlets. This could possibly be attributed to lack of suitable tree canopy for nest building. Myrmicaria, the biting, small, red ants are most well known to all. They are commonly seen everywhere, even foraging in houses and gardens. Tapinoma and Catalaucas are also found right up to the kitchen. Leptogenys ants are seen foraging in gardens and plantations. Camponotus are also common, often tending and protecting bugs that secrete sugary solution devoured by ants. Further studies on the ecology and behaviour of these omnipresent animals would be an interesting and rewarding endeavour even for other college students. Acknowledgements

Anand Padhye guided us all through. Utkarsh Ghate provided useful suggestions. RANWA supported our fieldwork. Prof. R. Gadagkar and Mrs. Tresi at the Indian Institute of Science, Prof. N. A. Madhyastha, Poornaprajna College, Udupi and Dr. Revathi Nandan, N.M. College, Sullia kindly provided methodological guidance, especially in identification. Our teachers and staff at the Abasaheb Garware college offered conducive environment. We thank them all.

References

Holldobler, B. and Wilson, E. O. 1990. The Ants. Springer-Verlag.

Gadagkar, R., Nair, P. Chandrashekhar, K. and Bhat, D. M. 1993. Ant species richness in some selected localities in Western Ghats, India. Hexapoda 5:70-94.

Gadgil et al, 2000. Participatory Local Level Assessment of Life Support Systems. Centre for Ecological Sciences, Indian Institute of Sciences, Technical Report no. 78.

Rastogi, N., Nair, P., Kolatkar, M., William, H. and Gadagkar, R. 1997. Ant fauna of the Indian Institute of Science campus- Survey and some preliminary observations. Jr.Ind.Inst.Sci. 77:133-140.

Sunil Kumar, M., Shrihari, K. T., Nair, P., Varghese, T. and Gadagkar, R. 1997. Ant Species Richness at selected localities of Bangalore. Insect Environment 3(1): 3-5.


TABLE 1 Habitatwise Genus Richness sampled at Pune and Bangalore cities

Habitat type

Pune

Bangalore

Forest/Scrub

5

25

Tree Plantation

8

28

Grassland

4

15

Agriculture

4

20

Human Habitation

4

12

TOTAL

12*

33

 

* comparatively much underexplored, comparison made only to highlight diversity pattern across habitat gradient


ANNEXURE: Distribution of Ant genera around Pune city

Habitats : F- Forest, S- Scrub, G- Grassland, P- Plantation, A- Agriculture, H- Habitation

Microhabitats :
Ab (Abundance): A- Abundant, C- Common, O- Occasional, R- Rare

Localities : Localities: Bg-Bhugaon, Bm-Bhamburda, C-Chandani Chowk, K- Kothrud, Pc-Pachgaon, Pv- Parvati, Ps-Pashan, U-University

Sub-family Genus

Habitats

Abd

Localities

Dolichodirinae

     

Tapinoma

PH

C

Bm,K

Technomyrmex

P

C

U

Formicinae

     

Polyrachis

P

C

K,U

Camponotus

FSGPAH

A

all but Pv

Myrmicinae

     

Aphaenogaster

P

C

C,K,U

Catalaucas

PH

C

Bg,K,P,T

Crematogaster

FSGPA

A

all but Pv

Monomorium

P

C

K,P,U

Myrmicaria

FSGPAH

A

all

Pheidole

F

C

Pc

Ponerinae

     

Cryptopone

S

C

Bm

Leptogenys

FSGPAH

A

all but Pv


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