P.G. Department of Zoology, Loyola College, Chennai-600 034, Tamil Nadu (India).
**Corresponding author and address: Prof K.S. Ananthasubramanian, Emeritus Professor (Retd.), 55 Brindavan Street, West Mambalam, Chennai-600 033, Tamilnadu (India).
*Present address: Central Sericultural Research and Training Institute, Mysore-570 008, Karnataka (India).
The mutualistic association of Eucoccosterphus tuberculatus (De Motschulsky) with the ant, Camponotus compressus Fabr., was studied during two years. Field survey of ant attendance revealed a positive relation between the number of membracids and the number of ants. The fluctuation in ant population was dependent on membracid population which in turn depended on the climatic factors, group size of membracids, and age of the nymphs. During the favourable month of March, 88.6% membracids were attended by ants, but thereafter the per cent ant attendance decreased with decreasing membracid population due to unfavourable climate. The larger aggregation having more than 10 membracids attracted an average of 5–20.8 ants, whereas the aggregation consisting of 1 or 2 membracids were attended by 1.3–2.7 ants. The nymphs:ants ratio during the first instar was recorded as 1:0.5, while during the final instar, it was 1:1.1. Cent per cent mortality of the nymphs occurred lluring the 10th day, when the ants were prevented from attending, while 84% of the nymphs survived (till V instar) when attended by ants.
