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Abstract
40 soil samples were collected from 13 cotton, 12 paddy, 3 coconut, 2 tomato and forest and each one from groundnut, coriander, jack fruit, zee mays, potato, blackgram and castor fields. The number of fungal isolate population was highest (1.8×107) and lowest (1.6×107) in the samples 11 (S11) and 15 (S18), which were collected from the coriander and paddy fields in Pavoorchathiram, Tirunelveli district and Sathoor, Virudunagar districts, respectively. Among the 40 samples collected from different areas, 21 samples consisted of Metarhizium anisopliae (Metsch.) Sorokin. Minimum M. anisopliae colonies (21 colonies) were recorded from the cotton field soil sample (S14) of Vilupuram District. But the highest fungal population (4.8×104) among cotton fields was also recorded from the samples of Thoothukudy district. M. anisopliae strain could not be isolated from the soil samples collected in Trichy, Madurai, Virudunagar, Kanchipuram, Tiruvallur, Dharmapuri, Salem, Namakkal, Chennai, Cuddalore, Pondicherry, Sivagangai, Dindhugal, Ramanathapuram and Karur Districts. The impact of all the 21 M. anisopliae isolates and also the standard MTCC892 were tested against Dysdercus cingulatus (Fab.) (Hemiptera: Pyrrhocoridae) adults and the LC50 values ranged from 2.25×105 to 3.66×108 spores/ml. The lowest (2.25×105) and the highest (3.66×108) LC50 values were recorded for the isolates CPRC16, and CPRC17, respectively. 11 sporulated D. cingulatus cadavers were observed with the isolate CPRC18.
Acknowledgements
Our sincere thanks to Rev. Dr. A. Antonysamy S. J., Principal and Prof. M. Thomas Punithan, Head, Department of Advanced Zoology and Biotechnology, St. Xavier's College, Palayamkottai for the laboratory facilities.