Studies on the Spider Fauna of Sugarcane Ecosystem in Southern Peninsular India

Surveys conducted in three states of southern peninsular India revealed the occurrence of 57 species of spiders belonging to 13 families of Araneae in the sugarcane ecosystem. Of these, only two species viz., Hippasa greenalliae BlackwaH (Lycosidae) and Cyrtophora cicatrosa Stoliczka (Araneidae) were abundant, while six species were less abundant and 49 species were rare in occurrence. The spiders were found to colonize the sugarcane crop 40·45 days after planting. The population of the wolf spider H.greenalliae which comprised more than 70% of the total population increased with age of the crop upto 180 days. There was no significant variation in the population of H.greenalliae in sugarcane cropped field and adjacent fallow land. The orbweaver spider C.cicatrosa started colonizing the crop 100 days after planting of the crop and its population increased upto 240 days. Population of H.greenalliae and that of all the species had negative association with maximum temperature and rainfall and positive association with relative humidity. A reverse trend was noticed in C.cicatrosa. Soil and foliar application of insecticides recommended for the suppression of shoot borer, Chilo infuscatelius Snellen in the early stage of the crop growth did not exert any significant influence on the colonization of spiders. Among the five insecticides tested as foliar sprays at six month old crop, quinalphos, monocrotophos and endosulfan significantly reduced the spider population.