Life History and Prey Acceptance of Commonly Occurring Spiders in Sugarcane Ecosystem

Life-history and prey acceptance of commonly occurring spiders of sugarcane ecosystem were studied in the laboratory and field. In the laboratory, males and females of Hippasa greenalliae Blackwall passed through eight and nine instars, and the total life cycle lasted 263.3 and 371.6 days, respectively. In the field, females of Cyrtophora cicatrosa Stoliczka passed through nine instars and the total life cycle lasted 195.2 days. In laboratory no choice feeding tests, neonate larvae of shoot (Chilo infuscatellus Snelllen), internode [Chilo sacchariphagus indicus (Kapur)] and pink (Sesamia inferens Walker) borers were the most accepted stage followed by third instar larvae for the spiders H. greenalliae and Oxyopes shweta Tikader. Amongst four sucking pests tested, aphid (Melanaphis indosacchari David), leafhopper (Pyrilla perpusilla Wlk.) and pink mealybug [Saccharicoccus sacchari (Ckll.)] were the most accepted preys while scale insect (Melanaspis glomerata Green) was completely avoided by the above two species of spiders. In field cage studies with H. greenalliae against C. infuscatellus, deadhearts formed by 10 neonate larvae were reduced by around 50 per cent by one spider per cage whereas the same number of third instar larvae needed four to six spiders per cage to reduce deadheart formation.