CAGE EXPERIMENTS ON ORIUS-TANTILLUS PREDATION OF HELICOVERPA-ARMIGERA

The role of Orius tantillus (Motschulsky) (Hemiptera: Anthocoridae) in the predation of H. armigera was studied on both sorghum (Sorghum bic olor L.) and pigeonpea (Cajanus cajan L.), the predominant intercrop o f small farmers in Andhra Pradesh, India. Adult Orius tantillus was ob served in cages where there were eggs and first-instar larvae of H. ar migera on sorghum and pigeonpea. We found that O. tantillus had two di urnal peaks of activity, after sunrise and before sunset. O. tantillus was found preying on first-instar larvae and not on eggs. However, a later immunoassay of O. tantillus collected on sorghum during period o f H. armigera oviposition activity showed that predation of eggs did o ccur under certain conditions. The activity of O. tantillus on sorghum was significantly higher on the flowers than elsewhere but this was n ot the case on pigeonpea. Therefore O. tantillus was a significantly m ore efficient predator on sorghum than on pigeonpea. The results indic ate that O. tantillus could be an important predator of early stages o f an H. armigera infestation, particularly in sorghum.