The effect of interaguild predation on avoidance behavior of the aphidophagous midge, Aphidoletes aphidimyza (Dip.: Cecidomyiidae) on its encounter with the predatory bug Orius laevigatus (Het.: Anthocoridae).

The predatory bug, Orius laevigatus (Fibber), and the predatory midge, Aphidoletes aphidimyza Rondani, belong to an aphidophagous guild, feeding on the cotton aphid Aphis gossypii Glover. In this study some avoidance behavior of the predatory midge such as dropping from the plant and choosing an oviposition site in the face of interaguild (IG) predator O. laevigatus are investigated. The results indicate that A. aphidimyza females prefer not to lay eggs when they discover that their offspring would be at risk of being attacked by the IG predator. The experiment also shows that the dropping behavior of predatory midge larva, upon being spotted by the predatory bug (44.5%), is significantly higher than the control (6.5%). Both the dropping behavior and mortality of IG prey are found to be influenced by all developmental stages of the cotton aphid. The percentage of mortality and dropping rates of A. aphidimyza larvae in the presence of 2nd instar nymphs of aphids were 10% and 12.5% and for 4th instar nymphs were 31% and 44.5%, respectively. These findings confirm the correlation between habitat choice of A. aphidimyza, in relation to predation risk for its offspring, and also underscore the population structure of prey for avoidance behavior strategy of the aphidophagous midge in an interaguild predation system.