Study of some behavioral characteristics of the predatory gall midge Aphidoletes aphidimyza Rondani on the melon aphid, Aphis gossypii Glover in laboratory conditions

One of the important criteria for assessing the efficiency of natural enemies is to study their behavioral characteristics. In the current study host stage preference, switching, and mutual interference of the predatory gall midge larvae Aphidoletes aphidimyza Rondani were studied on different nymphal instars of melon aphid, Aphis gossypii Glover. The experiments were carried out in Petri dishes with cucumber leaf discs in a growth chamber. Based on the results, no significant differences were found for the preference of A. aphidimyza larvae for each nymphal instars of the melon aphid. But, its highest eaten biomass was recorded on forth instars. In switching trial, at 20: 40 and 30: 30 (third instar: first instar) ratios, the predator had more preference for third instars of the melon aphid. In mutual interference, the per capita searching efficiency of the predator varied from 0.0623 to 0.1805 h-1, which the negative value of the regression slope indicated the mutual interference of A. aphidimyza larvae. The results showed that the behavioral characteristics of A. aphidimyza may be affected by the density of the pest as well as the predator larvae