Ants Reduce Fruit Damage Caused By Psyllids In Mediterranean Pear Orchards

BACKGROUND Psyllids are principal pests of pear orchards. Pest control based on the intensive use of chemicals is facing difficulties and strategies with a low impact on natural enemies are considered as the most suitable for psyllid control. Ants have been reported as the main predators of Cacopsylla pyri (Hemiptera: Psyllidae) in the southern Mediterranean area. The aim of this work was to determine the contribution of ants to the reduction of the fruit damage caused by psyllids at different intensities of spraying. Five levels of spraying intensity and ant exclusion were tested in a pear orchard with three blocks of five plots each.RESULTS The incidence of russet on fruits increased with the abundance of psyllids and with ant exclusion. In the absence of ants, the impact of russet increased progressively from the highest to lowest intensity of spraying. By contrast, when ants were present no significant differences were found between the lowest (two application of paraffinic oil) and the highest (six applications of abamectin plus paraffinic oil) spraying levels. In the presence of ants, the incidence of russet in the plots with three applications of paraffinic oil was similar to those with three or six applications of paraffinic oil plus abamectin).CONCLUSIONS The importance of ants for the control of psyllids and the reduction of fruit damage is shown. Reduction in the frequency of spraying and the use of low toxic insecticides for natural enemies is presented as the most sustainable strategy for psyllid control in pear orchards.