Control of the pear psyllid, Cacopsylla pyricola, in South East England by predators and pesticides

Abstract

The pear psyllid, Cacopsylla pyricola, is an important pest on pear in England. In orchard trials in Kent, Anthocoris nemoralis usually prevented the psyllid from increasing to high densities, provided that the pesticides applied were not damaging to the predator. Only small numbers of A. nemoralis appeared to overwinter on the pear trees, and synthetic pyrethroid insecticides used at the ‘bud burst’ stage, before colonization by the predators, did not disrupt regulation of the psyllid by A. nemoralis, and were very effective at reducing psyllid numbers. These broad-spectrum pesticides were very damaging to predator populations if used later in the season, generally resulting in an upsurge of psyllid populations. Of the more selective materials tested for post-blossom use, amitraz was the most effective against psyllids, and was not damaging to predatory anthocorids. Diflubenzuron was also effective against psyllids, although slower acting, and caused only slight reduction in anthocorid density. Chemical control of scab and, when necessary, of mite, aphid and lepidopterous pests, can be compatible with the preservation of A. nemoralis; this is the basis of integrated pest management on pear.