The Past and Present of Pear Protection Against the Pear Psylla, Cacopsylla pyri L.

This chapter discusses the history of strategies and methods to control Cacopsylla pyri (Hemiptera Psyllidae) on pear trees, with special attention to new active ingredients and their effects on the pest and on the beneficial insects, and also to resistance development phenomena. In the past decade Italian and European populations of C. pyri have been less damaging, probably because of success of integrated pest management (IPM) programs. In Northern Italy orchards the most common defense strategy against C. pyri involves treatments on second-generation pests by abamectin, or less frequently by spirodiclofen. The autumn and winter treatments based on synthetic pyretroids are common in France and North America but rarely employed in Italy because of high toxicity against auxiliary insects. Concerning the development of resistance, as for other phytophagous species, also for C. pyri it has been found that some insecticides employed in the past induced resistance. Surveillance programs have therefore been established in Northern Italy and Spain for abamectin: no relevant resistance effects have been yet detected, but since LC50 and LC90 values are always higher in populations undergoing repeated abamectin treatments, the pear orchards where C. pyri outbreaks recently occurred are still under close investigation.