ECOLOGICAL STUDY AND SUSCEPTIBILITY OF SOME PEAR VARIETIES TO INFESTATION BY Eriophyes pyri Pagest. (Eriophyidae, Acariformes)

The results of the study showed that the pear varieties Othmani and Kaleriana resist the infection by Eriophyes pyri Pagest., while Leconte and Zafrania varieties were heavily attacked by the Eriophyes pyri Pagest., Mites populations and Blisters appeared on pear leaf from the middle of April until the middle of September 2004, Mites population reach its peak 11.88, 21 per leaf on Leconte and Zafrania respectively on end of August for mites and on the middle of May for blisters. The correlation values between the average mites number, number of blisters, infection percentage and the average temperature, relative humidity and leaf space were varied according to pear variety. The results showed also that the pear variety and direction on tree exhibt undetermined effect on the average mites and blisters number also on infection percentage. The index of blister distribution on pear leaf showed that the blister exist in aggregation pattern.