STUDIES ON THE POPULATION DENSITIES OF CERTAIN INSECT PESTS ATTACKING GRAPEVINE TREES AND THEIR ASSOCIATED PREDATORS AT MANSOURA DISTRICT

The present investigation was carried out in the farm of AgricultureResearchCenter , Faculty of Agriculture, Mansoura
University to study the effect of some weather factors on the population density of per certain insect pests infesting grapevine trees and their associated predators during the successive seasons of 2014 and 2015 at Mansoura district. The obtained results revealed that four peaks for Retithrips syriacus Manget season were recorded during the period of study. The highest number for this insect was recorded in the second week of August in the two seasons of study. There were four peaks per season for Empoasca lybica deBerg during the period of investigation. The highest number of E. lybica was recorded in the first and third week of June during the two seasons of study. The obtained results showed that four peaks for Empoasca discipiens Paoliwere recorded during the period of study.  the highest number for this insect was recorded in the third week of July and in the third week of August during the first and second season of study. Data recorded three peaks for Lobisia botrana Schift during the two seasons of study, and the highest number was recorded in the third week of June in the first season and in the first week of July in the second season of study. There were three peaks for Chryptoblabs. Gnidiella Millerin the two seasons of study the highest number  was recorded in the third week of Jun in the two season of study , The obtained result assured that three peaks for Cydonia vicina nilotica Mulsin the two seasons of study. The highest number for this insect was recorded in the second week of May in the first season 2014 and in the first week of August in the second season of study. The obtained results revealed that there were four peaks for Coccinella undecimpunctata in the two seasons of study,and the highest number for this insect was recorded in the second week of May in the first season and in the third week of August in the second season of study. There were three peaks for Cydonia vicina isis in the two seasons of study. The highest number for this insect was recorded in the third week of Jun in the first season and in the first week of August in the second season of study. The obtained result assured that the temperature (maximum, minimum and average) positively affected on the population density of the most main insect species except C. gnidiella during the two seasons of study. The relative humidity affected negatively on the population density of these insects .the statistical correlation coefficient between the population density of predatory insects and the temperature and relative humidity showed a highly or slightly significant positive or negatively effect on population density of these insects during the two seasons of study.