Population Dynamic of Olive Pit Scale,Pollinia pollini Costa(Hemiptera:Asterolecanidae)on Two Olive Cultivars in North Region of Jordan

摘要

Olive tree,Olea europaea L.,is considered the most important tree in Jordan.The olive pit scale,Pollinia pollini Costa(Hemiptera:Asterolecanidae)has become a destructive threat to some olive groves in Jordan.A field study was conducted in an olive grove located in Northern Jordan during the growing season of 2015 to determine the population dynamics of this pest on two olive cultivars:Grossidi and Nebali Baladi,grown under rain-fed conditions.Terminal twigs were randomly sampled from the periphery of the canopy on each experimental tree at on month intervals throughout the entire year.Each sample was inspected thoroughly under a dissecting microscope in the laboratory for the presence of the immature and mature pit scale insect.The Grossidi olive cultivar was significantly more susceptible to P.pollini than Nebali Baladi,as indicated by the development of higher populations throughout the year.There was strong evidence that P.pollini overwintered as adults.Three generations were recorded per annum.The first generation occurred in February and March,followed by others from May to June and from August to November,respectively.The first two generations were significantly larger than the third one.Based on these observations,the greatest abundance of crawlers occurs in mid-March and mid-May,and therefore,application of insecticides is recommended during this period of time,since crawlers lack a waxy covering on their body and thus facilitates the chemical penetration through the cuticle,making them more susceptible to insecticides.Moreover,farmers are encouraged to cultivate the native Nebali Baladi cultivar rather than the more susceptible,introduced Grossidi cultivar in areas subject to heavy infestation.