DYNAMICAL FLUCTUATING OCCURRENCE OF THE PURPLE SCALE INSECT LEPIDOSAPHES BECKII (NEWMAN) (HEMIPTERA: DIASPIDIDAE) ON NAVEL ORANGES IN EL-BEHEIRA GOVERNORATE, EGYPT

摘要

A field study was carried out on Navel oranges at Abu Al Matamir area in El-Beheira governorate to determine the population fluctuation of Lepidosaphes beckii (Newman) under prevailing effect of some meteorological factors i.e, air temperature, relative humidity, wind speed and dew-point during the elapsed period from February the 11th, 2011 till January the 25th, 2013. Infestation of citrus purple scale insect was observed all over the year on the tested cultivar. Lepidosaphes beckii also known as purple scale, mussel scale, citrus mussel scale, orange scale, comma scale and mussel purple scale, is a scale insect known as a pest of Citrus trees. The small insects attach themselves to the leaves, fruits and small branches and cause injury by suckingthe tree's sap.It appeared as a narrow scale of about a tenth of an inch in length, slightly bent at one extremity, and always adhering so closely to the rind of the apple that it is scarcely possible to remove it entirely. The females are larger than the males, and never by any chance leave the spot where they first fasten themselves whereas the males are winged. The adult female citrus mussel scale is up to three millimeters long. The results showed that the estimated densities of fluctuating population of L. beckiion Navel oranges throughout both of the following growing seasons proved three distinctly prominent peaks for each. The first peak that occurred in the first year was observed in May, the second was limited during July-August and the third peak was recorded in November. In the second growing season, the first peak occurred in April, the second peak was observed in June, while the third was observed during October -November (of the same year).