ECOLOGICAL STUDIES ON THE WHITE PEACH SCALE INSECT PSEUDAULACASPIS PENTAGONA (TARGIONI–TOZZETTI) (HEMIPTERA: DIASPIDIDAE)

Abstract

This study included population dynamics of Pseudaulacaspis pentagona (Targioni-Tozzetti) (Hemiptera: Diaspididae) on peach, Prunus persica L. at Qualyobia governorate, on plum, Plum demestica L. at Giza governorate and on apple, Malus sylvestris Mill. at El-Beheira governorate. The study was conducted over two successive years in each site. The age structure method was used to determine the number of generations. Obtained trend over the study period indicated the occurrence of three generations per year for P. pentagona on peach and plum at Qualyobia and Giza locations. The three generations were nominated as spring, summer and fall-winter generations. The first one spring generation expanded from approximately Jan. to May. The second summer generation expanded from May. to Aug. and the third fall-winter generation expanded from Aug. to next Feb. Obtained results on apple at El-Noubaria location indicated two generations per year. They were nominated as summer and fall-winter generations. This insect overwintered as mature females. Population densities of this diaspidid were the greatest in fall-winter generation. The population of the spring generation was higher than the summer one. Great intensity of P. pentagona in fall-winter generation coincided with the vegetative cycle or phase before interring dormancy in winter (deciduous fruit trees). The spring generation expanded mainly on terminal branches and new twigs (where no fruits have been formed yet and the insect does not infest the leaves at high numbers). Summer generation coincided with the fruit forming phases with lowest general population.