Seasonal Abundance of the White Butterfly Pieris rapae L. in the old and reclaimed areas with reference to its relative susceptibility and damage to certain cabbage cultivars
The main goal of this study was to determine the seasonal abundance of the white butterfly Pieris rapae L. (Lepidoptera: Pieridae) on several local and imported cabbage cultivars in old and reclaimed lands. The impact of certain cabbage metabolites on P. rapae populations was examined, as well as the relative susceptibility of different cabbage cultivars. Damage caused by P. rapae Varies. During the first two months following transplantation, P. rapae can cause economic damage to cabbage plants in both areas. One month later, its population had multiplied several times in the old land. Three of the six tested cabbage cultivars were appeared as susceptible (S) cultivars and harbored high numbers of the pest with an average of 0.63, 0.60 and 0.53 Kenz, Crossina and Ganzory cultivars, respectively. However, the imported white cabbage hybrids, 728, 730 and 747 showed sort of resistance and appeared as low resistant (LR) hybrids and harbored 0.40, 0.41 and 0.45 individuals/plant, respectively. Chlorophyll only showed highly significant negative correlation with P. rapae populations. However, the remaining metabolites showed non-significant positive correlation. In a comparison between P. rapae populations in Assiut (the old area) and El-Fath province (the reclaimed area), it can be note that the pest populations, the damaged (infested and unmarketable) plants were multiplied several times in the later. It can be noted that the general mean of the pest numbers recorded in the reclaimed area (2.14 individuals/plant) was found to equal 4.28 folds more than that recorded in the old area (0.50 individuals/plant).