SUSCEPTIBILITY OF CERTAIN POTATO VARIETIES TO THE INFESTATION WITH APHIDS AND WHITEFLY Bemisia tabaci Genn. IN NEWLY RECLAIMED SANDY AREAS AT EL-KHATTARA DISTRICT, SHARKIA GOVERNORATE, EGYPT

Abstract

ABSTRACT Studies were carried out at El-Khattara district, Sharkia Governorate during two successive years 2016 and 2017 to study susceptibility of three potato cultivars (Spunta, Cara and Galactica) to infestation with aphids and whitefly. The results showed that the infestation differs from variety to another, whereas Galactica cultivar was less susceptible followed by Cara cultivar, while Spunta cultivar showed the most susceptibility to infestation by aphids and Bemisia tabaciand associated with the greatest number of insect predators (Coccinella septempunctata L., C. undecimpunctata L, C. 9 puncata , Chrysoperla carnea Steph. and Metasyrphus corollae F.) followed by Cara and Galactica cultivars. The statistical analysis showed that this difference was highly significant among the different cultivars by aphids and whitefly infestation. As regards the effect of mean temperature and atmospheric relative humidity as well as their total combined effect on the numbers of certain investigated insect species and their predators, it is obvious that the effect was clear. The effect of the chemical contents of potato plants on the population density of aphids and whitefly that infest certain potato cultivars, indicated that a negative correlation appeared between population density of (aphids and whitefly), and protein, carbohydrate, phenols, pH, Nitrogen (N) %, Phosphorus (P)% and potassium (K) % percentage in the three potato cultivars. Conclusively, the obtained results in developing the IPM programs against these pests on potato plants through activation the effect of both temperature and relative humidity on insect numbers and the need to conduct more of these studies.