Laboratory experiments were carried out in the Insectary of Economic Entomology Department, Faculty of Agriculture, Mansoura University to develop two artificial diets for rearing coccinelled predators during the period from 2017 till 2019. The results showed that the two predators reared successfully on these diets and the average period of larval instars lasted 24.64±2.5 and 21.67 ± 2.22 days for Hypodamia tridecimpunctata L. and Chilomenus propinqua isis(Mulsant)when reared on the artificial diet (AD1), while that were recorded 19.9±2.1 and 17.6±1.9 days when these predators reared on the artificial diets AD2 respectively. The pupal stage was durated in average of 6.24±0.48 and 5.42±042 days when reared on the artificial diet(AD1)for these two coccinellid predators respectively. Meanwhile the data indicated that the pupal stage lasted in average of 5.5±0.9 days and 4.95±0.97 days when reared on the artificial diets AD2. The female average fecundity of H. tridecimpunctata and C. propinqua isis were 150.7±8.1 and 193.4±10.5 eggs when these predators reared on artificial diet(AD1). Meanwhile the obtained results showed that the average fecundity of H. tridecimpunctata and C. propinqua isis females recorded 189.7 ± 10.6 and 250.8±14.6 eggs respectively when this predators reared on artificial diets (AD2). It can be concluded that the artificial diets (AD2) was very efficient for rearing H. tridecimpunctata and C. propinqua isis as the larval stage duration were two shorts on artificial diet (AD2) than artificial diet (AD1). The obtained data cleared that the females of each species deposited higher number of eggs on artificial diets (AD2).

Experiments in the field conducted to evaluate population density and effect of temperature and relative humidity of five lipedoptereous insect species attacking potato plants during the two successive seasons 2017 -2018 at Meniat El-Naser region Dakhlia Governorate. The results showed that Phathorimia operculella (Zeller) had four peaks in summer plantation and the highest peak was found in the first week of May, while in the winter plantation this insect recorded two peaks and the high peak was found during 4 th week of October, during tested seasons 2017 and 2018. Data revealed that Euzophora osseatella Treitske characterized by two peaks in the two potato plantations. The results revealed that, Tuta absoluta Povolony had three peaks in each summer and winter potato plantations, respectively. The obtained data assured that Spodoptera littoralis (Boisd) had three peaks in the summer and winter plantations and the highest peak were found during late of March, throughout summer plantation and in the winter plantation during 3 rd week from September month. Three peaks during summer seasons plantation were recorded on Spodoptera exiguae (H) while in winter seasons plantation recorded two peaks during the two tested years. Population density during the tested successive years, data obtained of "temperature degrees" and "relative humidity" resulted that, the correlation degree differed from slightly positive or negative to highly significant positive.

Field trials were conducted to study the dominant piercing-sucking insect species infesting potato plants in Dakahlia Governorate. The obtained results indicated that there were six piercing-sucking insects attacking potato plants and the dominant piercing-sucking insects were Myzus persicae (Sulker); Aphis gossypii Glover; Empouasca descipiens Polai. and Bemisia tabaci (Gennadius) during the two years of study. Data cleared that M. persicae and A. gossypii had one peak in each potato plantation and E. descipiens recorded two peaks in summer plantation, in the meanwhile three peaks in winter plantation during the two years of investigation. B. tabaci had three peaks in summer and winter plantation during the period of study. The obtained results revealed that there were four predators belonging to Family Coccinellidae namely: Hippodamia trideciapunctata L., Coccinella undecimpunctata L., Chilomenes propinqua isis (Mulsant) and Chilomenes propinqua nilotica(Mulsant), and one predator from family Chrysopidae, namely Chrysoperla carnea (Steph.) was recorded. It can be stated that most dominant species were H. tridecimpunctata and C. undecimpunctata.