الفهرس 
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Abstract
The present studies were carried out in the experimental farm belonging to the Faculty of Agriculture, Mansoura University, Mansoura, Egypt to evaluate the population abundance of the citrus mealybug, Planococcus citri (Risso) on different host plants as succari orange (Citrus sinensis L.), guava (Psidium guajava L.), mango (Mangifera indica L.), grapevine (Vitis vinifera L. ) and ficus (Ficus nitida L.) trees. Furthermore, the seasonal activity of the main associated predators with P.citri during the two successive years (2014/15) and 2015/16 was evaluated. All agricultural practices were applied except the insecticides during the two years of investigation.The citrus mealybug had three peaks of abundance during the first year and only two peaks during the second year on succari orange and the highest peak recorded on the first week of November 2014 (258 individual) during the first year (2014/15) and in the third week of October 2015 (388 individual) during the second year (2015/16). The P.citri had three peaks of abundance during the first year and two peaks during the second year on guava and the highest peak recorded on the first week of November 2014 (258 individual) during the first year (2014/15) and the third week of October 2015 ( 661 individual) during the second year (2015/16). The P.citri had two peaks of abundance annually on mango trees and the highest peak recorded on the first week of November 2014 (253 individual) during the first year (2014/15) and the third week of November 2015 (479 individual) during the second year (2015/16). The P.citri had two peaks of abundance annually on grapevine and the highest peak recorded on the third week of May 2014 (23 individual) during the first year (2014/15) and in the third week of October 2015 (47 individual) during the second year (2015/16).P.citri had three peaks of abundance during the first year and two peaks during the second year on Ficus religiosa and the highest peak recorded on the third week of May 2014 (273 individual) during the first year (2014/15) and in the first week of May 2015 (393 individual) during the second year (2015/16). Laboratory experiments were carried out to study the influence of different host plants on some biological characteristics of P. citri. The experiments were carried out in the insectary of the Economic Entomology Department, Faculty of Agriculture, Mansoura University under daily fluctuated temperature degrees of 28±2˚C and 70±5% RH.Determination of prey suitability for mass rearing program of insect predators only in their larval stages is relatively straight forward: the faster the development, the higher the survival, and/or the larger the adult, the more suitable the prey. Further, prey that enhances the functional and numerical responses is usually preferred for mass rearing program of a predator. The present work was undertaken to study the effect of prey type on development and reproduction of chrysoperla carnea (Neuroptera: chrysopidae), by offering the first instar larvae one of three food types [eggs of Ephestia kuehniella, citrus mealybug (Planococcus citri), and Seychelles scale (Icerya seychellarum)] at room temperature of 24.2 ± 2.9°C, 57.2 ± 5.6% RH and a 16:8 h L:D photoperiod. Significant effects of food type on development, fecundity and fertility of C. carnea were obtained. Moth eggs of Ephestia seem to be the most suitable prey supports the shortest total development time, highest juvenile survival, and highest fecundity and fertility. However, both other mealybug diets serve as essential preys that support both successful larval development and adult reproduction. Further, the effect of prey species on behavioural responses of E. flavipes was assessed by deriving functional and numerical responses for female predator at prey densities ranging from 10 to 50s and third-instar of P.citriand I. seychellarum per arena at 21 ± 1°C, and a 16:8 h L:D photoperiod. Prey species altered the functional response type for female of E. flavipes with a type II and I response to P.citri and I. seychellarum, respectively. The higher attack rate and shorter handling time was estimated on P. citri, resulting in the highest theoretical number of this prey that could consume per day. The curve of the reproductive response was similar to that of functional response confirming that both functions are interlinked. The shape of the con¬version rate of prey biomass was lower and higher at lower and higher prey densities, respectively. The higher rate at higher prey densities likely because the well-fed females laying higher number of eggs and investing less in metabolic costs.