الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 204 |  |  |
| | | from | 204 | | |
Abstract
This work was conducted on 6 varieties of two types of mulberry trees, Morus alba (var. Romy, Balady, Hendy and Japanese) and M. nigra (var. Omany white and Omany black), planted at the Silkworm Research Unit., Dept. of Plant Protection, Faculty of Agriculture, Ain Shams University, Shoubra El-kheimah, Qalyubia Governorate, Egypt, during the period from 2018 to 2022. The aim of this study was to survey insect pests that infest mulberry trees in Egypt, which in turn weaken the total vegetation and reflects on the nutritional value of the leaf crop and ultimately negatively affects the production of silk cocoons in quantity and quality.
Insect pests found in the study area were surveyed during two successive years at 2018 and 2019. Obtained insect pests were Parabemisia myricae, Icerya aegyptiaca, Ceroplastes rusci, C. floridennsis, Aleurocalva jasmine, Hemiberlesia lataniae, Parasaissetia nigra, Icerya seychellarum, Ferrisia varigata and Haplothrips sp. Also one predator was recorded, Vidalia Beetle Rodolia cardinalis (Mulsant) (Coleoptera: Coccinellidae). The most abundant pests in terms of numerical density were: Bayberry whitefly, Jasmine whitefly, Egyptian mealybug, and seychelles fluted scale.
Population dynamics of the most abundant insect pests infesting mulberry leaves were studied. Results revealed that the numbers of the Bayberry whitefly during the two years recorded 3 peaks on Japanese variety; while only two peaks were recorded on the other varieties. The numbers of mealybug individuals during the two seasons recorded 3 peaks on Roomy variety; while only two peaks were recorded on the other varieties.
Effect of some weather factors on pest population dynamics at the same two years were studied. Data showed that temperature and relative humidity% had no significant relationship with the population density of either mulberry whiteflies or the mealybugs found on M. nigra varieties. For the varieties of M. alba, relative humidity % had no significant correlation with the population density of mealybugs.
Effect of some leaf morphological characteristics on the rate of infestation of whitefly and mealybug were studied. Data revealed that trichomes on the mulberry leaves (density and length) play an important role in the infestation with both of mealybugs and whiteflies. Increased leaf trichomes density and length had led to increased infestation; this may attributed to that these dense trichomes offered shelter for insects for escape from their natural enemies and for safe egg deposition. The correlation between leaf thickness and population density of whiteflies and mealybugs was insignificant which reveal that leaf thickness is not a major component in insect infestation to mulberry leaves.
Leaf contents of N, P, K, total phenols, total carbohydrates, total proteins, flavonoids, phenol oxidase, peroxidase and alpha esterase were determined for the six tested mulberry varieties to study the effect of leaf components on the rate of infestation of whitefly and mealybug.
Control studies were conducted using four insecticides against the most abundant pests infesting two varieties of the mulberry trees on the study area and their effects on the life of silkworm larvae. The chemical insecticides Mospilan and Chinook (Neonectinoides group) proved to be effective insecticides against pests of mulberry trees, but they were not safe for silkworm larvae. The natural compounds insecticides, Techno oil and Top 9 proved to be effective on pests of mulberry trees and meanwhile safe for silkworm larvae.