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Abstract
Marwa Elsayed Sanad Amer: Improving an Integrated Programme for Management Scale Insects and Mealybugs on Mango trees in Egypt. Unpublished Ph.D Dissertation, Ain Shams University, Faculty of Agriculture, Department of Plant Protection, Egypt, 2017.
The present study aimed to developing an integrated programme for management scale insects and mealybugs on mango trees based on the following considerations; Ecological aspects of the main scale insects attacking mango trees, the role of some agricultural practices in suppressing population densities of mango insect pests and determination the most proper time for application insecticides, based on data of age structure.
The results obtained revealed the following:
• Many species of scale insects and mealybugs were recorded on mango trees. The white mango scale, Aulacaspis tubercularis (Newstead) and soft scale insect, Kilifia acuminata (Sign.) are the most widespread in all investigated governorates; Fayoum, Ismaleia, Monoufia, Qalyubiya and Sharqiya.
Also, some parasitoids and predators species were found associated with the surveyed scale insects and mealybugs inhabiting mango trees.
• The white mango trees scale, A. tubercularis, the most serious pest of mango trees, had four overlapping annual field generations, the peaks of these generations were occurred in April, June, September and January, the third peak was the highest population size. Data of age structure in different generations revealed that nymphal stage consist the main part of the population, especially during September (the third peak).
• The soft scale insect, K. acuminata, the second serious pest of mango trees had three overlapping annual field generations, generations were occurred during May, July and November. The third generation was the highest population density. Carefull examination of the age structure data revealed that nymphal stages represent the highest part of the population density, especially November generation.
- Regarding of the distribution of the two considered scale insects on mango trees, data revealed the following:
• East and South directions of the trees harboured the highest numbers of both two insect as compared to North, West and Core of the trees.
• All development stages of A.tubercularis preferred the upper surface of the leaves and K. acuminata preferred the lower surface of the leaves.
-The role of some agricultural practices on suppressing the population densities of A.tubercularis and K. acuminata, results revealed the following:
-Unwise use of nitrogen fertilization lead to significantly increase the population densities of both two insects, contrariwise, increasing the rate of potassium fertilization lead to suppressing the population of both two insects.
• Irrigation regimes were found significantly affect on the population densities of both insects infesting mango trees, whereas, increase of the rate of humidity of irrigation around trees such as rings and lines irrigations regimes lead to increase the population density of both two insects, while, trees that irrigated by corridor or regular irrigated harboured the minimum population density.
• Pruning mango trees at the end of the season after fruits harvest were found significantly decreased all developmental stages of both A. tubercularis and K. acuminata.
-Determination the most suitable time for application chemical control was investigated, based on biological aspects and data of the age structure of the two insect all over the year, the obtained results revealed the following:
• Performance of all tested insecticides were improved according to the time of application, whereas, the highest percentages of reduction in the population density of all developmental stage were obtained in September for A. tubercularis and in November in K. acuminata.
• Mixture of Royal king oil and Malathion was the most potent treatment against scale insects.
• Nymphal stage was the most susceptible toward the action of insecticides followed by adult females while gravid females were more tolerant.
• It could be concluded that, regulation of irrigation regimes, balance in rates of fertilization, especially wise use of nitrogen fertilization, pruning mango trees after fruits harvest and removing the waste of pruning and finally, application chemical control in the proper to time to achieve the pest results.
Keywords: Ecological studies, Aulacaspis tubercularis, Kilifia acuminata, natural enemies, population dynamics, annual generations, fertilization, surface irrigation regimes, pruning and chemical control.