Ecological and taxonomic studies on the scale insects that infest mango trees at Qaliobiya governorate

This study aimed to determine the recent status of the scale insects that infest the mango trees at Qaliobiya governorate during visiting four mango orchards (El-Khanka, Shebeen El-Qanater, Benha &El-Qanater El-Khayria, through twice visits monthly to each district for two successive years. This study was carried out to present an identification guide with key, diagnosis, important synonymes, figures & illustrations to the fourteen collected mango scale pests which included in the four families, Coccidae, Pseudococcidae, Margarodidae and Diaspididae; in additions to give an attention to the most serious species, with notes on the agricultural precautions which could decrease the infestation. Mango leaf morphology and anatomy is used to explain the reasons for the mango variety recommendation.


INTRODUCTION
Due to the great damage can be done by the scale insects not only by sucking the plant sap that give low photosynthesis and respiration which leads to curling, yellowing, dropping to leaves, so malformations, dwarfing & decreasing fruit production (quality and quantity), even plant death, where the mealy bugs only can cause losses of 750 million American dollars per year (Moffit, 1999); but also due to the excretion of large amount of honey dew that rich in sugars and nitrogenous components, so give good media to sooty molt fungi that increase the inhibition of photosynthesis qualities of the plant (Radwaan, 2003).In addition to the insect secretion of the toxic saliva that resulted in malformed leaf and shoot growth, these characteristic symptoms similar to damages caused by viruses (Fisheries & Foresty, 2008); on the other hand of bringing the associated insects: bees, ants and wasps that give the protection to these scales from their enemies, in turn of taking the honey dew.These specially ants (Fondling) (Myremcophiles, Sharaf, 2005) usually found in the vicinity of the scales and are cemented together to form a covering over the scale (Hamon& Williams, 1984).So the ant associated with soft scale colonies are larger than the same scales on the same host without associated ants.
Most soft scales can reproduce sexually or parthenogenetically so many differences can be found in scale colonies, sexual dimorphism is apparent, male usually smaller, slender, lighter and winged, with vestigial mouthparts.In dense population the infestation appears not only on the lower surfaces, but also attack the upper surfaces, twigs, stems fruits & even roots, it is very difficult to remove them from the fruits (Hosney, 1939).It is clear that, due to the differentiation in the climatic, agricultural & the biotic factors the picture of mango pests reflect differences from the previous studies, so this work is used to establish the updated survey to mango soft, hard scales & mealy bugs.

MATERIALS AND METHODS
Four orchards of mango trees (El-Khanka, Shebeen El-Qanater, Banha & El-Qanater El khayria) in Qaliobiya governorate, were chosen for collecting soft, hard scale insects and mealybugs.The first district was cultivated by Hendi, the second with Langra & Banha was cultivated with Alphonso; but El-Qanater El-Khayria was cultivated by Alphonso and Hendi, two ribbons in the same farm.
The collection was carried out twice monthly for two successive years from August 2005 to July 2007 in each area.
10 infested mango leaves were collected randomly from mango orchards, then these leaves were packed in paper bags with minute holes.The paper bages with infested leaves were taken to the laboratory for investigation.The collected mango leaves were picked up from the four main directions (East, West, South &North), also at 4.5-5.5 meter of the tree height.
The qualitative and quantitative examination was done by using binocular microscope; microscopic slides were prepared for detail characters.Identification were done by using different keys as Ezzat (1965), Ezzat & Husein (1967), Hamon & Williams (1984) & Miller etal, 2006.The leaf examination was done in Plant Department, Faculty of science, Ain Shams University.
The main climatic factors (Maximum Temperature (Max.Temp.),Minimum Temperature (Min.Temp.),Relative Humidity (R.H.), rain fall & wind speed) were recorded at Qaliobiya governorate with the aid of Meteorological Agency.

Survey of scale insects on mango trees at Qaliobiya governorate
The survey was carried out on mango trees in four districts (El-Khanka, Shebeen EL-Qanater, Benha & EL-Qanater EL-khayria) at Qaliobiya governorate from August 2005 to July 2007 twice visits monthly.

DISCUSSION
Fourteen insect species of mango scales were collected from El-Qaliobiya governorate during this study, this number is equal to that of the previous survey from eight governorates by Kwaiz 1999, but the picture shows many differences: instead of the last serious pest, fig wax scale, Ceroplastes rusci, then the recent mango scale Ceroplastes floridensis has been collected, this may be due to the absence of fig trees in the vicinity of the mango trees, where the mango is a secondary host for fig wax scale, this can also explain the absence of the ice citrus scale Unaspis citri during this collection.Many other changes specially in family Coccidae as Pulvinaria psidii which become the most serious soft scale and not collected with Kwaiz 1999, also Saissetia oleae and Saissetia coffea, this ensured the easily spreading the scale insects specially during cultivated activities and many scales are polyphagous (Waston, 2009).
Many other changes especially in family Diaspididae are made according to the recent nomenclature, synonyms are cleared.Due to the wide range of the morphological differences specially in the polyphagous and parthenogenatic strains, so the identification of most scale insects must be accompanied with diagnosis, figures or illustrations to decrease many confusions (Hamon & Williams, 1984).The scale insects appear to be very sensitive to the biotic and abiotic factors specially to the microclimatic factors as irrigation methods, distances between the trees through the process of pruning the trees, many other factors can effectely decrease infestation.
Mango variety is a very important factor that affect the mango scale list, where the Alphonso resistant variety shows morphological and anatomical adaptations as the thicker epidermis& schlerenchyma, deeper vascular bundle, condense pericyclic fibers and lignin, in addition to fewer numbers of resin ducts(food sources) that act as physically difficult and energetically cost for insect penetration; these results agree with the chemical analysis of mango leaves made by Radwan 2003, where the total carbohydrates are higher in Hendi susceptible variety than Alphonso resistant variety; in contrast, the repellant or toxic secondary metabolites are higher in Alphonso.
Many other explanations can be cleared through especial analysis, for example, the types and amounts of amino acids as mentioned by Laila, 2002: the larger amount of glutamine can cause paralysis and reduction of heart beats, so the concentrations and functions of some amino acids require future studies to give obvious determination.
Finally, according to these coordinated results, we can repeated that the highly susceptible variety to soft, hard scale insects and mealy bugs, is not recommended now for new cultivation till the genes for resistance in Alphonso is incorporated to other varieties by genetic engineering scientists to decrease the infestation by 79.4% and improve the mango product.

Fig
Fig. II: The collected scale insects on mango trees at Shebeen El-Qanater from August 2005-July 2007.

Fig
Fig. IV: The collected scale insects on mango trees at El-Qanater orchard from August 2005-July 2007.
a l l i d u l a A .n e r i i A .t u b e r c u l a r i s L .F l o r i d a n a P .o l e a e A . a u r a n t i i P .p s i d i i S .o l e a e S .c o f f e a e K .a c u m i n a t a C .f l o r i d e n s i s C .h e s p r i d u m .I .s e y c h e l l a r u m M .h i r s u t u sSpe cie s Total number collectedHendyAlfonse addition to the fewer numbers of resin ducts(food source) when compared with the other more susceptible variety (Hendi) (Figure52).

Fig. V :
Fig. V: The comparative abundance of the scale insects on mango trees from the four studied areas during the period of investigation

Fig. VI :
Fig. VI: The relative abundance of the all collected scale insects on mango trees from the four studied areas.

Table I :
The collected scale insects that infest mango trees at El -Khanka orchard from August 2005-July 2007.The collected scale insects on mango trees at El -Khanka orchard from August 2005 to July 2007.

Table II :
The collected scale insects on mango trees at Shebeen El-Qanater from August 2005-July 2007.

Table III :
The collected scale insects on mango trees at Benha from August 2005-July 2007.
Fig. III: The collected scale insects on mango trees at Benha from August 2005-July 2007.

Table IV :
The collected scale insects on mango trees at El -Qanater orchard from August 2005-July 2007.

Table V :
Comparative relative abundance of the scale insects on mango trees at Qalyubia governorate from August 2005-July 2007

Table VI :
Climatic factors during collection of scale insects on mango trees at Qalyubia governat through the perod of study.