Distributions of Armoured Scale Insects Infesting Citrus Trees in Different Localities in Egypt
The distributions of five armoured scale insect species attacking different species and varieties of citrus trees were studied in nine provinces in Egypt viz., Alexandria, Beheira, Gharbia, Menoufia, Kafr El-Sheikh, Qalyubia, Sharkia, Dakahlia and Ismailia during the growing seasons from 2008 through 2010. Tree branches carrying colonies of diaspidid species were brought to the laboratory for identification and counting the populations. Five armoured scale insect species representing four genera were collected and identified. These were: Lepidosaphes beckii (Newm.), Parlatoria ziziphi (Lucas), P. pergandii Comstock, Aonidiella aurantii (Maskell) and Chrysomphalus aonidum (L.). However, P. ziziphi dominated in Menoufia; C. aonidum had very high in numbers in Qalubia, Kafr El-Sheikh and Gharbia; L. beckii was abundant in Alexandria and Sharkia; A. aurantii distributed in Beheira, Ismailia and Menoufia and P. pergandii was found in a few numbers in Alexandria. On the other hand, the susceptibility and rate of infestation per leaf and per cm2 of leaf by the dominant armoured scale insect species, P. ziziphi on citrus trees were observed in Shibin El-Kom alone. The present study indicated that the level of infestation of armoured scale insect species differed from one location to the other.
Received: April 18, 2012;
Accepted: June 03, 2012;
Published: August 30, 2012
Armoured scale insects (Homoptera: Diaspididae) with piercing and sucking mouthparts
are considered among the most injurious plant pests. They attack different agricultural
crops, such as fruit trees and ornamental plants all over the world and cause
heavy damage to the plants. Individual species infest leaves, fruit, branches,
main stems, trunks and roots. They are distributed throughout the world except
in the cold extremes of the Arctic and Antarctic regions. The infested fruits
lose their marketing value because it is difficult to remove the insects from
the produce. Many diaspidid species are also of quarantine concern requiring
management to prevent their spread through export of plant products (Gullan,
2001; Miller, 2005; Miller et
In Egypt, citrus plantations are among the most important horticultural crops
especially grown for the export of their fruits. Many researchers have recorded
armoured scale insects attacking citrus trees in Egypt (Habib
and Attalah, 1960; El-Keiy, 1964; Habib
et al., 1971; Darwish, 1976; Abd-Elfattah
et al., 1978; Amin and Salem, 1978; El-Rahman
et al., 1979; El-Nabawi et al., 1986;
El-Nabawi and Ammar, 1987; Farag
et al., 1990; Tawfeek, 2007). Of late, in
comparison with the earlier surveys, some changes in the populations of scale
insects were observed. However, latest reports on the patterns of their distribution
are not available. Therefore, this work was carried out to identify the species
of armoured scale insects which attack citrus plants and to make a comparison
of their dominance in nine different localities in Egypt. The main purpose of
the study was to record the susceptibility of different citrus varieties to
the infestation of the black parlatoria scale insect, Parlatoria ziziphi
MATERIALS AND METHODS
The armoured scale insects attacking different species and varieties of citrus trees were studied in nine provinces in Egypt during the growing seasons of 2008 till 2010. These were: Alexandria (Abbies), Beheira (El-Azimah), Gharbia (Berma), Menoufia (Shibin El-Kom, Menoff), Kafr El-Sheikh (Beila), Qalubia (Kafr Shoker), Sharkia (Menia El-Kamh), Dakahlia and Ismailia (Wady El-Molak as a new reclined land, Kantrah Shark and Fayed).
Twenty small branches (about 15-20 cm) with leaves carrying colonies of diaspidid
species were plucked at random from different directions and heights of the
chosen citrus trees (at about 150-200 cm height) in the different nine localities.
The collected branches with live specimens were taken to the Laboratory of Department
of Applied Entomology, Faculty of Agriculture. El-Shatby, Alexandria University,
for identification and counting the populations of scale insects. Preparation
of slides and identification were carried out following the methodology of Kosztarab
and Kozar (1988).
The population densities and degrees of infestations of the ziziphi scale insect on different species and varieties of citrus were studied at the Research Farm of the Faculty of Agriculture, Shibin El-Kom. Samples of infested plants (more than 100 leaves) were brought to the laboratory for inspection. The data were recorded on total numbers of adult (females, males) and immature stages (other than movable crawlers) per leaf on both upper and lower surfaces of leaves.
Statistical analysis: Data were subjected to the analysis of variance
test (ANOVA), with mean separation at 5% levels of significance, Computer program
IRRISTAT and Duncans Multiple Rang Test was used to compare the averages
according to the method of Snedecor and Cochran (1967).
RESULTS AND DISCUSSION
Distribution of armoured scale insects on citrus trees: Five armoured scale insect species representing four genera belonging to the family Diaspididae were collected and identified from citrus trees in the nine provinces under consideration during 2008 through 2010. These were: the purple scale insect Lepidosaphes beckii (Newm.), the ziziphi, ebony or black parlatoria scale insect Parlatoria ziziphi (Lucas), the chaff scale insect (P. pergandii Comstock), the Florida red scale insect (Aonidiella aurantii (Maskell)) and the black scale insect and Chrysomphalus aonidum (L.).
Data in Table 1 presents the species compositions of the
armoured scale insects infesting citrus trees in the nine localities under study.
These data revealed that the level of infestation of armoured scale insect species
differed from one location to the other. The purple scale insect, L. beckii
occurred in all the nine localities; it had a high infestation in Alexandria
and a moderate in Beheira, Menoufia, Qalubia and Sharkia. The ebony scale insect,
P. ziziphi occurred only in two localities (Menoufia had a high infestation
and Qalubia a moderate). The chaff scale insect, P. pergandii, was found
only in Alexandria in few numbers. The red scale insect, A. aurantii,
was found in all the nine localities with different degrees of infestations.
It had high infestation in Beheira, Menoufia, Sharkia, Ismailia, a moderate
in Dakahlia, while a weak infestation in Alexandria, Gharbia and Kafr El-Sheikh.
|| Distributions of five armoured scale insect species on citrus
trees in nine different localities in Egypt from 2008 through 2010
|*Weak infestation (5-10 individuals/leaf), **Moderate infestation
(11-20 individuals/leaf), ***High infestation (more than 20 individuals/leaf),
-: No infestation
The black scale insect, C. aonidum, occurred in all the eight localities
and was absent in Alexandria. In Gharbia, Kafr El-Sheikh, Qalubia and Dakahlia
a high infestation was noticed whereas it was moderate in Sharkia and weak in
Beheira, Menoufia and Ismailia.
El-Keiy (1964) reported that Chrysomphalus ficus
Ashm. (C. aonidum L.), was in the maximal numbers of scale insect species
on citrus plants in Shibin El Kom, Menofia. Darwish, (1976)
stated that the purple scale insects, L. beckii was the most abundant
species infesting citrus trees in the same farm during 1974 and 1975 growing
seasons. Meanwhile, El-Nabawi and Ammar (1987) found
that A. aurantii was the most abundant species in the same orchard. Farag
et al. (1990) indicated that the purple scale insect was the major
pest infesting citrus trees in the same region followed by the red scale insect
and P. ziziphi was at third place. Tawfeek and Abu-Shall
(2010) observed that P. ziziphi on navel orange trees had three annual
peaks of abundance in Shibin El-Kom. Nowadays, as a result of interspecific
competition among armoured scale insect, the black parlatoria scale insect,
P. ziziphi has become the most dominant species on citrus in Shibin El-Kom,
The present results, to some extant, agree with the findings of Kamel
(2010) who recorded A. aurantii and P. ziziphi on citrus trees
(Baladi and Navel Orange) at Al-Qalyubiyah Governorate, Egypt. The present results
agreed with that of Miller and Kosztarab (1979) who
stated that citrus may be heavily infested by a particular coccoid in one area,
whereas it may be immune to attack in another area.
In Alexandria, Karam (1979) recorded that the diaspidid
insects on citrus, arranged in a descending order according to their abundance,
were: P. pergandii, L. beckii and A. aurantii. However,
in the present study L. beckii was the most abundant and the two other
scale insects were found in a few number.
Gerson (1977) mentioned that the chaff scale, P.
pergandii was a pest of citrus in Israel. It infested 10-12 years old trees,
attacking leaves, fruit and bark. Three to four generations occurred on leaves,
the live scale populations ebbing during early summer.
Susceptibility to infestation by P. ziziphi of different citrus species:
The level of infestation per leaf and per cm2 of leaf by the dominant
armoured scale insect species (P. ziziphi) on ten citrus tree types were
observed in Shibin El-Kom only. Susceptibility of citrus trees to infestation
was differed from one species or variety to another.
||Abundance of the ziziphi scale insect, P. ziziphi per
leaf on ten citrus tree species and infestation percentage of leaves in
Shibin El-Kom during the growing season of 2009/2010
|*Average of leaf area per cm2 based on measurement
of area of 10 leaves for each citrus kinds, LSD: 208.26 for upper surface
and 38.34 for lower surface, **Total No. of insects on upper and lower surface
area of leaf x2, In a column, means followed by the same letter are not
significantly different at the 5% level by DMRT
In general, all stages of black parlatoria scale insects were present in the
farm all the year-round, indicative of overlapping generations. However, this
scale insect was more abundant on leaves collected from the interior of the
tree canopy than the exterior canopy.
Data shown in Table 2 indicated that the upper surfaces of leaves were infested by higher numbers of P. ziziphi than that of the lower surfaces on all citrus tree kinds.
The highest mean numbers of this scale insect species on the upper surfaces of leaves was recorded on Adalia lemon (464.7 individuals/leaf) followed by sweet orange (398.9 individuals/leaf) then sour orange (303.0 individuals/leaf), while the lowest mean numbers was noticed on kumquat leaves (7.8 individuals/leaf). On the other hand, the highest mean numbers of P. ziziphi infested the lower surfaces of leaves was also on Adalia Lemon (56.5 individuals/leaf) followed by Grapefruit (49.3 individuals/leaf), Navel orange (48.3 individuals/leaf), while the lowest mean numbers was found on Kumquat leaves (1.2 individuals/leaf).
The present results support the findings of Darwish (1976)
who found and reared this insect species on the upper surfaces of Mandarin leaves
under the natural field conditions for the first time in Shibin El-Kom. Host
plants often show varying degrees of susceptibility to particular scale insect
(Miller and Kosztarab, 1979). Saighi
(2006) investigated the effect of chemical constituents of lemon and clementine
tree on the invasion of P. ziziphi. The results of mineral analysis showed
that there was a larger amount of potassium in lemon tree than in the clementine
tree, which was most infested. Sellami and Biche (2006)
found that P. ziziphi had four generations per year in the area of Boufarik,
in Mitidja, Algeria and the plant host and the climate influenced the distribution,
evolution and also the mortality of the individuals. Black parlatoria was discovered
infesting citrus trees in southern Florida in 1985 (Capinera,
Noticeably, induced data in Table 2 revealed since the leaf area of the ten citrus varieties differed from one variety to another therefore, it is more accurate to calculate the number of insects per 1 cm2. The largest mean area was measured in Sweet lime (53.0 cm2) followed by lemon (43.9 cm2) Grapefruit (35.6 cm2), Sour orange (31.2 cm2), while the smallest leaf area was recorded for Kumquats (7.3 cm2). However, the mean numbers of P. ziziphi per cm2 occurred in higher number on Mandarin leaves (9.95 individuals/cm2) followed by Sweet orange (8.10 individuals/cm2) and the smallest one was on Kumquats (0.53 individuals/cm2).
The results in Table 2 revealed that although the highest
population density was found on Adalia lemon per leaf, yet the insect population
on the same host was at fourth rank of infestations (5.93 individuals per cm2
of leaf); the population density on Mandarin took the first rank at 9.98 individuals
per cm2 followed by sweet orange, then naval orange, sour orange
and kumquat which was at the last rank. The present results, However, do not
agree with that of Farag et al. (1990) who observed
the Mandarin leaves having light infestation.
Moreover, the level of infestation per 100 citrus leaves of all citrus varieties were calculated and recorded on both upper and lower surfaces of leaves (Table 2). In this respect, the occurrences or infestation level of P. ziziphi on the upper surfaces, in this descending order, was: Sour orange (98%), navel orange (96%), sweet lime (96%), sweet orange (94%), Adalia lemon (93%), Baladi orange (92%), mandarin (87%), grapefruit (79%), lime (36%) and the lowest one was kumquat (10%). On the other hand, the infestation level on the lower surfaces, in the descending order, was: Adalia lemon (87%), sour orange (82%), navel orange (73%), grapefruit (63%), sweet orange (59%), Baladi orange (43%), mandarin (42%), sweet lime (33%), lime (15%) and the lowest one was kumquat (2%).
Statistical analysis of data given in Table 2 showed that there were highly significant differences among the distribution and susceptibility of ten citrus trees to infestation by P. ziziphi. There were significant differences between the population densities on Adalia lemon and Sweet orange and that lime and kumquat. However, no significant differences were noticed either between the susceptibility of Adalia lemon and sweet orange or among the susceptibility of eight citrus types to infestation by this insect.
Recently, some changes in the abundance of scale insects were observed. Therefore, this work aimed to identify the species of armoured scale insects, which attack citrus plants and to compare their dominancy in nine different localities in Egypt and to study the susceptibility of different citrus varieties to the infestation of the black parlatoria scale insect, Parlatoria ziziphi (Lucas). This study indicated that the dominations of armoured scale insect species were differed from a location to another. Both were differed from one species or variety to another.
1: Abd-Elfattah, M.I., A. El-Minshawy and E.T.E. Darwish, 1978. The seasonal abundance of two scale insects Lepidosaphis beckii (New.) and Anoidiella aurantii Mask. Infesting citrus trees in Egypt. Proceedings of the 4th Conference Pest Control, September 30-October 3, 1978, Cairo, Egypt, pp: 78-84
2: El-Rahman, A.I., S.M. Metwally and F.M. El-Agamy, 1979. Population density and sex ratio of certain scale insects on different citrus hosts at Kafr-El-Sheikh region. J. Agric. Res. Tanta Univ. Egypt., 52: 101-110.
3: Amin, A.H. and Y.S. Salem, 1978. Population studies on scale insect species Parlatoria ziziphus, a new pest of citrus trees in Egypt (Homoptera, Coccoidea, Diaspididae). Proceedings of the 4th Conference Pest Control, September 30-October 3, 1978, Cairo, Egypt., pp: 49-56
4: Capinera, J.L., 2008. Encyclopedia of Entomology. 2nd Edn., Springer, Dordrecht, Netherlands, pages: 896
5: Darwish, E.T.E., 1976. Ecological and control studies on the scale insects attacking citrus trees in Menoufia province. M.Sc. Thesis, Faculity of Agriculture Tana University, Egypt.
6: El-Keiy, I.A., 1964. Factors affecting the population density of Chrysomphalus ficus Ashm. on citrus plants. M.Sc. Thesis, Ain Shams University Faculity of Agriculture, Egypt.
7: El-Nabawi, A. and I.M. Ammar, 1987. Population studies on the red scale, Aonidiella aurantii (Mask.) on different citrus hosts in Shebin El-Kom. Bull. Soc. Entomol. Egypte, 67: 13-21..
8: El-Nabawi, A., M.M.A. El-Rahim and I.M.A. Ammar, 1986. Factor affecting the population density of three scale insects on grapefruit trees. Minufiyaic. Res., 11: 1025-1043.
9: Farag, A.I., M.M.A. El-Rahim, E.T.E. Darwish and A.M. Zaki, 1990. On the abundance of certain insect and mite pests on different citrus varieties. Proc. Int. Conf. Econ. Entomol., 1: 313-324.
10: Gerson, U., 1977. La capsilla Parlatoria pergandii Comstock y sus enemigos naturales en Israel [The scale insect Parlatoria pergandii Comstock and its natural enemies in Israel]. Bol. Serv. Plagas., 3: 21-53.
Direct Link |
11: Gullan, P.J., 2001. Why the taxon homoptera does not exist? Entomologica, 33: 101-104.
12: Habib, A. and Y.H. Attalah, 1960. Population studies on the black scale Chrysomphalus ficus Ashm. III. The buildup of the population on different kinds of citrus. Bull. Soc. Entomol. Egypte, 29: 13-19.
13: Habib, A., H.S. Salama and A.H. Amin, 1971. Population studies on scale insects infesting citrus trees in Egypt. Z. Fur Angew. Entomol., 69: 318-330.
14: Kamel, A.S., 2010. Insects attack citrus trees in Al-Qalyubiyah Governorate Egypt. Egypt. Acad. J. Biolog. Sci., 3: 107-117.
Direct Link |
15: Karam, H.H., 1979. Studies on some scale insects (Hymenopterous parasitoids and predacious mites associating Parlatoria pergandii, Lepidosaphes beckii and Aonidiella aurantii in Alexandria). Ph.D. Thesis, Faculty of Agriculture, Alexandria University, Alexandria, Egypt.
16: Kosztarab, M. and F. Kozar, 1988. Scale Insects of Central Europe. W. Junk, Publishers, Budapest, Hungary, ISBN-13: 9789061936237, Pages: 455
17: Miller, D.R., 2005. Selected scale insect groups (Hemiptera: Coccoidea) in the southern region of the United States. Florida Entomol., 88: 482-501.
18: Miller, D.R. and M. Kosztarab, 1979. Recent advances in the study of scale insects. Ann. Rev. Entomol., 24: 1-27.
19: Miller, G.L., D.R. Miller, G.S. Hodges and J.A. Davidson, 2005. Introduced scale insects (Hemiptera: Coccidea) of the United States and their impact on U.S. agriculture. Proc. Entomol. Soc. Wash., 107: 123-158.
20: Saighi, H., 2006. The relation of mineral salts content in foliage of two citrus varieties (lemon and clementine) to invasion with parlatoria ziziphi in Algeria. Proceedings of the 9th Arab Congress of Plant Protection, November 19-23, 2006, Damascus, Syria -
21: Sellami, M. and M. Biche, 2006. Ecology of the black louse parlatoria ziziphi on citrus in the area of boufarik, algeria. Proceedings of the 9th Arab Congress of Plant Protection, November 19-23, 2006, Damascus, Syria -
22: Snedecor, G.W. and W.G. Cochran, 1967. Statistical Methods. 6th Edn., Oxford and IBH Publishing Co. Pvt. Ltd., New Delhi, India, Pages: 593
Direct Link |
23: Tawfeek, M.E., 2007. Bioecological studies on some armoured scale insects and their parasitoids. Ph.D. Thesis, Faculity of Agriculture Alexandria University, Egypt.
24: Tawfeek, M.E. and A.M.H. Abu-Shall, 2010. Seasonal population dynamics of Parlatoria ziziphus (Lucas) (Homoptera: Diaspididae) in Menoufia Gavernorate, Egypt. Alex. Sci. Exchange J., 31: 331-338.