Role of pteromalid parasitoid Scutellista caerulea ( Fonscolombe ) ( Hymenoptera : Pteromalidae ) for biological control of the soft scale insects ( Hemiptera : Coccidae ) in Egypt

The pteromalid parasitoid, Scutellista caerulea (Fonscolombe) (Hymenoptera: Pteromalidae) is one of the most effective parasitoid associated with soft scale insects. This work dealt with the biological role of this parasitoid during 2009 and 2010 in Egypt. The results indicated that the parasitoid, S. caerulea was emerged from 8 species of soft scale insects. The host soft scale insects were Ceroplastes floridensis Comstock, Ceroplastes rusci (L.), Coccus hesperidum L., Kilifia acuminata (Signoret), Parasaissetia nigra (Nietner), Saissetia coffee (Walker), Saissetia oleae (Olivier) and Waxiella mimosae (Signoret) (Hemiptera: Coccidae). Population abundance studies of S. caerulea were carried out on the aforementioned soft scale insects in eight locations in Egypt, being Beni Seuf, Gharbiya, Giza, Ismailia, Marsa Matruh, Northern Coast, Qena and Sharqiya. The highest rate of parasitism attained with S. oleae was found to be 38.2 and 40.9 % during the first and second years, respectively. While average parasitism rates was 21.3 and 23.5 % during the two years under consideration, respectively. The results indicated that S. caerulea was the effective parasitoid attacking some soft scale insects in Egypt. Key worlds: Pteromalidae, Scutellista caerulea, Coccidae, soft scale insect and distribution.


INTRODUCTION
Soft scale insects (Hemiptera: Coccidae) are one of the largest families of scale insects classified together with armored scales and mealybugs.There are 1000 species distributed worldwide and these comprise 100 genera approximately (Hamon and Williams, 1984).Of which Egyptian Coccidae comprise about 23 species included in 10 genera (Abd-Rabou, 2003).Soft scales occur in all geographic regions of the world (Ben-Dov, 1993).The severity of damage caused by soft scales is graded according to the level of infestation.At the lowest level, sucking the sap is the only damage.This is followed by the appearance of honey dew on the leaves, resulting in spread of sooty mould.Then, more serious symptoms appear, such as the fall of leaves extending gradually to an almost complete defoliation and entire branches dryness on the tree.Severe infestation do not result in the tree death, but cause the reduction or even absence of yield for a number of years (Ben-Dov and Hodgsen, 1997).The parasitoid, Scutellista caerulea (Fonscolombe) (Hymenoptera: Pteromalidae) is a gregarious endoparasitoid and prefers pre-ovipositing females, also it parasitizes other stages from the third instar larva to an ovipositing and is one of the most important parasitoid attacking different soft scale insects in different countries of the world.The aim of this work is to study the role of the parasitoid, S. caerulea in controlling soft scale insects in different localities in Egypt.

MATERIAL AND METHODS
Samples of soft scale insects were collected from different host plants in Egypt throughout the period of study 2009 and 2010.As this parasitoid was found to exist in Hoda Badary and Shaaban Abd-Rabou 50 eight locations a incidence was conducted on different stages of Ceroplastes floridensis Comstock on citrus (Citrus sp.) in Gharbiya, Ceroplastes rusci (Linnaeus) on citrus (Citrus sp.) in Beni Seuf, Coccus hesperidum L.on guava (Psidium guajava) in Giza, Kilifa acuminata (Signoret) on mango (Mangifera indica) in Sharqiya, Parasaissetia nigra (Nietner) on mango in Ismailia and Saissetia coffeae (Walker) on olive (Olea europaea) in Marsa Matruh, Saissetia oleae (Oliver) on olive (Olea europaea) in Northern Coast, Waxiella mimosae (Signoret) on sunt (Acacia tortilis) in Qena.Gravid females of soft scale insects (as well as insect species other than these soft scales) were eliminated through stereoscopic examination.
Thirty leaves inches of citrus and mango, thirty leaves of olive and thirty leaflet of sunt from different locations were stored in well-ventilated glass tubes for one week for emergence the adult parasitoid and for identification and counted.Rate of parasitism was determined by dividing the number of emerging parasitoid from each by the number of hosts existing.Simple correlation and regression values were calculated to obtain information about the relationships between the three tested weather factors and pecent parasitism by parasitoid.

RESULTS AND DISCUSSION
Eight soft scale insects were collected associated with the parasitoid, S. caerulea.These are: a.

1-On Ceroplastes floridensis Comstock
The parasitoid, S. caerulea was recorded for the first time associated with Ceroplastes floridensis by Priesner and Hosny (1940).The parasitoid S. caerulea which associated with C. floridensis infested citrus in Gharbiya.The maximum parasitism rate reached 4.1 and 3.1 % during the first and second years, respectively (Fig. 1).While average parasitism rates was 1.2 and 0.7 % during the first and second years, respectively.In the first year 2008-2009, statistical analysis showed that the simple correlation between the population of parasitoid, minimum temperature and percent of relative humidity and the mean number of C. floridensis were non-significant (r = 0.33, 0.28 and 0.21), while significant between maximum temperature and the population of C. floridensis (r = 0.78.Also, Statistical analysis showed that the simple regression for changing the population of parasitoid, minimum temperature and %relative humidity and the mean number of C. floridensis were non-significant (b = 0.21, 0.37 and 0.26), while significant between maximum temperature and the population of C. floridensis (b = 0.75).In the second year 2009-2010, statistical analysis showed that the simple correlation between the population of parasitoid, minimum temperature and %of relative humidity and the mean number of Ceroplastes floridensis were nonsignificant (r = 0.33, 0.31 and 0.35), while significant between maximum temperature and the population of C. floridensis (r = 0.75).Also, statistical analysis showed that the simple regression for changing the population of parasitoid, minimum temperature and %relative humidity and the mean number of Ceroplastes floridensis were nonsignificant (b = 0.41, 0.42, and 0.39), while significant between maximum temperature and the population of C. floridensis (b = 0.79).

On Ceroplastes rusci (Linnaeus)
The parasitoid, S. caerulea was recorded for the first time associated with Ceroplastes rusci by Morsi (1999).The parasitoid S. caerulea which associated with C. rusci infested citrus in Beni-Suef.The maximum parasitism rate reached 1.1 and 1.3 % during the first and second years, respectively (Fig. 2).While average parasitism rates was 0.4 and 0.3 % during the first and second years, respectively.
In the first year 2008-2009, statistical analysis showed that the simple correlation between the population of parasitoid and the mean number of Ceroplastes rusci were non-significant (r = 0.32), while significant between maximum, minimum temperature and %relative humidity and the population of Ceroplastes rusci (r = 0.83, 0.78 and 0.79).Also, Statistical analysis showed that the simple regression for changing the population of parasitoid and the mean number of Ceroplastes rusci were non-significant (b= 0.26), while significant between maximum, minimum temperature and %relative humidity and the population of Ceroplastes rusci (b = 0.81, 0.77 and 0.75).In the second year 2009-2010, statistical analysis showed that the simple correlation between the population of parasitoid and the mean number of Ceroplastes rusci were non-significant (r = 0.19), while significant between maximum, minimum temperature and %relative humidity and the population of Ceroplastes rusci (r = 0.75, 0.71 and 0.72).Also, Statistical analysis showed that the simple regression for changing the population of parasitoid and the mean number of Ceroplastes rusci were non-significant (b= 0.21), while significant between maximum, minimum temperature and %relative humidity and the population of C. floridensis (b = 0.79, 0.72 and 0.74).

On Coccus hesperidum L.
The parasitoid S. caerulea was recorded for the first time associated with C. hesperidum by Abd-Rabou (2010).The parasitoid S. caerulea which associated with C. hesperidum infested guava in Giza.The maximum parasitism rate reached 4.1 and 2.1% during the first and second years, respectively (Fig. 3).While average parasitism rates was 1.4 and 0.7 % during the first and second years, respectively.
In the first year 2008-2009, statistical analysis showed that the simple correlation between the population of parasitoid and %relative humidity and the mean number of Coccus hesperidum were non-significant (r = 0.41 and 0.32), while significant between maximum, minimum temperature and the population of C. hesperidum (r = 0.80 and 0.85).Also, Statistical analysis showed that the simple regression for changing the population of parasitoid, %relative humidity and the mean number of C. hesperidum were non-significant (b= 0.40, and 0.28), while significant between maximum, minimum temperature and the population of C. hesperidum (b= 0.77 and 0.75).In the second year 2009-2010, statistical analysis showed that the simple correlation between the population of parasitoid, %relative humidity and the mean number of Coccus hesperidum were non-significant (r = 0.21, and 0.26), while significant between maximum, minimum temperature and the population of C. hesperidum (r = 0.75 and 0.78).Also Statistical analysis showed that the simple regression for changing the population of parasitoid, %relative humidity and the mean number of C. hesperidum were non-significant (b = 0.31 and 0.32), while significant between maximum, minimum temperature and the population of C. hesperidum (b = 0.71 and 0.74).

On Kilifa acuminata (Signoret)
The parasitoid, S. caerulea was recorded for the first time associated with K. acuminata by Abd-Rabou and Hafez, (2001).The parasitoid S. caerulea which associated with K. acuminata infested mango in Sharqiya.The maximum parasitism rate reached 1.1 and 0.9% during the first and second years, respectively (Fig. 4).While average parasitism rates was 0.2% during the first and second years, respectively.In the first year 2008-2009, statistical analysis showed that the simple correlation between the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of Kilifa acuminata were non-significant (r = 0.37, 0.29, 0.38 and 0.35).
Also, Statistical analysis showed that the simple regression for changing the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of K. acuminata were (b= 0.42, 0.32, 0.34 and 0.28) .In the second year 2009-2010, statistical analysis showed that the simple correlation between the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of Kilifa acuminata were non-significant (r = 0.32, 0.21, 0.26, and 0.29).Also, Statistical analysis showed that the simple regression for changing the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of K. acuminata were (b= 0.31, 0.24, 0.28 and 0.32).

On Parasaissetia nigra (Nietner)
The parasitoid, S. caerulea was recorded for the first time associated with P. nigra by Priesner and Hosny (1940).The parasitoid S. caerulea which associated with P. nigra infested mango in Ismailia.The maximum parasitism rate reached 0.4 and 0.2% during the first and second years, respectively (Fig. 5).While average parasitism rates was 0.8 and 0.4 % during the first and second years, respectively.In the first year 2008-2009, statistical analysis showed that the simple correlation between the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of Parasaissetia nigra were non-significant (r = 0.25, 0.27, 0.26 and 0.32).Also, statistical analysis showed that the simple regression for changing the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of Parasaissetia nigra were (b = 0.31, 0.27, 0.29 and 0.26).In the second year 2009-2010, statistical analysis showed that the simple correlation between the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of Parasaissetia nigra were non-significant (r = 0.44, 0.31, 0.29 and 0.36).Also, statistical analysis showed that the simple regression for changing the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of Parasaissetia nigra were (b = 0.41, 0.36, 0.29 and 0.31).

On Saissetia coffeae (Walker)
The parasitoid, S. caerulea was recorded for the first time associated with S. coffeae by Priesner and Hosny (1940).The parasitoid S. caerulea which associated with S. coffeae infested olive in Marsa Matruh.The maximum parasitism rate reached 6.4 and 7.1 % during the first and second years, respectively (Fig. 6).While average parasitism rates was 1.6 and 1.9 % during the first and second years, respectively.
In the first year 2008-2009, statistical analysis showed that the simple correlation between the population of parasitoid, minimum temperature, %relative humidity and the mean number of Saissetia coffeae were non-significant (r = 0.43, 0.31, and 0.27), respectively, while significant between maximum temperature and the population of S. coffeae (r = 0.86).Also, statistical analysis showed that the simple regression for changing the population of parasitoid, minimum temperature, %relative humidity and the mean number of Saissetia coffeae were (b = 0.28, 0.47 and 0.25), while significant between maximum temperature and the population of S. coffeae (b = 0.81) .In the second year 2009-2010, statistical analysis showed that the simple correlation between the population of parasitoid, minimum temperature, %relative humidity and the mean number of Saissetia coffeae were non-significant (r = 0.37, 0.41 and 0.29), respectively, while significant between maximum temperature and the population of S. coffeae (r = 0.77) .Also, statistical analysis showed that the simple regression for changing the population of parasitoid , minimum temperature, %relative humidity and the mean number of Saissetia coffeae were (b = 0.33, 0.39 and 0.28), while significant between maximum temperature and the population of S. coffeae (b = 0.79).

On Saissetia oleae (Oliver)
The parasitoid, S. caerulea was recorded for the first time associated with S. oleae by Abd-Rabou (2004) .The parasitoid, S. caerulea which associated with S. oleae infested olive in Northern Coast.The maximum parasitism rate reached 38.2 and 40.9 % during the first and second years, respectively (Fig. 7).While average parasitism rates was 21.3 and 23.5 % during the first and second years, respectively.
In the first year 2008-2009, statistical analysis showed that the simple correlation between the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of Saissetia oleae were significant (r = 0.79, 0.93, 0.77 and 0.82), respectively.Also, statistical analysis showed that the simple regression for changing the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of Saissetia oleae were (b = 0.76, 0.89, 0.74 and 0.81).In the second year 2009-2010, statistical analysis showed that the simple correlation between the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of Saissetia oleae were significant (r = 0.79, 0.91, 0.76 and 0.77), respectively .Also, statistical analysis showed that the simple regression for changing the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of Saissetia oleae were (b = 0.72, 0.83, 0.79 and 0.78).

On Waxiella mimosae (Signoret)
The parasitoid, S. caerulea was recorded for the first time associated with W. mimosae by Priesner and Hosny (1940).The parasitoid S. caerulea which associated with W. mimosae infested sunt in Qena.The maximum parasitism rate reached 0.6 and 1.1 % during the first and second years, respectively (Fig. 8).While average parasitism rates was 0.1 during the first and second years, respectively.
In the first year 2008-2009, statistical analysis showed that the simple correlation between the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of W. mimosae were non-significant (r = 0.35, 0.29, 0.34 and 0.26), respectively.Also, statistical analysis showed that the simple regression for changing the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of W. mimosae were nonsignificant (b = 0.23, 0.37, 0.36 and 0.29).In the second year 2009-2010, statistical analysis showed that the simple correlation between the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of mimosae were non-significant (r = 0.31, 0.35, 0.34 and 0.22), respectively.Also, statistical analysis showed that the simple regression for changing the population of parasitoid, maximum, minimum temperature, %relative humidity and the mean number of mimosae were non-significant (b = 0.32, 0.39, 0.30 and 0.24) during 2009 and 2010 years, respectively.
This parasitoid was recorded in Egypt by Priesner and Hosny (1940) associated with W. mimosae on Acacia nilotica, Albizzia lebbek,Ficus carica, also P. nigra on Ficus sycamorus and S. coffeae on olive in Lower and Upper Egypt.El-Minshawy and Saad (1977) mentioned that S. caerulea (Scutellista cyanea Motsch) was the most important enemy attacking S. coffeae and recorded in 33.9, 42.0 and 30.5 during its peaks during the periods under investigation in Alexandria.Abu El-Khair (1978) stated that the activity of the parasitoid S. caerulea found to be associated with the occurrence of the gravid females of the fisrt generation during the period from March to May and those of the second generation during October.The efficacy of the parasitoid S. caerulea on S. coffeae, S. oleae and C. floridensis.This parasitoid was prevent on S. coffeae and S. oleae from August to November and on C. floridensis in March and September (El-Minshawi et al., 1978).The parasitoid, S. caerulea associated with different species of soft scale insects in Alexandria (Abou El-Khair, 1999).Abd-Rabou (2010) recorded S. caerulea with other parasitoids associated with C. rusci in Beni-Suef.S.caruleae was recorded attacking C.floridensis infested citrus trees in Beheira governorate with an average parasitism rate 4.5% and the maximum parasitism rate was 13% (Abd-Rabou, 2001a).Later Abd-Rabou et al. (2003) recorded average parasitism rate of 2.0 and 3.5% during the two years under considerations, respectively.Maximum rate of parasitism was estimated to be during mid June and early June as 5.5 and 11.1, respectively.This parasitoids was reared from K. acuminate, with an average parasitism rate 1.8% (Abd-Rabou and Hafez, 2001).Later, Abd-Rabou (2004) mass reared and released the parasitoid at monthly intervals in olive groves infested with S. oleae at three localities in Egypt and percentages of parasitism increased after releasing from 14 to35%.Abd-Rabou (2001b) studied the dynamic of the hemispherical scale, S. coffeae in Alexandria.The abundance of the parasitoids attacking C. floridensis.He recorded eight primary parasitoids includung S. caerulea (Abd-Rabou, 2001a).Abd-Rabou and Hafez (2001) recorded five parasitoid associated with K. acuminate including also, S. caerulea.

Fig
Fig.(7): Percent parasitism by Scutellista caerulea associated with Saissetia oleae on olive in Northern Coast during 2009 and 2010