Parasitoid Species Associated with Immature Stages pieris rapae (L.) Inhabiting Cabbage Plantations in Assiut Governorate, Upper Egypt

: This work was initiated for the first time to identify parasitoid species associated with the immature stages of Pieris rapae (L.) inhabiting cabbage plantations in Assiut governorate, Upper Egypt during the 2018 and 2019 cabbage growing seasons. Attacking periods and parasitism percentages (PPs) of the identified parasitoid species were calculated. One solitary parasitoid species, Hyposoter ebeninus was found to attack P. rapae larvae in the field 110 days after transplantation. However, one hyperparasitoid species Baryscapus galactopus was recorded as an internal gregarious hyperparasitoid of H. ebeninus . The solitary larval parasitoid H. ebeninus strikes were recorded throughout the last five weeks of the season with a marked decline before harvesting. Although H. ebeninus revealed 42.00% abundance, it presented 21.69% PP on P. rapae larvae during the entire period of study. One solitary, Brachymeria femorata and two gregarious parasitoid species [ Pteromalus puparum (L) and Tetrastichus sp. (Haliday) were recorded as P. rapae pupae parasitoids on October, 2 nd . Parasitism peak was recorded on October, 16 th with an average of 56.25%. The first appearance of the gregarious pupal parasitoid P. puparum was recorded on October, 9 th . Four weeks later, the second gregarious parasitoid ( Tetrastichus sp.) was recorded on November, 6 th . Both pupal gregarious parasitoid species were found to be active until harvesting. The gregarious parasitoid P. puparum presented high PP (23.73%) as compared with Tetrastichus sp. which exhibited 6.96% PP during the entire period of study. In conclusion, two solitaries, one hyperparasitoid, and two gregarious parasitoid species were identified. Pupal gregarious parasitoid species together reduced P. rapae pupae populations by 30.69%. These parasitoids could be used in the IPM programs for this pest in the future. At the same time, the effect of hyperparsitoides must be taken into consideration.


Introduction
The white butterfly (WB), Pieris rapae (Linnaeus, 1758) (Lepidoptera: Pieridae) occurs in temperate regions around the world. WB larvae feeding habits caused ragged holes in the leaves of the host plant. Under heavy attack, only the veins are left, resulting in considerable losses to commercial growers. Less heavily infested plants become stunted and fouled with dark green pellets [1]. In Egypt, cabbage plantations have been subjected to attack by sever key insect pests e.g. the WB P. rapae [2].
Pesticide massive application and appearance of pest resistance strains, outbreaks of secondary pest, the absence or ineffective presence of natural enemies, and global worming and climate change are all contributing to changes in insect pest problems faced by farmers in Egypt's newly reclaimed land as well as in the old valley [6]. Recording natural biological control agents for plants is becoming increasingly important in order to expand our knowledge. The main objective of this manuscript is to identify parasitoid species attacking P. rapae immature stages (larvae and pupae) inhabiting cabbage plantations in the reclaimed areas in Assiut, Upper Egypt. Parasitism percentages and attacking duration were also taken into consideration.

Experimental Design
Experiments were conducted at a reclaimed area at the border of the eastern desert of Assiut governorate (private farm at El-Fath province) during the 2018 and 2019 cabbage growing seasons. Area of about 1050 m 2 divided into plots (10.50 m 2 /plot). Cabbage seeds were planted in the greenhouse on 17 th June during both seasons. One month later cabbage seedlings were transplanted at a 50 cm distance at the sustainable farm. Regular agricultural practices were used. Chemical treatments were completely prevented.
The natural parasitism rates on P. rapae larvae were estimated weekly in the field by counting parasitized and non-parasitized larvae/plant (4 plants/ plot). However, parasitism rates on P. rapae pupae were estimate d weekly by picking up P. rapae pupae inhabiting the outer and/or the middle leaves of randomly selected cabbage plants. The collected larvae and pupae were transferred to the laboratory and kept individually in moistened test tubes (10 replicates) at the laboratory conditions (22± 3 °C and 60± 5 R. H. %). The test tubes were carefully labeled and covered with a piece of cotton to provide aeration. Emerged parasitoids were killed by chloroform and preserved at -5 °C in a freezer for later identification by the specialists in the biological control and taxonomy Departments in the Plant Protection Research Institute, Ministry of Agriculture.
Parasitism percentages (PP) on larvae and pupae were estimated by the equations used by Puneeth

Pupae Parasitoids
Data illustrated in Figure 1 revealed that the first appearance of the solitary parasitoid Brachyrneria femorata (Panzer, 1801) was recorded on October, 2 nd (75 days after transplantation) with an average of 12.50% PP. Two weeks later PP of B. femorata multiplied and showed 51.25%. The highest PP (peak) of B. femorata on P. rapae pupae was recorded on October 16 th with an average of 56.25%. A gradual decrease in B. femorata PPs was recorded. The general PP of B. femorata during the entire period of the study recorded 22.92% (Table 1). On the other hand, B. femorata showed the highest abundance percentage (75.00%) and the absolutely highest PPs on P. rapae pupae (56.00%).
Data illustrated in Figure 1 revealed that two gregarious parasitoid species were recorded as parasitoids of P. rapae pupae in cabbage fields, vs. Pteromalus puparum (L., 1758) and Tetrastichus sp. (Haliday, 1844). The first appearance of P. puparum was recorded 82 days after transplantation (October, 9 th ). Four weeks later, the second parasitoid, (Tetrastichus sp.) was recorded in cabbage fields (November, 6 th ). It is important to point herein that both gregarious parasitoid species was found to be active until harvesting. Data revealed that P. puparum ranked the first and presented the highest PPs with an average of 23.73% compared with Tetrastichus sp which exhibited 6.96% PP during the entire period of study. Gregarious parasitoid species together reduced P. rapae pupae populations by 30.69% (Table 1). Concerning the gregarious parasitoids parasitism and abundance percentages, data presented in Table 1 showed that P. puparum ranked the first and parasitized P. rapae pupae by the highest PP (ranged between 49.50 and 16.00%). This parasitoid abundance percentage (75.00%) was found to be equal to 1.71 fold of that presented by the second gregarious parasitoid (Tetrastichus sp.). Although, Tetrastichus sp. presented throughout 5 weeks only in the field, its PP (ranged between 26.00 and 12.50%). This finding reflects the importance of this pupal parasitoid as an effective biological control agent against (WB) in cabbage fields.

Discussion
The present study was conducted for the first time in this area of northern Egypt. Results demonstrated the finding of just one solitary p. rapea larval parasitoid H. ebeninus and one hyperparasitoid B galactopus. These results of the current investigations are in agreement with those obtained by the earliest, Abbas and Hassanein (1989) [9] who recorded the absolutely first parasitism in Egypt on P. rapae larvae in cabbage fields. Also, Deen & Bhagat [10] found three parasitoids, C. glomerata, H. ebeninus and B. femorata from larvae and pupae of P. rapae as a first parasitism of this pest in India. Notable gradual decline of H. ebeninus abundance through the time, this finding could be attributed to the appearance of its eolophid hyperparasioid B. galactopus which appeared at the same period. Results of Settele et al. [11] confirmed the complementary need for parasitoid based knowledge. Their article explained that parasitoid complexes are not closed systems, and there is no a prior way of assessing whether a parasitoid reared from a particular species also uses related hosts, or perhaps unrelated ones occurring in similar environments. Therefore, researchers need to establish comprehensive knowledge not only of which species attack butterflies, but also of the host associations of each one. This is gradually accruing, at least for common parasitoid species, especially through smallscale rearing's involving a large number of host species.
These parasitoid species could be efficient in the IPM field. In this approach, [21] results revealed that, Tetrastichus howardi parasitized on the larvae, pupae and adults of the sugarcane borer D. saccharalis, and therefore seems to be a suitable candidate for the biological control of this insect pest in commercial sugarcane. Parasitism and the emergence of T. howardi from the fifth instar larvae, pupae and adults of D. saccharalis revealed the ability of this natural enemy to establish itself in culture, even in the absence of host pupae.

Conclusion
Results showed that no egg parasitoid species were recorded, but for larvae, one solitary parasitoid species, H. ebeninus and one hyperparasitoid species B. galactopus was recorded as an internal gregarious hyperparasitoid of H. ebeninus. Regarding the pupae parasitoids, one solitary B. femorata and two gregarious parasitoid species P. puparum and Tetrastichus sp. were recorded. These results are important and could be used for the control of the pest in IPM programs in the future.