27-32 27 A.F. Mekhlif & M. S. Abdul- Rassoul Bull. Iraq nat. Hist. Mus. (2002) 9(4): 27-32 EFFICIENCY OF PARASITOIDS OF PEA LEAFMINER PHYTOMYZA HORTICOLA GOUREAU AND THEIR APPEARANCE TIME IN THE FIELD *A. F. Mekhlif and **M. S. Abdul-Rassoul *Department of Biology, College of Education, Mosul University, Mosul ** Iraq Natural History Museum, University of Baghdad, Baghdad, Iraq. ABSTRACT Eleven hymenopterous species: two braconids, seven eulophids and two pteromalids parasitized the larvae of Phytomyza horticola Goureau. The activity of the parasites began at the end of April and evidently increased during May. The female of the parasites fed and parasitized mostly on the second and third larval instars of P. horticola. Diglyphus iseae Walker and Cirrospilus vittatus Walker were dominant larval parasites. Chrysocharis pentheus Walker and Pediobius acantha Walker were main pupal parasites. INTRODUCTION The pea leafminer Phytomyza horticola (Diptera, Agromyzidae) is a polyphagous species (Griffiths, 1976), and it may be of economic importance (Spencer, 1973). In Iraq, more than 40 host plant of this pest have been known, including some crops and ornamental plants (Al- Azawi, 1967 and Mekhlif, 1984). Female of many hymenopterous parasites kill the host, either by oviposition or feeding on host fluids, since reproduction is impossible without protein in their diet (Bartell and Pass, 1978; Sugimoto et al., 1983). However, the growing emphasis on biological control in pest management, demands a greater knowledge of important parasites (Bartella and Pass, 1978). Takada and Kamijo (1979); Drea et al. (1982) investigated the parasitic complex of P. horticola and its effective parasitoids in Japan and Europe respectively. However, in Iraq P. horticola was found to have 15 parasites (Al-Azawi, 1967, 1971; Mekhlif, 1984). Therefore, the aim of this work was to know the effective parasitoids and the time of their appearance in Mosul. MATERIALS AND METHODS In spring of 1988 and 1989 regular collection of immature stages of P. horticola from various host plants were conducted in order to determine its mortality, parasitism and parasites identification. Adult parasites were obtained by caging the host leaves containing immature stage of the pest during April and May. Larval ectoparasites were confirmed through the dissecting microscope. Pupal endoparasite and larva-pupal endoparasite were determined by the scar on the host pupa. The dead larvae due to host-feeding were clear and their contents were extruded by female parasites. RESULTS AND DISCUSSION 1. Host Mortality In March, the activity of the parasitoids had not begun, so that, the mortality of immature stages of P. horticola were very low. Yet, in April and in the beginning of May, mortality 28 Parasites of pea leaf miner started and increased (table 1). This observation was also reported by Mekhilf and Khazraji (1989). Most of the moralities were due to host-feeding and parasitization. Table 1 also shows that the larval mortality was higher than the pupal mortality. Drea et al., (1982) and Sugimoto, (1979) reported that larval parasites were vary aggressive for some agromyzid leafminers, which one of them P. horticola. Most of larval mortality probably was due to host-feeding of parasites as well as parasitization. Table 1: Mortality of immature stages of P. horticola in the field. * Numbers in paranthesis indicate the mortality of larvae or pupae. Date of sampling No. of hosts examined No. of dead hosts Total mortality % larvae pupae larvae pupae 1989 18.3 354 2 3(0.8)* 0(0)* 0.8 31.3 369 143 0(0) 0(0) 0.0 20.4 294 144 264 (89.8) 5 (3.5) 61.4 30.4 675 56 596 (88.3) 3 (5.4) 81.0 7.5 906 21 887 (98.0) 9 (42.9) 96.7 10.5 218 3 216 (99.0) 1 (33.3) 98.2 2. Selection of the host instar Female parasites evidently attacked second and third host instar larvae more than the first instar (table 2). Sugimoto (1979) observed that Chrysocharis pentheus experimentally fed on and parasitized second and third instars of runuculus leafminer, P. ranunculii (Schr.) this may be attributed to the parasites in having not enough ability to distinguish first instar larvae insides mines. Table 2 also reveals that the first instar larvae were rarely parasitized, on the other hand nearly half of the second instar larvae were parasitized. Parasites oviposited in most of third instar larvae causing their death. Perhaps the parasites preferred third instar larvae to ensure enough nutrients for their progeny to complete their development. Table 2: Parasitism of P. horticola in different larval instars. Host instar No. of hosts found killed No. of hosts parasitized Parasitism % I 50 4 8 II 71 37 52 III 118 99 83.9 3. Parasitisum mode of dominant parasites It was found that eulophid parasites D. iseae and C. vittatus completed their life-cycle on the host larvae (table 3) and P. acantha and C. pentheus were pupal endoparasites. These observation were also reported by Takada and Kamijo (1979), for the same host, and Ibrahim and Madje (1979) for the host P. syngensiae (Hardy). The braconid Opius sp. is larval-pupal endoparasite, which lays its eggs on the host lavra, and completes its development up to the adult stage inside the host pupa . Opius spp. are also found as larval-pupal endoparasites of Liriomyza munda (Frick Hardling, 1965. 29 A.F. Mekhlif & M. S. Abdul- Rassoul Table 3: Parasitizing phase of dominant parasites. Ect., Ectoparasite, End., Endoparasite. Parasites Developmental stage of host at Oviposition Emergence Mode of parasitism Diglyphus iseae Walker Larvae Larvae Ect. Cirrospilus vittatus Wlk. Larvae Larvae Ect. Pediopius acantha Wlk. Pupa Pupa End. Chrysocharis pentheus Wlk. Pupa Pupa End. Opius sp. Larva Pupa End. 4. Effective parasites In the field, the efficiency of the parasite is mostly depended upon the period of its appearance, the parasite abundance in a given area and the ability of the female parasite to attack various host species, either for feeding or parasitization. Table 4 reveals the field appearance of the eulophid parasites D. iseae and C. vittatus during April and May and Opius sp. during April but was not obtained in May. The parasites Dacnusa sp. and Halticoptera circulus (Welker) appeared for a short time in samples collected at late April and first third of May. The parasites; Chrysonotomya formosa Westwood, P. acantha, C. pentheus and Tetrastichus strobilanae were obtained throughout May while C. formosa at first week of the same month. Table 4: Parasitic efficiency of P. hotrticola during April and May as indicated by parasitism of each parasitoid. Family and species No. of parasites emerging / rearing date 20.4 30.4 7.5 10.5 15.5 Braconidae Dacnusa sp. - 3(0.4) - 1(0.6) - Opius sp. 14(8.3) - 1(0.2) - - Eulophidae Chrysocharis pentheus - - - 5(3.2) 5(9.6) Chrysonotomya formosa - - 1(0.2) - - Cirrospilus vittatus 1(0.6) 2(0.2) 8(1.4) 13(8.2) 1(1.9) Diglyphus iseae 154 (91.1) 817 (99.2) 555 (97.0) 121 (76.7) 15 (28.8) D. crassinervis - - 1(0.2) 1(0.6) 1(0.6) Pedicbius acantha - - 2(0.3) 5(3.2) 27(52) Tetrastichus strobilanae - - 1(0.2) - 1(1.9) Pteromalidae Halticoptera circulus - 2(0.2) 3(0.5) 3(1.9) - Spegigaster sp. nr. orobnchiae - - - - 2(3.9) Larvae and pupae of host examined 438 731 927 221 60 According to Drea et al., (1986); Ibrahim and Madje (1979); Takada and Kamijo (1979) D. iseae and C. vittatus were the main larval ectoparasites of various agromyzid leafminers. The present study confirms this observation, for the parasite D. iseae, its percentage to total parasites was more than 98% during April and first week of May, contrary C. vittatus rarely reared in some samples at the same time (table 4). The low number of C. vittatus may be attributed to competition between the larvae of D. iseae and C. vittatus. D. iseae is a multiple 30 Parasites of pea leaf miner parasite and as many as four parasites was emerged from one host (Mekhlif, 1984). Table 4 also confirm this observation, thus, at 30th April collection, the number of D. iseae adults were only more than immature stage of the examined host. The main pupal parasites were P. acantha and C. pentheus, parasitizing nearly all the host pupae during the second half of May (table 4) which agrees with Ibrahim and Madje (1979); Kamijo (1978) they recorded that Chrysocharis spp. are main pupal parasites of many leafminers of Diptera, Lepidoptera and Hymenoptera. The braconid parasite Opius sp. was active only during April (table 4), but latter disappeared. It is probable that the larval ectoparasite D. iseae kills the host and Opius sp. larvae which needs alive host larva to continue its development. LITERATURE CITED Al-Azawi, A.F. (1967) Agromyzid leafminers and their parasites in Iraq. Bull. Ent. Res., 57(2):285-287. Al-Azawi, A.F. (1971) Parasites of Agromyzid leafminers in Iraq. Bull. Iraq nat. His. Mus., 5(1):35-37. Bartell, D.P. and B.C. Pass (1978) Morphology, Development and behaviour of the immature stages of the parasite Bathyplectes curculionis. Ann. Ent.Soc. Amer., 7(1):23- 29. Drea, J.J., D. Jeandel and F. Gruber (1982) parasites of Agromyzid leafminer. (Diptera; Agromyzidae) on alfalfa in Europe. Ann. Ent. Soc. Amer., 75:297-310. Drea, J.J. and R.M. Hendrickson (1986) Analysis of a successful biological control project: the alflfa blotch leafminer (Diptera; Agromyzidae) in the Northeastern United States. Environ. Entomol., 15(3):448-455. Griffiths, G.C.D. (1976) Studies on boreal Agromyzidae (Diptera) Phytomyza chromatomyia mines on Astereae (Compositae). Quaest. Ent., 12(3):239-278. Hardling, J.A. (1965) Parasitism of the leafminer Liriomyza munda in the winter garden area of Texas. J. econ. Ent., 58:442-443. Ibrahim, A.G. and D.S. Madje (1979) Parasitization of the chrysanthemum leaf-miner Phytomyza syngenesiae (Hardy) (Dip.; Agromyzidae), by Diglyphus iseae (Walker) (Hym.; Eulophidae). Ent. Mon. Mag., 114:71-81. Kamijo, K. (1978) Chalcidoid parasites (Hymenoptera) of Agromyzidae in Japan, with description of a new species. Kontyu, Tokyo, 46:455-469 Mekhlif, A.F. (1984) Aspects of the biology of the pea leafminer, Phytomyza horticola Goureau (Dip.; Agromyzidae) infecting the leaves of wall-flower Cheiranthus cheiri L. MSc. Thesis, Coll. of Sci., Mosul Univ. (in Arabic). Mekhlif, A.F. and A.T. Khazraji (1989) The importance of Sonchus aspar (Compositae) and Sisymbrium irio (Crusifera) in distribution of pea leafminer, Phytomyza horticola. J. Educ. and Sci., 9:85-97. (in Arabic). 31 A.F. Mekhlif & M. S. Abdul- Rassoul Spencer, K.A. (1973) Agromyzidae (Diptera) of Economic importance. Series Entomological. G.Junk, The Hague, pp. 1-405. Sugimoto, T. and M. Ishii (1979) Mortality of larvae of Rununculus leafmining fly, Phytomyza ranunculi (Dip.; Agromyzidae), due to parasitization and host- feeding by its eulophid parasite, Chrysocharis pentheus (Hym.; Eulophidae). Appl. Ent. Zoll. 14:410-418. Sugimoto, T.T. Imoara and H. Tsuji (1983) Oosorption in eulophid wasp Chrysocharis pentheus Welker (Hym.; Eulophidae). App. Ent. Zoll., 18:287-289. Takada, H. and K. Kamijo (1979) Parasitic complex of the Garden pea leaf-miner, Phytomyza horticola in Japan. Kontyu, 47:18-37. 32 Parasites of pea leaf miner Bull. Iraq nat. Hist. Mus. (2002) 9 (4): 27-32 ل حق ورها ف ال خ ه ال وت ري ز ور البا ت فار ط يليا فعالي ف خل هللا ف د طا ل ع د ا رسو ح ب ص ل حمد م متحف التاريخ الطبيعي قسم علوم الحياة، كلية التربية جامعة الموصل جامعة بغداد الخالصة لوحظ نشاط أحد عشر طفيليًا من رتبة غشائية األجنحة، تقضي على األطوار غري الكاملة يبــدأ نشــاط الطفيليــات يف ايــة نيســان ويــزداد بشــكل .Phytomyza horticolaحلفــار ورق البــازالء غالبــًا مــا تتغــذى إنــاث الطفيليــات وتتطفــل علــى الريقــات وهــي يف الطــورين . واضــح خــالل مــايس أهــم و ، Cirrospilus vittatusو Diglyphus iseaeاكثــر الطفيليــات الريقيــة فعاليــة . الثــاين والثالــث .Pediobius acanthaو Chrysocharis pentheusالطفيليات اليت اجم العذارى