Abstract: The species of genus Aphytis Howard (Hymenoptera: Chalcidoidea: Aphelinidae) are considered to be the most important natural enemies of the armored scale insects (Homoptera: Diaspididae). A new species, Aphytis alexandrina (Hymenoptera: Chalcidoidea: Aphelinidae) was collected from the armored scale insects Pinnaspis aspidistrae (Homoptera: Diaspididae). This study aimed to describe and illustrate the diagnostic and recognition characteristics of both male and female to help the biological control entomologists to adequately identify the species.
INTRODUCTION
The species of genus Aphytis Howard (Hymenoptera: Chalcidoidea: Aphelinidae) are considered to be the most important natural enemies of the armored scale insects (Homoptera: Diaspididae). They develop as primary ectoparasitoids, the adult wasps emerge through an exit hole in the cover scale (Rosen and DeBach, 1976). Systematic work of this genus is difficult, due to the minute size, the relatively scarcity of reliable distinguishing characters and the common occurrence of sibling species. Probably a great many more forms of Aphytis exist than have been described, it seems hopeful that new species or strains may be described (DeBach, 1959). Also, Viggiani (1984) in his study on family Aphelinidae stated that many genera and species of this family remain to be undescribed. The taxonomic scientific researches in Egypt still need more work in revising the families and genera of insects in hope of finding any spieces other than those recorded before.
A worldwide biosystematic revision of the species of Aphytis was undertaken by Rosen and DeBach (1979) comprises 90 distinct species including 14 that have been transferred from other genera and 34 that were recognized as new to science. Abd-Rabou and Hayat (2003) surveyed 15 species of Aphytis from the Egyptian fauna, 9 of them were new species. Then, Abd-Rabou (2004) revised the Egyptian species, he described 17 species two of them are new. Later on, he recorded another new species from Sinai emerging from California red scale Aonidiella aurantii (Abd-Rabou, 2005). By revising the description of the 90 world species of Rosen and DeBach (1979) and that of Egypt by Abd Rabou, it was found that the species under consideration of this study disagree completely with any of them. Therefore, it is suggested to be a new species and the aim of this study is to concentrate on the diagnostic characters.
MATERIALS AND METHODS
Samples of the armored scale insects Pinnaspis aspidistrae (Signoret) were collected with the infested leaves of Aspidistra sp. (Liliaceae) in August 2011 from Alexandria, Egypt and kept in ventilated jars until the parasitoid emergence. The collected specimens were cleared by immersing in pure lactic acid in watch glass for one day, rinsed in distilled water and then mounted on slides by using Hoyer’s medium. The slides were dried in an oven at 45°C then examined by using stereoscopic microscope. Measurements of the diagnostic characteristics were made by using micrometer eyepiece. The description and morphological terms follow those of Rosen and DeBach (1979) who gave the commonly used characters for intraspecific variation of Aphytis. They include: (1) number of antennal segments (2) ratio of length to width of the antennal club (3) ratio between the lengths of the various antennal segments (4) number, size and relative melanization of the setae on the mesonotal sclerites (5) shape of the crenulae on the posterior margin of the propodeum (6) number of setae in the abdominal cerci (7) wing shape (8) ratio of the length of the longest setae in the marginal fringe of the forewing to the greatest width of the disk (9) number of setae along the marginal vein (10) number of bullae along the submarginal vein (11) number of setae in the delta area of the forewing (12) relative visibility of the inter-ommatidial setae on the compound eye (13) sculpture on the thorax (14) general color of live adults and (15) degree of duskiness (melanization) of the integument and its location on the body, head, antennae, legs and wings, especially in cleared specimens.
The holotype, allotype and four male and female paratype are deposited in the Department of Applied Entomology, Faculty of Agriculture, Alexandria University, Egypt.
RESULTS AND DISCUSSION
According to Compere (1955) and Rosen and DeBach (1979), four aphelinid genera may be regarded as most closely related to Aphytis Howard. These are Marlattiella Howard, Marietta Motschulsky, Centrodora Forster and Bestiola Nikolskaja. The main distinguishing characters separating Aphytis from the closely related genera are: (1) the well-developed relatively long propodeum with distinct, sculptured median salient, usually bearing posteromarginal crenulae (2) the chaetotaxis and venation of the forewings (delta-shaped area basad of the speculum with several rows of setae, marginal vein longer than the submarginal) and (3) the absence of parameres in the male genitalia. Also, Compere (1955) mentioned three groups of species in the genus Aphytis, the proclia, mytilaspidis and chrysomphali groups, afterwards Rosen and DeBach (1979) recognized another four groups i.e., vittatus, chilensis, lingnanensis and funiculars in addition to the previous three ones.
Holotype female: Aphytis alexandrina (a pale member of the lingnanensis group) this group is characterized by a relatively long propodeum with large strongly overlapping crenulae. General coloration yellow; wings uniformly setose and hyaline. The species under study is biparental species. It is about 0.86 mm. long, yellow in colour in all body regions and appendages, wings hyaline.
Head: Rectangular in shape the length/width ratio 0.55, with large fine setose compound eyes. Antennae (Fig. 1a) 6 segmented; scape slender about 6 times as long as wide and 2.2 times as long as pedicel. Pedicel 3 times as long as F1 and about 1.1 as long as F3.
| Fig. 1: | Aphytis alexandrina characteristic parts: (a) Male (M) and female (F) antennae (b) Mesosoma (c) Forewing (d) Midtibia and midtarsus (e) Ovipositor |
First funicular segment as long as wide, second one slightly broader than long while F3 2.75 as long as F1. Club 3 times as long as wide with 5 rhinaria.
Mesosoma: Mesoscutum (Fig. 1b) 1.21 times as long as scutellum with 10 fine and pale setae. Parapsis with 2 setae while axillae with 1seta; scutellum about as long as propodaeum with 4 setae and 2 punctures. Propodaeum about 1.73 times as long as metanotum, with 6 large overlapping crenulae.
Wings and legs: Forewing (Fig. 1c) hyaline, 2.79 times as long as wide, veins pale, marginal vein with 12 subequel setae, submarginal vein with 2 setae, 14 bullae, delta with 36 setae in 5 rows. Marginal fringe 0.16 as long as width of disk. Hind wing narrow, 7.5 times as long as wide. Basitarsus as long as midtibial spure. Midtibia (Fig. 1d) 2.14 as long as ovipositor sheath.
Gaster: Elongate, 1.5 times as long as mesosoma, ovipositor (Fig. 1e) long 1.71 as long as midtiba, 3.64 times as long as ovipositor sheath. Abdominal tergites 7 and 8 with 6 and 4 setae, respectively. Syntergum (terga 9+10) triangular in shape with 4 setae. Cerci button shape with 2 long and 2 short setae.
Allotype male: Essentially similar to female but shorter in length (0.79 mm) marginal vein with 10 setae. Antennal rhinaria 2.
The species under study is completely differ from all the closely related species in the colour of antennae, proportion of the length of the antennal club to its width, proportion of ovipositor and its sheath to middle tibia and the proportion of the fore wing length to its width. Also, the size of crenulae.
Remarks: Aphytis diaspidis and A. flavus were recorded on the same host scale, P. aspidistrae, by Abou-Elkhair (1999). These species are distinguished from each other by the strongly infuscated gaster tergites with distinct transverse cross-bands in the former species, in addition to the blackish apex of antennal club and mesoscutum with 15 or more setae. The latter species is completely yellow. Also, Aphytis hispanicus was recorded by Zamar and Claps (2003).
Etymology: The species is named for the location where the species was found.