First record and description of two species of genus Scaeva Fabricius (Diptera: Syrphidae) from Balochistan, Pakistan

The current study was continued from March 2016 to April 2017. The specimens of the genus Scaeva Fabricius were collected from different localities of Balochistan. Two species Scaeva albomaculata Macquart and Scaeva selenitica Meigen were identified and described. Saeva albomaculata Macquart is first time recorded from Balochistan province of Pakistan and Scaeva selenitica Meigen is new country record. These species were identified on the bases of morphological characteristics, body coloration, male and female genitalia. The identification and description of these new records will serve as an important contribution in the insect fauna of Balochistan and Pakistan. Furthermore both the identified species are aphidophagous on serious pests of various crops so these can be used for the biological control of various pests.


Introduction
Family Syrphidae is a one of the largest families of the order Diptera with more than 6000 described species all over the world [1,2].This family comprises the three subfamilies, Syrphinae, Eristalinae and Microdontinae.Majority of larvae of syrphinae are polyphagous predators of a broad range of soft-bodied arthropods, such as lepidopteran, coleopteran larvae, mites, hemipterans and thrips (e.g., coccids, whiteflies, psyllids and mainly aphids) being the preferred prey [3,4].The genera, Scaeva, Syrphus, Sphaerophoria and Baccha are rapacious predators of aphids and others soft bodied insects.Thus they can play an important role as a biocontrol agents for the suppression of the pest on various crops [5][6][7][8].Genus Scaeva Fabricius of the sub family syrphinae is one of the genera having largest size species.Species of Scaeva are beneficial because their larvae are aphidophagous and adults are pollinator of various types of crops, vegetables, ornamental flowers and fruit trees.Species of genus Scaeva possess yellow stripes and black bars on the abdomen, resembling bees or wasps like shape.Adults often hover over the flowers and feed on nectar and pollen

Materials and methods
A total of 241 specimens of genus Scaeva Fabricius were collected from various crops such as wheat, barley, Brassica spp: ornamental flowers and as well as weeds from Balochistan, Pakistan during March 2016 to April 2017.The two species of genus Scaeva albameculata.Macquarat and Scaeva selenitica Meigen were identified by using standard keys [30-32].The terminology followed of [33].For the observation of male and female genitalia, tip of abdomen boiled in 10% potassium hydroxide (KOH) solution for 6-8 minutes then removed the genital capsule by using needle and forceps.Dissected the genital capsule under dissecting binocular microscope by the help of a pair of fine needles.Dissected materials were conserved in micro vial cavity plate with a few drops of glycerin.Measurement of different body parts taken with the micro millimeter and illustration drawn by using the ocular graph.The terminology used for the external and internal morphology of female genitalia was adopted from [34] and the method of exposing male genitalia was adopted from [31].(2002).Head Head box shape on top view, eyes dark brown, small with pale dense hairs; head broader than thorax; vertex triangular very narrow, ground color black; frons inflated, yellow and dense black hairs stripe on front, black hairs small than male hairs, below small white hairs present; occiput broad silvery or white, white hairs on margin; antennae thumb like structure, dorsal side black, ventral side orange, 3 rd segment long, few black hairs on margin, 1 st and 2 nd segment orange, 1 st segment longer than 2 nd , aristae yellow or orange; face inflated, thin black stripe present on middle area,) yellow, covered with white or pale hairs; female eyes separated, mouth margin yellow and male eyes fused.Thorax Thorax narrower than head, covered with thin yellow hairs, thoracic dorsum glossy and bluish-black; humeri bare slightly raised and black; thoracic pleura covered by long yellow hairs, yellow pleural thorax stripe broken; scutellum raised, semicircular, yellow, scutellar marginal bristles long yellow, central area bare; female pleural thorax stripe thicker than male.Wing Transparent, spurious vein pale, reach near outer cross vein; vein R4+5 more dipped in cell r5; m second basal cell without microtrechia; cell r3, cell r5 covered with tiny microtrachia; stigma yellow; squama small, white, densely covered by mirotrechia; alula entirely covered with microtrachia; halter club shape and yellow color.

Abdomen
Abdomen broader than thorax, elongated, oblique yellow marking on tergites 3 and 4, middle region broad; half lateral marginal part covered with yellow hairs, dorsal surface covered with pale hairs; on sternite 2, 3 and 4 possess black or brown patch, entire sternites covered with long pale hairs; female abdomen oval shape, wider than male; black patch on sternite 2, 3 and 4 broader than male.Legs Half femur swollen, swollen part black, covered with white hairs, front coxa and trochanter black, tibia and metatarsus yellow brown band covered with small white hairs; middle legs similar shape to front legs; hind coxa, trochanter black, femur slightly swollen black, tip of femur yellow, covered with white hairs.Male genitalia (Figure 4A to D) Genital capsule, brown 0. 9 mm length; epandrium, dark brown, inflamed; pair of cerci rod shape, large 0.5mm length, located above epandrium, yellow with orange hairs, black spots; systilus elongated 0.5mm length, yellow, curve, covered with pale hairs; hypandrium 0.8mm length, dark brown, smaller than epandrium, claspers with yellow hairs, small finger like shape; aedegus small 0.3mm length and pale color.Female genitalia (Figure 4E to F) Segment 10 transparent with tiny black spots, external genitalia broad and dwarf, 0.5 mm length; cerci glob shape, 0.3mm length, whitish yellow with minute spots and yellow hairs; post genital (sub anal) plate wide, length small 0. 2mm length, vault shape and covered by black spots.

Abdomen
Abdomen broad than thorax, tergite 3 rd and 4 th with yellow common like bars, lateral margin 1 st and 2 nd tirgite covered with long pale hairs; abdomen dorsal surface covered with black and gray hairs; lateral margin 3, 4 and 5 tergite covered with small black hairs; sternite covered with gray hairs and black spots on 2 nd sternite.

Legs
Half front femur black, black part swollen and yellow part slender, coxa, trochanter with long hairs on black part, tibia and tarsus covered with minute hairs; middle and hind femur slightly swollen.Male genitalia (Figure 7A to E) Genital capsule large 1. 2mm length, brown; epandrium, dark brown raised; pair of cerci slender, elongated, 0.3mm length, located on epandrium, rod shape, yellow with orange hairs and black spots; systilus broad, 0.6mm length, covered with pale and black bristles, brown; hypandrium broad 1.0 mm length, smaller than epandrium, dark brown, with orange hairs; aedegus tube shape, small 0.4mm length, bright yellow color.Female genitalia (Figure 7F) Segment 10 transparent covered with minute black spots; external genitalia broader but dwarf length, 0.6 mm length; cerci small and round, 0.1mm length, pale with minute spots and yellow hairs; post genital (sub anal) plate wide, length small 0. 2mm length, vault shape, covered with black spots.

Comparative note
Scaeva selenitica Meigen is related with Scaeva dignota having eyes hairy, male terminalia very same structure in both species but differ on the bases of face narrower, ocular hairs minute, anterior angle of eyes narrow, frons slightly raised on middle area.Yellow comma like bars present on tergite 3    Different researchers have adopted various methods for the description of specific characteristics of hoverflies species e.g.male genetilia [31], female genetilia [34] and morphological characteristics but our method includes all the methods i.e. male and female (external and internal) genetilia, body measurements and morphological characteristics.Sum of all these criteria ensures the exact identification of said species and leaves no ambiguity.The identification and description of these new records is an important contribution in the insect fauna of Balochistan and Pakistan.Both the identified species are aphidophagous on serious pests of various crops so these can be used for the biological control of various pests

Conclusion
We have reported two species Scaeva albomaculata Macquart and Scaeva selenitica Meigen for three first time from Balochistan.
The identification and description of these new records will serve as an important contribution in the insect fauna of Balochistan and Pakistan.

Figure 1 .
Figure 1.Map of Balochistan showing the study area

Table 1 & 3) Synonyms
Scaeva albomaculata Macquarta is closely related with Scaeva pyrastri Linnaeus glossy black thoracic dorsum, oblique bars on tergites 2 to 4, pleura yellow with hairs and differ on the base of thoracic pleura with well-developed yellow stripe and broad oblique bars on tergite 2 to 4 in S. albomaculata Macquarta.Thoracic pleuran with narrow yellow stripe, tergites 3 and 4 have comma like oblique bars S. pyrastri Linnaeus.

Table 1 . Measurement of different body parts of Scaeva albomaculata Macquart
Scaeva selenitica Meigen was not reported from any region of Pakistan, authors first time recorded it from Balochistan, Pakistan.