ISSN 2321-743X International Journal of Research in Engineering and Bioscience Volume 2 Issue 6 (Pages 79- 85) IJREB Journal home page: www.ijreb.org A SURVEY OF SEASONAL OCCURRENCE OF HOVERFLIES (DIPTERA: SYRPHIDAE) IN GORAKHPUR, U.P., INDIA Raina N. Samuel and I. J. Dass Department of Zoology, St. Andrew’s College, Gorakhpur- 273001, U. P. India ABSTRACT Adult syrphids are frequent flower visitors and pollinators of major significance. Larvae of subfamily Syrphinae are predacious and feed on soft-bodied aphididae which are considered to be the most important family of crop pests on a world scale. Syrphids are potentially good bioindicators as they inhabit wide range of habitat. This faunistic study of Gorakhpur Syrphidae presents 9 genera viz. Ischiodon scutellaris (Fabricius), Syrphus Sp., Eupeodes (Metasyrphus) Sp., Episyrphus balteatus (De Geer), Allograpta Sp., Sphaerophoria Sp., Betasyrphus Sp., Helophilus Sp. and Eristalinus Sp. KEYWORDS: syrphids, pollinators, Syrphidae. A SURVEY OF SEASONAL OCCURRENCE OF HOVERFLIES (DIPTERA: SYRPHIDAE) IN GORAKHPUR, U.P., INDIA - Raina N. Samuel and I. J. Dass 2014 Vol. 2 (Issue 6) Page 79 INTRODUCTION some 6,000 known species, placed into some Adults of the family Syrphidae, 300 distinctive groups (Thompson 2010). commonly called flower or hover flies, are The last revision of the Syrphidae species- rather conspicuous members of the terrestrial groups was done more than 60 years ago ecosystem. Their size ranges from 4 mm to (Hull 1949). Three subfamilies are currently over 25 mm and their coloration from bright recognized (Eristalinae, Microdontinae and yellow or orange to dull dark black or gray Syrphinae). with a few iridescent forms. Many syrphid flies are Batesian mimics of stinging Bigot (1892) published a catalogue of Hymenoptera. Flower flies, as their name the oriental Diptera, in which he listed the implies, are abundant on flowers, which are Indian syrphid flies. Keiser (1958) published used as mating sites and energy sources. notes on 56 species belonging to 18 genera of Only the microdontines are not found subfamily Eristalinae from Ceylon. Coe associated with flowers, but rather with their (1964) identified 127 species alongwith 28 ant hosts. new ones under 29 genera from Nepal. Patel (1969) described diagnostic characters of 13 The economic importance of flower species of syrphids from Gujrat (India). flies is great. Adults are pollinators of major Vockeroth (1969) revised 37 genera of the significance. In some agroecosystems tribe Syrphini of the world, giving their (orchards), they out-perform native bees in descriptions distribution and synonymy. pollinating crops (Thompson, 1998). Larvae Knutson et al. (1975) published the of the subfamily Syrphinae are predacious synonymic catalogue, which included 771 and feed on soft-bodied aphididae which are species under 84 genera from the Oriental considered to be the most important family of region. Ghorpade (1979) studied 13 species crop pests on a world scale (Van Enden, under five genera of the tribe Eristalini from 1972). India. Kapoor and Kohli (1985) collected and Syrphidae represents one of the identified 260 species under 63 genera and largest families of Diptera. Their widespread eight tribes from India. Datta and Chakraborti distribution, availability of excellent (1985, 1986a,b) identified 68 species of the taxonomic keys for species identification and family Syrphidae from various parts of India. differences in environmental requirements of Agarwal (1987) described nine species of larvae are features that promote Syrphidae as aphidophagus syrphids from the Northeast potentially good bioindicators. India. Kumar and Kapoor (1992) collected and identified 29 species giving descriptions Flower flies (Insecta, Diptera: Syrphidae), a large world-wide group of A SURVEY OF SEASONAL OCCURRENCE OF HOVERFLIES (DIPTERA: SYRPHIDAE) IN GORAKHPUR, U.P., INDIA - Raina N. Samuel and I. J. Dass 2014 Vol. 2 (Issue 6) Page 80 of the four new ones of the tribe Syrphini Gorakhpur lies between Lat. 26°13′N and from the East Punjab (India). 27°29′N and Long. 83°05′E and 83°56′E) between October, 2011 to March, 2012. This This paper presents, preliminary paper encompasses syrphid genera collected faunistic list of Syrphid fauna of Gorakhpur from 10 acre lush green college campus and includes 9 genera which is sampling of located in the heart of the city. The flowering the more abundant species that hover in this season in this part of the country starts in the area. month of November and lasts up to April, Diagnostic characteristics of syrphids reaching a peak in March. are as follows: With a few exceptions, In the present investigation traditional hoverflies are distinguished from other flies methods were employed for the collection of by a spurious vein, located parallel to the syrphids; hand nets and yellow water traps fourth longitudinal wing vein. Eyes holoptic were used for the adults and immature stages (touching above the antennae) in males, were collected by inspecting the aphid dichoptic in females (moderately or broadly infested plants. separated), but in some species, narrowly or broadly separated in males; and usually bare, RESULTS AND DISCUSSION but in some species with short sparse or Syrphids first appeared in the month dense hairs; Eyes usually unicolorous, but in of November and remained active till the mid some species with dark spots or markings. of April. The climate during the period of Vertex flat or slightly depressed; Ocellar study fluctuated a great deal, the months of triangle prominent with three ocelli. Legs October and November are moderately usually slender and simple but sometimes (in warm, sunny and almost not at all windy males) femur and/or tibia swollen; tibia, during these two months the adult syrphids tarsus flattened or dilated; hind coxa or were collected from the garden and sampled. trochanter sometimes with a minute spur or The months of December and January were spines. Abdomen varying in shape, usually quite cold and the last week of December and oval to suboval, elongate or petiolate in some first three weeks of January the weather was genera but never with bristles. The male bit hostile for the adult syrphids, but genitalia are almost always asymmetrical, immature stages were abundantly present usually twisted to the right. amidst the prey colonies. They were collected and brought in the laboratory and reared up STUDY AREA AND METHOD to maturity and then identified. The study was conducted in Gorakhpur, Uttar Pradesh (The district of A SURVEY OF SEASONAL OCCURRENCE OF HOVERFLIES (DIPTERA: SYRPHIDAE) IN GORAKHPUR, U.P., INDIA - Raina N. Samuel and I. J. Dass 2014 Vol. 2 (Issue 6) Page 81 List of syrphids collected is given in keys given by Vockeroth (1969). table. 1and identified as per the identification Table 1. List of syrphids collected S.N. Syrphid Sub Family Larval feeding Habit 1. Episyrphus balteatus (De Geer) Syrphinae aphidophagous 2. Syrphus Sp. Syrphinae aphidophagous 3. Betasyrphus Sp. Syrphinae aphidophagous 4. Ischiodon scutellaris (Fabricius) Syrphinae aphidophagous 5. Eupeodes (Metasyrphus) Sp. Syrphinae aphidophagous 6. Allograpta Sp. Syrphinae aphidophagous 7. Sphaerophoria Sp. Syrphinae aphidophagous 8. Helophilus Sp. Eristalinae Saprophagous 9. Eristalinus Sp. Eristalinae Saprophagous Subfamily Syrphinae sometimes with faint, dark, narrow median The larvae of this Subfamily are and submedian vittae; sides of scutum and all primarily aphid predators. Adults have bare of pleura usually slightly but distinctly humeri (postpronotal lobes), though these are yellowish- or greenish-grey pollinose. often hidden by the concave posterior of their close fitting heads. Betasyrphus Sp. (Plate – 1.iii) have Episyrphus balteatus (De Geer) face densely gray pollinose; eye densely and (Plate – 1. i) is a Batesian mimic ( harmless uniformely pilose; scutum black, with at most but closely resembling a dangerous or a poorly defined dull yellow pollinose lateral distasteful model ) in this case having the vitta; katepisternal pile patches separated appearance of a solitary wasp.It is just one of posteriorly; abdomen margined; metasternum a large number of hoverflies (family bare; metaepisternum bare; abdominal Syrphidae) with narrow bodies, and with maculae yellow or grayish, always very abdomens barred with black and yellow – densely pollinose though in this case the yellow tends towards Ischiodon scutellaris (Fabricius) orange. (Plate – 1. iv) Face in lateral view not Syrphus Sp. (Plate – 1. ii) Small to receding below to oral cavity. Eyes glabrous. medium sized, robust species with Antenna with segment 3 only twice as long mesonotum yellowish- or greyish-pollinose as broad. Abdomen flat or slightly convex laterally and tergites with transverse yellow dorsally; slightly, but distinctly margined on fasciae or pairs of maculae. Eye usually bare, tergites 2 to 5. Lateral mesonotal margin rarely sparsely or densely pilose. Scutum bright yellow, distinctly demarcated from shining or subshining, aeneous to black, dark dorsum. Lower lobe of squama bare A SURVEY OF SEASONAL OCCURRENCE OF HOVERFLIES (DIPTERA: SYRPHIDAE) IN GORAKHPUR, U.P., INDIA - Raina N. Samuel and I. J. Dass 2014 Vol. 2 (Issue 6) Page 82 above. Anterior flat portion of mesopleuron black or black and yellow flies. Occur in bare, with only microscopic hairs and not various situations. The "rat-tailed" larvae are with long hairs. Metasternum bare. found in accumulations of foul or stagnant Sternopleural hair patches separated