Key for Identification of Adult Female of Scirtothrips dorsalis (Thysanoptera: Thripidae) Based on External Morphology

Thrips are minute insects and belong to the family thripidae of the order Thysanoptera. Thrips are less than two millimeters long, slender like and agile insects. Head of Scirtothrips dorsalis is pale in colour longer than broad, 217.5-237 μm long and 175-194 μm wide across the eyes. Eyes are redish in colour, 75-89 μm long and 63-70 μm wide at the middle and three occili are arranged triangular manner. Measurements of individual antennal segment length (width)are as follows18(25), 34(28), 50(25), 56(21), 46(21), 43(21), 37(20) and 25(12). Wings are well developed, devoid of microtrichia, veins and setae. The abdomen is long, narrow and tapering into a tubular structure and measures 1.45 mm in length and 0.370-0.385 mm in width at its maximum. Key word: Chilli thrips Morphology Antennae Abdomen INTRODUCTION nature of damage caused [7] while [8] studied it on Castor, Scirtothrips dorsalis is a cosmopolitan distribution stages. The effects of abiotic factors studied on and it found all over India. It has been reported as an development of the chilli thrips [9]. important pest on tea plant in Assam, so it is also called Classification of order thysanoptera is given based as yellow tea thrips. Scirtothrips dorsalis is a major pest on the assumption of close relationship between of peanuts in India. Severe infestations of chilli thrips can Thripidae and Phlaeothripidae [10]. Chilli thrips is a vector result in total defoliation. The damage of cashew, tea, of the bud necrosis virus of groundnut [11]. chilli, cotton, tomato, mango, castor, bean, tamarind and grape by Scirtothrips dorsalis, is given by [1]. MATERIALS AND METHODS Thrips word derived from a Greek, means woodworm, thrips also referred to as “Fringed wing insects, Bladder For the present experimental study, Scirtothrips footed insects, Storm flies and Thunder flies.” Adults dorsalis were collected from Dahlia hybrida and Rosa have two pairs of narrow fringed wings with long hairs; indica plant of Motilal Nehru Park, Near Taj Mahal, Agra they readily fly and can easily migrate into and around the and after that, they transferred to the laboratory, preserve green houses. Insects of the order thysanoptera have and reared to develop colonies for experimental works. peculiar, pearsing and sucking type of mouthparts with Thrips collection trays are made-up of stiff cardboard of vestigial right mandible, protursible bladder like structure about 30x25cm, having one white and other black surface, at the apex of tarsae of leg. which could be used as need. The tray held under a Thrips received rather delayed recognition, in flowering branch, which was shacked to dislodge thrips. comparison to large sized insects. DeGeer was the first Transparent glass jars of various sizes (10x10, 12x10 and who described thysanopteron insects for the first time as 15x10cm) having screw type neck and cap were also used ‘Physapus’ [2]. Some researchers gave the keys for the to collect plant parts with thrips as thrips remained alive identification of the genera of the order thysanoptera for a longer period in such container as compared to [3 and 4] while some studied on external morphology, pouch container. Adult of thrips species required for distribution and host-plants of the pest species morphological studies were brought to the laboratory Scirtothrips [5 and 6]. The life history of Scirtothrips and properly fixed and preserved. The preserved dorsalis Hood is studied on chilli crops and assessed the materials were also stored for mounting at later in Delhi and described detailed structure of immature World Appl. Sci. J., 9 (12): 1430-1432, 201