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Labelling and Banding Patiern of Polytene Chromosomes in the Melon Fly, Bactrocera Cucurbitae Coq. (diptera : Tephritidae)

Reza Md. Shajahan
IFRB, AERE, GPO Box 3787, Ganakbari, Savar, Dhaka, Bangladesh

Anwara Begum
Department of Zoology, University of Dhaka, Dhaka-1000, Bangladesh

Farzana Yesmin
IFRB, AERE, GPO Box 3787, Ganakbari, Savar, Dhaka, Bangladesh

Md. Hasanuzzaman
Department of Zoology, University of Dhaka, Dhaka-1000, Bangladesh

Abstract/ Executive Summary:

Larval salivary gland polytene chromosomes of the melon fly Bactrocera cucurbitae from laboratory reared stocks were observed. In the present study attempts were made to construct a diagrammatic sketch of the polytene chromosomes of this species. This species had five pairs of polytene chromosomes which were numbered 1-V according to their gross size. Several dark bands (ILB) and a group of dense bands (IRB) were found in chromosome I. Chromosome II was recognized by a compact dark band (IILA), three light bands (lIRA) and three successive pairs of dark bands (IIRB). Chromosome III was characterized by the presence of different bulbs and puffs in different regions. Chromosome IV possesses three successive dark bands (IVLA) and a swollen tip (IVRA). Chromosome V was recognized by different bulbs and puffs in the marker regions (VLA, VLB, VRB).

Keywords: Bactrocera cucurbitae, Polytene chromosomes, Salivary glands, Banding patterns

Location: Pest Control and Management Laboratory, IFRB, AERE, Savar, Dhaka and Department of Zoology, University of Dhaka, Bangladesh

Start Date:

End Date:

Program Area: Pest Management

Commodity: Insects

Objectives:

In this investigation, the polytene chromosomes from the larval salivary glands are diagrammatically analysed to provide some basic cytogenetic data of Bactrocera cucurbitae.

Methodology:

Fly stocks - Bactrocera cucurbitae larvae, orginating from laboratory reared stock, were obtained from Pest Control and Management Laboratory, IFRB, AERE, Savar, Dhaka. The flies were reared on sugar-yeast-casein hydrolysate diet (2 : 1: 1) and 1% agar gel. Polytene chromosome preparations were made following the method of Zacharopoulou and Mavragani-Tsipidou et al. Larvae (5 - 6 days) were dissected in insect Ringer's solution and the salivary gland was first transferred to 45% acetic-acid followed by fixation in 3N HCl for 3 - 5 min. These tissues were transferred to lacto-acetic-acid (80% lactic acid - 60% acetic acid, 1 : 2) for approximately 5 min and stained in lacto-aceto-orcein for about 30 min. Excess stain was removed by washing the tissue three or four times in a drop of lacto-acetic acid before squashing. A Nikon phase-constrast microscope was used to examine the polytene chromosome preparations and sketches were drawn by visual inspection under 500 X. The salivary gland chromosomes were numbered from I to V according to their gross size, however emphasis was given on the banding pattern and landmarks. The chromosomes were labelled following the system proposed by Zacharopoulou. This labelling is arbitrary. In each polytene chromosome the long arm is designated as the left arm (L) and the short as the right arm (R).

Source of Information: Dhaka Univ. J. Bioi. Sci. 9( 2): 211-215, 2000 (July), ISSN 1021-2484

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Salivary glands of Bactrocera cucurbitae were found to possess ten long chromosome arms. Each arm of each chromosome showed diagnostic characteristics by the appearance of specific bands. The banding pattern in salivary gland polytene chromosomes of Dacus olecut is quite different from that of larval fat body cells. The differences are so great that even the chromosome tips cannot be matched . However, fat body tissues maintain many lipid droplets which make it difficult for further cytogenetic research on thia species.

Knowledge Management: Journal