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Effects of Gamma Irradiation on the Reproductive Organs of Melon Fly, Bactrocera Cucurbitae(coquillett)(diptera: Tephritidae)in Relation to Sterile Insect Release Method Sirm)

A. K. SAHA
Institute of Food and Radiation Biology, Atomic Energy Research Establishment, G.P.O. Box-3787, Dhaka

FARZANA YESMIN
Institute of Food and Radiation Biology, Atomic Energy Research Establishment, G.P.O. Box-3787, Dhaka

GUL NAHAR
Institute of Food and Radiation Biology, Atomic Energy Research Establishment, G.P.O. Box-3787, Dhaka

Abstract/ Executive Summary:

The melon fly, Bactrocera cucurbitae (Coquillett) pupae were exposed to gamma radiation (⁶⁰Co) at doses of 10, 20, 30, 40 and 50 Gy one day before this emergence. Dissection was made on 14 days old mature adults and significant changes were observed in the size and shape (length and breadth) of testis and ovary. Both parts of testis and ovary decreased gradually with the increase of radiation doses. Compared to control more than 50% reduction was recorded in testis at a dose of 50 Gy. Reduction in ovary size was much more prominent than that of testis. This investigation suggested that the reduction of testes and ovary could be used as an indicator of irradiation of trapped adults flies during the field release for Sterile Insect Technique (SIT).

Keywords: Radiation, Reproductive organs, Melon fly, Sterile insect

Location:

Start Date:

End Date:

Program Area: Pest Management

Commodity: Insects

Objectives:

The objective of this study was to determine: how much reduction occurred in testis and ovary of melon fly following different doses of gamma radiation in order to develop the methodology needed to determine the number of sterile flies trapped during SIT field application.

Methodology:

Eggs were collected from a laboratory colony of 14 days old flies (50 r x 50 E) that has been maintained at 25 ± 2°C temperature and 60 - 65% relative humidity. The eggs were then placed on artificial larval diet mixed with local ingredients for pupation. Pupae were collected after 7 days of egg collection and irradiated one day before their emergence with doses of 10, 20, 30, 40 and 50 Gy. Each group of pupae treated with different doses were maintained separately and waited for adult emergence. Adults were fed on artificial diet made of proteose peptone: sugar ( 1: 4) and water in conical flask soaked with cotton . At the age of 14 days the full grown treated male and female flies from each dose were dissected under a binocular microscope in saline solution (pH 6.8). The length and breadth of the testis and ovary from five males and females for each treatment were measured with a micrometer . Freshly dissected organs were photographed from a Nikon Phase-Contrast microscope and finally scanned. Due to the magnification problem, the microphotograph of untreated and 10 Gy treated ovary of female fly could not be taken.

Source of Information: J. Asiat. Soc. Bangladesh, Sci. 31(1): 21-30, June 2005

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

In B. cucurbitae, it appeared that eggs were not developed at dose level of 30 - 50 Gy. In the present study it was also observed that lower radiation exposures during a growth stage of melon fly had a greater impact on their reproductive fitness. Fluorescent powder marking of the released flies, which were later caught in traps, was not sufficiently reliable in field application of SIT. So, for the successful application of SIT, the reduction in size of testis and ovary can be used as a direct method for determining any fruit fly whether it is treated or wild after release in the field. It will also help to develop methodology needed to determine the sterility/ fertility of trapped unmarked adult

Knowledge Management: Journal