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Effect of Steroid Hormone (ecdysone) on the Pupal and Larval Developments of Tribolium Castaneum (herbst)

Dipali Rani Das
Department of Zoology, Rajshahi University, Rajshahi 6205, Bangladesh

S. I. Faruki
Department of Zoology, Rajshahi University, Rajshahi 6205, Bangladesh

A.M. Saleh Reza
Department of Zoology, Rajshahi University, Rajshahi 6205, Bangladesh

Selina Parween
Department of Zoology, Rajshahi University, Rajshahi 6205, Bangladesh

Abstract/ Executive Summary:

Ecdysone is a steroid hormone especially found in insects and mammals. One day old pupae of Tribolium castaneum were exposed to crude ecdysone at different concentrations of 10, 20, 40, 80, 160, and 320 μl/kg of whole wheat flour each for 1, 3 and 5 days. Adult recovery was significantly reduced in the treated pupae (F=3.47, P<0.01, df=7), and produced deformed individuals (F=39.29, P<0.001, df=7) at all exposure periods. The developmental time was similar in both the treated and untreated ones. The latent effect of the ecdysone treatment increased both the larval (F=4.26, P<0.001, df=7) and pupal (F=8.56, P<0.001, df=7) periods of the progeny reared on untreated foods. Similarly, the latent effect hampered recovery of the adult progeny (F=7.79, P<0.001, df=7) producing deformed individuals (F=2.65, P<0.05, df=7).

Keywords: Ecdysone, T. castaneum, Developmental period, Adult recovery.

Location: Department of Zoology, Rajshahi University, Rajshahi

Start Date:

End Date:

Program Area: Pest Management

Commodity: Insecticide

Objectives:

The present research was aimed at to assess the direct and latent effects of crude ecdysone on their developments and metamorphoses in the next (F1) generations when the pupae of red flour beetle, Tribolium castaneum (Herbst) were exposed to treated foods.

Methodology:

Insect used: The laboratory strain of Tribolium castaneum was used for this experiment as a model insect which is also a major pest of a variety of stored products throughout the world. Ecdysone: Crude ecdysone was used at concentrations of 10, 20, 40, 80, 160, 320 and 640μl. Each of these quantities of ecdysone was taken by a micro pipette, mixed with 10 ml of acetone. This mixture was then mixed thoroughly with 1 kilogram of flour by using an electric blender. The treated flour kept uncovered at room temperature for evaporation of the acetone. Experimentation: Adults of T. castaneum from the stock culture were collected and subcultures were established on sterilized whole wheat flour at 30+1^OC in an incubator without controlling light and humidity. From these subcultures, 1-day old pupae were collected for the experiment. The collected pupae were sexed according to Halstead (1963). Male and female pupae were exposed to the ecdysone-treated flour separately until adult emergence. Experiment I: Twenty 1-day old pupae of both the sexes were used separately for each concentration of ecdysone. The pupae were exposed to treated flour for 1, 3 and 5 consecutive days. After exposure, the treated pupae were kept separately according to ecdysone concentration, sex and exposure period in glass Petri dishes (6 cm diameter) at room temperature (15-17 ^OC) up to adult emergence. For Control batch, 20 male and 20 female pupae were kept in untreated flour up to five days. After five days all the pupae of treated and untreated batches were replaced in other set of Petri dishes without food at the same temperature. The experiment was replicated three times. The pupal period, percentage of adult recovery and number of deformed individuals were recorded for the treated (each concentration and exposure levels) and the untreated ones. Experiment II: From the experiment I, 10-day old male and female adults were collected from each concentration of hormone treatment and for each exposure period. Five pairs of adults were allowed to mate for four days on untreated flour in Petri dish. The adults were then removed. The eggs in the flour were kept for 10 days and the live larvae thus obtained were replaced in a new Petri dish with fresh untreated flour. After each five day, the flour medium was changed by fresh one to avoid conditioning. Larvae were carefully checked until they pupated. The larval period was noted and the pupal recovery (%) was determined. The pupae were removed from flour and kept for adult eclosion. The pupal period was recorded along with adult recovery (%). Number of deformed individuals was also recorded. Five pairs of adult were introduced into the untreated control batch under the same condition and termed as Control. All the experiments using treated and untreated T. castaneum, were replicated three times and conducted at room temperature (15-17^OC) and relative humidity (average 70%). The direct and latent effects of ecdysone treatment at different levels of concentration and exposure periods were compared to the Control by Analysis of Variance (ANOVA). The effectiveness of each concentration of ecdysone was analysed by Tukey's Test of Multiple Comparisons (1953).

Source of Information: Bangladesh J. Sci. Ind. Res. 45(1), 63-68, 2010

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The present results state that ecdysone treatment to immature stages of T. castaneum could hamper their normal metamorphoses. Higher ecdysone titre in pupae would normally enhance adult emergence but in this experiment due to abnormal metamorphosis the percentage of viable adults were reduced not only in the parental generation but in the following generation also. More research work is needed by allowing different ages of immature stages of different coleopteran pests of the stored products to ecdysone. The effectiveness of ecdysone as a ecofreindly agent that might be used in the management of the coleopteran insect pests in the storage ecosystem.

Knowledge Management: Journal