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Intrinsic Rate of Increase (rm) of Aphis Gossypii Glover Infesting Brinjal Plants

Md Matiur Rahman
Institute of Biological Sciences, University of Rajshahi, Rajshahi-6205, Bangladesh

Pankoj Kumar Sarker
Institute of Biological Sciences, University of Rajshahi, Rajshahi-6205, Bangladesh

Bidhan Chandra Das
Department of Zoology, University of Rajshahi, Rajshahi 6205, Bangladesh

Abstract/ Executive Summary:

Context: Intrinsic rate of natural increase (rm) of Aphis gossypii is important factor to know the actual increase of population which is governed by physical factors of environment. Objectives: The aims of this study were to determine the intrinsic rate of natural increase (rm) of A. gossypii which is the basic knowledge of IPM program. Materials and Methods: The nymphal duration, pre-reproductive period, reproductive period, fecundity, longevity, etc. were observed within the glass chimneys. The newly born nymphs were considered as F1 generations. Similarly, the first progeny of F1 generation were released in other glass chimneys to have F2 generation. In this way, F3, F4 and F5 generations were obtained. Data for duration between birth of a nymph and its first laid progeny (d) and number of progeny (Md) per female were recorded. Altogether data of 8 replications were considered for the calculation of intrinsic rate of natural increase (rm) of A. gossypii infesting brinjal plants. Results: Intrinsic rate of natural increase (rm) value was highest (0.322 ± 0.005) for the F1 generation, followed by F2 (0.317 ± 0.003) and it was lowest (0.303 ± 0.002) for F5 generation. Temperature influenced the rm significantly (r= 0.903, p<0.05). Dew point also influenced the rm of A. gossypii significantly (0.882 P<0.05). Relative humidity played insignificant role (r= 0.428) on the rm of A. gossypii. Conclusion: The results obtained in this study are essential to know the actual populations increase which important to pest control.

Keywords: Aphis gossypii, Brinjal, Intrinsic rate of increase.

Location: Research fields of the Institute of Biological Sciences, University of Rajshahi

Start Date:

End Date:

Program Area: Pest Management

Commodity: Brinjal

Objectives:

The aims of this study were to determine the intrinsic rate of natural increase (rm) of A. gossypii which is the basic knowledge of IPM program.

Methodology:

Experimental design: Experiments were carried out at the research fields of the Institute of Biological Sciences, University of Rajshahi. Forty earthen tubs (40 cm height and 40 cm diameter) were prepared by soil and bio-fertilizer for planting healthy brinjal seedling (variety shingnath). Five tubs with plants were enclosed by fine nylon mosquito nets which served as experimental plants for the aphids. Adult A. gossypii (apterous) were collected from the nearest fields and were released on the experimental plants. In order to record the data for life cycle of A. gossypii the methodology of Das and Chakrabarti (1985) was followed with some modifications. Special type of detachable platforms were made by the hard board and set below the twigs or leaves of the experimental plants. For each platform, tetrapods were made according to the required heights of the plants. Adhesive tapes were used to keep the twig / leaf on the centre of hard board. Glass chimneys were placed on the hardboard so that a micro-chamber around the twig/leaf was created. The open top of each glass chimney was enclosed temporarily by a piece of fine cloth to protect from the entry of unwanted insects. Only one female A. gossypii was released in each chimney. All the observations, viz. the nymphal duration, pre-reproductive period, reproductive period, fecundity, longevity, etc. were recorded from the aphids reared within the glass chimneys. Accordingly, to record the instarwise duration about 30 apterous females were kept within 30 glass chimneys. The experiments were repeated five times. Calculation of intrinsic rate of natural increase (rm): Wyatt and White (1977) postulated an equation for the calculation of intrinsic rate of natural increase (rm) for aphids. In the present study rm was calculated according to the equation: rm = c(loge Md)/d, where, c = correcting constant, d = duration between birth of a nymph, and its first laid progeny, Md =number of progeny produced in an equal time. The numbers of progeny (Md) were considered until the parent aphids were 2 days old. Correcting constant (c) is 0.735 (Wyatt and White 1977). Altogether data of 8 replications were considered for the calculation of intrinsic rate of natural increase (rm) of A. gossypii infesting brinjal plants.Temperature, relative humidity and dew point were recorded regularly from the Meteorology Station, Rajshahi.

Source of Information: J. bio-sci. 17: 123-127, 2009 ISSN 1023-8654

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The results obtained in this study are essential to know the actual populations increase which important to pest control.

Knowledge Management: Journal