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Orthopteran Diversity at Keraniganj, Dhaka

Mahmuda Aktar
Department of Zoology, Jagannath University, Dhaka-1100, Bangladesh

Md. Aminul Islam
Department of Zoology, University of Dhaka, Dhaka-1000, Bangladesh.

Md. Abdul Alim
Department of Zoology, Jagannath University, Dhaka-1100, Bangladesh

Abstract/ Executive Summary:

This study was conducted to assess the divesity of Orthopteran species at some grasslands and crop fields of Keranigonj upazila in Dhaka district, Bangladesh from April, 2014 to September, 2014. A total of 20 species under 18 genera belonging to 7 families have been recorded. Among them 4 species were more common, 6 species were moderately distributed and 10 species documented as rare. The highest number of Orthopterans was from the family Acrididae 60.58% (10 spp.) followed by Tetrigidae 15.32% (2 spp.), Gryllidae 14.23% (4 spp.), Tettigonidae 10.33% (1 sp.), Locustidae 2.55% (1 sp.), Mantidae 2.55% ( 1 sp.), and the lowest from the family Gryllotalpidae 2.19% (1 sp.). During observation period the number of Orthopterans was highest recorded in the month of May (20.44%) followed by April (19.34%), June (17.52%), July (14.60%), August (14.23%), and the lowest in September (13.87%). Shannon’s diversity index and Simpson’s diversity index represent moderate value (H = 2.82) and moderately low value (λ = 0.07), respectively indicating moderate diversity richness for Orthopteran species. The value of species evenness (E = 0.94) tends to be higher indicating that the species are eventually distributed.

Keywords: Orthopteara, Diversity, Abundance, Acrididae, Shannon’s index, Simpson’s index, Evenness

Location: Keraniganj in Dhaka district, Bangladesh

Start Date: 00-04-2014

End Date: 00-09-2014

Program Area: Pest Management

Commodity: Insects

Objectives:

To assess the divesity of Orthopteran species at some grasslands and crop fields of Keranigonj upazila in Dhaka district, Bangladesh from April, 2014 to September, 2014.

Methodology:

Study site: The study was conducted in different grasslands and crop fields at Keraniganj in Dhaka district. Geographically the area Keraniganj Upazila is 166.87 sq km, located in between 23°37´ and 23°47´ North latitudes and in between 90°13´ and 90°29´ East longitudes. Materials: Sweep net, collecting jar and polythene bag, cotton, ethyl acetate, a pair of forceps and needle, camera (Canon), magnifying glass, envelopes, permanent ink pen and label paper were used. Samplings and identification: Sampling of the Orthopterans was carried out one day per week from April, 2014 to September, 2014. Sampling was executed from 7.00 a.m. to 2.00 p.m. where Orthopterans were directly collected by hand and sweep net. After collection, insects were kept into a plastic jar that contained cotton soaked in ethyl acetate. The Orthopterans were stretched and pinned then oven dried at 60ºC for 48 hrs in laboratory. Afterwards preservation, the samples were set in wooden boxes (Thakkar et al. 2015). Identification of Orthopterans was performed using the keys developed and followed by Capinera et al. (2004), Uvarov (1921), Kirk and Bomar (2005). Simpson index of diversity (1 - λ ): The probability that two randomly selected individuals in a community belong to different categories e.g. species. Simpson reciprocal index (1/ λ ): The number of equally common categories e.g. species that will produce the observed Simpson's index. Species evenness (E) = H / In(S); S is Total Number Species.

Source of Information: Bangladesh J. Zool. 46(1): 21-31, 2018 ISSN: 0304-9027 (print) 2408-8455 (online)

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

The present study is a work of six months which deals with the taxonomy, distribution and abundance of Orthoptera. This is the first report from Keranigonj as no notable work has been done on this aspect. Most approach for estimating species richness is based on extrapolation from known species accumulation curve, describes species richness in a local homogeneous assemblages as a function of sampling effort. In the present study the species accumulation curve could not attain asymptote after six sampling in six months indicated that most of the probable species have not been encountered during the inventorying process. Better understanding of the abundance, species richness and seasonal composition of Orthopteran communities has been achieved in this investigation, which should be very useful for improving predictive models and developing management guidelines for their control. A long term study is needed to observe the species occurrence in all seasons and their interaction with the environmental changes in order to get better and comprehensive information. However, this study will definitely add more information to the existing knowledge of entomology in Bangladesh.

Knowledge Management: Journal