Taxonomic Analysis of Gastropod Snail Occurrence in Agroecosystems
Abstract
Gastropods have a very important position in our ecosystem as pest, intermediate host, food source and as bioindicators for environmental quality but the taxonomic work regarding snail species has not been carried out in this part of the world after 19th century. Total 19290 snails were collected from agro ecosystem of Faisalabad for their taxonomic characterization. The identification of the specimens was made on the basis of number of whorls, coiling of the shell, umbilicus, shape, colour, shape of the aperture, presence or absence of operculum, height (mm), diameter (mm) and the diameter of the aperture (mm) using vernier caliper. Microscopic identification was done by using recent identification keys and diagrammatic description provided in them. We found snails belonging to 2 orders 7 families 9 genera and 15 species. This is a baseline study to get the basic information about the malacofaunna of Faisalabad which will be important in various applied fields. However, new sibling species might be proposed of Zooctecus insularis after molecular characterization.
Introduction
Land snails are generally considered as typical herbivores, fungivores and detrivores (Burch and Pearce, 1990) that show intraspecific competition at weak levels (Cain, 1983, Barker and May hill, 1999). Annual litter input of about 0.5% per year can be consumed by land snail communities (Mason, 1970). They are designated as serious pests of ripening fruits i.e. tomatoes and strawberries as they are grown near the ground. However, they also depend on foliage and fruit of some trees like citrus (Flint, 2003).
It has an important position in the food webs of different ecosystems as snails are mostly consumed by fish, water fowl, crayfish, leeches and sciomyzid flies (SWCSMH, 2006). Most of the studies on the land snails have been carried out approximately a century before in the Indian subcontinent. Hutton (1842) collected and studied the land snails of neighborhood of Bolan pass, from Suliman range and the hills of south laying west to Indus. According to the Blanford and Godwin (1908), in the areas of Saw at, Dir or Chitral no terrestrial snails have been observed except Petraeus snails, while in the Kuram valley only very few species were found. They worked chiefly on the conchological side of the families Testacellidae and Zonitidae of Indian subcontinent.
Pokryszko et al. (2009) collected 3500 dry shells and described 22 species out of which 12 were new species from 77 localities. The specimens were preserved in alcohol. The shell variations in most species were described and nine species were illustrated with Figs of detailed reproductive system. In the Northern area of Pakistan there is highest diversity of Pupilliods due to wetter climate and wider altitudinal range. Ten out of twenty two species were considered to be endemic to Pakistan, while the distribution of the rest of species was extended to other regions i.e. Asia, Europe and Holarctic.
Pupilloid fauna showed great diversity of Palaearctic/Holarctic influence on general. Recently researches have been conducted on the biodiversity of soil macro inverteberate in the low and high input fields of wheat and sugarcane in District Faisalabad (Rana, 2012; Siddiqui, 2005) with the major focus on impact of chemical on the diversity of different macroinverteberates. Rana (2000) studied the ecological distribution of earthworm species along some water bodies in the agro ecosystem of Faisalabad Division. Khanum (2010) studied the taxonomy of the plant nematodes of sugarcane fields.
Very less work has been done with reference to the taxonomy and ecology of snails in the agro ecosystem. Previously Ali (2005), Altaf (2006) and Rahman (2011) have attempted to study the diversity of snails in agro ecosystem of Faisalabad which has augmented the previous information of the malacofaunna in Faisalabad. The work of the Ali (2005) and Altaf, (2006) was just about the sugarcane fields and wheat fields near Gutti village area; however Rahman (2011) covered only few villages of Faisalabad focusing only one family of snails. The diversity index was found highly significant in agricultural fields however the results were non-significant in case of ditches. It can be concluded that due to environmental degradation and water pollution the snail diversity is non significant, in ditches however in the agro ecosystem it is a pest (Altaf et al. 2016).
This study is focuses mainly on the taxonomic account of the different species found in the agro ecosystem of Faisalabad, Pakistan.
Source : Taxonomic Analysis of Gastropod Snail Occurrence in Agroecosystems | InformativeBD
