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ISSN 1811-0231 / ISEIS Publication Series Number P002

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  Paper EIA06-001, Volume 4 (2006), Pages 1-25 = complimentary

The Structure and Host Plant Selection of an Acridid Community on the Edge Between a Desert and an Agro-Ecosystem in Egypt

M. M. El Shazly* and W. M. El Sayed Shahpa

Entomology department, Faculty of Science, Cairo University, Giza-12211-Egypt. *Corresponding author: mohamedmelshazly@hotmail.com.

 

Abstract

It is generally accepted that insects play a major role in both energy flow and the regulation of plant communities in terrestrial ecosystems. In the present work, a field study was conducted for three years, extended from June, 1999 to May, 2002, in the boundaries between cultivated lands and the natural ecosystem of the western desert at Abu-Rauwash district, Giza-Egypt. To assess the temporal structure and the host plant selection of the acridid community, a sampling area consisted of 100 transects, each one with 100 m length and 2 m width, was visited weekly for sampling grasshopper and plant specimens. At the community level, the study revealed that the most common grasshopper species were Acrida pellucida, Aiolopus thalassinus, (Acridinae); Acrotylus insubricus, Sphingonotus carinatus (Oedipodinae); Chrotogonus lugubris and Pyrgomorpha conica (Pyrgomorphinae). These species responded in different ways to the changes in environmental conditions. The extent of fluctuations in the relative abundance varied among them. Dominant degree test (D %) revealed that A. thalassinus was the most common acridid species, whereas S. carinatus was the least one. The six co-existing species acquired random distribution pattern as indicated by Taylor's coefficient of aggregation. Application of diversity indices revealed that species richness was fairly poor and fluctuated with time. The selection of the food plant by the six coexisting species was determined through the gut contents analysis technique. A total of 53 cultivated and wild plant species were found in fragmentary condition in the guts of different grasshopper species. Wild plants constituted the bulk (31 species) of the floral richness in the guts of the acridid species. The diet breadth (B) was determined for each acridid species. Kulczynski similarity index (KSI) and Grass-forb index (GFI) were applied to the obtained results. The possible impact of the grasshopper, as a selecting force, on the plants was discussed.


Keywords: acridids, population dynamic, community, host-plant selection, desert- and agro-ecosystem

 

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