Journal of Entomology

Year: 2008 | Volume: 5 | Issue: 6 | Page No.: 334-355
DOI: 10.3923/je.2008.334.355

Pictorial Keys of Chironomid Species (Order: Diptera) in El-Tall El-Keber Wastewater Treatment Plant, Egypt

R. Saleh-Ahmed, F.M. Ismail, A. Abo-Ghalia and N.S. El-Shenawy

Abstract: In the present study, pictorial keys are given for the identification of larvae, pupae and adults of chironomid species collected from El-Tall El-Keber wastewater treatment plant, Egypt. Two genera: Chironomus Meigen and Kiefferulus Goetghbuer and six species: C. calipterus Kieffer, C. formosipennis Kieffer, C. caffrarius Kieffer, C. imicola Kieffer, C. seydeli Goetghebuer and K. brevibucca (Kieffer) are recorded from this region for the first time. Outline drawings of the representatives of each genus were presented.

Keywords: Chironomidae, keys, wastewater treatment plant and Egypt

INTRODUCTION

The Chironomidae, known popularly as non-biting midges are considered the most widely distributed and abundant family of aquatic insects (Mousavi et al., 2003). Adult chironomids are most evident when forming conspicuous swarms, hovering over bushes, trees or other proud markers, before dusk on summer days. The developmental stages of Chironomidae are typically aquatic and benthic. Larvae often represent a major component of the multi-plate fauna in all types of waters and are used frequently as bio-indicators of ecosystem health. Also, they are playing an important role in detritus processing and food chains (Garcia and Suárez, 2007).

The country of Egypt, although important for its location, serving as a corridor between the Palaearctic and the Afro tropical regions, presently offers little knowledge of its chironomids fauna. The most old publications (Kieffer, 1925; Freeman, 1958; Steyscal and El-Bialy, 1967) are now outdated. While the present knowledge of taxonomy, ecology and biology of the Egyptian chironomid fauna remain limited, there are efforts to remedy the situation (Zalat et al., 1992; Ghonaim et al., 2001a, b, 2004, 2005a, b). The purpose of the present study is to add some knowledge on the taxonomy of this family, which has not fully studied in Egypt.

MATERIALS AND METHODS

The Study Area
El-Tall El-Keber wastewater treatment plant was designed to serve the population of El-Tall El-Keber city (Fig. 1). Wastewater is pumped to the plant from a pumping station located outside the plant. The station was built on five feddans by the Egyptian government; it lies in the Eastern South of El-Tal El-Kbeer city (Fig. 2).

The exact areas that feed the station are El-Tal El-Sagheer, Abd Al Dayem suburb, El-Tal City and north of rail way station. The output water runs through Al Wadi drain from El-Tal El-Kbeer to Ismailia waterway to reduce the under ground water level.

Sample Collection and Preparation
Field investigations were conducted monthly from September 2003 to August 2004. Chironomid larvae were collected by short sweeps at depth up to about 1 m from inlet and outlet lagoons. They sorted live, separated from the sludge and returned to the laboratory in plastic buckets with some field water.

In the laboratory, each sample was washed by distilled water and sorted under the microscope, some larvae were fixed in 70% alcohol with few drops of glycerin for identification by dissection of head capsule, the remaining sorted larvae were reared to the adult stage as the methods described by Chattopadhyay (1991).

Identification and Preservation
Identifications were mainly based on available keys (Epler, 2001; Ghonaim et al., 2001a, b, 2004, 2005a, b) with updates from more recent available literature. The examination and drawing of specimens were made by using a binocular microscope and a camera Lucida. Identification of each species was based primarily on reared adult male specimens; then females, larvae and pupae were later identified by association with males.

Dissection of the Head Capsule
The mouth parts are of great importance in the identification of chironomid species. Therefore, larval specimens were dissected for extraction and examination of head capsule and mouth parts. Then mouth parts were mounted on cleaned slides using the technique described by Epler (2001).

RESULTS AND DISCUSSION

The field-collected larvae simply cannot be identified with certainty. The most desirable procedure for associating larvae with their respective pupae and adult is by rearing. A successfully reared individual yields all the larval, pupal and adult characters for that particular species. Confirmation of species identifications by rearing larvae is important to ensure the integrity of chironomid database (Watts and Pascoe, 1996). The identification of the collected species depends on the rearing mechanism and studying the characters of all stages.

Chironomids as biomonitors should prove to be quite valuable once taxonomy is improved and environmental requirements are defined at the species level. If this were done, the accurate species lists and identification keys would be valuable tools in the biological assessment of water quality (Seire and Pall, 2000). According to this study Two genera: Chironomus Meigen and Kiefferulus Goetghbuer and six species: C. calipterus Kieffer, C. formosipennis Kieffer, C. caffrarius Kieffer, C. imicola Kieffer, C. seydeli Goetghebuer and K. brevibucca (Kieffer) are now confirmed to the Egyptian fauna. Outline drawings and pictorial keys are given for the identification of larvae, pupae and adults of the collected species (Fig. 3-20).

REFERENCES