Reliability of egg rafts electron micrographs for confirming the taxonomic status of Culex pipiens mosquitoes collected from Al-Ahsa, eastern Saudi Arabia

Mosquitoes are undesirable arthropods transmitting many diseases not only in Saudi Arabia but also worldwide. Identifying mosquito species relied for long time on both larval and adult characters whilst little or no attention was given to eggs. Electron microscopic studies of mosquito eggs are important as it is not only characterizing the external morphology of the eggs never seen by stereoscopic microscopes but also facilitates mosquito species identification. Accordingly, morphology and morphometric of Culex pipiens eggs collected from AI-Ahsa oasis, eastern Saudi Arabia were examined by scanning electron microscopy (SEM) for the first time in Saudi Arabia in the present work. Mosquito egg rafts were collected from breeding sites in AI-Ahsa by using of special long aquatic net. A portion of the rafts was reared for identification whilst the other portion was preserved in glutaraldehyde and prepared for SEM examination. Eggs appeared to be conical in shape with two ends, the anterior one that is represented with the micropyle is more tapered than the posterior end. The morphometrics gave many characteristics for the eggs such as length, width, proportion of length /width and so on. Eggs morphology and morphometrics were then compared to that of other Culex eggs. Our findings using SEM of the eggshell confirmed that the present mosquito species is Cx. pipiens. Scanning electron micrographs of any mosquito species eggs are valuable in correlating its fine structure that cannot be easily seen by light microscope and can assist in species separation. Thus, identifying medically important mosquito species is crucial in both mosquito and disease control.