No abstract

Pesticides are the major source of concern as water pollutants. Chlorpyrifos (CPY) (O,O-diethyl-O-(3,5,6-trichloro-2-pyridinyl) phosphorothioate; CAS No. 2921-88-2). CPY is a widely used organophosphate insecticide. The aim of current study was to determine the effects of CPY on the second instar larvae of Culex mosquito as a bio-indicator of water pollution. Levels of CPY in stream water was evaluated. Toxicity of CPY was estimated on mosquito. Along with the evaluation of effects of water polluted with CPY on mosquito to predict the water pollution levels. Results showed that LC95 of CPY was 6331.30 mg/kg after 24hr and increased to 230506.4 ppm after 48hr of exposure. It was noted that the activity of CPY is concentration and time dependent. The 0.09 ppm concentration of CPY (the amount that was found in the stream water) had no effect on the second instar Culex larvae similar to the control (tap water). There is no effect after 72,96h of exposure of the population to the detected insecticide. It could be concluded that mosquito is not a bioindicator of CPY pollution at the detected level in stream water.

No abstract

The environmental problems have raised the interest for bio-indicators able to reflect their environment. Among these life forms, the insects may contribute to a viable evaluation of the sustainability degrees. The Egyptian Mediterranean coast exhibits six lakes which are situated along the Nile Delta coast; Northern Delta lakes; Manzala, Borollus, Edku, and Mariut, and to the east of the Suez Canal, Port-Fouad and Bardawil. The current study aimed to evaluate different heavy metals in aquatic insects Ochthebius (Asiobates) rugulosus Wollaston 1857, taken from Lake Manzala, and to estimate their effect on the oxidative stress markers to employ insects as sensitive bio-monitors for environmental pollution. A lot of fluctuations were observed affected by the poor connection of the water body of the lake Manzala. The mean level concentrations of Pb, Cd, Cu and Zn in loc.#1, whereas; 0.98, 3.02, 0.35 and 1.99 µg/l; respectively with the arrangement of Cu < Pb < Zn < Cd in location #1 whereas it was reported as 1.8, 3.64, 1.32 and 2.2 µg/l in location#2, giving the arrangement of Pb < Cu < Zn < Cd in loc.#2. The mean concentration level of Pb in both locations was less than that recommended by the USEPA, 2005 (2.5-65 µg/l), Cd in the present study was higher than that of the water quality criteria; (0.2-2 µg/l) recommended by USEPA, 2005 in both locations in Lake Manzala. The pH values of water were alkaline throughout the lake. It is concluded from the obtained data that the southeastern region showed worse quality parameters. The pH of the water lake (loc.1; 7.7), (loc.#2; 7.3) was found to be slightly alkaline throughout the spring (March-May, 2018). The pH was within the prescribed limits (6.5-9) of USEPA, 2005. In the current study, Cu and Zn concentration in Ochthebius (Asiobates) rugulosus Wollaston 1857, in Lake Manzala ranged from (0.2-0.1µg/g, 0.07-0.09 µg/g). The mean concentration of heavy metal was significantly (p<0.05) different in water samples collected from Lake Manzala, Spring; 2018. The arrangement of elements in the insect tissue was as; Cu > Pb > Zn > Cd. There was a significant increase in the mean concentrations level of ALT activity in insects from loc. #2; 42.6 (U/mg protein), while it was 37 (U/mg protein) in that of loc.#1. The mean concentration level of