Abstract:
The  study  of  the  aerial  parts  extracts  toxicity  of Euphorbia  guyoniana Boiss.  &  Reut 
(Euphorbiaceae) collected in Wadi Metlili, northern Sahara of Algerian on the larvae of Culex pipiens 
(Diptera, Culicidae)  in the third  stage. The aqueous extract of Euphorbia guyoniana generates a total 
mortality was reached after less than 2 hours of Culex pipiens L3 larvae, the mortality rate observed was 
100% for concentrations 100%, 75%, 50% and25 %. In addition, the calcul of the CE 50 and 90 were 
conducted  to  assess  the toxicity degree of  these  plant  extracts  vis-à-vis  third  stage  larvae  of Culex 
pipiens. The results show that the concentrations causing 50% mortality and 90% of larvae are 0.0015 
mg  /  ml  and  0.0094  mg  /  ml,  respectively. Otherwise,  the  assessment  of  lethal  time  50  (LT
50
)  shows 
that the aerial  part extract  of Euphorbia  guyoniana exhibits a particular  speed  of  action  especially a 
high concentrations with 100%, 75%, 50% and25%.