The evaluation of the insecticidal effect of plants presents one of the approaches to the enhancement of phylogenetic heritage and an alternative to the use of chemical insecticides while preserving the environment. The insecticidal effect of the 2 plants Pistacia lentiscus and Zizyphus lotus naturally grown in Algeria was tested on the pine processionary larvae Thaumetopoea pityocampa. The aqueous extracts of the fresh and dry leaves of the 2 plants are tested at three different concentrations, according to two modes of administration (contact and ingestion). We determine the daily mortality and T.pityocamparesidual larval population. The extract from fresh leaves of Z. lotus is toxic to T. pityocampa, those from dry leaves of Z. lotus and P. lentiscus are moderately toxic, while those from fresh P. lentiscus leaves is not toxic. The biocidal effect of these extracts is greater when administered by contact than by the digestive tract.
Keywords: Thaumetopoea pityocampa, insecticidal activity, residual population, Pistacia lentiscus, Zizyphus lotus, Algeria.