Essai de lutte biologique contre la mineuse des agrumes Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) par l’utilisation de champignons entomopathogènes

Abstract

The experimental work involves the isolation and the identification of fungi naturally present on the nymphs of Phyllocnistis citrella as well as the study of the pathogenicity of these fungi stocks on the larvae of this pest. The isolation and the identification showed the existence of eleven species different of entomopathogenic fungi. It is about Helminthosporium sp., Cladosporium sp., Stemphyllium sp., Alternaria sp., Coelomycidium sp., Phoma sp., Fusarium sp., Metarhizium sp., Penicillium sp., Aspergillus niger and of unidentified specie. The calculation of abundance indicates that Fusarium sp. (with 20 %) is most frequent. Regarding the pathogenicity of fungi on the larvae of P. citrella, the results show that: • By direct injection in the mine in the presence of the alive and healthy larva, the death rate (mortality) corrected is 88,23 % for the species Metharizium sp and Stemphyllium sp, 82,35 % for Helminthosporium sp, 76,47 % for the four species Coelomycidium sp, Fusarium sp, Alternaria sp and Cladosporium sp., and 58,81 % for Aspegillus niger. • By damping of the infested leaves by the larvae of P. citrella, the death rates corrected recorded are 84,21 % for the Helminthosporium sp. specie and 73,68 % for Fusarium sp. For this method, only Helminthosporium sp. and Fusarium sp. have been able to effectively divert the defense strategy of P. citrella and thus represent potential agents of microbiological control against this depredator.