Effet de l’anatomie de la feuille sur l’évolution des acariens ériophyides de l’olivier en Tunisie

Le choix de variétés résistantes ou tolérantes aux nuisibles est une voie privilégiée de la lutte intégrée. Face à la recrudescence des acariens ériophyides (Aceria oleae Nalepa et Oxycenus maxwelli Keifer) sur les oliviers en Tunisie, aussi bien en pépinière qu’en verger, nous avons étudié la sensibilité à ces phytophages de 12 variétés : Arbequina, Chemchali, Chemlali Ontha, Chemlali Sfax, Chemlali Zarzis, Chétoui, Koroneiki, Meski, Oueslati, Picholine, Zalmati et Zarrazi. Les variétés d’olives à huile sont plus infestées que les variétés d’olives de table. L’étude histologique des feuilles montre que les variétés ayant une cuticule plus épaisse (Chétoui, Picholine, Oueslati et Zarrazi) sont moins infestées par ces acariens. Les épaisseurs seuils permettant de limiter la détérioration de l’acidité de l’huile induite par les acariens sont de 3,9 μm sur la face inférieure et 7,52 μm sur la face supérieure. La variété de table Meski, malgré une épaisseur de la cuticule inférieure à ces seuils, montre une résistance, en dehors de la période de floraison, ce qui suggère l’implication d’autres formes de résistance telles que la synthèse de composés biochimiques spécifiques

Phytoseiid mites (Acari: Mesostigmata) from Tunisia: catalogue, biogeography and key for identification

The authors give a report on results of several surveys carried out to collect Phytoseiid mites, between 1994 and 2008, from the main crops and surrounding vegetation in some regions of Tunisia. A catalogue of all species found is provided with some information on their biology, when available, and biogeography. Almost all species are new to Tunisian and two to African fauna. One genus and one species are new to Science and previously described. A key for the identification of the species found is also provided

Exploring Bacterial and Fungal Biodiversity in Eight Mediterranean Olive Orchards (Olea europaea L.) in Tunisia

A wide array of bacteria and fungi are known for their association with pests that impact the health of the olive tree. The latter presents the most economically important cultivation in Tunisia. The microbial diversity associated with olive orchards in Tunisia remains unknown and undetermined. This study investigated microbial diversity to elucidate the microbial interactions that lead to olive disease, and the bio-prospects for potential microbial biocontrol agents associated with insect pests of economic relevance for olive cultivation in the Mediterranean area. Bacterial and fungal isolation was made from soil and olive tree pests. A total of 215 bacterial and fungal strains were randomly isolated from eight different biotopes situated in Sfax (Tunisia), with different management practices. 16S rRNA and ITS gene sequencing were used to identify the microbial community. The majority of the isolated bacteria, Staphylococcus, Bacillus, Alcaligenes, and Providencia, are typical of the olive ecosystem and the most common fungi are Penicillium, Aspergillus, and Cladosporium. The different olive orchards depicted distinct communities, and exhibited dissimilar amounts of bacteria and fungi with distinct ecological functions that could be considered as promising resources in biological control