Invasive organisms are among major threats to biodiversity. Insects, due to their mobility and short life cycle represent a vast category of expanding organisms.  The black locust (Robinia pseudacacia) is also an alien species to Europe but due to the relatively long history of naturalization, it is integrated in most of central Europe landscapes. A process of natural enemy acquisitions is taking place and two new pests affect stands, hedgerows and windbreaks where R. pseudacacia vegetates: Parectopa robiniella and Phyllonorycter robiniella (Lepidoptera Gracillariidae). A heavy infestation mostly with the newly introduced Phyllonorycter robiniella was observed in western and central Romania during 2003-2004. In many cases, leaves presented also mines of Parectopa robiniella. The mines of Phyllonorycter robiniella were attacked by several natural enemies: birds predated pupae, Beauveria bassiana was isolated from mines where larvae mortality was reported and also pupae of parasitoids where found in several cases. Having the same target, the foliage of the host and being members of the same guild, mining insects utilize the same niche. The study is interested in separating the niche components, mostly spatial of the two species based on the analysis of the results of C score of association. The shape of mines and their extension on the leaflet blade were assessed using image analysis.

Robinia pseudacacia; Parectopa robiniella; Phyllonorycter robiniella; niche partition; co-occurrence; C-score; Pianka index; shape index

Presentation: oral