En 1979-1980, une étude concernant la faune présente sur Pirus amygdaliforrrais Vill. et P. communis L., poussant spontanément en garrigue, et sur les poiriers d’un verger abandonné depuis plusieurs années, a été menée dans la région de Montpellier. La plupart des différences observées dépendent davantage du passé des arbres ou de leur environnement que de l’espèce hôte. Ainsi la faune du verger abandonné était encore proche de celle des cultures intensives avec, d’une part, les mêmes ravageurs (dont Psylla pyri L., Dysaphis pyri Boyer de F. et Zeuzera pyrina L. constituent les principaux) et, d’autre part, la même pauvreté en auxiliaires. Sur les poiriers sauvages, les ravageurs dominants sont le psylle Psylla pyricola Foerster, le carpocapse Laspeyresia pomonella L. et la cochenille Epidiaspis leperii Sign. Deux espèces nouvelles ont en outre été découvertes : un homoptère du genre Psylla sur P. communis et un acarien phytoséiide Pegodromus crassipilis Athias-Henriot sur P. amygdaliformis. Ce dernier hôte abrite aussi Cenopalpus lanceolatisetae Attiah (Acarien, Ténuipalpidé) indiqué jusqu’à présent en Egypte et à Chypre. Les auxiliaires intervenant sur les poiriers sauvages et dans le verger abandonné sont identiques à ceux mentionnés dans la littérature, Anthocoris nemoralis F. étant le plus important ; nos observations confirment l’influence de l’environnement sur leur intervention dans la régulation des populations de phytophages.

Investigations have been undertaken in the Montpellier area on the fauna of wild Pyrus communis L. and P. amygdaliformis Vill. in two places with garrigue vegetation type and of P. communis in an abandoned orchard found in a cultivated area. Weekly or fortnightly, 9 to 13 trees were sampled in each place. Methods used were beating of 45 to 65 branches, visual observations of 100 leaves and Berlese extractor. In the abandoned orchard, the fauna was still close to that of cultivated pear orchards : we found the same pests, the main ones being Psylla pyri L., Dysaphis pyri Boyer de F. and Zeuzera pyrina L., and the same poverty of beneficial species. On wild pear trees, the principal pests were Psylla pyricola F6rster, Laspeyresia pomonella L. and Epidiaspis leperii Sign. Natural enemies which occurred in the different situations were those usually mentioned in the literature. Among them, Anthocoris nemoralis F. which preys on P. pyri and P. pyricola appeared to be the most abundant. Our observations confirm the influence of the environment and of cultural practices like chemical sprays on the composition of the fauna and on the natural regulation of pests in the 3 places studied. Two new species were discovered on the wild pear trees : Psylla sp. (Homoptera) and a phytoseiid mite Pegodromus crassipilis Athias-Henriot. Furthermore Cenopalpus lanceolatisetae Attiah known from Egypt and Cyprus, which was met on P. amygdaliformis, was recorded for the first time in France. This study showed that the abandoned orchard, with its important population of P. pyri, constitutes a far from negligible focus for the pests of managed orchards. Wild pear trees shelter species like E. leperii, D. pyri, L. pomonella, Contarinia pyrivora Ry., Epitrimerus pyri Nal., Phytoptus pyri Pgst, which could migrate onto nearby pear crops, but it is not known whether such a risk would hold also for P. pyricola and Psylla sp. as these insects did not develop in the abandoned orchard. Concerning natural enemies, wild pear trees represent a potential reservoir for the useful fauna and especially for A. nemoralis against psyllids.