Bioecology of oak Phylloxera and its natural enemies on urbanand peri-urban holm oaks


Abstract: Phylloxera quercus B.d.F is one of the most well-known holm oak aphids and cancause serious damage, mostly on urban and peri-urban ornamental oaks. From 2005 to 2007 andagain in 2010, samplings were carried out regularly in order to survey Phylloxera and other aphidinfestations. Samples were collected from early spring to summer on holm oaks from 4 areas: apublic garden in the centre of Florence, a peri-urban green area near Florence, a tree row inBarberino Val d’Elsa and a mixed woodland in Montepaldi near the town of San Casciano Val diPesa (Florence). The investigations permitted comparisons of the life cycle and the degree ofinfestation of the various aphid species in the different typologies of green spaces considered.Over the last year particular attention was paid to the aphid entomophagous insects, alreadydetected in previous years, considering their activity in relation to the level and the evolvement ofthe phylloxerid infestation. In the course of samplings, natural enemies were identified and theiroccurrence was ascertained. Results showed several groups of generalist predators, such asAntochoridae (Rhynchota), Chrysopidae (Neuroptera), Cecidomyiidae (Diptera), Syrphidae(Diptera), Coccinelllidae (Coleoptera). Coccinellids were often observed and among them Adaliadecempunctata L. and Oenopia conglobata L. were recurrent. Trials were carried out to assessthe trophic requirement of the most common predators during their preimaginal development.

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