Pollen availability and abundance of predatory phytoseiid mites on natural and secondary hedgerows

Mites occurring on a number ofnatural and secondary (i.e., planted) hedgerowslocated in north-eastern Italy were monitoredwith particular attention being paid tophytoseiids (Acari: Phytoseiidae). Pollendiversity and abundance were analysed tohighlight potential relationships betweenpollen availability and phytoseiids. Secondaryhedgerows were structured in modules containinga single species (field maple, hornbeam,dogwood, hazel, and elderberry) andmodules containing a mixture of theabove-mentioned species. These hedgerows werelocated in an experimental farm where they werecontiguous to a vineyard. Natural hedgerowswere located in the same area. The pollen ofPoaceae was the most important component ofnon-arboreal pollen (NAP), and that ofelderberry of arboreal pollen (AP). Pollendiversity was higher on natural than onsecondary hedgerows. Generally, pollendensities reached relatively high levels fromlate April to late June and decreased insummer. Pollen was more abundant on naturalthan on secondary hedgerows and phytoseiidabundance showed a similar trend. On elderberryand hornbeam in natural hedgerows a potentialrelationship between pollen availability andthe abundance of phytoseiids, in particular ofEuseius finlandicus (Oudemans) was found.Experimental pollen applications increased thefecundity and the abundance of this species.