The within-field spatial distribution of beneficial arthropods was assessed using two-dimensional grids of pitfall traps and suction sampling across two winter wheat fields of 4 and 16 ha, before and after an application of dimethoate. An unsprayed 6 m wide buffer zone was left around half the edge of the larger field. Arthropod numbers fluctuated to varying extents prior to spraying. Two speci...

Many parasitic wasps that exploit herbivores as their hosts make use of herbivoreinduced plant odours to locate their victims and these wasps often exhibit an ability to learn to associate specific plant-produced odours with the presence of hosts. This associative learning is expected to allow generalist parasitoids to focus on cues that are most reliably associated with current host presence, ...

The parasitoid complex associated with Monochamus galloprovincialis (Olivier), vector of the pine wood nematode, is discussed. Four species of the family Braconidae and one Ichneumonidae were found associated with Monochamus galloprovincialis in Portugal, namely Atanycolus denigrator (Linnaeus), Atanycolus ivanowi (Kokujev), Cyanopterus flavator (Fabricius), Doryctes striatellus (Nees) (Braconi...