Decrease in feeding niche breadth of Melasoma lapponica (Coleoptera: Chrysomelidae) with increase in pollution.

We studied host-plant preference and performance of the leaf beetle, Melasoma lapponica, around Severonikel smelter situated in Monchegorsk, Russia. The breadth of feeding niche (Smith's measure) based on both field counts and preference tests decreased with an increase of ambient SO concentration, but showed no relationship with either metal pollutants or beetle population densities. In heavily polluted plots (mean annual SO concentrations 400-1000 μg/m) the beetles concentrated on Salix borealis, Whereas in moderately and slightly polluted plots they used other willow species as well.