POPULATION-DENSITY AND PERFORMANCE OF MELASOMA-LAPPONICA (COLEOPTERA,CHRYSOMELIDAE) IN SURROUNDINGS OF SMELTER COMPLEX

We studied populations of the willow feeding leaf beetle, Melasoma lap ponica L., in the vicinity of the Severonikel smelter complex at the K ola Peninsula, northwest Russia. Increased abundance of M. lapponica a round the smelter is explained by habitat changes that have resulted i n higher density of the most preferred host plant, Salix borealis (Fri es) Nasar. Within the polluted territory, 10- to 20-fold higher densit ies occurred in moderately polluted sites than both in heavily and sli ghtly polluted areas, Laboratory experiments demonstrated the highest survival of insects fed with leaves of S. borealis from the moderately polluted site, whereas female life span, fecundity, and egg viability decreased toward the smelter. Host-plant quality together with parasi te-induced mortality explained the density pattern observed along poll ution gradients.