THE ROLE OF PARASITISM AND INTRASPECIFIC COMPETITION IN THE POPULATION-DYNAMICS OF THE BARK BEETLE, LEPERISINUS-VARIUS (FABR) (COL, SCOLYTIDAE) ON THE EUROPEAN OLIVES (OLEA-EUROPEA L)

Mortality from parasitism and intraspecific larval competition was mea sured for the olive bark beetle, Leperisinus varius, in cut logs withi n a Spanish olive orchard. Mortality due to parasitism was inversely d ensity-dependent, whilst that due to competition was directly density- dependent. The consequences of these mortality effects of parasitoid a nd host population dynamics were investigated using a simple populatio n model. In the absence of parasitism, beetle populations stabilized a t around 12 adult females per dm(2) of olive ion surface. Using Roger' s Random Parasite Equation to model the parasitoid-host interaction, t he effects of parasitism were to destabilize an otherwise stable inter action. The limitations of the model in its current form are discussed in detail. Suggestions are also made for future improvements to the m odel including the incorporation of spatial heterogeneity in parasitis m and the effects of interspecific competition between parasitoids.