Phenology of three exotic pine bark beetle species (Coleoptera: Scolytidae) colonising Pinus radiata logs in the south-western Cape Province.
Orthotomicus erosus, Hylastes angustatus and Hylurgus ligniperda are exotic bark beetle pests of pine plantations in South Africa. Results from weekly trapping of adult beetles (using Pinus radiata trap logs in P. radiata stands) over a period of five years in SW Cape showed that the different species have activity peaks at different times of the year. H. angustatus was the most consistent, with 95% of the beetles trapped in September and October. The O. erosus activity peak was more variable, but always occurred in the summer (October to February) when 84% of the beetles were captured. H. ligniperda was the most variable, being found in every month of the year, although an autumn peak representing 37% of the beetles occurred in April/May. Control measures are discussed, including biological control by introducing natural enemies absent in South Africa (one parasite of O. erosus pupae, viz. Dendrosoter sp. near labdacus, is restricted to SW Cape), and spraying seedlings threatened by H. angustatus with prophylactic sprays at the spring activity peak.