Determining whether biosecurity incursions are worthy of eradication attempts a case study of Epithora dorsalis

Abstract

The Australian longicorn beetle Epithora dorsalis (Coleoptera Cerambycidae) was detected in South Canterbury in December 2009 This insect attacks dead and dying Eucalyptus species and had not previously been recorded in New Zealand (NZ) Surveys conducted to determine eradication feasibility found adult beetles at independent locations 7 km apart No imported goods or other entry pathways were identified at surveyed sites Surveillance to detect E dorsalis is difficult because available trapping methods are not very effective larval feeding damage is hidden beneath bark and adult seasonal flight duration is short Insecticidal control of E dorsalis is not considered feasible as effective delimitation of populations is difficult and the insect exhibits cryptic biology An impact assessment concluded the economic significance of E dorsalis to the NZ eucalypt timber industry would be low and that post harvest bark removal would reduce infestations to a minimum Four other Australian longicorn beetles that produce similar subcortical feeding damage are already present in New Zealand It is possible that E dorsalis has gone undetected in NZ for some time These and other considerations are presented to illustrate how MAF Biosecurity NZ determines whether biosecurity incursions merit eradication