Cabbage-centre grub, Hellula hydralis Guenée, not resident in Tasmania

This paper collates information about cabbage-centre grub, Hellula hydralis Guenée (Lepidoptera: Pyralidae) to indicate that this pest is not established in Tasmania despite frequent immigration from mainland Australia and the presence of suitable host plants in Tasmania. Light trap data demonstrates the erratic but frequent occurrence of cabbage-centre grub adults at Devonport, Tasmania. Examples of several probable migrations are illustrated by back air trajectory analysis coinciding with several large catches in one permanent light trap at Devonport. Substantial inspection of crops by many entomologists and agronomists over decades has never detected immature stages of this pest in Tasmania. A day-degree development model for this pest is not available so that the suitability of the Tasmanian climate cannot be assessed by that method but records of the pest breeding as far south as Victoria do exist. The results provide one example to biosecurity entomologists of a pest that repeatedly fails to establish, even ephemerally, in Tasmania despite frequent introductions and the presence of host plants and a mainland distribution extending into Victoria. It also demonstrates how the status of a pest in a region can be misconstrued if merely assessed by records of adult captures, which dominate records for many insects in official databases such as the Australian Plant Pest Database of Plant Health Australia.

Cite this article as:

Hill, L. (2012). Cabbage-centre grub, Hellula hydralis Guenee, not resident in Tasmania. Plant Protection Quarterly 27(3), 91-100.

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First published online: September 15, 2012