This paper collates information about lesser armyworm Spodoptera exigua Doubleday to indicate that it is not established in Tasmania. Nevertheless, it occasionally migrates to Tasmania. Suitable host plants occur widely in Tasmania, including in glasshouses. Substantial inspection of crops by government entomologists and commercial agronomists over many decades have never detected immature stages of this pest in Tasmania. Evidence for breeding in Victoria was not found in official national pest records. Captures of S. exigua moths in Tasmania are coincidental with other known long-distance migratory species and usually closely preceded by airflows favourable for migration across Bass Strait. Published data from three sources for the duration of life cycles are used in heat summation models to explore the likelihood of establishment in Tasmania. The shortest three durations from a set of simulations for each month of the year are 138, 108 and 90 days at Launceston, Tasmania for cohorts of eggs laid on 1 October, 1 November and 1 December, respectively. These durations straddle the maximum period recorded of 126 days in southern California. The results provide another example to biosecurity entomologists of a pest that fails to establish, even ephemerally, in Tasmania despite the presence of host plants in Tasmania and marginally suitable heat in Launceston. There are records of adults in Victoria and Tasmania, literature indicating its presence in South Africa, and erroneous literature implying its presence in northern Chile and New Zealand. Three other lepidopteran examples are heliotrope moth Utetheisa pulchelloides Hampson, cabbage-centre grub Hellula hydralis Guenée and eggfruit caterpillar, Sceliodes cordalis Doubleday. It is also concluded that S. exigua is an alternative to S. cordalis as an indicator for the likelihood of establishment of Queensland fruit fly, Bactrocera tryoni in Tasmania in response to global warming.
Cite this article as:
HIll, L. (2014) Lesser armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), a vagrant moth in Tasmania. Plant Protection Quarterly 29(4), 131-142.