1. In the globally significant, lowland terrestrial systems of the subAntarctic's South Indian Ocean Province Islands, caterpillars of the flightless moth genus Pringleophaga (Lepidoptera: Tineidae) are typically responsible for much nutrient turnover.2. On Marion Island, Pringleophaga marioni is a keystone species for this reason.3. Rising temperatures have led to increasing populations of introduced house mice, which, in turn, feed extensively on Pringleophaga caterpillars.4. Because of the caterpillars' keystone role, predation by mice is leading to changes in the functioning of the terrestrial system. 5. Given the estimates of an extended life cycle duration for P. marioni (and its congeners), that is, two to more than 5 years, an ongoing puzzle is why the species has not shown greater population declines on Marion Island than have been recorded (in some habitats 40-97% in 20 years), given extremely high estimates of predation (c. 1% of standing biomass per day). 6. One reason may be inaccurate previous estimates of life cycle duration for the species.7. Here, we provide a new, quantitative estimate, by rearing caterpillars at different temperature regimes (5, 10, 15 and 5-15°C), and combining these results with additional data from a prior study, to demonstrate that the life cycle duration for this species is approximately 1 year -half the previous minimum estimate.8. The new quantitative data provide grounds for improved models for estimating population persistence of this species, and information for models assessing the costs and benefits of conservation interventions such as the eradication of invasive house mice.

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The distribution, abundance, size distribution and diurnal activity patterns of invasive land snails, Theba pisana, in the West Coast National Park (WCNP), South Africa, were investigated. The park was divided into 1 km 2 grids, within each of which five 1 m 2 quadrat counts of live snails were recorded. Of 106 grids sampled, 19% contained live snails. The average density of snails was 4.04 m -2 ± 24.9, significantly lower than in disturbed habitats adjacent to the park (57 m -2 ± 96.25), but very high densities were recorded at two sites. Snails were most abundant along roadsides and densities decreased dramatically with distance from roads. T. pisana in the WCNP appear to have an annual lifecycle, breeding in autumn to winter and growing to adult size of about 14 mm diameter by the end of the following summer. Snails were observed on a wide variety of endemic and introduced plant species and appeared to have a catholic diet. They are active mostly at night and especially during periods of high humidity, irrespective of temperature. Given the very high densities that T. pisana can attain at some sites, plus their apparently catholic feeding habits, their potential impact on the vegetation of the park is cause for concern and should be further investigated. Control of the main colonies should also be considered.

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