New insights from old data: the complex migration and breeding patterns of the bogong moth, Agrotis infusa (Boisduval) (Lepidoptera: Noctuidae), in eastern Australia

Abstract

The bogong moth, Agrotis infusa, an endemic noctuid moth of Australia, is known for its extensive long-distance movement and summer aestivation in the Australian Alps. Recent studies have focused on moth activity in the Alps, but there are limited data for other regions. This study aims to build on the current understanding of bogong moth movement and breeding patterns using unpublished historical data across eastern Australia. We analysed historical data from moth traps in Victoria, New South Wales (NSW) and South Australia (SA) from the 1960s to early 1990s. The study employed the HYSPLIT model for trajectory analysis of moth flight paths and DARABUG2 for phenological modelling. We examined moth catches across different seasons to infer movement patterns, breeding sources and over-summering activity. Our findings question several long-standing assumptions about the spatial ecology of the bogong moth. The trajectory analysis suggests that many aspects of A. infusa movement can be explained via dynamic migration, without fully relying on inherent navigation abilities. Important breeding areas may be beyond the self-mulching clays of NSW and southern Queensland and include far western NSW, south and central SA and southern Victoria. Substantial moth activity during summer in many traps suggests alternative over-summering strategies including local breeding or even aestivation in areas other than the Alps. Furthermore, the autumn and winter data imply return migrations from diverse source areas and potential local breeding, expanding the understanding of the moth's life cycle beyond a univoltine pattern. In conclusion, the bogong moth appears to exhibit a more complex and adaptable migration and breeding strategy than previously understood, utilising a range of habitats across eastern Australia for breeding and possibly aestivation. This underscores the need for a revised understanding of bogong moth ecology, which is crucial for its conservation and management, especially considering its recent classification as ‘Endangered’ on the IUCN Red List.