Notes on sexual size dimorphism, sex ratio and movements of adult ground weta Hemiandrus maculifrons (Walker) (Orthoptera: Anostostomatidae)

Abstract

The ground weta (Hemiandrus maculifrons) is an apparently abundant species with a New Zealand-wide distribution. Despite this, there is a paucity of ecological and biological information concerning this species. We aimed to gain new information about movement patterns, capture rates and body size differences by tagging individuals and conducting nightly surveys of a single H. maculifrons population in the Otanewainuku Forest, Bay of Plenty, New Zealand. Over a 26-night period between March and April 2012, we tagged 53 females and 78 males with queen bee tags and small reflector strips and recorded the location of animals that were subsequently re-sighted. Adult females were significantly larger than males, but capture and re-sight rates suggested males were the more abundant sex during the study period. Female weta moved further over consecutive nights than males (average distance moved, 1.57 m vs. 1.01 m, respectively); however, the tagging method, time of year and study area may have resulted in underestimates. These results indicate areas for further research into aspects of sexual selection, such as potentially biased sex ratios, sexual size dimorphism and mate competition, within H. maculifrons.

Keywords:

• abundance
• invertebrate tracking
• mark-recapture
• New Zealand
• queen bee tags

Acknowledgements

We would like to thank Adam Brown, Scott Lyon and Simon Holmes for assisting with field surveys. Permission to access the forest and conduct research on a native species was granted by the Department of Conservation, Mr. M. Tapsell and Mr. D. Flavell of the local iwi, Ngāti Ranginui. Two anonymous reviewers and Darren Ward provided useful comments to improve this manuscript.

Funding

This research was funded by the Bay of Plenty Polytechnic Taiorangahau (Pacific Coast Applied Research Centre) Research Fund.