The distribution of Halotydeus destructor and Penthaleus major (Acari : Eupodidae) in Australia in relation to climate and land use

Abstract

The red-legged earth mite, H, destructor, is restricted to the southern parts of Australia having a Mediterranean-type climate, with warm dry summer and cool wet winter. The northern or inland distribution agrees closely with the 205-mm isohyet for the growing season May-October inclusive. The eastern distribution is limited by the quantity of midsummer (December-March) rainfall and agrees closely with the 225-mm isohyet for this period. Other limitations to distribution within these isohyets are imposed by high summer temperatures (mean monthly maximum of hottest month, 33°C). The blue oat mite, P. major, can tolerate a drier climate, reaching a May-October isohyet of about 190 mrn, and a higher proportion of summer rain. This enables it to survive on the south coast of New South Wales and on the northern tablelands of New South Wales as far as southern Queensland, but not in north coastal areas where the midsummer rainfall exceeds about 500 mm. On the evidence available, the likely future movements of these mites both within Australia and overseas are discussed. Vigilance will be needed to prevent H. destructor from becoming a pest in the Americas and in the Mediterranean region.