The life history and abundance of the introduced earthworms<i>Aporrectodea trapezoides</i>and<i>A. caliginosa</i>(Annelida: Lumbricidae) in pasture soils in the Mount Lofty Ranges, South Australia

Abstract

Abstract The introduced earthworms, Aporrectodea trapezoides and Aporrectodea caliginosa , are common in agricultural soils in southern Australia. The seasonal abundances of these species were monitored in five pastures in the Mount Lofty Ranges, South Australia. Highest numbers occurred from winter to early spring: densities of up to 407 and 446 m −2 were recorded for A. trapezoides and A. caliginosa , respectively. Adults were restricted to winter and spring, when breeding occurred. Subadults and juveniles survived summer. Aporrectodea trapezoides and A. caliginosa were abundant in the surface layers of the soil (0–10 cm depth) for between 3 and 7 months (autumn to spring), when soils were moistest. During summer, most individuals were found &gt; 20 cm below the surface where they were inactive, coiled tightly within sperical chambers. The abundance of A. trapezoides and A. caliginosa varied within and between pastures. Numbers were lowest where the clay content of the soil was low. A dipteran parasite attacked a small proportion of A. trapezoides at one site in spring.