Dispersal of the Scotch broom gall mite <i>Aceria genistae</i> implications for biocontrol

Abstract

The gall mite Aceria genistae a biological control agent of Scotch broom Cytisus scoparius was first released in New Zealand in 2007 The dispersal ability of A genistae was investigated to determine whether slow dispersal might limit its ability to control Scotch broom in forestry plantations where a rapid impact of biocontrol is required Transects were set up from the original release plants at four sites in Canterbury New Zealand and the presence or absence of galled plants was recorded at increasing distances from the release plants until no more galled plants could be found The maximum dispersal rate recorded was 833 m/year which is unlikely to be fast enough to greatly benefit forestry in New Zealand Techniques may have to be developed to enhance mite dispersal in forestry plantations