Host range and potential distribution of Aceria thalgi (Acari: Eriophyidae): a biological control agent for Sonchus species

Abstract

AbstractSowthistles, Sonchus arvensis, S. asper and S. oleraceus (Asteraceae), are serious weeds that impact on crop production in many regions of the world. A recently described eriophyid mite, Aceria thalgi from Sonchus species found in southern Australia, was assessed for its potential as a biological control agent for these weeds. Glasshouse host range testing and field observations of 11 species from seven genera from the Lactuceae tribe of Asteraceae showed that A. thalgi survived only on plants within the Sonchinae subtribe (S. asper, S. oleraceus and S. hydrophilus) and not on the closely related Actites megalocarpus, Reichardia tingitana or other test plants. Under glasshouse conditions and varying plant ages, A. thalgi infestation caused significant growth reduction of the exotic species S. oleraceus (up to 97%) and, to a lesser extent, the Australian native S. hydrophilus (up to 33%). Six temperatures from 9.1 to 33.7°C were used to determine population growth parameters for A. thalgi. The range of temperatures suitable for population growth was used to modify a CLIMEX model based on its host S. oleraceus. The projected world distribution of the CLIMEX model indicates that the mite could establish in some areas of North America, making it a possibility for an augmentative approach to biological control of Sonchus spp. in that region. The model confirms the potential for a widespread distribution of A. thalgi in southern Australia where it could be considered for a conservative approach to biological control of Sonchus spp. in cropping systems.