Host species and plant part specificity of the polyphagous onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), in an Australian cotton-growing area

We determined the pattern of host plant use of Thrips tabaci by surveying wheat and five weed species growing near cotton crops in the area centred on the Namoi Valley, northern New South Wales. Highest densities of T. tabaci females and larvae were found on inflorescences and vegetative parts of turnip weed, Rapistrum rugosum, and lowest on wheat, Triticum aestivum. The other plant species (Paterson's curse, Echium plantagineum, curled dock, Rumex crispus, Mayne's pest, Verbena tenuisecta and sowthistle, Sonchus oleraceus) hosted intermediate densities of T. tabaci. The presence of high densities of reproductive T. tabaci on flowering and vegetative parts of turnip weed suggests that this species is a primary host of T. tabaci in the study area.