The high levels of resistance occurring in Western Australia have caused considerable economic losses due to ineffective chemical applications and mortality of crop plants at seedling establishment. These findings highlight the need for a comprehensive resistance surveillance programme to be developed for H. destructor within Australia. Growers need to consider non-chemical approaches for pest control and should be encouraged to implement pesticide resistance management programmes for H. destructor.

Broad-spectrum pesticides used to protect field crops and pastures from invertebrate pests are frequently reported to reduce populations of nontarget fauna, but there is often little relevant field data. Nonetheless, this notion is used to promote the adoption of more selective pesticides with less impact on nontarget invertebrates, including beneficial insects. Selective pesticides are not widely available for broad-acre grain crops and pastures in southern Australia; however, several options available in other industries could be compatible with these agricultural systems. In this study, the impact of broad-spectrum pesticides and several selective pesticides on nontarget invertebrate fauna was assessed in five field trials in wheat and canola fields. Despite extensive sampling over short and medium timeframes, few treatment effects on nontarget groups were detected. In cases where broad-spectrum pesticides were detrimental, patterns were often inconsistent among nontarget groups and between field trials. In contrast, the pest species, Halotydeus destructor Tucker and Penthaleus spp., were effectively controlled by the broad-spectrum treatments and less effectively by the selective pesticides. The inconsistent and relatively small impact of broad-spectrum pesticides on some nontarget invertebrates demonstrates that caution is required when extrapolating from laboratory-based assessments routinely used to assess the impacts of pesticides to field conditions in agriculture.

Shifts to Integrated Pest Management (IPM) in agriculture are assisted by the identification of chemical applications that provide effective control of pests relative to broad-spectrum pesticides but have fewer negative effects on natural enemy (beneficial) groups that assist in pest control. Here, we outline a framework for identifying such applications and apply this framework to field trials involving the crop establishment phase of Australian dryland cropping systems. Several chemicals, which are not presently available to farmers in Australia, were identified as providing moderate levels of pest control and seedling protection, with the potential to be less harmful to beneficial groups including predatory mites, predatory beetles and ants. This framework highlights the challenges involved in chemically controlling pests while maintaining non-target populations when pest species are present at damaging levels.