Aphids can cause substantial damage to cereals, oilseeds and legumes through direct feeding and through the transmission of plant pathogenic viruses. Aphid-resistant varieties are only available for a limited number of crops. In Australia, growers often use prophylactic sprays to control aphids, but this strategy can lead to non-target effects and the development of insecticide resistance. Insecticide resistance is a problem in one aphid pest of Australian grains in Australia, the green peach aphid (Myzus persicae). Molecular analyses of field-collected samples demonstrate that amplified E4 esterase resistance to organophosphate insecticides is widespread in Australian grains across Australia. Knockdown resistance to pyrethroids is less abundant, but has an increased frequency in areas with known frequent use of these insecticides. Modified acetylcholinesterase resistance to dimethyl carbamates, such as pirimicarb, has not been found in Australia, nor has resistance to imidacloprid. Australian grain growers should consider control options that are less likely to promote insecticide resistance, and have reduced impacts on natural enemies. Research is ongoing in Australia and overseas to provide new strategies for aphid management in the future.

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BACKGROUND The redlegged earth mite, Halotydeus destructor (Tucker), is a destructive and economically important pest of winter grain crops and pastures in Australia. It is largely controlled by pesticides, but this mite has evolved resistance to pyrethroid and organophosphate chemicals. A national Resistance Management Strategy has been developed for pro‐active management to delay further resistance evolution, though its success is reliant on a detailed understanding of the incidence, patterns of spread, current distribution and the nature of resistance in the field. Here, we report on a long‐term resistance surveillance programme undertaken between 2006 and 2019 informed by resistance risk forecasting. RESULTS By mapping the Australian distribution of resistance through time, we show that resistance is present across three Australian states and covers more than 3000 km. This current range includes a recently identified population exhibiting organophosphate resistance representing the most easterly location of resistance in H. destructor. Using field history information, we identify associations for the first time between crop management practices employed by farmers and the presence of pyrethroid resistance. Management strategies that could minimize the risk of further resistance include limiting local spread of resistance through farm hygiene practices, crop rotations and reducing pesticide usage. CONCLUSION This study highlights the challenges of resistance in H. destructor but also indicates how quantitative resistance risk analysis can be developed to target field surveillance and delay further resistance. The management strategies highlighted in this study can help maintain the effectiveness of control options but will depend on farmer engagement and adoption. © 2021 Society of Chemical Industry.

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.

Grain crops in southern Australia are subject to attack by countless pests, with greater than 40 invertebrate species threatening seedling establishment. Control tactics for crop establishment pests rely heavily on the application of pesticides, especially in canola, which is the most susceptible crop to invertebrate damage. There is genuine interest in integrated pest management (IPM) among growers, but relatively little adoption of classical IPM in broadacre farming in southern Australia. The driving forces behind the lack of adoption are unknown, although over-reliance on broad-spectrum pesticides – which are inexpensive and often applied prophylactically as a means of negating the need to monitor crops – is undoubtedly a key factor. Recent control failures against important pests due to pesticide resistance, increased restrictions on pesticide applications, environmental concerns about pesticide applications and strong support for grain quality assurance programs by exporters, highlight the need to consider IPM principles as a means of reducing chemical inputs. IPM guidelines for broadacre farming systems are limited in scope and there is a need to develop practical management tools that encompass a whole system approach. This paper provides an overview of the main invertebrate pests affecting crop establishment and identifies gaps hindering the wide-scale adoption of IPM.