Redlegged earth mite

The redlegged earth mite (RLEM) - (Halotydeus destructor) is a major pest of pastures, crops and vegetables in regions of Australia with cool wet winters and hot dry summers. The RLEM was accidentally introduced into Australia from the Cape region of South Africa in the early 1900s. These mites are commonly controlled using pesticides, however, non-chemical options are becoming increasingly important due to evidence of resistance and concern about long-term sustainability

Crop Updates 2011 - Pests and Diseases

This session covers four papers from different authors: 1. Grains biosecurity – everyone’s business, Jeff Russell, Department of Agriculture and Food 2. Control of insect and mite pests in grains – insecticide resistance and integrated pest management (IPM), Paul Umina1, Svetlana Micic2 and Laura Fagan3, 1CESAR and The University of Melbourne, 2Department of Agriculture and Food, 3University of Western Australia 3. Effect of cropping rotations on pest mites of broadacre agriculture, Svetlana Micic, Mark Seymour, Tony Dore and Pam Burgess, Department of Agriculture and Food 4. Common bunt resistance in Western Australian wheat varieties, John Majewski, Manisha Shankar and Rob Loughman, Department of Agriculture and Foo

Global patterns in genomic diversity underpinning the evolution of insecticide resistance in the aphid crop pest Myzus persicae

Abstract: The aphid Myzus persicae is a destructive agricultural pest that displays an exceptional ability to develop resistance to both natural and synthetic insecticides. To investigate the evolution of resistance in this species we generated a chromosome-scale genome assembly and living panel of >110 fully sequenced globally sampled clonal lines. Our analyses reveal a remarkable diversity of resistance mutations segregating in global populations of M. persicae. We show that the emergence and spread of these mechanisms is influenced by host–plant associations, uncovering the widespread co‐option of a host-plant adaptation that also offers resistance against synthetic insecticides. We identify both the repeated evolution of independent resistance mutations at the same locus, and multiple instances of the evolution of novel resistance mechanisms against key insecticides. Our findings provide fundamental insights into the genomic responses of global insect populations to strong selective forces, and hold practical relevance for the control of pests and parasites.Peer reviewedFinal Published versio

The Genome Sequence of the Grape Phylloxera Provides Insights into the Evolution, Adaptation, and Invasion Routes of an Iconic Pest

Background: Although native to North America, the invasion of the aphid-like grape phylloxera Daktulosphaira vitifoliae across the globe altered the course of grape cultivation. For the past 150 years, viticulture relied on grafting-resistant North American Vitis species as rootstocks, thereby limiting genetic stocks tolerant to other stressors such as pathogens and climate change. Limited understanding of the insect genetics resulted in successive outbreaks across the globe when rootstocks failed. Here we report the 294-Mb genome of D. vitifoliae as a basic tool to understand host plant manipulation, nutritional endosymbiosis, and enhance global viticulture. Results: Using a combination of genome, RNA, and population resequencing, we found grape phylloxera showed high duplication rates since its common ancestor with aphids, but similarity in most metabolic genes, despite lacking obligate nutritional symbioses and feeding from parenchyma. Similarly, no enrichment occurred in development genes in relation to viviparity. However, phylloxera evolved > 2700 unique genes that resemble putative effectors and are active during feeding. Population sequencing revealed the global invasion began from the upper Mississippi River in North America, spread to Europe and from there to the rest of the world. Conclusions: The grape phylloxera genome reveals genetic architecture relative to the evolution of nutritional endosymbiosis, viviparity, and herbivory. The extraordinary expansion in effector genes also suggests novel adaptations to plant feeding and how insects induce complex plant phenotypes, for instance galls. Finally, our understanding of the origin of this invasive species and its genome provide genetics resources to alleviate rootstock bottlenecks restricting the advancement of viticulture

Review of the biology and control of Creontiades dilutus (Stål) (Hemiptera: Miridae)

Here we review the current knowledge of green mirids, Creontiades dilutus (Hemiptera: Miridae). Creontiades dilutus are highly polyphagous pests that are endemic to Australia. They are widely distributed across Australia and feed on a broad range of agricultural crops. Recently, C. dilutus has become an important focus of pest control in Australian cotton crops, most likely due to a decrease in insecticide use associated with the widespread uptake of transgenic cotton varieties. Prior to this, C. dilutus had been coincidentally controlled in cotton by applications of insecticides targeted at other pests such as Helicoverpa spp. Further, the pest status of C. dilutus in summer pulse crops has become more apparent due to the increased research dedicated to this area over the past decade. We review various aspects of the biology and ecology of C. dilutus, including their life cycle, feeding behaviour and host plants. We also examine current control methods and laboratory-rearing techniques, which will be important for the development of novel control strategies in cotton and other cropping environments. Possible future research directions are highlighted, such as dispersal capabilities and extent of genetic structure within C. dilutus populations, as these will have important implications for effective and sustainable control in the future

Ontogeny in the European earwig (Forficula auricularia) and grain crops interact to exacerbate feeding damage risk

The preference of herbivores for different host plants can be modulated by plant ontogeny. In agricultural pest management, this has implications for sowing dates and pest monitoring. In the last 20 years, the European earwig (Forficula auricularia ), a cosmopolitan pest, has been increasingly implicated in damage to grain crops in Australia. Among these, rapeseed, Brassica napus , appears especially at risk, but little information on F. auricularia as a grain pest is available. We tested the susceptibility of seven grain crops commonly grown in Australia to infestation by F. auricularia using closed microcosm experiments, exposing plant seedlings at two early growth stages to four different life stages of F. auricularia . Lucerne and rapeseed were shown to be the most vulnerable crops, and younger seedlings experienced significantly more damage than older seedlings across all crop types. Fourth instar F. auricularia were found to cause greater feeding damage than younger or older earwigs, while adults collected in winter generally caused more damage than those collected in summer. Surprisingly, even second instar F. auricularia caused greater damage than summer adults. This variation could reflect the ontogenetically dynamic nutritional needs of earwigs. Recent studies of F. auricularia 's life cycle in southern Australia indicate that these damaging life stages have some overlap with sowing dates of the crops tested here, exposing their vulnerable seedling stage to infestation. The phenology of F. auricularia in southern Australia therefore partly drives its ability to act as a pest. Future monitoring will likely need to track the distribution of F. auricularia life stages in order to effectively mitigate risks to vulnerable crops.This work was supported by the Grains Research and Development Corporation

Hymenopteran Parasitoids of Aphid Pests within Australian Grain Production Landscapes

In grain crops, aphids are important pests, but they can be suppressed by hymenopteran parasitoids. A challenge in incorporating parasitoids into Integrated Pest Management (IPM) programs, however, is that parasitoid numbers can be low during periods within the season when aphids are most damaging. Understanding the population dynamics of key aphid species and their parasitoids is central to ameliorating this problem. To examine the composition and seasonal trends of both aphid and parasitoid populations in south-eastern Australia, samples were taken throughout the winter growing seasons of 2017 and 2018 in 28 fields of wheat and canola. Myzus persicae (Sulzer) was the most abundant aphid species, particularly within canola crops. Across all fields, aphid populations remained relatively low during the early stages of crop growth and increased as the season progressed. Seasonal patterns were consistent across sites, due to climate, crop growth stage, and interactions between these factors. For canola, field edges did not appear to act as reservoirs for either aphids or parasitoids, as there was little overlap in the community composition of either, but for wheat there was much similarity. This is likely due to the presence of similar host plants within field edges and the neighbouring crop, enabling the same aphid species to persist within both areas. Diaeretiella rapae (M’Intosh) was the most common parasitoid across our study, particularly in canola, yet was present only in low abundance at field edges. The most common parasitoid in wheat fields was Aphidius matricariae (Haliday), with field edges likely acting as a reservoir for this species. Secondary parasitoid numbers were consistently low across our study. Differences in parasitoid species composition are discussed in relation to crop type, inter-field variation, and aphid host. The results highlight potential focal management areas and parasitoids that could help control aphid pests within grain crops