Cows, cockies and cockchafers!

This project was completed in June 2014. A great technical overview of this project and research undertaken can be found here in a paper entitled Biology and management of the redheaded pasture cockchafer Adoryphorus couloni (Burmeister) (Scarabaeidae: Dynastinae) in Australia: a review of current knowledge by Gordon Berg, Ian G Faithfull,Kevin S Powell, Rebecca J Bruce,David G Williamsand Alan L Yen.

Red headed cockchafers (RHC) are a growing threat to milk production and profitability of Victorian pasture-based dairy farms.  RHC have expanded into formerly unsuitable areas and are causing up to $200,000 in lost production per year on heavily affected farms (estimated to be around 15-20% of dryland farms). We suspect that this is driven by a drying climate in conjunction with the development of high quality pastures. There are no effective control measures available and preliminary system dynamics modelling suggests that some management options used by farmers may sustain or exacerbate the problem. 

This project helps farmers identify the scarab beetle that is causing their damage and will provide up–to–date information about RHC distribution and abundance.

Currently there are no effective or cost-efficient means of controlling RHC populations, but many farmers are trying a wide assortment of unproven treatments, including ploughing up and resowing pastures which can have potential unintended consequences that exacerbate the problem. Since there is a time delay between infestation by cockchafers and expression of visible damage symptoms, by the time identification has been confirmed as RHC the farmer has little option but to plough and re-sow, which is expensive.  Development and application of a RHC prediction system could allow early targeted intervention, identification of ‘high risk’ paddocks and reduce economic losses.

Soil characteristics both physical and chemical (including the quantity and characteristics of organic matter) will have a primary influence to some degree on RHC establishment, oviposition, fecundity, survival, development, feeding behaviour and overall spatial distribution and population dynamics.  Soil physiochemical properties may also influence host-plant susceptibility, the beetle’s competitive ability, establishment and distribution of other cockchafers and the ecology of natural predators and pathogens. Understanding the influence of soil properties on the RHC and its interactions with host plants and other invertebrates and microbes is therefore a fundamental requirement in developing a sustainable pest management strategy.

Preliminary research conducted during the recent Cockchafer project run by GippsDairy indicated that maps of baseline soil-apparent electrical conductivity (ECa) patterns produced using electromagnetic induction sensors (EM38) which measure soil ECa at specific depth profiles could provide useful guidance on where to conduct insect surveys and soil cores to determine spatial distribution in association with soil properties.  The preliminary studies were conducted on a small number of properties in South, East and West Gippsland, and need to be repeated and extended in other areas of the state potentially identified in a telephone survey as having significant economic losses due to RHC. 

It was also apparent from the results of the recent project, that many dairy farmers and service providers are incorrectly identifying the cockchafer species present in pastures.  Examination of specimens collected during preliminary surveys suggests that it may be possible to develop a diagnostic system based on larval morphology that, once trained, farmers could use to identify common cockchafer grubs to species level.  Ideal vehicles for dissemination and utilization of such a system include PadIL, which is a web-portal that provides access to high quality image libraries, diagnostic networks such as Bowerbird, and RMD (remote microscope diagnostics), training workshops and Agnotes.

 This project is funded by the Geoffrey Gardiner Dairy Foundation, the Department of Primary Industries and GippsDairy.

 

Read more about Red Headed Pasture Cockchafers in the literature review written by Gordon Berg.