Cool-season clean-up puts stop to phosphine-resistant-pest cycle

Implementing a thorough winter cleaning program around grain storage sites could prevent spring-to-summer incursions of phosphine-resistance grain storage pests, such as the rusty grain beetle (Cryptolestes ferrugineus) according to a two-year trapping study funded by the Plant Biosecurity Cooperative Research Centre.

The rusty grain beetle has a range extending from tropical to temperate regions, attacks the germ of grains and is one of the most common stored grain insect pests across many countries, including Canada, USA, Vietnam, and Australia.

Compared with the lesser grain borer (Rhyzopertha dominica), the rice weevil (Sitophilus oryzae) and the red flour beetle (Tribolium castaneum), the rusty grain beetle has been considered a minor pest of stored grain.  However, with the detection of the strong levels of resistance to phosphine concern has increased.

The trapping study was carried out from January 2014 to June 2016 in a farming district around the town of Wagga Wagga, NSW.  Monitoring flight activity at four-weekly intervals near and away from grain silos indicated a strong seasonal pattern. Flight activity only occurred between September and May (spring to autumn) in two years of trapping, with no flight detected during the winter months of June, July, or August.

Understanding species’ ecology helps to develop successful management strategies. While most studies on stored grain insects concentrate on the storage environment, knowledge of seasonal flight patterns and spatial distribution contributes to understanding population dynamics and the potential spread of resistance genes.

Knowing that flight activity is seasonal indicates storage clean outs during the cooler months is likely to reduce the risk of re-infestation and lower the development of a strongly-phosphine-resistant population

While more work is required, information garnered from this study provides a basis for tailored control strategies for rusty grain beetle in south-eastern Australia.

For more information see original paper; Holloway, J.C., Mayer, D.G. & Daglish, G.J. J Pest Sci (2018). https://doi.org/10.1007/s10340-018-0981-1

Hygiene & Structural Treatments for Grain Storage – GRDC Fact Sheet June 2013

 

Grain Silo Hygiene

 

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