The Plant Biosecurity CRC has been researching the ecology of stored grain insect pests to refine industry resistance management strategies for grain storage.
The research team, led by Dr Greg Daglish from the Queensland Department of Agriculture and Fisheries, has focused on key insect pests of stored grain.
“As a starting point we’ve been keen to understand the flight behaviour of the insects and where they are at any given time in the landscape” said Dr Daglish.
“This information can really help us to better understand resistance to the fumigant phosphine and to work with industry to plan responses.”
The research revealed flight activities of key grain storage pests for the first time.
“In southern Australian grain regions we found that pests such as the flat grain beetle, lesser grain borer and red flour beetle are quite good at getting around. But the rice weevil seems to rarely fly,” said Dr Daglish.
The research shows that insects resistant to the fumigant phosphine or grain protectant insecticides can potentially fly between farms and these species of flying beetles pose a threat for much of the year. This highlights the need to minimise the chance of infestation by eliminating places to breed.
“We’ve also been using the insect flight data to help us understand the risk of infestation of newly harvested grain on farms” said Dr Daglish.
“We’ve learnt that an existing infestation in nearby silos greatly increases the risk of infestation of new grain and this really underlines the importance of managing insect pests effectively in all storage areas.”
The research showed that bulk storages located two kilometres from farm silos were also at risk of infestation, but that the risk was lower than those that are located close to farm silos, especially in situations where the farm silo has an existing infestation of grain insects.
“A key finding was that flight activity is strongly seasonal. We saw very few insect flights during the coldest months of the year and the learning here is that for industry, undertaking your main storage facility clean-up should be timed for winter.
“By removing residual insect populations in winter you can head off the rapid insect breeding and flight activity that we found linked to spring,” he said.
The research findings have been published for peer review and presented at various industry forums.
At industry days the team has focussed on the following key messages for farm hygiene practices:
- With flight activity being linked to seasonal changes in ambient temperature it follows that farmers and others who store grain should not delay hygiene practices until close to the wheat harvest (spring-summer), but undertake them well before flight increases in spring.
- Grain bulks were more likely to be infested on farms when infested grain was already present. This shows that farmers and others who store grain need to monitor their silos for insect infestations and to eliminate them when they occur.
- There may be no safe distance from farm silos to dump waste grain. Although the risk of infestation from waste grain will be reduced with distance, the safest option is to bury or burn the waste grain to reduce the risk to nil.
The research team has also completed ground-breaking work on analysing the movement of genetic material, or what is known as “gene flow”, amongst grain insects, to better understand how resistance to the fumigant phosphine is developing.
“When we looked at the flat grain beetle and resistance we found extensive gene flow in Australia, although it was somewhat restricted between WA and the rest of Australia” said Dr Daglish.
“We got a different story when we looked at the rice weevil where the gene flow was less distinct and this makes sense when we connect this to the knowledge we gained about how the weevil has limited flight dispersal”.
The gene flow results reveal the potential for movement of beetles and resistance genes within and between regions.