Optimising pollination of macadamia and avocado in Australia (MT13060)

What was it all about?

In Australia, a significant amount of pollination is believed to occur as a free service by unmanaged feral honey bees and by other unidentified species, but the contribution of these insects has remained poorly quantified. Should the exotic mite Varroa destructor reach Australia, feral bee populations are predicted to fall so this preparedness project sought to identify the most effective pollination management strategies.

The aims of this project were to establish…

• The actual and potential rates of pollination in macadamia and avocado
• The floral biology of macadamia
• The key pollinators of macadamia and avocado
• Recommendations for optimising pollination.

The research team developed a large amount of data on macadamia and avocado pollination and the contributions of honey bees and stingless bees in orchards.

They concluded that there is considerable potential to improve pollination of macadamia and avocado in the regions that they assessed.

Recommendations for growers of these crops included the below.

For macadamia growers…

• Investigate more strategic placement of honey bee hives in orchards
  
  
• Monitor the strength of hives
  
  
• Assess pollinator numbers and yields
  
  
• Consider placement of stingless bees within orchards if pollinator numbers are low
  
  
• New orchard designs should incorporate more than one variety to improve cross pollen flow
  
  
• In blocks of one variety, consider removal of weaker or poor yielding trees and interplant different varieties
  
  
• Prune trees to encourage bees to visit flowers
  
  
• Time pesticide application to avoid periods of pollinator activity as much as possible
  
  
• If pesticide application is necessary, try to apply pesticides with short life (less than 12 hours) in the evening.

For avocado growers…

• To improve honey bee effectiveness, avoid siting new avocado orchards near to citrus blocks, which provide competing bloom
  
  
• In tri-state orchards, the receptive period of Hass flowers occurred at a wide range of times during the day, so pollinator diversity will increase pollination.
  
  
• Minimise the use of pesticide during flowering to avoid losing pollinator diversity.
  
  
• Growers paying for hives should be encouraged to observe honey bee foraging activity at different times and on different days to determine whether honey bees are visiting their orchards.
  
  
• Encourage non-bee pollinating species including blow flies and some hover fly species.

Further understanding of factors influencing populations of key non-bee pollinators of avocado is needed to inform farmers of management practices that will retain their populations.

ACT NOW

• The project discovered that blow flies are actually the chief pollinators of avocados in the Sunraysia – read more in this Hort Innovation article

• Read an article about the project on ABC News, about tracking bees and insects in macadamia orchards