Small hive beetle preparation in a La Niña event

During a La Niña weather event, eastern Australia is likely to be wetter than average, with an increased risk of heavy rainfall and widespread flooding. That will result in higher humidity, creating greater opportunities for small hive beetle to successfully breed and affect honeybee colonies not at full strength.

Small hive beetle (SHB) (Aethina tumida) is a small brown–black beetle with clubbed antennae which originated from sub-Saharan Africa. In Africa, the SHB is not a significant honeybee pest species. However, since arriving in Australia in 2002, the SHB has had a major impact on honeybee colonies throughout the warm and humid coastal strip between Victoria and North Queensland.

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SHB infestations in strong honeybee colonies, that have frames with 100 per cent bee coverage, have little or in most cases no impact.

These beetles fly up to 15 kilometres in the search for honeybee colonies to infest. Hives that are weak or queenless are favoured targets as they are attracted to the honeybee pheromone that indicates the colony is in a compromised state.

Beetle eggs require higher temperatures in conjunction with high humidity for successful hatching conditions, which have not seen in large areas of eastern Australia in recent years due to drought.

La Niña events in 2010–2011 and 2011–2012 saw considerable damage from beetle larvae in many areas of Victoria. These included:

• spoilt frames after small hive beetle larvae tunnelled through the combs
• small hive beetle eating pollen and bee brood (eggs, larvae and pupae)
• small hive beetle defecating in frames causing fermentation, creating a fermenting citrus odour
• honey bee colonies absconding due to odour and stored honey no longer palatable for honeybee consumption
• honey bee queens cease laying eggs, resulting in hive strength decline
• beetles taking control of the honey bee colony with their larvae sliming out the entire hive, slim being evident at the entrance of the hive where the larvae had exited the honey bee hive to burrow into the nearby soil to pupate and eventually emerge as an adult.

What can we expect for our honey bee hives during a La Niña weather event?

Beekeepers will most certainly see increased small hive beetle activity, with small hive beetles being attracted to apiaries which are not full strength or have the warm honey ripening odours that beekeepers also enjoy. Minimising the opportunities for small hive beetle damage should begin now by:

• maintaining strong colonies that have 100 per cent coverage of the frames
• uniting weak hives
• minimising the time clearer boards are under honey supers
• ensuring bottom boards are clear of debris that offers refuge for small hive beetle
• avoiding using beekeeping equipment which has cracks and splits in the woodware, as these offer hiding spots for beetles
• minimising hive manipulation where possible.

How to minimise the impact of small hive beetle

Below are some tips to assist you manage this pest.

• Good colony management, such as maintain strong colonies, minimise opening the hive, minimise the cracks and crevices of the hive and remove burr comb and propolis, ensure hive is in a sunny location and well ventilated.
• Maintain good apiary hygiene and avoid using untreated infested hive material.
• Install products that trap and bait SHB (as they seek protection from the harassment of the honeybees and light). However, ensure if needed you fill these with approved products.

Diatomaceous earth (DE), also known as amorphous silica, is sometimes recommended as an in-hive small hive beetle control in other states or online. Beekeepers need to use only ‘food grade’ DE and to ensure they are using DE products which are registered agricultural products.

All DE products used in beekeeping must be registered with the Australian Pesticides and Veterinary Medicines Authority (APVMA) all the registered products will display on the product label an APVMA Approval Number.

Find out more about using chemicals.

Floods and small hive beetle

There are two types of flooding (flash and riverine) that can affect your apiary. Therefore, placement of your apiary is critical in managing for flood damage and secondary small hive beetle impacts.

Flash flooding

• Flash flooding usually results from intense storms with high rainfall intensity in a short period of time.
• Flash flooding occurs with little or no warning, can be fast moving, dangerous and destructive and can reach full peak in only a few minutes.
• Response to flash flooding is highly reactive.
• Some areas burnt in last summer’s bushfires will have an increased risk of flash flooding.
• These type of flood events subside quickly.

Riverine flooding

• Riverine flooding is a result of high rainfall over extended periods of time over a catchment area which may result in rivers and/or creek systems ‘bursting their banks’.
• The size spread and how long the flood lasts can depend on the landscape and how much rain has fallen.
• A longer lead time and flood intelligence may allow for time to plan and respond.

Find out more about preparing for a flood.

Damage to your apiary from both types of flooding is avoidable by good summer apiary location selection. Areas of higher ground not subject to flooding and looking at vegetation types including ground flora are often a good hint in selecting a site and the likelihood of it being inundated.

During El Niño or dry summers afternoon shade is desirable. However, during humid moist summers as predicted in the current La Niña, hives positioned in mottled shade are also attractive to SHB.

Hives that have been subject to flooding or that have water inundation in the brood or bottom box are highly susceptible to small hive beetle attack and will quickly succumb to total slime out by larvae.

Access to and from the apiary prior to and after heavy rainfall or localised flooding will assist access for hive swarm management, brood examination, honey harvesting and SHB monitoring and management.

Flooding during 2010–2011 and 2011–2012 resulted in several apiaries being locked in flooded areas where vehicle access was not possible, and some of these apiaries were severely affected by small hive beetles. Agriculture Victoria conducted a survey to assist in determining the impact of the 2010–2011 flooding. Key statistics included that 535 hives were reported as swept away in flash flooding and 1,077 hives were killed through drowning or suffocation in riverine flooding. Many of these hives succumbed to SHB attack.

A La Niña weather event carries a prediction of wetter than average conditions. Beekeepers should choose their apiary sites carefully with flooding in mind. SHB will flourish in the predicted weather conditions.