Japanese Encephalitis Virus (JEV) has recently been detected for the first time in February 2022 in South Australia, Victoria, New South Wales, and Queensland. It is a mosquito-borne virus that circulates between mosquitoes, water birds and/ or pigs, with the potential to be transmitted (via mosquitoes) to people.
Severe illness arising from JEV infection in humans is rare and most people will have no symptoms at all if infected. JEV infection is a nationally notifiable disease and must be reported if suspected/ detected in either people or animals.
JEV has been declared a Communicable Disease Incident of National Significance. Control measures are required where appropriate to break the disease transmission cycle, including the use of registered insecticides, a critical component of the response.
Beekeepers are advised that mosquito insecticide control will be undertaken as required throughout affected areas, and this will likely be ongoing for some time. The response is being undertaken with measures in place aiming to have minimal negative impacts on beekeeping.
Mosquitoes – land use area controls
Land use areas where mosquito control may impact honey bees
Two land use areas that honey bees could access where they may be exposed to potential mosquito insecticide control include:
piggeries: pigs are a host and a virus amplifier, are kept in high numbers, and are affected by JEV, whilst the large bodies of water associated with piggeries (including effluent ponds, dams, troughs, ditches, channels, and recently inundated on-farm areas) are ideal mosquito breeding grounds,
public and private land with land/ water body(s) recently subjected to inundation: sudden flood/ rain inundations, especially where water then ponds (at volumes greater than about ½ a cup) including recently flooded wetlands/ dams/ ditches/ channels, are ideal mosquito breeding grounds.
APVMA registered/permitted insecticides recommended for mosquito control
All recommended mosquito insecticide products are registered with the Australian Pesticides and Veterinary Medicines Authority (APVMA), and specific label/permit directions for use apply. When used as per the label/permit, there are two potential situations (locations) where honey bees may be exposed to insecticides (Table 1).
Beekeeper risk assessments
Some of the mosquito control insecticides may adversely impact honey bees if they were to be directly exposed to the product or treated surfaces (including treated building surfaces, vegetation and water). Registered/permitted insecticide labels/permits provide appropriate Directions for use to minimise these impacts; however beekeepers are advised to undertake their own risk assessments, particularly in relation to locating, monitoring, and removing hives if in proximity to these land use areas.
Considerations
To assist in determining the risks, consideration should be given to the following:
communication:
are you able to communicate regularly with the land manager regarding potential insecticide applications
are you able to communicate regularly with the land manager regarding potential insecticide applications
site location:
are you able to locate your hives a suitable flying distance from potential insecticide application area(s), noting that honey bees:
are highly attracted to some types of pig feed during times of pollen dearth,
shouldn’t be watering from/ accessing livestock farm effluent ponds/ inundated areas, at any time
is there sufficient floral resources to attract honey bees away from potential application area(s) over the time period hives will be present,
minimisation:
are you able to supply your own water in sufficient volume and of suitable quality such that bees don’t access water bodies requiring potential control,
are you able to manage the supplied water to prevent mosquito breeding,
is there vegetation around piggery shedding/ effluent ponds requiring spraying that is likely to flower over the time period hives will be present,
co-operation:
are you able to assist in monitoring vegetation requiring spraying for the presence of flowers/ honey bees prior to each spraying, over the time period hives will be present,
is the land manager able to undertake required vegetation spraying around shedding/ effluent ponds using a ‘least hazardous to honey bees’ product/ at night/ after hive removal (note – night spraying may not mitigate the risks to honey bees for some products),
qualification:
are you confident that any applied insecticide application will be undertaken using a registered/permitted insecticide as per label/permit directions,
preparation:
do you have the alternative sites and the ability to move hives off-property quickly if required,
do you have the insurance and resources to manage hives potentially affected by an insecticide application.
evaluation:
are you able to monitor your hives regularly to ensure there is no post-application side-effects,
Mosquitoes – beekeeper controls
In general, but particularly if keeping hives on land use areas where JEV is suspected/ detected, mosquito control is being undertaken, and/ or where mosquitoes are prevalent; beekeeper controls should include:
wear personal protection: beekeepers should ensure they are protected from mosquito bites, particularly when loading/ moving hives at night,
supply suitable water: provide water of a sufficient volume and of a suitable quality within 200 m of all hives at all times to minimise the potential for honey bees to access insecticide treated waters,
control mosquitoes in beekeeper supplied water: mosquitoes can breed in this water. To minimise mosquito breeding, either monitor and control, or control, as outlined in Table 2 noting:
completion of development (egg-adult) averages 6-10 days (September-April), and 30 days (May-August),
to minimise available mosquito larval food (eg. algae), and maximise control:
only use clean water (free from organic matter/algae)
place container in shade and screen using chicken wire to reduce inclusion of organic matter (eg. leaves/branches),
non-chemical control options include regular rotation of containers and landing platforms and by pressure cleaning then rinsing to waste, or placing in full sun to desiccate mosquitoes/ algae,
chemical control options include treating supplied water with registered/permitted insecticides/products as per label/permit directions, where approved for use and following a risk assessment that demonstrates at label/permit rates product safety to honey bees and product efficacy against algae/mosquitoes, (note – for further information on registered insecticides/products, refer to Further Information).
when monitoring, approach container slowly whilst facing into the sun, as cast shadows, vibration and sudden movement cause larvae to submerge to the point where sampling won’t detect any larvae,
if monitoring using a wide mouthed deep container (eg. 10 L white bucket/ purpose made mosquito dipper), sample using either a:
shallow stroke – insert horizontally into water so about half submerged (to collect from top 3-5 cm of water), and skim across surface, fill ≈ ¾ full, tilt bucket upright, and remove, or
quick plunge – insert vertically into water so fully submerged, wait 30 seconds, then remove vertically, (note – for further information on purpose made mosquito dippers, and larval sampling techniques, refer to Further Information).
Managing potentially insecticide affected hives
Given the uncertainties associated with suspected honey bee poisoning, management should generally be both proactive and reactive; and may include:
moving hives to a safe area, preferably where there is some nectar flow, and close enough to enable regular hive monitoring/ management,
match hive entrance and hive volume to hive strength (ie. remove supers/ place into nucs/ reduce entrance as required),
monitor for signs of queen failure (which may not show up until several weeks post-poisoning),
monitor for and prevent small hive beetle, wax moth and rodent damage (which may not show up until several weeks post-poisoning),
consider testing samples (collected and frozen immediately after detection), and/ or notifying your packer,
consider removing contaminated honey/ pollen (and potentially hive components), and replacing the water,
consider in-hive supplementary feeding (using thick syrup), whilst also preventing robbing by honey bees/ ants/ wasps,
consider strengthening/ uniting hives whilst preventing spread of affected product/ components between hives
