The varroa mite is expected to have a bigger impact on the agriculture industry than can be predicted.
All fruit and nuts and any vegetables that form as fruit, such as pumpkin and field tomato, rely on insects to pollinate their flowers.
Flowers that are not pollinated do not form a fruit or nut.
At present, pollination comes from three main insect groups: honey bees managed by beekeepers, native insects (including native bees) and feral honey bees.
The bee industry is heavily reliant on beekeepers placing their hives in orchards and farms during a crop’s flowering period.
Victoria’s almond groves flower during August which is a peak nectar collecting time for hives, which farmers hire from beekeepers.
There are not enough hives in Victoria to service either our almond or canola production (which starts straight after August), so hives are being permitted this year to come from NSW.
It is this relocating of hives across the border which is expected to bring varroa mite for the first time onto Victorian soil.
The biggest unknown for food production is the impact the expected loss of feral bees will have on food production.
Feral bees are common European honey bees which have swarmed from their managed hives into the Australian bush where they make new hives in tree hollows and under rocky ledges.
They are unrelated to Australia’s native bee species.
Because feral hives will not be managed for varroa mite, any infestation will simply kill a hive, and so the pest is expected to wipe out the entire feral bee population in only a few years.
The unknown factor in all this is how much the feral bee population contributes to pollinating food crops.
There is very little research on this and I think there should be urgency in wanting to find out, now that varroa has landed.
A single paper from Western Australia 18 years ago has flimsy estimates due to very little survey work done to date.
However, using the smallest estimate from the study, the feral bee population in Australia could be 33 times that of managed hives.
Therefore, wiping out the feral bee population may have a much larger impact than can be expected.
Tempering these numbers, however, is the consideration that horticulture takes up almost half a million hectares nationwide (Victoria has one quarter of that area) and calculating the numbers again within these regions suggests the impact is much less with there being in fact a reversal of fortunes: 50 managed hives for one feral hive.
That’s where the research stops and where the ecologist asks ‘where to from here?’.
One can hypothesise two things.
The 50-to-one ratio assumes an even spread of feral hives across Australia; therefore, there is little to worry about for food production.
Or else the concentration, management and growth in honey bees in that concentrated area is going to have more feral swarms spawned from it into the local bush, and of course being in a region of such high flower concentration will ensure those feral bees will want to hang around.
I wager that this is the most likely scenario, which suggests feral bees may be responsible for a sizeable fraction of our agricultural pollination.
But it’s not enough to guess.
We need to get the boffins out there collecting the numbers so we can forecast our managed hive needs into the future which I dare say will require many, many more apiaries.
As one of Victoria’s leading apiarists told me last week:
“This is the end of free pollination.”
Therefore we need the numbers now to plan for our food production.
Andy Wilson writes for Country News. He is a pre-peer review science editor in a range of fields and has a PhD in ecology from the University of Queensland.