Bee Tubes in Fruit pollination
Abstract
Bees kept in cardboard tubes are a new development for orchard pollination which solves some orchard problems.
I
will run through what we have done with these things. The tube itself
has won a few awards. It won an award at Karragullen in '97, state
government award about '96, and an award in Canada last year. It is
mainly set up for people who have high density orchards where they
plant with trellising, or on remote stations. To get bee hives there to
put on their rockmelon or watermelon crops is expensive and difficult.
It is easier to send them a package of bees they can use for about 10
weeks or so and then dispose of them when they have finished
pollinating.
Some of the beekeepers
who have used them have modified them a little bit. These have been
wax-dipped so they are a little more waterproof. It adds to the cost,
but this fellow was doing quite well with them. This is what I mean by
high density orchards. The trees trellised into one single plane offer
barriers to the feral bees from the forests. Some of the rows are too
long for honeybees to penetrate very deeply. Some growers haven't left
enough room for bee hives in groups, and the method of putting single
bee hives in the rows is very time consuming. If you have big orchards,
you can't fit big trucks down the rows, which makes it difficult to
carry out pollination effectively.
With
the tubes, bee densities in orchards can be manipulated. You might be
in a forest situation where there is a high density of feral bees, or
you might have a commercial beekeeper delivering hives for pollination,
and what happens is the bees, at distance, when they are away from
orchards too far, show a steady decline in numbers penetrating the
orchards. Once bee numbers are down in orchards, yield drops. If you
can manipulate the bee density to reasonably high levels in the orchard
by putting in disposable hives or other methods of getting bees or
insects into your orchards, there is a steady increase of yield, which
is what the grower is always looking for.
One
thing about apples, once the pollen germinates, it forms a pollen tube
that goes into the ovule and forms a seed. The more seeds you get in
apples, the higher the calcium content which gives the apple a higher
ability to be cold-stored, to give a longer shelf life in the
supermarket. With the lower calcium content, there is a fruit disorder
that makes the fruit go brown inside, especially during cold storage.
In
Japanese plums, a common variety, as you get more insects into an
orchard, yield goes from about 22 kg per tree up to about 30 kg, just
by increasing the pollinating insects. One way of doing it is to use
some sort of disposable pollinating system. These plums are growing on
trellising in high density orchards. There are many types of trellising
used in orchards.
Up in the north of
Western Australia, where we use these tubes in melons and curcubit
crops, which are grown in big, long rows; the longer the row and the
longer the distance from the bees, the less yield you get, because the
percentage of foragers decreases over distance. After about 500 metres
the bees on this crop are down to about less than 10%. With many of
these curcubit crops, eg rockmelons, water melons, pumpkin, because
they have so many seeds, the flowers need a lot of pollen. Each pollen
grain forms a seed. You need that seed development to form the actual
size of the fruit. If you have less than 400 seeds in a rockmelon, you
won't get a commercial-sized rockmelon. A lot of research shows that if
you get about 8 bees visiting every flower, you will have a successful
commercial crop.
Beetubes
are made out of cardboard and hold about a kilo of bees, plus the queen
bee. They have to actually build their own comb in there. You feed them
sugar syrup or honey to get them established. In about 4 weeks they
have the comb established, and then a huge volume of pollen starts
coming in to feed all their young.
We
experimented with this tube, just to make sure that it worked. We set
up an experiment in a cherry orchard where we had Tatura trellising,,
the varieties used were Van and Bing. In order to get the distance
between the rows, to separate experimental treatments so we could
manipulate the bee density in each of the rows, we actually bulldozed
one row of cherries in every second row. In this particular row we used
3 tubes. Another row we used none. This zero bee tube row was in the
middle of the rows where we put bee tubes in. The other row at the
other end had 8 tubes so it had quite high density. There were
pollinator trees (Bing) every third tree, so the insect shift of pollen
between the two varieties was quite good. This is essential to get the
yield of cherries.
Then we monitored
what the bee densities were doing. This is the 8 tube row; it is just a
wall of flowers. When you have the bees in there they move up and down
the face of flowers on the trellis. When you look down the next row,
the bee penetration across rows is not great. In some years it is, and
depends on the weather. On an overcast or wet day the bees stay fairly
close.
This is the feral bee
population before we started, a year later. We were getting less than 2
bees per tree. An orchardist won't get an economic yield off the trees
with that. When you put the bee tubes in, you can get the density up
around 10 or 11 bees per tree, which is about what you need for a
commercial crop.
In the zero bee tube
row, you see only a few of the flowers produce fruit. Essentially, it
was a very poor yield. That is what you would see in an orchard that
has very low bee activity. Subsequently, the tree yield in December was
just a smattering of good-sized fruit.
In
the 8 tube row, you can see a lot more flowers are pollinated, and you
can see it in the harvest in December where there is a lot more fruit.
These trees were running at an average of about 30 kg per tree, whereas
the trees in the centre, where there were no bees, were running at
about half that. About half, or 15 kg, would be of export size.
This
is an illustration of what happens with the bee densities. This is the
basic export size of cherries: anything bigger than that is exported,
anything smaller, the exporters don't want. You see where there are
high densities of bees about half the fruit are big. The trees in the
centre row produced less fruit, but there was an increase in fruit size
so that essentially the whole 18 kg yield is export size. When we got
to the 3 tube row, we were averaging 32 kg per tree. We also had a much
higher number of cherries that moved into the export range, compared to
the 8 tube row. In this experiment, the 3 tube density was about the
best in that situation. It just illustrates that manipulation of basic,
simple bee densities in an orchard can have some dramatic results in
yield. That is what orchardists are looking for in their income.
When
we first started this experiment, the trees in the orchard were 7 years
old. We hadn't had any bee hives in the orchard and consequently we had
low yields. From 1993 to about1995 we brought some bee hives in, and we
had mixed yields, up and down, because the hives had to be placed some
distance away from the orchard. If it is raining or overcast, bees will
only fly when it exceeds about 12.6 degrees. Anything less than that,
they generally don't forage. This variable yield here is because the
hives were situated away from the orchard. We think the weather had a
big effect on the bees.
In 1996 and
1997, two years in a row, we had bee tubes in the orchard and both
years we had pretty good yields, quite consistent yields. Some people
said the yields were up because the trees were getting older. This is
year 14 out here: we took the bee tubes away and just relied on the
feral bees. In that year, '98, the yield fell back to 10 kg on average,
from roughly about 30 kg. So it is quite a big difference. That
demonstrated that the bee tubes were actually working and doing their
job, it wasn't a tree age effect.
Because
of the differences in distance, this one is the 8 tube row, the
cherries were more mature more quickly. This one was the centre row,
only 30 feet away, with no tubes in it. You see there is quite a
difference in maturity of the fruits. Because of this, we felt that
there was some application in which you could use bee tubes to muck
around with the dates of picking, and therefore orchardists could have
have their workers working different days to do all this instead of
having them all there all the time. You could actually stagger the bee
tubes and have the fruit maturing on different days, so it was a little
fresher when it was picked.
These
are the frames of brood the bees build in these tubes. Each cell
contains an egg the queen bee lays, that develops into a larva. Larvae
must have pollen. They must have protein, which the bees eat. They have
little glands in their heads that make royal jelly out of the protein
in pollen, called worker jelly in this case. They are feeding worker
bees. There is a continuous cycle of bee breeding. To produce those
sorts of numbers of bees you need a lot of pollen. When the bees go
into orchards, they really have to hammer the trees to get pollen to
survive. That is basically why the tube works. It puts the bees into an
artificial swarming mode, where they actually have to survive. To
survive, they have to work hard. Sometimes they work themselves to
death in about 10 days.
Each bee hive
maintains itself at 35 degrees, so it is fairly warm inside a hive,
especially if it is cold outside. They have to burn a lot of
carbohydrate (from nectar) to generate heat. The orchard trees don't
produce a lot of nectar, so they run out of nectar and they run out of
heat and the colony of bees collapses.
It
is typical of the way comb gets built. You can rip the red lids off and
look inside. This has been blown with a bit of smoke to clear away the
bees, so you can see the comb.
Q. What do you do with the hives if you are spraying with insecticides?
A.
We hang them up in the orchards. They have a hook we use to hang them
on the trellising. We just get a garbage bag, slip in over and pull
tight. Then the sprayers can come through in the evening, about 4 or 5
o'clock. We get them to use lower toxicity sprays, maybe six hour. Then
the following morning, the bags get pulled off and they are away again.
They have to be released before the sun comes up or they will get too
hot. There is no loss this way. Whereas, with bee hives you have to
actually remove or cover them.
This is
what I mean about 'excluders.' When the bees squeeze past each other,
each bee has a heap of pollen on it, coming in from the orchards. As
they move backwards and forwards through here, the body hairs will mix
the pollen up. The pollen coming in gets mixed with the pollen coming
out. The black plastic here has a positive charge that it picks up from
the bee movement. A lot of the pollen sticks to the edges of the
plastic and gets mixed around by the bees. This is its purpose.
Because
there are so many bees milling around, bringing in lots of pollen, the
pollen gets knocked off their legs and you will see bits and pieces on
the ground here. A lot of experiments show that if you remove the
pollen from the bee the inside of the hive gets more and more short of
pollen. More and more of the bees that go to collect nectar get changed
over to foragers for pollen, so it actually increases the pollen yield,
and increases the effectiveness of the bees in the orchard.
Here
is another plum orchard. You can see bees flying around the six tubes
here. You can go to the next bay and see a few, and then in the next
bay there is nothing. These new man-made structures in orchards are
almost like barriers to bees coming in. So if there are hives situated
in front, the penetration isn't very good. In Europe they find there is
a huge depression in yield in the centre of orchards. They lose lots of
money on it. You could actually run lines like old fashioned washing
lines that can be raised and lowered. You can hang the bees on that and
raise them up so they are flying above the trees.
We
have used them in avocados. After a period you get quite a build-up of
the bee population, so you have all these bees to feed and they chase
the pollen.
These are rockmelon crops
up in the north west of Australia we pollinate with the tubes. A lot of
this stuff is planted in rows a few weeks apart, so there are always
plants coming on. Once the rows have been picked they are hoed in and
the next row comes on stream. The bees have to be kept moving from row
to row. We can keep bees in a 5 degree cold room for about six days,
provided they have a fair bit of honey in with them. Most of the
growers have cold rooms. They can take the bees out and put them into
the next row when they need them.
We
pioneered a delivery system of bees in chiller trucks at 5 degrees C.
We have taken them from Perth all the way to Broome, Derby, and
Kununurra. We could take them anywhere in Australia by that method.
This
is the first batch we sent up, just a little batch of three, all wired
up, a test run into a rockmelon crop at Broome. You can deliver quite a
few in a ute which can fit down a row in this high density orchard,
whereas some of the trucks can't get in, can't deliver the bees, and
have to put them away from the orchard, which defeats the purpose. In a
lot of orchards now, you will see bird netting. A lot of trucks can't
fit under the bird netting, and the bees can't go in, so these have to
go underneath. Beetubes are more effective than the traditional bee
hive. They are a lot easier to use.
Q. Does putting bees in an orchard keep other insects away?
A.
I have noticed that putting bees in an orchard seems to generate a lot
of insect activity, especially hoverflies. It has been demonstrated
that once you have removed nectar out of a flower, the flower actually
secretes more. So over a period of 5 days that a flower is open, if you
keep taking nectar out, it keeps pumping out more and more. Nectar is
the attractant for its pollination system, for the plant to survive,
keep evolving.
The other thing, when
you have tubes in these sorts of trellis orchards, when there is a lot
of background weeds, capeweed or radish, for instance, these plants are
more attractive than plum flower. The nectar and pollen in these plants
differ. The oil content of pollen from the capeweed and radish is much
greater than the oil content of plum flower pollen, and the bees can
prefer the high oil content pollen. If you haven't got all this mowed
down, you have got Buckley's of keeping the bees on the target crop.
I
was going to explain that normal bees in hives do have a disease called
American Foulbrood, a bacteria that affects the larvae. It is quite a
persistent disease because it forms spores. Everywhere in Australia
there is a Beekeeper's Act that is quite specific about this American
Foulbrood disease. Rules and regulations about where you shift bees and
quarantine because of this disease. But, because we are wanting to
shake a lot of bees into these tubes the industry was concerned that we
would spread this disease around and affect them. In the beekeeping
world honey samples are tested in the agricultural labs and the spores
germinated on a special agar plate, which tells anybody looking at the
agar plate how infected the honey is with American Brood disease.
So,
we did some experiments where we shook fairly heavily diseased bees
into tubes and maintained them for sixty days, which is long enough for
them to be used in pollination. Pollination of cherries and almonds
occurs in 10 days, so there is a fair bit of leeway there. It was just
to show the beekeeping industry that this was a reasonably risk-free
method even if we happened to shake some diseased bees out of a hive.
Therefore we wouldn't be spreading disease. The infection dropped down
to almost zero after 60 days when we tested the honey in these tubes.
Diseased bees have spores on their bodies and in their guts. So, what
it means is that when we sampled the bees sixty days later, all the
spores that had been there previously, had presumably been locked up in
the wax they built. The bees have wax glands under their abdomens and
they convert the honey they eat into wax. Their systems are purged of
spores.
Last year, we were looking at
something a bit bigger, for some of the cooler climates such as
Victoria. Bees in buckets have been developed in a similar system,
except now these can be filled with two litres of sugar syrup to keep
the bees going in terms of generating heat in the cold weather. Being
active enough to pollinate during the ten or so days they are needed in
the almond orchards. It is just another way of getting bees cheaply to
an orchard to do the job.
Another
reason for beetubes is that people involved in food have all these new
rules to follow in health and safety, food quality. Because,
traditionally, all the hives that were honey-producing hives went into
orchards when beekeeper opportunistically used them to pollinate, there
have been some instances where honey was contaminated with chemicals
the orchardists used. If that is detected going into our export honey
market, the export market can be ruined. So we try to shake the bees
out of these hives into special containers that are just used for
pollination, and then are destroyed after use.
We
are still trying to push the beekeepers down the track of taking the
honey hives out of the orchards and using something different. It is
perhaps a new business proposition for them. Something that may make
them more profitable.
Q. What happens if there isn't enough pollen?
A.
The bees will starve if we don't give them supplementary feedstuff. A
lot of research has gone into it; there are a lot of artificial feeds
you can make up that contain pollen that has been collected by
beekeepers. It is mixed with high-protein stuff like soy flour or
yeast, and that is blended into a patty and fed back into the hives and
the bees eat it. It contains their protein, and it maintains the young
bees, just for the short interval that you might need before you go
onto another crop.
Q. Do you take bees to warm places like Carnarvon?
A.
Yes, we take bees up there. There are low-chill plum orchards there on
trellis. We have sent them to Kununurra which is probably the hottest
place.
Q. Neem trees have a seven-week flowering period in January-February. Neem makes good honey.
A.
Yes, you would have to migrate the bees after that, they could probably
go onto Wandoo, which starts January, February. Powderbark, which is up
in the hills, and that will follow into the Marri, in February, March.
Q.
Are any commercial honey producers looking at bee tubes? A. There is
not enough honey in them to be worth doing it that way. There are about
six beekeepers going into bee tubes, one is quite large. Beekeepers
won't deliver hives to people who only want about six, because it is
not economic, so they switch them on to tubes which they pick up. We
have had people come in and pick them up and drive away home, as long
as the air conditioning is on to keep them cool.
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