Monday, December 12, 2011
In the 2011 season we were interested in increasing Osmia lignaria populations as well as O. aglaia, and that created a problem for cleaning out the bees. Although the two bees typically use different diameter nesting holes, apparently many of the O. lignaria were small enough to nest in the O. aglaia Binderboard. That presented a problem cleaning the bees, because we wash the O. lignaria cocoons to remove dirt and other debris and to wash off mites, whereas we don't wash O. aglaia cocoons. There was also a risk that if the bees nest together, mites will transfer to O. aglaia cocoons. We haven't seen mites on O. aglaia before.
We saw few if any mites on the O. lignaria nests, and didn't see any on O. aglaia. There were only a few Binderboard that had nests of both species. However, there were quite a few O. lignaria cocoons infected with Monodontomerus parasitic wasps. I removed as many as I could identify from the washed cocoons. Our final yield of O. lignaria was only 1.25 cups of cocoons with about 236 females per cup. Females were 35% of the cocoons. That means our total yield of females was about 300, enough to pollinate an acre of fruit trees, in theory. Compare that with a yield of 420 females from Sturm farms in 2010 that were released in spring 2011. To that we added about 90 additional females from other sources in Portland. That means our yield was about 58% of last year's yield. Not good.
The O. aglaia did not fare much better. Last season we removed about 31 cups of cocoons from the nests, with and estimated 21,700 bees. We did not try to estimate sex ratio. This year our total yield was about 10.3 cups, with about 650 cocoons per cup. That's only 6,700 cocoons total, 31% of last year's yield. Many of those cocoons had larvae in them that had not fully developed into adults. That suggests that the summer was not warm enough for the bees to complete development. We had the Sturms leave the cocoons in their garage for a month or so, in hopes that the temperatures would be warmer than on the porch where the cocoons have overwintered in the past. Hopefully more of the cocoons will complete development.
Why such a poor bee yield in the 2011 season. Certainly the cold, wet, late season must have had an impact. But perhaps the high numbers of honey bees also had an impact. There may not have been enough pollen for everyone.
Don says that the berry yields suffered from disease this past season, but the black raspberry had good pollination. Perhaps the presence of our managed native bees had a positive impact on the pollination, even if they did not reproduce as well as we would like.
Monday, July 4, 2011
The bees spent quite a bit of time sunning on the ground around the shelter; I even saw some sunning amongst the blueberry plants.
Here's an O. aglaia couple mating on a black raspberry leaf. Usually mating takes place early in the life of the bees, so this is further evidence that the O. aglaia had probably not yet started nesting.
We added some additional Binderboard nests to the shelters before we left. Here's the webcam shelter on June 17 after adding the additional nests. Before we left we put the lids back on the emergence containers and moved them to the sides of the shelter.
We also added more Binderboard nests to the Marion Berry shelter before we left.
One last thing that I should mention. After taking one last ride around the farm to see if there was any O. aglaia activity yet at Jim Cane's shelters (none seen) we saw Don's beekeeper setting up more honey bee hives just east of our marion berry shelter. There were 10 hives with a total of 24 supers. This makes a total of 29 honey bee hives in Don's fields. That's a large number. It will be interesting to find out if they have impact on our O. aglaia reproduction this season.
"We have some additional funds to field test this same strategy with a berry grower here in western Oregon and Washington, and I wanted to check with you to see if this might be a useful opportunity to compliment your existing Osmia aglaia project?"
Naturally, I suggested that the Sturm Farm might be interested in participating, but it wasn't until my visit to the Sturm Farm in June that I was able to arrange for Don and Eric to meet. Fortunately Eric was available on short notice to come out to Corbett the afternoon of June 16.
It turns out that Don already has an NRCS grant for wildlife plantings, so the Xerces grant will supplement it and provide some guidance on the most suitable bee-friendly plants. Don had a meeting at 1pm that afternoon with the local NRCS representative, and then he hurried back to the farm to meet Eric at 3pm. Eric showed up with another Xerces staff member, plant ecologist Brianna Borders. By then the clouds had cleared and the sun was out. Don loaded us into his truck for a quick tour of his 140 acres of berries, including all of the O. aglaia shelters.
Here we are at Jim Cane's central bee shelter near the marion berries. Don is on the right in white shirt; Eric is in the center with Brianna behind him, and my husband John is on the left. Notice that we moved the bee nests from the pallets on the right to the new wood shelter. If the bees had been active this would not have been a good idea, because they would not have found the new nest location. But since the bees were not yet active, it was a good time for the move.
Don and Eric decided that this location would be the best place on the farm for bee-friendly plantings. It's central location will make it accessible to bees from other parts of the farm, and this open area will be easy to cultivate. in preparation for planting.
In addition to checking out the nest sites for O. aglaia, we spent a little time seeing who was visiting the black raspberry. There seemed to be far fewer bumble bees in the afternoon than in the morning, when it was overcast and cold. I had collected a few of the bumble bees that I saw in the morning, and Eric identified the more common species as either Bombus melanopygus or mixta, and the less common species as B. vosnesenskii (see photo of this species in Part 2 of the posts on black raspberry bloom).
We also noticed a neat hole at the end of a prunned raspberry cane. Eric used his pen knife to slit the cane open, and there we found a couple of Ceratina sp., the small carpenter bee. This genus makes it's nest by burrowing into pithy stems such as Rubus canes and dead common mullein stems. One has to cut the stems so the pith is accessible to the bees. After creating a nest with a series of offspring cells in the stem, the mother Ceratina bee guards the entrance of the nest and periodically checks on her developing offspring, according to a thesis from University of Georgia in the 1970s. There were two bees in this tunnel, and not much of a nest, so I suspect that these bees were just beginning to nest. Don says that he leaves the prunned canes in the black raspberry but not other berry varieties. I recommended that he cut the brown stems of last year's common mullein stalks that are found around the edge of the farm so there are more nesting sites for Ceratina. There are some in the Himalayan blackberry patch where Jim Cane's mail tote shelters are located. Ceratina is probably a good raspberry pollinator, and it would be great to increase their populations.
Hopefully Eric and Don are moving forward on this project. Maybe we can get some photos of the site as it is planted on this blog. Eric is also hoping that we can have a farm field day next spring to showcase the bee plantings and alternative bees.
Sunday, July 3, 2011
Last year all of Jim's bees were released in the southwest corner of Don's field, next to a large patch of Himalayan blackberry (see last year's posts). They were released in several of Jim's mail tote shelters. This year three mail tote shelters are back, flanked on either side by one of Don's dad's wood shelters. The first photo shows the shelters from the west end looking east, the second photo shows the shelters at the east end looking west. The straws with bees are all in the wood shelters. We saw no O. aglaia activity in these shelters, but we did see a couple of O. lignaria working on nests in the wood shelter in the farthest southeast corner (first photo). As of June 17, the Himalayan blackberry had lots of buds but no bloom.
We did see O. lignaria in this third set of shelters. Some of the bees were hiding under the wood shingles of the roof. One is seen in the center of the first photo. Can you see the two in the second photo? They look superficially like flies, but they are O. lignaria. One is on the board on the right, the other seen from the side, between the boards.
Wednesday, June 29, 2011
In this post I'll address these questions:
-Does O. aglaia forage from black raspberry?
-What other bees forage from black raspberry?
-What other flowers does O. aglaia visit, and what else was available to them on the Sturm farm?
Notice that I won't say what's pollinating the raspberry leading to mature fruit. In many cases when bees visit a flower, they pollinate it, but not always. The only way to be sure would be to carefully control the visits that a flower gets by particular bee species, and then to follow the flower through fruit development.
When the sun poked tentatively through the clouds on the morning of June 16, the first foraging O. aglaia that we saw were visiting white clover and dandelion. These were the closest flowers to the webcam shelter. The O. aglaia seemed to be taking nectar but not pollen.
Sorry about the blurry image. It documents that O. aglaia foraged from dandelion. (Actually, on second thought this looks like it might be Agapostemon or Augochlora! - July 20)
When the afternoon turned sunny, we saw O. aglaia on the black raspberry flowers! They move rapidly, so they are hard to photograph on the flowers, but I managed to get a few photos of the foraging females. The first female is visiting a bud that is just starting to open.
I'm pretty sure that's a nectar visit. According to McGregor (Insect Pollination of Cultivated Crop Plants, Agriculture Handbook No. 496, 1976): "When the flower opens, the anthers are immature, with the filaments bent over the immature styles. Subsequently, the outer stamens bend back toward the petals and their anthers dehisce. As dehiscence progresses toward the center of the flower, the receptacle expands, the styles grow, and the receptive stigmas appear at their tips; later, the anthers nearest the stigmas dehisce, and, if cross-pollination has not already been brought about by insects, some selfing may result. The degree of such selfing seems to vary with species and cultivar, but most of them are largely self-sterile."
It's hard to be sure from this photo, but it is possible that there is a little pollen on the underside of the abdomen of this bee. We looked hard to try to determine if there was pollen in the scopae of bees returning to the nests, but did not see any either on foraging bees or on bees returning to the nests. I suspect that the O. aglaia were just beginning to search for nesting sites at this time.
A variety of other weeds were available in the area around our bee shelters, but none as abundant as white clover and dandelion. In addition, there were two crop species near the webcam shelter. South of the shelter was a small strawberry patch with blooms as well as immature and ripe berries. Just east of the strawberries were some blueberry plants in bloom. See the earlier post about bee introduction in May. On June 17, a sunny day, I saw few bees visiting the blueberry: especially compared with raspberry visitation. There were a few bumble bees. I saw some O. aglaia sunning on the ground in the blueberry patch, and I'm pretty sure that a couple of them flew up to the blueberry flowers, but I didn't get a good look at them.
Here's a photo from the west side of the Sturm fields. The white shapes on the left are honey bee hives.
Don doesn't pay anything to get honeybees in his berry fields. Rather, he works with a beekeeper who is happy to bring hives to Don's field because of the absence of insecticide sprays. On June 16 I counted 19 hives with a total of 50 supers in this row near the west end of the fields. Then on June 17, the beekeeper added 24 more supers in 10 hives closer to the marion berries where our second Osmia shelter is located. I hope that's all that were brought to the field. The honey bees are likely to have an impact on the growth of the O. aglaia population.
Bombus vosnesenskii is one of the species of bumblebees foraging on the black raspberry.
She is apparently only taking nectar, because there does not appear to be any pollen on the corbicula of her hind leg.
In addition to the honey bees and bumble bees, we observed a few ground nesting bees foraging on the black raspberry on June 17. The morning was sunny, though the temperature was only 55oF. These included some small Lasioglossum (Dialictus), and possibly an Andrena.
Visitors to the black raspberry seemed to change with the weather. The morning of June 16 there seemed to be equal numbers of honey bees and bumblebees in the cool, overcast weather. That afternoon when the sun came out the bumble bees became much less abundant.
We decided to quantify the numbers. At 5:45pm John and I each counted bee visits to 6 inflorescences of black raspberry close to the webcam shelter for 15 minutes. The temperature was 65oF, and the sky was overcast. John counted 10 honey bee visits and one visit by a Lassioglossum or Andrena (on 11 young open flowers, 41 total flowers in 6 inflorescences). On a different patch of 6 inflorescences I counted 19 honey bee visits (on 10 young open flowers, 73 total flowers in 6 inflorescences).
We repeated the counts on the morning of June 17. The temperature was 55oF, the sky was sunny. We started our 15 minute counts at 10:17am. John counted 23 honey bee visits, 2 O. aglaia visits, 2 Lasioglossum and 1 fly visit (on 10 young open flowers, 49 total flowers in 6 inflorescences). I counted 27 honey bee visits, 12 O. aglaia visits, and 6 Lasioglossum visits (on 17 young open flowers, 38 total flowers in 6 inflorescences). . We saw a few bumble bees, but bumble bees were much less abundant than they had been on the cold morning, and they did not show up in our counts.
One mystery that we never solved: What were the Osmia lignaria visiting? They were active at the shelter, even in the cold June 16 morning. They seemed to fly toward the blueberries, but I did not see them foraging on blueberries or raspberries. The nearby maple trees had developing fruit, so they were not attracting bees. So, it's not clear if the blue orchard bee was contributing to pollination of any berries.
The previous week had seen a couple of sunny days which brought out the bloom, but for the most part, the weather had been cold and damp all spring. Sun was predicted when we set out for Corbett, but on the morning of June 16 it was still overcast, with a temperature of 52oF at 10:24am.
When we got to the shelter next to the webcam (not yet functional), the first thing we did was remove the lids from the Osmia aglaia emergence containers and move them to the front of the shelter, in hopes that the bees would warm up quicker and fly. There were lots of emerged adult O. aglaia amidst the frass in the containers. It amazes me that they were still alive, since they probably had only one or two days of good weather since they had emerged about a month earlier. But the morning of the 16th they were not doing much. Here's what the shelter looked like after we arrived and opened the containers.
As the morning started to warm, O. aglaia began to appear from under the floor of the shelter where apparently quite a few bees, especially males like these, were hiding. Osmia lignaria (the big black bee sitting on the container lid) were more active than O. aglaia, but they also spent much of their time resting or waiting for the sun.
It's amazing to see these large female O. lignaria coming out of the small tunnels. Rosie had told us that the O. lignaria were using many of the smaller diameter tunnels, though larger tunnels are available. They seem to prefer the tunnels at the bottom of the Binderboard. The plugged tunnels are O. lignaria.
Our second stop was the shelter in the center of the fields, near the marion berries. The photo at the top of this post was taken from that shelter. It has only two O. aglaia emergence containers. Here we also opened the emergence containers to encourage the bees to fly. The O. lignaria were active.
A closeup of the O. aglaia Binderboard shows an O. aglaia abdomen in one of the nest tunnels. However, most of the plugs in these 1/4" tunnels are O. lignaria plugs of chunky mud.
The O. lignaria Binderboard in this shelter already has 43 plugged nests out of 98 available. Probably the unplugged tunnels have nests under construction.
Despite the cool, overcast conditions, there were lots of bees flying on the black raspberries, though they were not the Osmia. We saw plenty of honey bees and at least two species of bumble bees. There were bees flying fast above the berry bushes, too fast to identify. However, when I caught them with my net, they turned out to be bumblebees.
More about our visit to Corbett in the next post...
Thursday, June 23, 2011
Put some out yesterday and the rest today. Everybody wants out so I hope ok. Black rasp. not in bloom yet. Blues real real close nice day would do it I was standing at shelter when I took the pictures of the fields close by. Some dandelions by shelter they are thick this year. Need to put out rest of nests for them also.
Rosie saw blue orchard bees on the dandelions in bloom near the shelter. Here's a male O. lignaria.
The black raspberries that were in the field east of our main bee shelter, where the webcam is located, were pulled out last fall. Don Sturm is planning to plant blueberries in this field, although he says he will plant some black raspberries close to the bee shelter so we can see them from the webcam.
Some blueberries have already been planted at the far east end of the field, and 100 yards southeast of the bee shelter. The rectangle of lighter colored soil on the right side of this picture is the closest blueberry field. As you can see, there was plenty of mud available for the orchard bees that day.