Friday, June 22, 2018

More Bees from Spring '18

Here we are halfway through June. How is it already summer? It seems like just a few weeks ago the pears were blooming and I was working in rain and cold trying desperately to get the spring work done with the honey bee hives. Now it feels like summer is in full effect, rain is less and less in the forecast, and multitudes of bees are busily seeking mates and provisioning nests!
Cuckoo bee (Nomada, Apidae) on arrowleaf buckwheat (Eriogonum compositum, Polygonaceae) in the wilds
The most familiar and recognized bees are honey bees, poster child of pollinator conservation alongside monarch butterflies. But the overwhelming majority of native bees in the US and the world are solitary and nearly half of those collect pollen from only one family of flowering plants. Of course, the plant family varies between different bees. Many of the most common bees are generalists who visit a wide range of flowers from many families. In either case, a diverse range of flower types from a range of families is the best for facilitating a diversity of bees.
Male carpenter bee (Xylocopa tabaniformis, Apidae) on comfrey (Symphytum officinale, Boraginaceae) in my garden
Large carpenter bees, Xylocopa spp., are very conspicuous in my garden. My yard is fenced with ratty looking cedar boards serving as habitat for countless Xylocopa nests. The boards are only about 3/4" thick, but the large bees somehow create vertical nests within the boards without breaching the surface. I think this is incredible, and I have no idea how they can detect the outside edge of the wood.
Carpenter bee on a foxglove (Digitalis purpurea, Plantaginaceae) in my garden
Foxgloves, native to this part of Oregon, grow in my garden. Carpenter bees have no idea how to get in, so instead they just bite holes at the top. Even then, they are not very attractive to most of the bees in my garden.
Male carpenter bee on wood spurge (Euphorbia amygdaloides, Euphorbiaceae) in my garden
Wood spurge, Euphorbia amygdaloides, was surprisingly attractive to some pollinators in my garden. Carpenter bees, beetles, flies, and even paper wasps were attractive to the odd musky smelling flowers. Unlike most flowers visited by bees, euphorbia flowers don't produce nectar. For the species that do produce nectar, it is secreted from bracts below the actual flowers, sometimes appearing like petals or sepals which are absent from all euphorbias.
Xylocopa, a mosaic gynandromorph, perched on a Salvia (Lamiaceae) in my garden
Speaking of bizarre, did you know that some hymenopterans have both male and female characteristics? This is called gynandromorphism. Sexual dimorphism, present in the Hymenoptera, is where sexes of the same species exhibit differing characteristics beyond their genitalia (i.e. scopae, not found on male bees). I stumbled upon one or possibly two Xylocopa gynandromorphs in my garden.
Xylocopa, a mosaic gynandromorph, perched on a Salvia (Lamiaceae) in my garden
I took photos of the carpenter bee, found in the morning before it had warmed up enough to fly, and hadn't realized it might be a gynandromorph until looking at the photos later. It was a mosaic gynandromorph, only having patches of male characteristics rather than being a bilateral gynandromorph (literally half male and half female). Web searches revealed that gynandromorphism isn't unheard of in Xylocopa, but maybe not all that common either.
Xylocopa gynandromorph under magnification (microscope courtesy Old Sol Bees). Male (L) and female (R)
After sharing the images of my Xylocopa gynandromorph on social media, I felt regretful for not having captured the insect. Returning home, I immediately went to my garden, net in hand, and watched as the carpenter bees foraged for resources and males chasing each other off. I captured and released a few males and one large female. I was about to give up when I saw a peculiar individual. I netted it exiting a nest tunnel, and sure enough it was a mosaic gynandromorph. It was an intermediate size between a typical male and female, and had scopae on both legs. It appeared to be provisioning a nest, so perhaps it was also fertile. Gynandromorphs are generally considered to be infertile. The specimen has been vouchered, and I am interested in donating it to a museum.
Halictus (Halictidae) visiting a foxglove, correctly, in my garden
As mentioned previously, few bees visited the foxgloves in my garden. The only bees I observed visiting the flowers properly (sans nectar thievery) were small carpenter bees (Ceratina) and sweat bees (Halictus). The most numerous visitors to the foxgloves were ants. They were probably attracted to the nectar, but ant pollination in this case seems unlikely because of how the reproductive structures are positioned within the flowers.
Halictus on a buttercup (Ranunculus sp., Ranunculaceae) in the wilds
Halictus is one of the most common genera that I observe. They visit a wide range of flower types, but mostly open flowers with either easily accessible pollen or nectar. Many can be easily identified by the small notch seen at the tip of the abdomen. Buttercup pollen is toxic to some bees, or at least to their offspring, though it seems to have no effect on some bees.
Small bees foraging on deerbrush (Ceanothus integerrimus, Rhamnaceae) in the wilds
Deerbrush (Ceanothus integerrimus) and the earlier blooming buckbrush (C. cuneatus) are both very attractive plants to many pollinators as well as this human. They are shrubs, and when in bloom are covered in panicles of tiny simple flowers. Most of the pollinators are also very small, typically bees and beetles. They are graceful and rewarding plants which also fix nitrogen into the soil with specialized root nodes formed by a bacterial partner.
Halictus ligatus on a yellow yarrow (Achillea sp., Asteraceae) at the Jackson County OSU Extension in Central Point, OR
When I first started researching what to plant for bees years ago, yarrow was one of the first plants I tried to grow. It was fairly easy from seed, and took practically no water once established. Yet, over the years I observed few pollinators visiting the flowers. Ladybugs are probably the most frequent visitors that I can recall. This yellow variety seemed to garner the attention of a variety of small sweat bees (Halictidae) and small carpenter bees (Ceratina) at the OSU Extension in Jackson County.
Halictus ligatus foraging on narrow leaf mule ears (Wyethia angustifolia, Asteraceae) in the wilds
A larger and more popular relative of yarrow, narrow leaf mule ears are very popular with bees where they bloom in forest clearings around the Rogue River area. Many types of bees visit Wyethia, including bees from the families Apidae (including honey bees), Halictidae, and Megachilidae.
Osmiine bee (Megachilidae) visiting narrow leaf mule ears
I attempted W. angustifolia from wild-collected seed. I managed to get the seeds to germinate with cold stratification (a fancy way to say I left the pot outside through winter), but killed most off after that. There were a few small individuals which I successfully managed to not kill into their third year, but they died promptly after transplanting into my garden. Perhaps they are not currently in cultivation due to tragically fragile root systems, or I just need to do a better job next time.
A honey bee foraging on carrotleaf horkelia (Horkelia daucifolia, Rosaceae) in the wilds
One of my favorite plants, perhaps only due to obscurity, is an uncommon rose relative native only to Southern Oregon and Northern California. The plant is somewhat uncommon, so when I happen upon it I feel fortunate and grateful. Pollinators of all types visit it for nectar and pollen, the open flowers don't care who is pollinating it. Many types of bees, flies, beetles, and butterflies are always attracted to it in my observations, weather permitting. Where situated near an apiary, it attracts honey bees.
Honey bees love trailing snowberry (Symphoricarpos hesperius, Caprifoliaceae) in the wilds
Snowberry, like carrotleaf horkelia, is very unassuming. Creeping or trailing snowberry likes growing in somewhat shady locations under a canopy of conifers or in clearings. The flowers, small and easy to miss, are typically hidden under the foliage. Honey bees don't have any trouble finding the flowers. Snowberry honey is highly sought after, apparently, though the author has never tried it. I have only ever seen honey bees visit these flowers, though I would bet they are also popular among bumble bees since not many bees forage in shady locations besides bumble bees.
European woolcarder bee (Anthidium manicatum, Megachilidae) forages on lamb's ear (Stachys byzantina, Lamiaceae) in my garden
Back in the garden, lambs ear is in bloom with fuzzy flower spikes interspersed with small purple flowers. European woolcarder bees, an introduced species, have a special relationship with this plant and seem to be attracted to it wherever it is grown. Females forage almost exclusively on the lambs ear, while males fiercely defend the area from other males and most other bees by chasing or grappling.
European woolcarder bee (Anthidium manicatum, Megachilidae) forages on lamb's ear (Stachys byzantina, Lamiaceae) in my garden
Woolcarder bees, introduced or native, are in the Megachilidae. All megachilid females collect pollen on scopae under their abdomens rather than their legs like most other bees. Woolcarder bee females also collect hairs from plants such as lambs ear to line and partition cells in small tunnels and other small cavities.
Small carpenter bee (Ceratina, Apidae) on a Penstemon in the Jackson County OSU Extension in Central Point, OR
Small carpenter bees, very unlike their larger relatives, nest in dried pithy stems of plants like roses or many woody perennials. These bees are very small, easily mistaken for small flies, but are also very common. Here I witnessed one perched on a penstemon flower to groom itself. The penstemon flowers are deep and narrow inside, perfect for small bees to climb right in to reach the nectar and in doing so brushing against the reproductive organs.
Cuckoo bee (Nomada, Apidae) on arrowleaf buckwheat (Eriogonum compositum, Polygonaceae) in the wilds
Growing in hot dry rocky locations by the Rogue River, arrowleaf buckwheat attracts a range of tiny flies, beetles, butterflies, wasps, and bees. One peculiar bee, one of my favorites, was visiting the eriogonum during one of my photo sessions. This is a nomad cuckoo bee related not too closely to honey bees and carpenter bees. The cuckoos are kleptoparasites, nest thieves, of other ground nesting bees.
Cuckoo bee (Nomada, Apidae) on arrowleaf buckwheat (Eriogonum compositum, Polygonaceae) in the wilds
As nest thieves, cuckoos require neither to collect pollen nor to build a nest. Needless to say, they don't possess specialized pollen collecting hairs, so they often appear very wasplike. Females fly low to the ground in a zigzag pattern trying to detect the scent of a host nest. Once a nest is located, she will enter and deposit one of her eggs in a finished or nearly finished cell, sealing it behind her. The cuckoo larvae either kills or starves the host larvae, and develops on the host provisions.
Masked bee (Hylaeus, Colletidae) on arrowleaf buckwheat (Eriogonum compositum, Polygonaceae) in the wilds
Yellow faced bees, or masked bees, are also wasplike due to lacking pollen collecting hairs. Instead of collecting pollen on scopae or corbiculae like other pollen collecting bees, they eat it. The pollen in regurgitated from their crop when they return to the nest, and formed into a ball within each cell.
Masked bee (Hylaeus, Colletidae) on arrowleaf buckwheat (Eriogonum compositum, Polygonaceae) in the wilds
Because cuckoo bees and masked bees do not have much hair on their bodies, they are not thought to be very effective pollinators. However, some pollen adheres via a static charge or with microscopic velcro-like projections. Flying insects, especially bees, develop a positive charge from flight while grounded objects like plants carry a negative charge. This helps the pollen become unstuck from the anther and attracted to the insect. The impact of the charge on the pollen is minimal, but every bit counts!
See the "mask" of a male masked bee
Bees, among other fascinating insects (like wasps), are fun to learn about! Observing which flowers they visit and what type of bee is visiting is an ongoing experiment that everyone can take part in. Gardens present an additional dimension of interest. Watching native pollinators visit nonnative garden plants or weeds, or watching nonnative bees visit native plants, is an interesting way to study the theory of pollination syndromes. I imagine someday someone could develop a pollination syndrome chart for specific types of bees based on flower shape, color, characteristics of pollen or nectar, et cetera. Maybe such a chart could aid in conservation efforts geared towards at-risk species of bees or other pollinators. Until then, just go watch some flowers and see what comes of it.

No comments:

Post a Comment

If leaving a comment as "Anonymous," please leave your name or contact information.