Posts Tagged: Robbin Thorp
It won't bloom until summer, but already many eyes are on the California buckeye.
The tree's blossoms are poisonous to honey bees. Bees are attracted to them and forage on them, but the end result of the food provisions to the colony can be deformed larval development.
We've seen bee hives within a quarter of a mile of California buckeyes (Aesculus californica). And we've seen honey bees, native bees and other pollinators foraging on the blossoms.
At the recent UC Davis Pollinator Gardening Workshop hosted by the California Center for Urban Horticulture, Extension apiculturist Eric Mussen talked about the poisonous plants. (See PowerPoint presentations.) That led to one workshop participant wondering if the flowers of the California buckeye are poisonous to native bees. (Honey bees are not native; the European colonists brought them to the Jamestown colony, Virginia, in 1622).
Responded Mussen: "My guess: either the native bees that have been in the areas around California buckeye for a long, long time are not poisoned by the pollen or they have been selected (by death of the other genetic types) to avoid the pollen, that eons of natural selection have adapted them to coexist with California buckeye while using their resources."
Native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, shared: "We know California buckeye nectar and/or pollen is toxic to honey bees from years of experience with managed hives. Toxicity to native bees and other flower visitors is not so easily determined and to my knowledge has not been investigated. The fact that populations of native bees and butterflies visit California buckeye flowers and continue to persist in areas where the tree is a dominant part of the plant community tends to confirm what Extension apiculturist Eric Mussen says about them. Some good research projects here. So we still do not know if it is the nectar, pollen, or both that may be toxic to honey bees, much less to native flower visitors."
According to gardeningguides.com, the seeds in their raw state are poisonous to humans, but native Americans learned to get around that and use them for food. They pounded the seeds into flour and then cooked the mixture. "This tree had multiple cultural uses among California Indian tribes," the website says. "Many indigenous groups utilized buckeye seeds for food, often when other plant food sources were scarce. These tribes included the Costanoan, Salinan, Kitanemuk, Serrano, Wappo, Sierra Miwok, Coast Miwok, Chumash, Kawaiisu, Northern Maidu among others. The Pomo ate the seeds even when other important food plants were plentiful. The seeds are poisonous to humans in the raw state. Thus, the nuts were cracked open with a rock, the shells removed, the seeds pounded into flour, and their toxic saponins removed in a lengthy leaching process. The meal was subsequently cooked and eaten. There are many different methods for processing and cooking buckeye seeds for food, depending upon the tribe. The seeds have medicinal properties and were cut into pieces, mixed with water, and made into suppositories for hemorrhoids by the Costanoan and Kawaiisu. The Pomo cut bark from the base of the tree and made a poultice, which was laid on a snakebite. Young buckeye shoots were sometimes used as spindles or twirling sticks in fire-making kits of the Sierra Miwok, Northern Maidu, Wappo, Yahi and other tribes. Many tribes mashed buckeye nuts and poured the contents into quiet pools to stupefy or kill fish."
And, no wildlife will eat buckeye seeds except squirrels, such as the California ground squirrel (Citellus beecheyi).
Meanwhile, the poisonous blossoms continue to beckon the honey bees--and their colonies keep producing deformed bees.
Honey bee foraging last May on a California buckeye, which is poisonous to honey bees. (Photo by Kathy Keatley Garvey)
A California buckeye blooming in May of last year on the UC Davis campus. (Photo by Kathy Keatley Garvey)
You sip some nectar, and suddenly, a flash of yellow.
A wolf is at your door.
It's a beewolf, a crabronid wasp from the genus Philanthus, as identified by Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis, and native pollinator specialist Robbin Thorp, UC Davis emeritus professor of entomology.
Beewolves, also known as bee hunters, prey upon small bees, thus their name. They carry their kill to their offspring in their underground nests.
The beewolf we saw yesterday wasn't big enough to prey on a honey bee, but yes, there are European species, European species, Philanthus triangulum, that can.
Thorp says that this particular beewolf (below) appears to be a Philanthus multimaculatus. Check out the BugGuide.net image.
So tiny, but so colorful, too.
A beewolf, or crabronid wasp, on buckwheat. (Photo by Kathy Keatley Garvey)
Beewolf maneuvering around the buckwheat. (Photo by Kathy Keatley Garvey)
Close-up of beewolf head. (Photo by Kathy Keatley Garvey)
Beewolf lands on the same flower occupied by a hungry praying mantis. The wasp quickly left. (Photo by Kathy Keatley Garvey)
Robbin Thorp saw it first.
Talk about an eagle eye.
Thorp, a native pollinator specialist and emeritus professor of entomology at the University of California, Davis, was monitoring the Häagen-Dazs Honey Bee Haven on Bee Biology Road, UC Davis, on July 23 when something caught his eye.
The California buckwheat was waving at him.
"While looking closely at the California buckwheat flower heads, I noticed a piece of one waving but there was no wind," recalled Thorp. "I watched a linear group of florets march across to another head. I tried to get a close-up on a flower head as background, but could not get the focus right."
So he placed the "unusual life form" on his finger to capture a better image. He captured it all right: a larva covered with buckwheat florets.
Later insect photographer Allan Jones of Davis, a regular visitor at the haven, obtained a spectacular photo of the camouflage.
Thorp identified the "unusual life form" as the larva of an emerald moth Synchlora (see http://bugguide.net/node/view/747823/bgimage). "The larva pupates with its camouflage still on then turns into a delicate green geometrid adult," he said. (See http://bugguide.net/node/view/316178/bgimage for the life cycle: caterpillar to moth).
Maybe it was serendipity, but Thorp found the larva during National Moth Week, July 23-29.
Larva of an emerald moth, Synchlora, disguised in florets. (Photo by Allan Jones)
Larva of an emerald moth, Synchlora, on Robbin Thorp's finger. (Photo by Robbin Thorp)
Davis photographer Gary Zamzow (far left); native pollinator specialist Robbin Thorp (center), emeritus professor of entomology at UC Davis, and Davis photographer Allan Jones in the Haagen-Dazs Honey Bee Haven. (Photo by Kathy Keatley Garvey)
A pond attracts dragonflies and damselflies.
Last weekend, though, we spotted a damselfly a good 65 feet away from our pond. It touched down on our passion flower vine (Passiflora). Lights, camera, action...
The enlarged photo revealed a surprise: a cluster of something reddish-orange beneath the thorax.
Now that's something you don't see every day!
"Water mites," said native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis. (There are also images on BugGuide.net.)
"Phoresy," said entomology graduate student Lesle Saul-Gershenz, and professor Sharon Lawler, both of the UC Davis Department of Entomology and Nematology. Phoresy is a symbiotic relationship in which one organism transports another organism of a different species. Bottom line: these bright red mites, from the tick family, are hitchhikers that feed on body fluids. They jump off when the host drops down over a new pond or wetland.
What's the effect of water mites on damselflies? Surely, that parasitic load of arachnid hitchhikers must be cumbersome.
Scientists Jose Andres and Adolfo Cordero of the Universidade de Vigo, Pontevedra, Spain, took a close look at parasitism in their research “Effect of Water Mites on the Damselfly, Ceriagrion tenellum,” published in a 2002 edition of Ecological Entomology.
They pointed out:
1. "Water mite parasitism is expected to have an important effect on damselfly survivorship and reproductive success, because mites drain considerable amounts of body fluids from their hosts," they wrote in their abstract. "This study tests the effect of water mite parasitism in a marked population of the damselfly Ceriagrion tenellum during 1995 (individuals marked as mature adults) and 1996 (individuals marked as tenerals)."
2. "Almost all teneral individuals were parasitized (98%) and mites were aggregated strongly on some individuals. Parasite load increased during the season."
3. "Parasites had no effect on the probability of recapture of hosts as mature adults. The average daily survival rate of lightly- and heavily-parasitized individuals, estimated with Jolly's stochastic method, did not differ significantly."
4. "In 1995 parasites had a significant effect on host mating success. The probability of mating was about 25% lower for heavily parasitized males than for lightly parasitized males. Lightly parasitized males also mated more times than heavily parasitized males, even if heavily parasitized males lived longer. In 1996, parasitism did not have an effect on male mating success. In both years mites had no effect on female lifetime mating success."
In conclusion, they found that "water mite parasitism does not reduce damselfly survivorship, but it could reduce male mating success in some circumstances. Further long-term studies are needed, especially in populations with a lower incidence of parasitism."
As for our little damselfly, it lumbered away with its distinctive load of little red hitchhikers clinging to its thorax...
Damselfly, with water mites attached, lands on the leaf of a passion flower vine. (Photo by Kathy Keatley Garvey)
When you visit the half-acre Häagen-Dazs Honey Bee Haven, a bee friendly garden on Bee Biology Road at the University of California, Davis, you might just see a cuckoo bee.
The cuckoo bee (see below) is a male Triepeolus concavus, as identified by native pollinator specialist Robbin Thorp, emeritus professor of entomology at UC Davis, who maintains an office in the adjacent Harry H. Laidlaw Jr. Honey Bee Research Facility.
Thorp has been monitoring the garden not only since it was planted--in the fall of 2009--but BEFORE it was planted, to collect the baseline data. To date, he's detected more than 80 species of bees, "and counting."
The cuckoo bee, nectaring on a blanket flower (Gaillardia), is just one of the species he's found in the garden.
The female cuckoo bee lays her eggs in the ground nests of other bees, including the sunflower bee, Svastra. Cuckoo bees are kleptoparasites, meaning that they steal the food stores provisioned by the host bee. Cuckoos lack pollen-collecting structures (scopa). So when the cuckoo bee eggs hatch, the larva will consume the pollen ball collected by the hosts, and kill and eat the host larvae.
Like human kleptomanias, they've found a way to make it in this world at the expense of others.
Thorp annually teaches at The Bee Course, described as a "workshop offered for conservation biologists, pollination ecologists and other biologists who want to gain greater knowledge of the systematics and biology of bees," and held at the Southwestern Research Station, Portal, Ariz. This year's dates are Aug. 25 to Sept. 4. The workshop attracts people from all over the world, including dozens from the UC system.
A male cuckoo bee, Triepeolus concavus, on a blanket flower (Gaillardia). (Photo by Kathy Keatley Garvey)
Male cuckoo bee sipping nectar. (Photo by Kathy Keatley Garvey)