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The Imposter
'Tis the season for the return of the insects.
Many a honey bee foraged in the flowering quince (Chaenomeles speciosa) last weekend. But wait, what's that? A spotted cucumber beetle (Diabrotica undecimpunctata) tucked inside a blossom.
Spotted cucumber beetles, which overwinter as adults, are major agricultural pests. The beetle is so named because of its preference for cucumbers (cucurbits), but just about anything will do before, during and after the cucumber crop. True, it gravitates toward other members of the cucurbits family, including squashes, gourds, pumpkins and melons, but it also goes after beans, peas, corn, potatoes, beets, tomatoes, eggplants, cabbage, and assorted ornamentals, such as roses and dahlias.
The yellowish-green beetle with black spots may look pretty tucked inside a flowering quince, but looks are deceiving.
Very deceiving.
Spotted cucumber beetle inside flowering quince blossom. (Photo by Kathy Keatley Garvey)
Honey bee inside flowering quince blossom. (Photo by Kathy Keatley Garvey)
What's in the Sunflowers?
So you're walking through a sunflower field and you're seeing lots of honey bees foraging on the flowers.
But wait, look over there. Are those beetles?
They are.
Melyrid or blister beetles (Melyridae family) and spotted cucumber beetles (family Chrysomelidae) are frequently found on sunflowers.
The spotted cucumber beetle is known as a major agricultural pest, as it eats or damages the leaves of such crops as cucumbers, cotton, soybeans and beans.
Are the melyrid beetles pests of sunflowers? "Yes, in the sense that they are pollen eaters," says Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at UC Davis.
However, beetles can also be pollinators. And there's a word for that.
Beetle pollination is called cantharophily. And cantharophily "may be the oldest form of insect pollination," say emeritus professors Penny Gullan and Peter Cranston of the Department of Entomology, University of California, Davis, in their textbook, The Insects, an Outline of Entomology.
As they point out in their book: "Beetles mostly visit flowers for pollen, although nutritive tissue or easily accessible nectar may be utilized and the plant's ovaries usually are well-protected from the biting mouthparts of their pollinators." They mention several families of beetles that can be pollinators--among them Cantharidae (soldier beetles), Cerambycidae (longhorn beetles), and Cleridae (checkered beetles).
And they mention Melyridae, the soft-winged flower beetles, as being pollinators, too.
Cantharophily in the sunflower field.
Melyrid beetle on a sunflower. (Photo by Kathy Keatley Garvey)
Spotted cucumber beetle on a sunflower. (Photo by Kathy Keatley Garvey)
A Pomegranate Kind of Day
It was a pomegranate kind of day. Red, bright and wonderful.
The papery-thin reddish blossoms in our yard draw both beneficial and pestiferous insects. Honey bees are there for the pollen and nectar; ladybugs are there for the pesky aphids. Occasionally we see another pest, the spotted cucumber beetle (which prefers cucurbits).
The pomegranate, an ancient fruit native to Persia (what is now Iran), is a long-lived tree. Indeed, some pomegranate trees in Europe are more than 200 years old. One in our yard spans 85 years.
Spanish settlers introduced the pomegranate into California in 1769, and today, the state leads the nation in the production of pomegranates. Agricultural statistics show that in 2010, California's San Joaquin Valley alone blossomed with an estimated 22,000 acres of pomegranates. That's about 200 trees per acre.
One of the primary pomegranate varieties is "Wonderful." The honey bees and ladybugs think so, too!
Honey bee nearly collides with a ladybug, aka ladybeetle. (Photo by Kathy Keatley Garvey)
A pest, a spotted cucumber beetle. (Photo by Kathy Keatley Garvey)
Honey bee foraging in pomegranate blossom. (Photo by Kathy Keatley Garvey)
A Flying Cucumber (Beetle)
You usually see them crawling around, but never about to fly.
The Western spotted cucumber beetles (Diabrotica undecimpunctata) is one of California's most common insects. And though quite attractive in coloring, it's a major agricultural pest.
"Come in, my pretty," is probably what a witch would say during the Halloween season.
Retired UC Berkeley entomologist Jerry Powell, in his book, California Insects (co-authored by Charles Hogue), describes the adult as "bright green with six variable black spots on each wing cover and variable amounts of black on (the) legs and underside."
"They eat leaves and flowers of all kinds except conifers; (they're) particularly abundant on plants of the squash family."
They're found throughout California, except at the highest elevations, he says.
But have you ever seen this insect take flight?
We recently watched a spotted cucumber beetle crawl beneath a tangerine leaf and vanish. Suddenly, like a submarine periscope, its antennae appeared, twitchy rapidly. Then its head popped up.
That huge dark object (camera!) startled it, though. It took flight, landing a few feet away on the sidewalk.
With its wing covers open, it looked very much like a polka-dotted airplane on a runway.
Spotted cucumber beetles crawls along a tangerine leaf. (Photo by Kathy Keatley Garvey)
Antennae twitching rapidly, the spotted cucumber beetle looks around. (Photo by Kathy Keatley Garvey)
Spotted cucumber beetle lands, and then opens its wing covers preparing for flight. (Photo by Kathy Keatley Garvey)
Gotcha!
It wasn't much of a fight.
The assassin bug scored a TKO.
Here's what happened: an assassin bug ambushed a spotted cucumber beetle in the Häagen-Dazs Honey Bee Haven at the Harry H. Laidlaw Jr. Honey Bee Research Faciility on Bee Biology Road, UC Davis.
It was "good guy vs. bad guy."
It was "beneficial insect vs. major agricultural pest."
The assassin bug (Zelus renardii) is a force to be reckoned with, especially when it comes to a spotted cucumber beetle (Diabrotica undecimpunctata).
The assassin bug wears no white hat but it should. A cunning predator, it lies in wait and stabs an unsuspecting prey with a lethal toxin powerful enough to paralyze and dissolve tissue.
Then it's all over but the feeding.
The assassin bug sort of looks like a cartoon character, with its beady eyes, long beak (proboscis) and its long, slender antennae.
The spotted cucumber beetle looks a little like a ladybug (aka lady beetle) except for its coloration. It's a 12-spotted greenish-yellow insect. And a pest. Diabrotica dines on young, tender plants like cucumbers, squash, pumpkins and melons (cucurbits). It also transmits a virus.
So it was the good guy vs. the bad guy. Zelus vs. Diabrotica.
This time the good guy won.
That loud cheering sound you hear is from all the melon growers out there.
Gotcha!
Predator and the prey: Assassin bug (left) corners a pest, a spotted cucumber beetle. (Photo by Kathy Keatley Garvey)
Assassin bug stabs the spotted cucumber beetle. (Photo by Kathy Keatley Garvey)
Assassin bug wins. (Photo by Kathy Keatley Garvey)
Assassin bug dining on spotted cucumber beetle. (Photo by Kathy Keatley Garvey)
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