You've probably watched those colorful painted ladies (Vanessa cardui) fluttering about in your yard, but have you read the newly published research about their wing color patterns and genetic codes?
In researching the color patterns and the genes responsible for those patterns, biologists Jeffrey Marcus and Roohollah Abbasi of the University of Manitoba, Winnipeg, Canada, found a previously undetected compartment boundary that may exist in all holometabolous insects. (Holometabolism, also called complete metamorphism, is a form of insect development that includes four stages: egg, larva, pupa and adult.)
Scientists have long known that in the common fruit fly, Drosophila melanogaster, the forewing is divided into two developmental compartments, but this newly published research in Scientific Reports, A New A-P Compartment Boundary and Organizer in Holometabolous Insect Wings, is a real eye-opener.
Writer Viviane Callier of Washington, D.C., a trained insect physiologist, wrote about the research in the Nov. 30th edition of Entomology Today, published by the Entomological Society of America.
In her piece, "Butterfly Color Patterns Reveal Clues About the Genes that Build Insect Wings," Callier described butterfly wings as "natural canvases decorated with elaborate color patterns," but noted that "how these patterns develop and evolve is still incompletely understood. Now, a new study in Scientific Reports (Nature.com) has identified the genetic code by which butterflies can assign color patterns to different parts of their wings during development. The code is based on a set of genes called transcription factors that establish compartments in most—perhaps all—insect wings. Each compartment, whose 'address' is determined by the combination of genes that are active in that sector of the wing, can evolve different color patterns independently from the other compartments."
Marcus and Abbasi explained in their abstract:
"Decades of research on the highly modified wings of Drosophila melanogaster has suggested that insect wings are divided into two Anterior-Posterior (A-P) compartments separated by an axis of symmetry. This axis of symmetry is created by a developmental organizer that establishes symmetrical patterns of gene expression that in turn pattern the A-P axis of the wing. Butterflies possess more typical insect wings and butterfly wing colour patterns provide many landmarks for studies of wing structure and development. Using eyespot colour pattern variation in Vanessa butterflies, here we show an additional A-P axis of symmetry running between wing sectors 3 and 4. Boundaries of Drosophila mitotic clones suggest the existence of a previously undetected Far-Posterior (F-P) compartment boundary that coincides with this additional A-P axis. A similar compartment boundary is evident in butterfly mosaic gynandromorphs. We suggest that this additional compartment boundary and its associated developmental organizer create an axis of wing colour pattern symmetry and a gene expression-based combinatorial code, permitting each insect wing compartment to acquire a unique identity and allowing for the individuation of butterfly eyespots."
The research "bears on some of our T-shock experiments back in the 70s-80s," observed Art Shapiro, distinguished professor of evolution and ecology when asked if he'd read the research paper. Yes. He wrote a chapter, The Genetics of Seasonal Polyphenism and the Evolution of 'General Purpose Genotypes' in Butterflies' in the Klaus Wöhrmann/Volker Loeschcke book, Population Biology and Evolution. You can read it online.
In his abstract, Shapiro, who has studied and monitored butterflies for more than four decades and maintains a website, Art's Butterfly World, points out that his Genetics of Seasonal Polyphenism chapter "is really a specialized appendix to Professor Scharloo's on 'The Genetics of Adaptive Reactions.' It deals with a particular set of such reactions — those of butterfly wing patterns to environmental factors — and asks whether those which seem adaptive are evolutionarily related to those which do not, and if so, how. Despite more than a century of interest in such phenomena, the answers are not yet in; we are only now able to do the carefully controlled experiments necessary to partition phenotypic variation into its environmental and genetic components and this work is still very much in progress. So this will be a very unsatisfying presentation — full of qualitative statements, long on speculation, short on hard data. If it serves as a provocation it will have done its duty."
Shapiro goes on to say that "a glance through any butterfly book of the coffee table variety reveals an astonishing diversity of patterns. The fact is that we have only the remotest idea of the functional significance of any of them, as we were recently reminded by Silberglied et al. (1980). One reason is that bewildering diversity which defies rational classification; another is that it is almost impossible to relate a pattern to an ecological and behavioral context when observing a specimen set on a pin."
All the more reason to marvel at the stunning diversity of butterflies that grace our yards. Or what Viviane Callier so eloquently described as "natural canvases decorated with elaborate color patterns."
Yes, it happens.
We've heard the stories and read some of the scientific literature about what a female praying mantis will do to her partner during the mating process. Sexual cannibalism. She'll bite the head off of her mate and eat it--but the mating process continues unabated. (Except the male has lost his head )
We spotted a mating pair of mantids in our bee garden on Saturday. It was early evening, around 7. They were hidden among the long strands of English lavender.
My camera caught a quick shot of the pair. Yes, two heads. The next picture I took was of the male minus his head. He "lived"--that is, moved around, for about eight hours before expiring. Or, as Lynn Kimsey, director of the Bohart Museum of Entomology and professor of entomology at the University of California, Davis, says: "It will live until it dries up."
Entomology Today weighed in on the sexual cannibalism behavior in its Dec. 22, 2013 edition.
"An urban legend about female praying mantises always eating males during or after mating has circulated for a long time. However, reality is much more complicated.
"Kyle Hurley, an entomology student from the University of Central Arkansas, spent two years observing praying mantises in the lab and made some startling observations. For example, in one out of 45 cases the male actually consumed the female. And in one out of 45 cases, the female removed the head of the male before mating (the males were still able to finish the job)."
Marianne Shockley Robinette, an entomologist at the University of Georgia, was quoted as saying in Entomology Today: "While it has been observed in artificial settings such as laboratories where they're rearing praying mantises, it's rarely been observed in a natural environment.”
Even Snopes, known for debunking urban legends, weighed in on this.
"Yes, the female praying mantis does sometimes eat her mate. In fact, male mantises will often offer themselves up as food to the female during the mating process, and from a biological standpoint this action makes sense: There's no point to mating with a female who might die from a lack of food before she can lay her eggs and pass the father's genes onto the next generation. This doesn't happen all the time, however, and its frequency of occurrence and the reasons for it are still a subject a debate within the entomological world."
The clincher is a YouTube video which clearly shows a female decapitating her mate. If this kind of thing makes you squeamish or queasy, you probably shouldn't watch it. (At least before breakfast.)
But yes, it happens. Nature is not always nice.
Why is that in a honey bee colony, workers can carry pollen but not the queen?
Well, scientists from Michigan State University and Wayne State University have discovered the answer.
They've isolated the gene that's responsible for leg and wing development, according to a news brief in Entomology Today, published by the Entomological Society of America (ESA). The 7000-member ESA, by the way, is headed by president Frank Zalom, integrated pest management specialist and professor of entomology at UC Davis.
The scientists' bee research is published in the current edition of Biology Letters.
“This gene is critical in making the hind legs of workers distinct so they have the physical features necessary to carry pollen,” said MSU entomologist Zachary Huang. “Other studies have shed some light on this gene's role in this realm, but our team examined in great detail how the modifications take place.”
"The gene in question is Ultrabithorax, or Ubx. Specifically, the gene allows workers to develop a smooth spot on their hind legs that hosts their pollen baskets. On another part of their legs, the gene promotes the formation of 11 neatly spaced bristles, a section known as the 'pollen comb.' The gene also promotes the development of a pollen press, a protrusion also found on hind legs, that helps pack and transport pollen back to the hive."
What the research team did was to isolate and silence Ubx, the target gene. "This made the pollen baskets, specialized leg features used to collect and transport pollen, completely disappear," Entomology Today reported. "It also inhibited the growth of pollen combs and reduced the size of pollen presses."
The scientists acknowledge that this won't provide a solution to Colony Collapse Disorder (CCD). They think, however, that their research could lead to bees becoming better pollinators; they could carry larger pollen loads.
Speaking of loads, have you ever seen a bee so heavy with pollen that you wonder if she can lift off? It seems somewhat like a human being weighted down with a bowling ball.
The next time you observe a bee foraging, check out the pollen load. If you're lucky, you'll see the bee packing the pollen, adjusting the load before she buzzes off back to her colony.