Archive for November, 2011

More Fun with Rhopalomyia

Sunday, November 20th, 2011

I continue to be fascinated by the life history of the coyote brush bud gall midge, Rhopalomyia californica. Lately I’ve been wondering about the midge’s pupation and emergence events. Russo writes in Field Guide to Plant Galls of California and Other Western States:

When fully grown, larvae burrow to the surface of the galls, where they develop their partially protruding white cocoons and pupate. This species represents one of the rare situations among gall insects where fresh galls and emergence of adults occur throughout the year, depending on location and environmental circumstances, even though there is a pulse of growth and gall activity in spring.

I’ve looked for, but so far have never found, a gall with intact pupae visible on its surface. I’ve found plenty of galls with spent exuviae, however. Here’s one I found a few weeks ago at the salt marsh:

Here’s another gall with visible exuviae. In this case, there are actually several individual galls that I assume were the result of the same egg-laying session, though they have not merged into a single gall, as they often do. I took this shot on the morning after our first good rain of the year; I think the exuviae on the left side of the large gall may have been knocked downward by raindrops:

Here’s a gall with an odd bumpy surface:

For those who don’t want to click through for the full-sized images, here’s a cropped portion of the previous shot so you can get a good look at the exuvia:

I don’t know how long pupation lasts, but I suspect it isn’t very long, or else I should have been able to find some galls with intact pupae protruding from their surfaces. Or maybe I’m misinterpreting Russo’s description of what the pupation stage looks like. Maybe the pupae are near the surface, or barely protruding, and the exuviae end up protruding as much as they do only as a result of the emergence itself.

Here’s a gall with some interesting discolored bumps. I wonder: Could those be pupation sites? If I had cut that gall open, would I have found individual larval chambers under each of those bumps?

Cell biologist Peter J. Bryant at UC Irvine has a neat page on Rhopalomyia californica on his Natural History of Orange County, California web site. Among the photos there are several showing newly emerged male and female midges, the females identifiable by their orange abdomens swollen with masses of eggs.

Although R. californica galls are found mostly in coyote brush, they also can occur in other plants. Dr. Bryant’s page shows a gall in a leaf of black sage and the midge that emerged from it; Bryant used DNA analysis to determine that it was R. californica. He also has photos of four different types of parasitoid wasp that emerged from R. californica galls.

Dr. Bryant was kind enough to correspond with me once before (concerning the bolas spider). I think I might try pestering him again to see if he would be willing to give me any pointers on rearing R. californica galls to adulthood. I don’t necessarily want to harm the insects. Could I simply keep a removed stem in water? Or would it require a living, growing plant to avoid disrupting the lifecycle of the gall’s inhabitants?

Even if I successfully raise gall midges to adulthood, it seems likely that I would be disrupting their chance to successfully breed. The adult midge only lives for a few hours; I would essentially be sacrificing its life merely to satisfy my curiosity. Am I okay with that?

As a young boy I loved Hugh Lofting’s Dr. Doolittle stories. While writing this post I suddenly remembered a passage I hadn’t read in 40 years. It turns out to have been from Doctor Doolittle’s Garden. Doolittle, after long effort, has managed to decipher the language of insects, and has become fascinated by the Ephemera — insects with very short-lived adult stages, such as mayflies (Ephemeroptera) and gall midges (Cecidomyiidae). Doolittle and his young assistant Stubbins (of whom I was always deeply envious) bring a delicate fly into the lab.

We worked on him for half an hour and our results were very meagre. He had things to say, we felt sure. But it was a language new to us. Clearly anyone who has to pack his whole life into one day must talk very fast. We soon got the impression that he was really pouring out hundreds of words a second. Only we weren’t catching them quick enough.

“Look here, Stubbins,” said the Doctor, “we are being entirely heartless. We can’t let this poor fellow spend more than half an hour talking to us. Why, half an hour out of his life is a forty-eighth part of the whole. That would be nearly eighteen months for us. What must he think of us? Imagine anyone talking to you for a year and a half without stopping! Let him go at once. We must do this on a different system. We will catch several singly and only keep them in the apparatus for five minutes at a time, If we are swift enough with our note-taking, we shall perhaps be able to gather a little from what each one says and piece it all together afterwards and make something of it.”

The more I study R. californica the more questions I have. But in answering those questions, I don’t want to harm the object of my curiosity. I’ll have to think about this more.

Snail Mail

Saturday, November 19th, 2011

I’ve written previously about the decollate snails (Rumina decollata) that live in the marsh. These non-native predatory snails are sometimes used as a biological control for the brown garden snail (Cornu aspersum). My daughter Julia took this photo of one climbing in blue-eyed grass (Sisyrinchium bellum) at the marsh a few years ago:

In early September I received an email from Shoichi Sano, a graduate student working with Prof. Akihiko Matsukuma of Kyushu University Museum. Shoichi had seen Julia’s photo on Flickr, and wanted to know if I might be able to send them a snail specimen. By examining the DNA of R. decollata from different parts of the world, they hope to learn more about how the snails are spreading.

After receiving the email I kept my eyes open at the marsh, but for a while all I could find were old, dried shells. Then in late September there was a light rain one night, and the next morning I found a group of a half-dozen decollate snails crawling near the path that parallels Ash Avenue. Here’s the one I collected:

I’ve always had something of a soft spot for snails; they seem like such peaceful, inoffensive creatures (at least if you’re not their prey, or if your garden isn’t being consumed by them). Deb Talan has a song about snails, “Angels Marching”, on her Sincerely album, and the lyrics have always resonated with me.

So I felt bad about killing this snail. But I’d told Shoichi I would, and after researching how to properly preserve and mail it, I dropped the snail into an airtight aluminum pill fob filled with alcohol, wrapped that in enough paper towels to absorb any leaks, and put the whole thing in a padded envelope.

I felt a little anxious waiting in line at the post office. Would my packing job be deemed adequate? I had to fill out a customs form, which required a detailed description of what I was sending. I wrote, “Preserved snail specimen (Rumina decollata)” and handed it in. The postal clerk didn’t even raise an eyebrow. Moments later my “snail mail” was stamped and on its way.

After a few weeks I received an email from Prof. Matsukuma:

Dear Dr. Callender,

I received an animal of Rumina decollata from the Carpinteria Salt Marsh, California preserved in ethanol. Thank you very much for your kind help to obtain the animal from California.

In Japan the invasive land snail R. decollata was found first at Kitakyushu City, Fukuoka Prefecture, northern Kyushu in 1988. At present the snail dispersed in various regions of western Japan, including northern Kyushu, Shikoku, Kinki and Kanto districts. I am afraid the snail will be a serious pest for vegetables in our country near future. I believe studies of origins and migration of the snail are important.

Once again, thank you very much for your kindness.

Best regards,

Akihiko Matsukuma
Kyushu University Museum

It was flattering, if inaccurate, for him to address me as Dr. Callender; I’m not a PhD, or any kind of scientist (unless you count political science, my major in college, as a “science”, which I don’t). But it was fun to feel included, and to participate, in a small way, in doing some “citizen science.”

After the Rain at the Marsh

Friday, November 18th, 2011

Last Saturday was my turn as docent at the marsh, but as sometimes happens at this time of year, no one showed up for the tour. Which was a shame, because it was a really nice day for a walk in the marsh, so I gave myself a tour and snapped a few photos.

It had rained the night before, and was near a max high tide (+5.9), so the basin next to Ash Avenue was full of water, with lots of ducks feeding in the inundated pickleweed. There were mallards (Anas platyrhynchos), blue-winged and green-winged teal (A. discors and A. carolinensis, respectively), and a single female northern shoveler (A. clypeata). In one group of green-winged teal a male was doing a really cute courtship display for the benefit of the nearby females; I’d never seen that before.

A branch of the big arroyo willow (Salix lasiolepis) near the amphitheater had blown down in the wind during the night:

Here’s a shot I took of the Franklin Creek bridge. If you’re used to the bridge’s appearance at an average tide, it’s really noticeable how high the tide is here:

Not far away, a good-sized raccoon (Procyon lotor) had left a trail through the mud:

All in all, a really nice walk at the marsh.

New Page Added: Climate Change Impacts on Water Supplies

Tuesday, November 15th, 2011

I’ve added a new page to the site: Climate Change Impacts #2: Water Supplies. It includes a discussion of factors like the reduction in Sierra snowpack shown in the following graphic:

I also talk about some of the things I think Carpinterians could be doing to prepare for these impacts, including:

  • setting up a groundwater management plan,
  • increasing our water conservation efforts, and
  • exploring the idea of a front-country reservoir to save more of our winter rain for use in the summer.

Again, see Climate Change Impacts #2: Water Supplies for the details.

Coyote Brush in Bloom

Tuesday, November 1st, 2011

I took this photo at the Carp salt marsh last Sunday, October 30, 2011. It shows a time at the marsh that is my favorite in two ways: It’s the peak of the coyote brush blooming season, with the female coyote brush looking like they’ve been dusted with snow, and at the time I took this photo the marsh was at a +6 high tide: