Saturday, July 12, 2008

July 2008 More about the Coontie

Atala colonies are irrupting with full force this month, and the host plants are being completely devoured by the larvae. This is signaling a crash soon to follow, as the butterflies run out of available host plants for the larvae. The crash cycles in the past indicate a beginning in mid-to-late July, with a complete fall by
September. Some sites are crashing now, with little or no host
plant left for the larvae, such as these decimated plants at Nova.

The flags are the only clue I have that there was a coontie plant there, but new growth will follow...until the larvae emerge to devour it!

Solutions range from buying more coontie, to culling the ‘herd’ by removing the excess atalas to establish new colonies ---there are several other alternatives, none of them very pleasant. The eggs can be scraped from the leaves, or the larvae and pupae removed and placed in a freezer (where they will die, but that is a little more humane than crushing them or poisoning them with pesticides). Unfortunately, with the massive
changes in our ecosystem, there are no humane alternatives for managing a crash (or irruption…sooner or later, there will simply not be enough host plant food.)

Females often lay their eggs on the cones of the female coontie plants when this happens and the larvae will consume the flesh from the cones. Many of the cones are ripening now and opening to accept pollen from the male cones via the weevil that pollinates the plants. See my blog page (August 2005, Coontie Crazy) for pictures of the cones of the male and female coontie plants. Dr. Taylor, from Panama, gave a presentation at Montgomery Tropical Botanical Gardens earlier this year, in which he pondered this unique relationship between the cycads and the herbivores (Eumaeus minyas). He discussed the possibility that herbivory of the cones actually helped with the pollination and germination of the viable seeds by removing the red flesh from the seeds. This is certainly a possibility, as many coontie propagators deliberately remove the flesh to speed germination. Being a rather lazy gardener, I usually let the insect associates in the soil detritus do that for me and wait for the seeds to germinate in their own time. Maybe lazy isn’t the correct word…more like just allowing nature to do it the way its been done for centuries…. Being a patient gardener is a better term.

There are over fifty species of cycads in the Zamia genus, in Central and South America, and in the Caribbean archipelago, which includes South Florida. Each one of these cycads has its own obligate feeder, which have evolved to metabolize the toxins that each type of Zamia contains in its leaves, rootstocks and cones. The herbivores in this case all belong to the genus Eumaeus (our atala is known as Eumaeus atala florida, a subspecies of the Caribbean nominal race, E. atala atala.) In Central and South America, some of the six Eumaeus species are E. minyas, E. childrenae and E. toxea (some with subspecies as well), each obligate herbivores to a particular species of Zamia. They are larger and more colorful than our little hairstreak, but have the same basic characteristics.

The ‘coontie,’ as our Zamia cycad is commonly called, is our only native cycad, not only in Florida, but in the North American continent. Botanists are still arguing over the taxonomy of our Zamia plants, and you will see the plant labeled as Zamia pumila, Zamia floridana, Zamia integrifolia, and historically labeled with a half-dozen other monikers.

I had the pleasure of touring the coontie areas at Fairchild Tropical Gardens with Marilyn Griffiths, one of the horticulturists there, who has been sending atala population data to me for over a year. We noted that the plants have a tremendous amount of variation in leaf structure, and even differ from the coontie in my own garden or the gardens of my Broward County friends. Others have noted those variations for a hundred years, and that is one reason why there is so much disagreement among botanists as to the taxonomy for the plant. They are all “coontie” plants, but the variation is significant.

This is a picture of Marilyn with one of the oldest coonties at Fairchild, a thirty+ year old that was still hosting atalas in abundance. All of the coonties at Fairchild are labeled as Z. integrifolia, although none of them look the same! Curiously, the original documentation (Linnaeus) refers to the Caribbean species as Z. pumila, and our native Floridian species as Z. integrifolia (among other names)…but the Fairchild coonties were originally collected in the Caribbean (Z. pumila). Go figure!

The pollination of the coontie plant is another mysterious relationship with a type of beetle called a weevil (known as Pharaxonotha zamiae), which is its obligate pollinator. (The cardboard plant, Zamia furfuraceae, also has its own obligate pollinator.) In biology, an organism is considered an obligate when it has very specific needs without which it will not survive. This could be any specific relationship between organisms, whether plants and bacteria, insects and host plants, or even mammals and their food—a panda is considered an obligate feeder of bamboo, for example, and all cats are obligate carnivores.

An insect is considered “obligate” when it cannot survive without a specific host plant. In this case, the atala insect is an obligate feeder of Zamia species cycads, and the weevil is an obligate pollinator of the coontie plants.

The weevil’s life cycle is as complex as that of the coontie. The larvae of the weevil pupate in the ground beneath the plant. When they emerge, they feed on the pollen of the cones on the male plant. Occasionally, they fly out looking for another male cone and visit the cones, of the female coonties, rather accidentally,which are conveniently opening to allow their entry. Shortly thereafter the female cones break apart and fall to the ground. They get covered by the debris of dead leaves in the vicinity (their own as well as pine needles, cypress leaves, oak leaves, or whatever other plants) surround them.

Over the course of the season, the flesh on the seeds is eventually broken down by the soil, rain, and the decomposer insects that live in the detritus (worms, other beetles, sow bugs, cockroaches and other soil-building insects). By the spring of the following year, the viable seeds sent down roots and then the first leaves of the newly born coontie plant.

If this doesn’t sound like a very efficient system, you are correct, but it has worked for a long time for the plant. Some gardeners prefer to speed the process along by removing the flesh from the seeds, or hand-pollinating the coonties. See Tom Broome’s excellent cycad site for the details.
Researchers have documented that in the wild, there is usually a two male coonties per female ratio with the plants, which would help pollination take place more quickly. That’s something to keep in mind in your atala garden.

We had a very successful Summer Count for NABA this month, and I am happy to report that Zebra Heliconian populations seem to have fully recovered from the devastation of Hurricane Wilma two years ago. We counted 59 Zebras today at Hillsboro Pineland Natural Area and are awaiting total results for the North Circle. While NABA national is deciding what exactly to name a plethora of butterflies, I personally like one suggestion of “a majesty of butterflies”. We did indeed have a majesty of Zebras on July’s count! This is most of the team at lunch (Sherri Barberi, me, Mary Ierubino, Art Constantino and Sandy Fernandes). Everyone at the bistro was Italian except me!

This Horace’s Duskywing decided to decorate my sandal. We’ll be posting the total results on the Broward County Butterfly Club’s NABA website soon.

Julia Heliconians were not as abundant (13), but this female was very cooperative.

This incredibly beautiful little nymph is an immature Stink Bug…he was munching on the Crotalaria lanceolate in the park.

This unidentified beetle was slurping up nectar on my Bloodberry plant at home (Cordia globosa).

Looking forward to seeing some of you at the annual Butterfly Days at Fairchild Tropical Gardens in Miami, July 26-27, 2008. This event is a tremendous opportunity to visit the gardens, buy plants, meet friends and hear presentations by some of the best butterfly experts in the field (Jaret Daniels, Naomi Pierce, and Roger Hammer to name a few). Visit the Miami Blue NABA Chapter site to learn more! It is SOOO much fun to be there!