It was early March 1999, a rare drizzly day during the drought that would worsen in coming months. I was standing under a dripping canopy of unusually tall scrub oaks in the Savannas State Reserve in St. Lucie County. With me were Dr. Howard Frank of the University of Florida and Mike Thomas of the Florida Department of Agriculture Division of Plant Industry.
At our feet and stretching out for many yards around was a thick, natural, green groundcover consisting of hundreds of our states' largest air-plant, Tillandsia utriculata. Having fallen from their usual arboreal dwellings as seedlings or immature plants, they had taken root in the sandy soil and had created, over time unknown, a place of unusual wonder.
There was little excitement among us for being witnesses to this unlikely and bizarre landscape. We simply pondered the fact that what we were seeing would soon be just a story to tell or a photograph to show. Some months earlier, I had discovered that the "Mexican" or "Evil" weevil - an exotic insect with a lustful hunger for native air-plants - had invaded this delicate domain.
Seven months later, this place in the Savannas eastern ridge is a killing ground. For some miles to the north and to the south, where these plants once defined the tropical aura of this sand-pine scrub ecosystem, a tragedy of alien invasion has occurred.
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| T. utriculata growing terrestrially in 200 sq. ft. study plot in Savannas State Reserve. In only six months the 'Evil Weevil' destroyed most of these plants. |
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The invader is a weevil, unknowingly imported from Mexico or Central America during the 1980s in collector or dealer shipments of bromeliads from that region. The weevil's scientific name is Metamasius callizona, and in Florida, it is commonly called the "Evil Weevil" or "Mexican Weevil."
The sad disaster occurring in the Savannas Reserve is only one example around a vast sixteen-county semicircle. In the center are the immense and so far uninfected state and national treasures of the Big Cypress, Fahkahatchee, and Everglades National Park. Not infected as of today, maybe, but that day will arrive, and likely very soon.
My own contact with the evil weevil began in 1990 at a place called Hidden Forest, in east central Broward County, Florida. It was the last twelve acres of a cypress strand that once snaked for miles throughout that now urban setting. A condo complex was built on the remaining acres, but the developer thankfully saved most of the cypress trees.
I lived there from 1985 to 1993. Before 1990 - before the weevil - it was a tillandsia paradise. At least eight species could be found in abundance.
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One day I realized that two small species of tillandsia - T. paucifolia and T. flexuosa - had disappeared entirely. I only recently found the answer to this mystery, using captive weevils. It seems the adult weevils eat these plants in their entirety, leaving behind only a small unidentifiable mass of chewed leaves.
In a few months there occurred what I have come to call the "evil weevil blitzkrieg." As the adult weevils and their larvae reach a peak in numbers, thousands of tillandsias begin to litter the ground or to hang limply from tree limbs. I estimate that more than eighty percent (80%) of the local tillandsia biomass disappeared during this 4 - 6 week period late in 1990.
Today, this location serves as a valuable example of the effects of the "evil weevil" over a long span of time. All that remains are a few hundred clumps of the more tenacious T. fasciculata, and a few individuals of the less common but even more resistant T. balbisiana, many in various stages of dying. Unfortunately though, both species are also acting as nurseries for a constant stream of adult weevils. Because of the continued, nine-year presence of these hungry adults, seedling and immature tillandsias are almost absent. Partially due to this, I have discarded the hypothesis of re-population by seedlings after all larger plants have been destroyed. I've replaced it with my own theory of "entrenchment."
Without successful human intervention, these invading weevils will indeed entrench themselves, over the next several decades, within all of the bromeliad rich strands, domes, hammocks, forests, sloughs and scrub-ecosystems throughout the Florida peninsula. Since the evil weevil appears little affected by occasional freezing temperatures, its northern limit should only be determined by the northern limit of its victims.
Back in St. Lucie County, observing the weevil's rapid march from the Savannas, westward into the St. Lucie River buffer zone, produced a fascinating footnote to this story. In March of 1999, I discovered the rare native weevil Metamasius mosieri. A close cousin to the evil weevil and previously known to exist only from a small region of Florida near Fort Myers, this native weevil had never before been known to be a killer of wild native tillandsias.
I have found that this tiny, native, red and black jewel of a weevil is responsible, in St. Lucie County, for killing members of six species of Tillandsia: seedling and immature plants of T. fasciculata, T. utriculata, and T. x-smalliana; mature T. balbisiana, and mature forms of two smaller species (not known to be attacked in the wild by the evil weevil), T. setacea and T. bartramii. Sadly, two small Tillandsia species, T. flexuosa and T. paucifolia, that may have interacted with the native weevil, appear to have become locally extinct recently due to the presence of the exotic evil weevil.
The native weevil's presence here raises far more questions than it answers. Although the damage it does can be rather widespread among smaller tillandsias, especially in conjunction with this attack by its immigrant cousin, I don't believe it will play a significant role in this story, except for being an amazing and rather mysterious creature to study.
The greatest impact of the immigrant evil weevil will be an ecological one on two fronts. First, our native tillandsias do not live in a vacuum. Many are the homes, nurseries, feeding or watering stations, or hideouts for masses of known and unknown native organisms - including birds, mammals, reptiles, insects, mollusks, and microorganisms. We might draw a parallel with the coral heads of a reef system. When they are gone, what will go with them? A second impact is the loss of a vast genetic pool, strikingly illustrated by the species Tillandsia fasciculata as it once existed in Hidden Forest, Broward County - before the weevil.1
Extrapolate this one small example to statewide ecosystems currently or imminently under attack by this weevil. The potential genetic loss is large indeed. Little wonder that participants in the World Conservation Congress of 1996 rated exotic invasives as second only to habitat destruction as a leading threat to global biodiversity. The preservation of ecosystems is pointless if exotic species will be allowed to destroy the biodiversity that made these places so special to begin with.
The short- and long-term answers for dealing with the evil weevil are: funding and research into a biological control agent. All of this should be centered around Dr. Howard Frank's ongoing, imaginative, and tirelessly sacrificing work - both at the University of Florida and throughout our state.
In addition, I believe that a statewide, detailed rescue operation, located in a designated central facility, could be undertaken by a willing agency in order to salvage the widespread genetic diversity being quickly destroyed by this immigrant invader. The long-range benefit of such an operation might be decades away - when the reintroduction of groups of survivors with varying genetic backgrounds could be safely accomplished.
To witness the initial attack that the exotic evil weevil unleashes upon an unsuspecting, ancient ecosystem, and to watch a large slice of that ecosystem continue to decline over the years due to the weevil's prolonged entrenchment, is to know the future of all of Florida's bromeliad-rich wonderlands. Any attempt to mitigate the spread of this disaster can be successful only if the appropriate state and federal agencies create a new commitment to allocate the necessary resources.
To have lost something as unique (and unknown to most) as the "terrestrial air-plant gardens" of the Savannas State Reserve, is by itself, too high a price to pay in this exotic-native "tug-of-war" for Florida's environment.
1Over the years, I have been fortunate to salvage and of course fumigate about fourty "forms" of Tillandsia fasciculata from these few acres. Included are eight different 'alba' types, many striking and unusual color and inflorescence variations, and as far as I know, the only variegated example of Tillandsia fasciculata.
See article Up Close and Personal With the Evil Weevil - One Man's Encounters with Metamasius callizona
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