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Feb 26th
Don’t Blame Bromeliads! PDF Print E-mail
Written by Jeff Shimonski, BT Contributor   
October 2016

A good cleanup will go far to reduce Zika spread

NPix_YourGarden_10-16ormally, I wouldn’t tackle the same subject two issues in a row, and normally I’d include a cool plant or mushroom photo with the column, but this month I’m making an exception.

I’ve been driving around neighborhoods and seeing huge numbers of bromeliads that have been pulled out of landscapes and dumped. Maybe some of the dumping has been because of landscaping projects and a desire for change, but this wholesale bromeliad dumping appears more like a knee-jerk reaction that hasn’t been well thought through.

Yes, many species of mosquito can breed in the cups and leaf axils of bromeliads when they’re filled with water that remains in place for a couple of weeks or more. And, yes, that can include major disease vectors.

But are the people telling you to rip out all your bromeliads also telling you what species of mosquito are normally found in bromeliads? Do they explain that normally in South Florida the native genus Wyeomyia is found in bromeliads -- and that this species doesn’t appear to be a major disease vector or vector of Zika?

Do these same people discuss action thresholds and methods to control mosquitoes in bromeliads? Wait -- are they speaking from experience, or did they just do a Google search?

Over a period of six years, a number of interns who worked for me helped me sample thousands of bromeliads. We collected the mosquito larvae found in a small percentage of those samples. I identified all of the collected larvae and then treated the bromeliads they’d been taken from with various larvicides.

I kept detailed records of my study and found that when the very occasional leaf axil had the larvae of Aedes aegypti in it, it was most often an old, recently flowered bromeliad that was in the process of dying. The water in which the larvae were found was very polluted with decayed material. So we began to remove the bromeliads once they’d finished blooming and were beginning to die. In doing so, we removed a potential habitat.

Check out the photograph that accompanies this. It’s a discarded car tire that is filled with rainwater containing hundreds of mosquito larvae. I photographed this tire on a property this week. This tire is in plain sight. People can see it clearly from neighboring properties and from the street. In fact, while I was working on the property, I saw at least two municipal workers drive by the site.

When I looked closely, I saw that many of the larvae were at the Stage 3 size, and there were dozens of pupae ready to emerge as adult mosquitoes. I’m positive these were not Wyeomyia species. I didn’t take any larvae back to my office to identify under the microscope, but I am pretty sure they were either Aedes or Culex species, some of the worst disease vectors.

From my experience working, identifying, and controlling mosquitoes, I feel comfortable saying that the water and mosquito larvae had been inside this tire for at least two weeks. How many people had seen this tire and not done anything about it?

In the past month, of all the properties I’ve inspected (to rate the condition of their trees and palms), at least three had some discarded tires, and several others had containers or buckets filled with water and mosquito larvae. It’s definitely a lack of knowledge -- coupled with sheer laziness -- that is our biggest problem.

With all the Cubans in Miami, I’m surprised I haven’t heard anything about the Spanish-American War that was fought in Havana and environs, and how yellow fever struck thousands of soldiers on all sides, especially the foreign occupiers. The outbreak was the impetus to perform research on the cause of yellow fever, and in 1898 the U.S. Army Typhoid Board was established.

You know what they found out? Yellow fever was vectored by the Aedes aegypti mosquito. They also discovered that this mosquito species took advantage of small bodies of water usually found in discarded trash, water barrels, and so on. You know what the U.S. Army did? They cleaned up the place and dramatically reduced the incidence of yellow fever.

I’ve spoken with folks who want to remove their bromeliads anyway and just not bother with some of the available mosquito larvicides or cultural practices to control the larvae, even though some of these property owners also spend a fortune contracting with pest control companies and landscape contractors to overfertilize and overspray their properties. They don’t want to see a single mosquito.

You know that will never happen. I tell them to discuss action thresholds and chemical resistance issues with their pest control operators. This doesn’t seem to happen, either.

 

Jeff Shimonski is an ISA-certified arborist municipal specialist, retired director of horticulture at Parrot Jungle and Jungle Island, and principal of Tropical Designs of Florida. Contact him at This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

 

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