Tenacious, Tasty and Deadly

To round off my threesome of plant posts, I thought that today we could look at a plant (in fact a group of plants) that has stirred up a bit of trouble here in Brazil.

Right next to the orchid collection at Jardim Botanico there is a huge collection of Bromeliads.

The Bromeliad group contains over 3,000 species – some are tenacious others delicious and some of them can be deadly.

Tenacious – these are epiphytic bromeliads, happily growing on telephone wires all over tropical America (Image)

Above you see the tenacious side of Bromeliads – epiphytes that grow very successfully on telephone wires! Then there are the delicious Bromeliads that we all know and love – pineapples (in Portuguese, ‘abacaxi’ which sounds like abbacash-EE):

Pineapples in their natural growing habitat. I spotted these in Colombia but there are plenty grown here in Brazil. In fact, pineapple fans, Brazil is the world’s 6th largest producer!

So we’ve seen the tenacious and the delicious, what about the deadly? Many species of Bromeliad hold significant quantities of water at the base of their leaves (like the one in the first picture of this post). These water pools can sustain whole ecosystems of life, from tiny insects to tree frogs, salamanders and even a crab!

But it’s the tiny insects that cause the problems. Mosquitoes lay their eggs in these small pools and with mosquitoes (well, certain varieties) comes malaria. In fact this correlation between bromeliad, mosquito and malaria parasite was so strong that the phrase ‘Bromeliad Malaria’ was been coined back in the 1940s.

From the 19th Century up until the 1950’s, Bromeliad Malaria was a serious health problem in large areas of Brazil. It is thought that deforestation was the main reason for its decline, though it remains a threat in some regions (particularly in São Paulo state).

Rather apt graffiti I found here in the neighbourhood of Catete.

So nowadays the big public health risk for Brazil’s urban population is Dengue Fever, another mosquito transmitted disease. There have been over 160,000 cases and 135 fatalities reported in Rio state this year alone. There are prominent public education programs here, focusing on the removal of any containers or places where rainwater can accumulate and provide a place for the mosquito larvae.

And that brings us back to the bromeliads. During Dengue outbreaks there have been large-scale removal programs to eliminate this obvious source of standing water. And yet a recent study suggests that the Dengue-carrying mosquitoes aren’t actually using the plants!

So if you’re living in a Dengue affected area, maybe concentrate on the plant trays and empty paint pots before you go ripping out your pretty Bromeliads.