Yesterday I had the opportunity to join a Eric Francius, a botanist from Guadeloupe, as he conducted a cactus survey with help from Marie and the interns from the Reserve Naturelle. Friday’s survey was at Babit Point in Oyster Pond, an area that the Reserve Naturelle is trying to establish as part of the reserve.

En route, I walked from Quartier d’Orléans, passing Étang aux Poissons, Baie de l’Embouchure and Coralita Beach. It was a lovely walk just after a rainstorm.

The cactus survey focused on one of three species of cactus in the area, Melocactus intortus, often referred to as turk’s head or pope’s head cactus. When healthy, these cacti have a single cephalium (the red part that sticks up) and produce small, pink fruits. Under stress, if they are kicked over by a donkey, for example, they create many small cactus buds. The survey counted the number of adults and immature cacti and recorded the number of cephalia on each cactus. Multiple areas were surveyed, including flat areas with other vegetation and the preferred habitat of steep, rocky hillside.

Eric taught me quite a few things about cacti. One thing I didn’t know was that cacti are all native to the Americas. He also explained that there is an Argentinian pyralid moth that feeds on cactus, particularly opuntia. This moth was used to control invasive cacti in Australia, South Africa and St. Kitts, but now is spreading around the Caribbean, threatening native cacti. The large, orange and black caterpillar is found inside the cactus pad.

The survey location was also a convenient vantage point to watch the sailboats participating in the Heineken Regatta.

While there, I stumbled upon a fly that was busily engaged in something on an unopened candlestick cactus flower bud. It was extending its abdomen and rubbing it against the flower bud, strongly suggesting that it was trying to lay eggs inside it. Although it briefly left a couple times, it was doing this for at least fifteen minutes. Close examination of the bud revealed some sort of liquid left on the surface, but it was unclear what this was. Photos will be sent to a specialist.

This entry was posted on Saturday, March 5th, 2011 at 8:50 am and is filed under Les Fruits sur la Terre, Pour les Sciences. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.