ALEX CHADWICK, host:
This is DAY TO DAY, I'm Alex Chadwick.
MADELEINE BRAND, host:
I'm Madeleine Brand. It's on Mexico's flag. The ancient Aztec capital that became Mexico City was named after it. And, it's a major food source in Mexico. I'm talking about the humble cactus. People all over the country eat the nopal, as the prickly pear cactus is called there. The trouble is certain moths like to eat it too. They've recently arrived in Mexico and are threatening many cactus species. NPR's Lourdes Garcia-Navarro reports.
LOURDES GARCIA-NAVARRO: The wind whips over a grassy bluff on the vacation hot spot Isla Mujeres, a small island surrounded by sparkling aquamarine waters off the coast of Cancun. It's an unlikely spot for a time bomb.
Ms. MARIE CLARE PIUS(ph) (Program Director, Nature Conservancy, southern Mexico): Well this was a nice opuntia cactus, probably a couple months ago, still. Big area covered with it, now you can see all this dead material.
GARCIA-NAVARRO: Marie Clare Pius is the southern Mexican program director for the Nature Conservancy. She bends down over the squelchy remains of what had been a vibrant patch of prickly pear cactus. As she roots through the dying leaves, she sees something that's small, wriggling, striped red and black.
Ms. CLARE PIUS: This is the larvae. This is the - this is the criminal. I'm going to have to kill this one and make sure there is no more in this patch here.
GARCIA-NAVARRO: Had she not killed it, the larvae would have grown into Cactoblastis cactorum, better know as the cactus moth. It's a small insect, but it strikes a big fear into the hearts of scientists in Mexico who have been on the lookout for its arrival for years.
Ms. PIUS: It's very efficient. It's a cactus moth that is very efficient at eating the cactus.
GARCIA-NAVARRO: So efficient in fact, that a memorial hall was dedicated to it in Australia where it was successfully introduced to control wild cactus populations. The moth is originally South American, but it has spread all the way up to the Caribbean and into the Southern United States. In a different area of the island, workers hack with machete's at a large cactus plant. The Mexican government, through the Ministry of Agriculture is taking the lead in trying to control the spread of the moth. Raphael Satina(ph) is heading the government effort.
Mr. RAPHAEL SATINA (Mexican Ministry of Agriculture): (through interpreter): Right now we are destroying the cactus plant on the island. We are reducing their number where the plague is located so we can stop the moth from reproducing itself.
GARCIA-NAVARRO: The female moth lays its eggs on the leaves of the cactus plant in an egg stick that can turn into dozens of larvae. The tiny worms then feed as a colony, eating their way through the moist cactus center. Apart from destroying the plants that allow the moths to reproduce, the Mexican government has set up 66 traps across Isla Mujeres that lure adult moths with a pheromone.
Mr. SATINA: (through interpreter) We think that the only way to succeed in controlling this plague is to keep it here on the island. The only positive thing is that the moth was discovered on a small island with not many nopal plants where we hope the plague can be managed.
GARCIA-NAVARRO: The moth was first sighted at the end of July, but there is speculation that it arrived on Isla Mujeres last year, brought in from the Caribbean through one of the hurricane's that swept through the region. Satina's team has set up traps on the mainland too as a precaution. The moth would only have to fly six miles to get to the land of plenty. Arturo Veja(ph) also works for the Mexican government.
Mr. ARTURO VEJA (Mexican Ministry of Agriculture): (through interpreter): The stories we have done projecting the risk from the moth shows that the moth could establish itself perfectly in Mexico. It would be a paradise for it.
GARCIA-NAVARRO: And that would be an enormous problem. There are 86 species of prickly pear cactus in Mexico, making it an area of high diversity. But more importantly, thousands of jobs depend on the cultivation of the nopal. In the town of Milpa Alta in the chilly hills surrounding Mexico City, 57-year-old Abrahm Avila tramps through his nopal field and carefully cuts leaves off dark green cacti. This town lives off of Nopal cultivation. Everywhere you look, people are harvesting cactus to sell in the markets of Mexico City.
Mr. ABRAHM AVILA (Nopal farmer): (through interpreter): Nopal changed the life here. Before we lived in a more simple way. I remember when I was a child, we didn't have the opportunity to live in the way we do. Our life is better thanks to the cultivation of the nopal.
GARCIA-NAVARRO: Wearing a large straw sombrero, Eno Cento Morales(ph) also stands in the field. And suddenly bursts into a song about the nopal.
Mr. ENO CENTO MORALES (Nopal farmer): (Singing in foreign language).
GARCIA-NAVARRO: Morales says the cactus is part of the indigenous fabric of the central region of Mexico. In fact, as the story goes, the nomadic Aztecs were searching for a place in which to finally settle down and found their capital city. Their Shaman's prophesized that they would know the spot when they encountered an eagle perched on a prickly pear cactus with a snake in its mouth. That image is now emblazoned on the national flag. But more than just a symbol, the nopal today is eaten everywhere here.
Mr. ENRIQUE OLVERA (Pujol restaurant owner): We're going to make an interpretation of nopal salad.
GARCIA-NAVARRO: Enrique Olvera owns the restaurant, Pujol, in Mexico City which serves modern Mexican food with traditional ingredients. As he prepares the salad, he says the nopal is a key part of the cuisine here.
Mr. OLVERA: It has a completely different consistency, it has a completely different flavor to it. It's very healthy for you. And it's something that -it's very Mexican too.
GARCIA-NAVARRO: And the Mexican government and concerned scientists here and around the world are trying to make sure that the nopal and all it symbolizes stays protected and available for both residents and visitors to eat.
Should we taste it?
Mr. OLVERA: Sure.
GARCIA-NAVARRO: Lourdes Garcia-Navarro, NPR News, Mexico City.