Saturday, February 21, 2009

This Week's Sci-Fi Worthy Parasite

This isn't the first time I've mentioned Parasitic Wasps. They're a rude sort of parasite, laying their eggs inside unwitting hosts to grow up and eat them from the inside out. While it sounds gross and, frankly, a little evil, it makes them also really good at one thing: biocontrol.

Olive Fruit FlyWhen Sarah Palin made her off-putting remark about research on fruit flies, everyone assumed she meant the bio model Drosophila. But she was actually referring to research on the Olive Fruit Fly, Bactrocera oleae. The pest infiltrated Californian olive groves in the late 1990s, and has been wreaking havoc ever since. Olives are the second largest cash crop in Napa County, below, of course, grapes. The impact of the fly has reduced olive yields by at least 30% - and, in some coastal areas, as high as 100% losses. A 2004 USDA report said it simply: "The recent establishment of the olive fruit fly ... in California has threatened to destroy the U.S. olive industry."

Pesticides and traps are expensive and hurt other wildlife. So, instead, Californians are trying out a new control method: Parasitic Wasps.

It turns out that a wasp from Africa, Psyttalia concolor, happens to deposit its eggs in the maggots of fruit flies. It was introduced to Italy and other Mediterranean areas to control the same pest that plagues California's olive industry. Now scientists from the USDA's Agricultural Research Service are working on understanding the interaction between the wasp and its host to use it as a biological control measure in California's olive groves. Their initial data is promising (PDF). They're discovering exactly how and when the parasite lays its eggs in its host, and how well it parasitizes populations when released into the wild. It's picky about its host, too - thankfully, it doesn't infect beneficial flies native to the area. Studies like this one get us step by step closer to using natural means to keep our crops safe from pests.

So what's so sci-fi about a wasp? How about the fact that it's convinced us to single-handedly increase its habitat from Africa to Europe and the Americas. Talk about an increase in range! It may not use mind control or voo-doo to manipulate us, but we sure are doing it a lot of favors. Imagine a world where we team up with all kinds of parasites... It's a Sci-Fi Utopia! Until, like all Sci-Fi scenarios, something goes terribly wrong... *suspenseful music*

Cited: Victoria Y. Yokoyama, Pedro A. Rendón, John Sivinski (2008). Psyttalia cf. concolor (Hymenoptera: Braconidae) for Biological Control of Olive Fruit Fly (Diptera: Tephritidae) in California Environmental Entomology, 37 (3), 764-773 DOI: 10.1603/0046-225X(2008)37[764:PCCHBF]2.0.CO;2


liliannattel said...

Parasites rule?

Zoe Brain said...

They certainly do, but rule badly. Just look at congress.

Irradiatus said...

Awesome parasite!

I'm skeptical that any "introduce a species to stop another species" plan will ever work according to plan in the long run.

It could happen - I just tend to think that there will always be way too many variables to predict the outcome.

These campaigns always remind me of Tom Robbins, from the hilarious Still Life With Woodpecker:

"Hawaii once had a rat problem. Then, somebody hit upon a brilliant solution. Import mongooses from India. Mongooses would kill the rats. It worked. Mongooses did kill the rats. Mongooses also killed chickens, young pigs, birds, cats, dogs, and small children. There have been reports of mongooses attacking motorbikes, power lawn mowers, golf carts, and James Michener. In Hawaii now, there are as many mongooses as there once were rats. Hawaii has traded its rat problem for a mongoose problem. Hawaii was determined nothing like that would ever happen again."

Stephanie said...

I can understand reticence about introducing a new species to control another one - sort of the old woman who ate the fly scenario. However, when invasive and destructive species find new habitats that have no (or too few) natural predators, you may have no choice but to find some to address them.

We've worked in concert with bugs before. Our use of the honeybee in agriculture makes much broader use and goes much farther to protect it than it would have on nature. I have no heard, unfortunately, that we know what has been killing off the bees this past couple of years. Pity. A surprising amount of our pollinating needs in agriculture depend on them.

As for science fiction usage, I agree. By a strange coincidence in the book I just finished...

jtheory said...

...but I don't know why she swallowed that fly; perhaps she'll die.