Screwworm eradication in South America

Aside from the effects of the fly’s depredations, one of the most compelling reasons to continue with screwworm eradication (throughout South America) is that if we don’t, there will always be a dire threat of Cochliomyia hominivorax spreading to other areas – not just in the Americas, but to many other parts of the world. Continually increasing travel, and transport of goods and livestock says it will. It already has (Vargas et al).

[caption id="attachment_145" align="alignleft" width="300" caption="Cochliomyia hominivorax; COMEXA (Public Domain, Wikimedia Commons)"][/caption]

But now the countries of South America are banding together to eradicate it there, presumably the place where it evolved. Could there be any negative consequences of deliberately exterminating this nasty fly? The Mexican American Commission for the Eradication of Screw-Worm (COMEXA) believes that, to date, in the eradication zones, “there has been no evidence of any impact at all on biodiversity, perhaps because a multitude of fly species occupy the same biological niche” (qtd. in Godoy).

There’s no fly like the screwworm fly for causing mortality among livestock and other animals. The insect must play a role in controlling populations of wild animals. Granted, human livestock rearing has been a bonanza for C. hominivorax, but once upon a time it must have been an important part of the balance of nature in its home territory. Is it possible that eradicating it to extinction will have NO impact on biodiversity?

People who investigate the environmental impact of screwworm eradication invariably see many positive effects. I suspect the question of negative impact is one that no one wants to examine very closely. In an era where we’re just beginning to understand how nature balances itself, I hope that doesn’t come back to haunt us.

Godoy, Emilio, and Raúl Pierri. 2010. “Latin America: Radioactive Attack on Flesh-Eating Screw-Worm.” Inter Press Service

Vargas-Terán, M., H. C. Hofmann, and N. E. Tweddle. 2005 “Impact of Screwworm Eradication Programmes using the Sterile Insect Technique.” In: V.A. Dyck, J. Hendrichs and A.S. Robinson (eds.), Sterile Insect Technique. Principles and Practice in Area-Wide Integrated Pest Management, Netherlands: Springer.