The value of basic science into insect biology is no more evident than when a crisis arises involving a devastating insect pest like the New World screwworm, says University of Illinois Urbana-Champaign entomology professor and department head May Berenbaum. In a 2016 essay in the journal Science, Berenbaum wrote about the successful — if temporary — eradication of the pest in many parts of the world. She spoke with News Bureau life sciences editor Diana Yates about the screwworm’s return.
What makes the New World screwworm especially problematic?
Cochliomyia hominivorax is a parasitic fly, the maggots of which consume the flesh of living warm-blooded hosts, including mammals and sometimes birds. Before they were eradicated from the U.S., where they were native to the southern and southeastern states, New World screwworm flies caused major livestock losses amounting to hundreds of millions of dollars.
How did basic entomological research contribute to eradicating this pest?
The screwworm was eradicated by implementation of the sterile insect technique — a method developed about 60 years ago involving the mass-rearing of the pests and exposing them to sterilizing radiation. This approach doesn’t work in all species, but in this species it works because the sterilized males are capable of mating but not of producing offspring. Female C. hominivorax flies mate only once, so flooding an area with lab-reared sterile males can basically halt the reproductive cycle.
This approach is called autocidal control and has no known adverse environmental impacts. Basic entomological research laid the groundwork — first, by revealing that exposure to radiation could render certain male insects sterile, and, second, by discovering that screwworm fly females mate only once in their lives, so infestations could be stopped by flooding an area with sterile males to ensure that the majority of females mate first with a sterile male and never lay fertile eggs.
Could the same methods work again?
Yes, definitely!
Should we have been continuously dispersing sterile male screwworm flies in areas that are now affected? Or is waiting for a new emergence of the pest a better strategy?
More is not better in terms of pest management; continuous use of management techniques that involve killing a significant proportion of the target pest population is an excellent way to select for resistance, which can render the technique useless.
In your Science essay, you wrote about public misunderstanding of the importance of funding basic research into insect reproduction. What contributes to such confusion?
Well, it probably didn’t help that the target pest for this method of interrupting reproduction is called the screwworm fly. By the way, it’s called “screwworm” beause the maggots seem to twist their way into the living flesh of their hosts.
Another contributing factor, I think, was the fact that the screwworm fly was primarily a problem in tropical and subtropical regions historically, due to the fact that it can’t typically survive harsh winter conditions, so most Americans didn’t have first-hand experience with it.
How can scientists better promote the public understanding of basic science?
Being willing to engage with journalists is a great start!
Editor’s note:
To contact May Berenbaum, email maybe@illinois.edu.