Since the 1950s, the Sterile Insect Technique (SIT) has been used to control screwworm flies and other insects. This technique currently involves irradiating male and female insects to make them sterile, and then releasing them to mate with fertile insects.

Now an article published in the journal BMC Biology suggests that populations of New World screwworm flies (Cochliomyia hominivorax) could be greatly suppressed with the introduction of male flies that produce only males when they mate, which could enhance the Sterile Insect Technique.

“Genetic suppression of a pest population is more efficient if only males survive, so we manipulated screwworm genes to promote a female-lethal system that works when a common antibiotic is not provided at larval stages,” said Max Scott, one of the co-authors.

Withholding tetracycline in the larval diet essentially means “It’s a boy” when the genetically modified male flies successfully mate with females in the field. The study shows that the genetically modified males both compete well for the attention of fertile females and mate successfully with fertile females. The genetically modified flies also do not mate with other very closely related fly species.

New World screwworm flies parasitize warm-blooded animals in the Western Hemisphere tropics and sub-tropics, causing massive financial and animal losses. The flies were eradicated from North and Central America years ago using the Sterile Insect Technique, which has resulted in annual savings of more than $1 billion per year. However, the flies continue to wreak havoc across South America and some Caribbean islands.

However, “[The Sterile Insect Technique] is a bit inefficient, as sterile males will mate with sterile females, which is totally unnecessary,” Scott said. “Releasing only males, would cut down on the costs of rearing sterile female flies and should significantly increase the efficiency of the suppression program. Plus, it would take fewer resources to begin screwworm eradication programs in other afflicted areas, like the west coast of South America, for example.”

In addition, the technology should be easily transferable to other flies that are pests of livestock, such as the Old World screwworm.

Read more at:

– A transgenic male-only strain of the New World screwworm for an improved control program using the sterile insect technique