The larvae of the screwworm, a fly, feed on living tissue. They are the epitome of flesh-eating parasites straight out of a horror movie.
The screwworm, or Cochliomyia hominivorax, lays its eggs in wounds or mucous membranes of warm-blooded animals. After hatching, the larvae burrow into the tissues and quickly worsen the wound. Without treatment, the infestation can lead to the death of the animal. In rare cases, it can also affect humans.
Male screwworm
Image Wikimedia
To strengthen the fight against this parasitic fly, researchers in Panama are preparing outdoor trials of a genetically modified strain. Named NovoFly, it could increase the number of sterile insects available to combat its spread.
The method relies on a technique already used for several decades. Males sterilized by irradiation are released in large numbers. They mate with wild females, which then do not reproduce. Since these females generally mate only once, each release progressively reduces the number of offspring.
Current production generates both males and females. However, only sterile males are actually useful in this strategy. NovoFly aims to solve this problem by producing batches consisting solely of males.
It is through a genetic modification that NovoFly intends to achieve a production consisting only of males. This modification acts very early, at the embryonic stage: it causes the death of female embryos. Surviving males also carry a red fluorescent marker, making them easier to distinguish from wild flies. They are then irradiated to prevent any reproduction before release.
This organization could almost double the number of sterile males obtained from the same production. It does not rely on the spread of a gene in nature, nor on the establishment of a new population of modified flies. The goal is to produce more sterile male insects, then use them in the existing program.
The planned trials in Panama must first verify NovoFly's behavior in conditions close to the natural environment. Researchers will need to measure male survival, their dispersal, and their ability to compete with wild flies. These results will determine whether the strain really works outside of rearing facilities.