Sterile Insect technique

The Sterile Insect Technique (SIT) is a cost-effective, sustainable method for the suppression or elimination of target pest populations.

SIT involves releasing millions of sterile insects over a wide area to mate with the native insects present. Mating of released sterile males with native females leads to a decrease in the females’ reproductive potential because their offspring do not survive. Ultimately, if males are released in sufficient numbers over a sufficient period, this leads to the local elimination or suppression of the pest population. SIT is species-specific and has no effect on other ‘non-target’ species. This ‘birth control’ strategy is therefore environmentally clean and sustainable. SIT approaches are good at reducing low populations to very low levels in contrast to insecticides which are good at reducing high populations to low ones.

Tried and tested

SIT was pioneered in the 1950s by Dr. R.C. Bushland and Dr. E.F. Knipling who jointly received the 1992 World Food Prize. The first SIT programme started in 1954 on the island of Curacao to control the New World screwworm (Cochliomyia hominivorax), a parasitic fly that lays its eggs in the living tissue of warm-blooded animals, such as livestock and even humans. The US officially eradicated the screwworm using SIT in 1982 and the eradication programme moved steadily south through Central America until the whole region was declared screwworm free in 2001. A permanent sterile fly barrier is maintained in Panama to prevent re-infestation.

The wider use of SIT is currently limited by available technology.

The irradiation used to sterilise insects is too damaging for many species and makes high levels of training and security necessary. For some insect pests, there are no methods for cheap, large scale rearing or to separate the sexes. Oxitec has developed a new solution which will replace the need for irradiation and make it easier to sort males from females – making SIT more affordable, even safer, and applicable to a wider range of pests.

Further reading:

Sterile Insect Technique: Principles and Practice in Area-Wide Integrated Pest Management edited by V.A. Dyck.