A major step forward in the environmentally friendly control of invasive insect pests: Researchers involved in the REACT project, together with international partners, have solved a long-standing mystery in insect biotechnology.

Led by Justus Liebig University Giessen (JLU) and the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture in Seibersdorf, Austria, the team has, for the first time, identified the gene responsible for the so-called temperature-sensitive lethal (tsl) effect in the Mediterranean fruit fly (Ceratitis capitata). This discovery has immediate relevance for improving the Sterile Insect Technique (SIT), a well-established biological method for controlling pest insects — and it directly reflects the research goals of the REACT project, which is focused on advancing innovative insect control technologies.

“By identifying the tsl gene, we are closing a critical knowledge gap that has long prevented the expansion of genetic sexing systems beyond the Mediterranean fruit fly. This paves the way for highly specific and sustainable insect control strategies – without chemical insecticides,” says Prof. Marc F. Schetelig, coordinator of the REACT project and Professor of Insect Biotechnology in Plant Protection at JLU.

The tsl principle was first discovered in the 1980s at the FAO/IAEA Insect Pest Control Laboratory in Seibersdorf. In tsl-based genetic sexing strains, female embryos die following brief heat exposure, allowing the mass-rearing and release of sterile males only. However, the genetic basis of the tsl effect remained unknown for more than 35 years – hindering its transfer to other pest species.

Now, researchers have identified a point mutation in the gene encoding lysyl-tRNA synthetase (LysRS). When this mutation is introduced into wild-type strains via genome editing, the result is the same: only males survive heat treatment at the embryonic stage. For the first time, the genetic mechanism behind temperature-sensitive lethality is clearly defined and can be used to develop sexing strains in other pest insects of agricultural, veterinary, and public health importance.

“This discovery is a real milestone. After more than 35 years of research, we now have a precise molecular tool for temperature-dependent lethality. This opens up new possibilities for applying genetic sexing to a wide range of insect species — a major advance for SIT programs around the world,” says Kostas Bourtzis, molecular biologist at the FAO/IAEA Centre and co-author of the study.

This publication highlights the strong collaboration between JLU and international partners, particularly the FAO/IAEA Centre in Seibersdorf. It also exemplifies the strategic vision of the REACT project: to enable sustainable pest control through cutting-edge genetic and biotechnological solutions.

See the news on the IAEA Website: https://www.iaea.org/newscenter/news/genetic-discovery-advances-insect-pest-control-worldwide 

The full study is available online: Roswitha A. Aumann, Georgia Gouvi, Maria-Eleni Gregoriou, Tanja Rehling, Germano Sollazzo, Kostas Bourtzis, and Marc F. Schetelig (2025). Decoding and engineering temperature-sensitive lethality in Ceratitis capitata for pest control. Proceedings of the National Academy of Sciences (PNAS). https://doi.org/10.1073/pnas.2503604122