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Research Project: Improved Biologically-Based Methods for Insect Pest Management of Crop Insect Pests

Location: Insect Behavior and Biocontrol Research

Title: Genetic breakdown of a transgenic Tet-off conditional lethality system for insect population control

item ZHAO, YANG - University Of Florida
item SCHETELIG, MARC - Justus-Liebig University
item Handler, Alfred - Al

Submitted to: Nature Communications
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/19/2020
Publication Date: 6/18/2020
Citation: Zhao, Y., Schetelig, M., Handler, A.M. 2020. Genetic breakdown of a transgenic Tet-off conditional lethality system for insect population control.. Nature Communications. 11:3095.

Interpretive Summary: The availability of genetically modified (GM) insects presents an attractive alternative to conventional pest control methods especially in regards to Sterile Insect Technique (SIT). One concern for the use of GM insect strains is the potential for genetic breakdown or developed resistance to the genetic modification when billions of insects are produced for an Integrated Pest Management Program. Researchers at USDA, Agriculture Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, examined the genetic stability of introduced genetic modifications that produced lethality and found that, when extremely large numbers of insects are produced, there can be genetic breakdown of the system. From these results, it was estimated that for 100 million GM fertilized eggs deposited in the field, several hundred adults may survive from a breakdown in the introduced lethal genetic construct and then contribute to a lethality resistant population. In order to avoid the development of such a resistant population, recommendations are made for the use of a secondary redundant lethality system that would prevent insects resistant to either one of the systems to survive.

Technical Abstract: Genetically modified conditional lethal insect strains have been created to improve the control of insect pest populations of agricultural and medical importance. However, the potential for genetic breakdown of these strains by spontaneous mutations resulting in suppression or resistance to the lethality system have not been addressed, which is critical since field release studies are already in progress. This knowledge gap was addressed by analyzing the frequency and structure of spontaneous mutations resulting in survivors of a Drosophila tetracycline-suppressible embryonic lethality system under large-scale rearing. Lethal revertants due to primary-site deletions and indels occurred at a frequency of 5.8 x 10-6 per generation, in addition to maternal effect survivors. We presume that these second-site modifier lines could result in a population resistant to the lethality system in the field, which could be mitigated by the use of strains carrying dual redundant lethality systems.