In the face of climate change and the associated species migrations, we must ensure that we and generations to come have enough food to eat. Conventional, environmentally harmful chemical pesticides are species-agnostic and often kill harmless insects; technologies that selectively control or kill pest species are a safer choice.
Drosophila suzukii, an invading insect pest, is a threat to agricultural yields, especially to the production of fruits such as strawberries, cherries, plums, and grapes in western countries. Until now, control measures to stop the spread of D. suzukii have been inadequate.
A research published in GEN Biotechnology (Precision Guided Sterile Males Suppress Populations of an Invasive Crop Pest) describes the development of a programmable CRISPR-based technique that might, if implemented at large in the wild, eliminate fertile male D. suzukii, effectively, specifically, and safely controlling this pest population.
The team at the University of California, San Diego (UCSD) implemented a temperature-inducible, precision-guided, sterile insect technique (pgSIT), described by the team in an earlier investigation, to breed infertile but fit D. suzukii males with modest shorter lifespans. Through empirical experimentation and mathematical modeling, the researchers demonstrated that repeated release of sterilized males can rapidly and successfully eliminate D. suzukii populations.
Akbari, a professor in the School of Biological Sciences department of cell and developmental biology at UCSD, believes it is a safe, evolutionary stable system. Both are critical safety features that will help it get approvals for use.
Rodolphe Barrangou, PhD, author of The CRISPR Journal, summarizes research that demonstrated how next-generation CRISPR-based genedrives could be utilized to control croppests. This approach allows population suppression through the deployment of competitive sterile males, which is crucial for commercial applications.
The pgSIT system edits essential genes that determine sex and fertility. Two transgenic D. suzukii strains were used, one expressing Cas9 in germline and somatic cells, and the other expressing guide RNAs targeting genes essential for female survival and male fertility, such as sex lethal (Sxl), double sex (dsx), and transformer (tra).
The authors demonstrated that the pgSIT system was beneficial when pgSIT sterile males were released at rates comparable to those used for conventional SIT approaches, and they were lower than the release rates recommended for conventional SIT approaches.
pgSIT D. suzukii males had a shorter lifespan than wildtype males, according to the study [adapted from Kandul NP, et al, GEN Biotechnology, 2022]; the authors found that combining pgSIT D. suzukii with wildtype males increased egg hatching rates; these findings suggested that the sterile males are competitive and can successfully match with females.
Kutubuddin Molla, PhD, is a scientist at the National Rice Research Institute in Cuttack, India, and an editor at the The Plant Cell journal. Nevertheless, before environmental release,we must be careful to avoid any anticipated risk and unintended ecological consequences. If we could developarecalled system of gene drive, we might have more confidence in environmental release of gene-driveinsects.
Barrangou agreed. We need to be sensitive and cautious about practical deployment and ensure that appropriate studies are conducted to assess release safety and ecological implications. Depending on release scale and pattern, population reduction and control will likely result.
Akbari said his team has developed pgSIT for several species in the last four years, and that they intend to utilize it as a platform technology to safely control the spread of other pests in the real world.
