The Emerald Ash Borer (EAB), scientific name Agrilus planipennis, is an invasive beetle that poses a severe ecological and economic threat to ash trees in Europe and North America.
Figure 1. Map representing Emerald Ash Borer infested areas in North America. Red pin represents Guelph, Ontario, Canada, where iGEM Guelph resides.
Since its introduction, EAB has led to devastating mortality rates, with up to 99% of ash trees in affected areas dying within a few years of infestation1. As ash trees play a crucial role in maintaining ecosystem balance by promoting soil health, influencing nutrient cycling, and providing habitats for wildlife, their loss has cascading effects on biodiversity and forest health2. Moreover, ash wood is highly valued for its strength and adaptability, making it economically important for various industries3.
Current efforts to manage EAB infestations primarily rely on chemical pesticides. However, these approaches have proven to be unsustainable in the long term. Pesticide resistance, environmental contamination, and the negative effects on non-target species and human health highlight the need for alternative solutions. The limitations of chemical pesticides inspired iGEM Guelph to explore a more sustainable and eco-friendly approach: bioinsecticides.
Objective of Project Ash Guard
Our project, Ash Guard, seeks to leverage synthetic biology to protect ash trees from EAB infestations. Specifically, we aim to engineer a bioinsecticide using Saccharomyces cerevisiae (S. cerevisiae), also known as brewer's yeast, to express the Cry8Da protein, a crystal toxin derived from Bacillus thuringiensis (Bt). Cry8Da has shown specificity against insects from the Chrysomeloidea superfamily, which includes the EAB5.
Why Yeast?
Yeast, particularly S. cerevisiae, was chosen as the expression host for Cry8Da due to its natural symbiotic relationships with plants and insects. S. cerevisiae has been shown to produce volatile compounds that attract insects, which it uses to disperse itself into new environments6. Additionally, S. cerevisiae naturally inhabits the bark of trees, including ash trees, making it an ideal candidate for this project3. By genetically engineering S. cerevisiae to express Cry8Da, we aim to create a living barrier on ash tree bark. When EAB larvae burrow into the bark to begin their maturation process, they will encounter the Cry8Da toxin and this will lead to larval death, preventing the beetles from continuing their lifecycle and stopping the damage to ash trees before it can escalate.
Figure 3.Implementation proposal for project Ash Guard, where Cry8Da is expressed in a genetically engineered Saccharomyces cerevisiae strain. This genetically engineered strain aims to halt Emerald Ash Borer infestation.
Bioinsecticide as a Sustainable Solution
The use of bioinsecticides offers a sustainable alternative to conventional chemical pesticides. Bioinsecticides produced using synthetic biology, such as S. cerevisiae expressing Cry8Da, can target specific pests with minimal environmental impact. In contrast to chemical treatments that often harm non-target species and contaminate ecosystems, bioinsecticides provide a more precise pest control method. This project represents a significant step toward achieving Sustainable Development Goal (SDG) #15, which focuses on protecting the environment and promoting biodiversity.
Our approach combines advanced genetic modification techniques with a focus on ecological sustainability. The engineering success of this project will hinge on the ability to clone and express the Cry8Da protein in S. cerevisiae. Our Engineering Success page dives into the technical processes behind our design, including plasmid construction, protein expression, and experimental validation. Our efforts aim to provide a long-term, effective solution to EAB infestations that aligns with environmental preservation goals.
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