Against the Invasive Hemlock Wooly Adelgid

The Pro bl em

The Hemlock Wooly Adelgid Invasive species introduced from Japan Infests hemlocks and feeds on their sap Problems? o Uncontrolled population growth o Kills adult trees and saplings Hemlock population decimated Ruining forest ecosystems

Current Solutions Chemical solutions: Horticultural soap – Human application to trees Insecticidal sprays Soil Drenches – Insecticide diluted in water, fed to tree Bark injections

Chemical Solutions Issues Poisonous to other species Needs to be applied one tree at a time Needs to be applied with precision Expensive

Current Solutions Biological solution: Introduce the natural predator of the hemlock wooly adelgid Pseudoscymnus tsugae; the ladybeetle o Feeds on hemlock wooly adelgid and the balsam wooly adelgid (Adelges piceae) o Native to China and Japan

Issues with existing biological solutions Newly introduced species without existing predator – potential invasive species Is not able to eradicate enough of the population – only up to 40-55% max Slow acting Doesn’t take hold quickly in new habitats o May take up to 5-7 years to reach detectable levels of population o Hemlocks in afflicted areas may be wiped out before beetle can act So, these solutions are not helping.

The ever-worsening effects

My Solution Engineered bacteria incorporated into water source o E-coli bacteria o Engineered with genes of sap dwelling bacteria (Pseudomonas) When adelgid drinks sap, bacteria releases toxin Adelgids die BUT… What would stop the poison from killing other non- harmful species in the ecosystem?

My Solution Superfamily Aphidoidea – includes adelgids and aphids o Contains bacteria Buchnera aphidicola in the gut o Present since common ancestor; 400 million years ago Through quorum sensing, engineered bacteria can sense presence of Buchnera aphidicola Gene could be found – entire genome of B. aphidicola has been sequenced

Some design specifics Chassis: E-coli bacteria o Known genome o Previous experience using engineering them To allow it to survive properly in the soil and inside the plant, the E-coli bacteria will have some carefully selected genes from Pseudomonas syringae, which is A pathogen in a lot of plants Very hardy (resistant to water, cold) A gram-negative gammaproteobacteria, like E-coli Also has fully sequenced genome

Unknowns Buchnera aphidicola’s loss of independent function B. aphidicola’s placement inside the adelgids The specific gene for B. aphidicola’s quorum sensing device Best toxin to kill adelgid and gene for that toxin o Possibly Methyl Salicylate, as there is a known gene for it o Could exist a better option Specific genes for survivability from P. syringae

Advantages Easier to administer on a large scale o Could be put into water sources o When administered from tree to tree, less precision required Will not harm ecosystem o Only targets pests Works quickly and effectively o Has potential to wipe pest out in 2 generations (of adelgid) After adelgids gone, no further effects Could also work for use against other invasive species in that family o Balsam wooly adelgid o The greater than 100 species of invasive aphid pestering Hawaiian farmers

Works cited Phylogenetic characterization and molecular evolution of bacterial endosymbionts in psyllids (Hemiptera: Sternorrhyncha). Spaulding AW, von Dohlen CD.Department of Biology, Utah State University, Logan 84322, USA.Spaulding AWvon Dohlen CD

Pictures cited