BACTERIAL INSECTICIDES

Against the Invasive Hemlock Wooly Adelgid

The Problem

The Problem

The Problem

The Hemlock Wooly Adelgid• Invasive species introduced from Japan• Infests hemlocks and feeds on their sap• Problems?

o Uncontrolled population growtho 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 ladybeetleo 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 habitatso May take up to 5-7 years to reach detectable levels of populationo 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 sourceo E-coli bacteriao 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 aphidso Contains bacteria Buchnera

aphidicola in the guto 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 bacteriao Known genomeo 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 toxino Possibly Methyl Salicylate, as there is a known gene for ito Could exist a better option

• Specific genes for survivability from P. syringae

Advantages

• Easier to administer on a large scaleo Could be put into water sourceso When administered from tree to tree, less precision required

• Will not harm ecosystem o Only targets pests

• Works quickly and effectivelyo 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 familyo Balsam wooly adelgido The greater than 100 species of invasive aphid pestering Hawaiian farmers

Works citedhttps://microbewiki.kenyon.edu/index.php/Bacterial_nucleation_in_pseudomonas_syringae

https://www.ces.ncsu.edu/depts/ent/notes/O&T/trees/note119a/note119a.htm

http://www.fs.fed.us/foresthealth/technology/pdfs/FS_hwa.pdf\

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC383098/

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.

https://microbewiki.kenyon.edu/index.php/Buchnera_aphidicola

http://www.na.fs.fed.us/fhp/hwa/

http://www.growingagreenerworld.com/control-of-the-hemlock-wooly-adelgid/

https://en.wikipedia.org/wiki/Aphididae

Pictures citedhttp://www.agri.ohio.gov/plant/hwa/imgs/hwa3.jpg

http://cdn.c.photoshelter.com/img-get/I00007.qiYccQCR0/s/860/860/Fphoto-67211205B-6WR.jpg

http://www.americanforests.org/wp-content/uploads/2013/06/HWA.jpg

http://www.backtree.com/images/eab-page/icons-large/trunk.jpg

http://www.brandtlawnandgarden.co/Images/Products/600x900/Monterey-Horticultural-Oil.jpg

https://upload.wikimedia.org/wikipedia/commons/a/a0/Adelges_tsugae_3225077.jpg

http://news.maryland.gov/mda/wp-content/uploads/sites/5/2013/04/HWA_small.jpg

https://encrypted-tbn2.gstatic.com/images?q=tbn:ANd9GcTwHOqXNgfkPgqU1Ri3w2V1eR9gvC2bPILVLKMHLVMC7Wnp7GJB

https://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Journal.pbio.0050126.g001.png/220px-Journal.pbio.0050126.g001.png

http://myaquanui.com/wp-content/uploads/2013/07/Ecoli.jpg

https://microbewiki.kenyon.edu/images/3/3e/Pseudosmonas_syringae_SEM.jpg

http://www.undergroundwineletter.com/wp-content/uploads/2014/08/question-mark-red.png

http://www.undergroundwineletter.com/wp-content/uploads/2014/08/question-mark-red.png