Turning tobacco plants into factories for cleaner pesticides

Moth pheromones are environmentally safer alternatives to traditional pesticides for trapping bugs, but manufacturing them requires harmful chemicals. Here’s a safer alternative for the safer alternative.
Written by Janet Fang, Contributor
tobacco with moth phermone biosynthesis.jpg
For more eco-friendly pest control, scientists have genetically modified tobacco plants, making them factories for producing insect pheromones. 

Pheromones, those chemicals produced by animals and released into the environment, are used by moths for finding mates. Synthetic pheromones -- which can disrupt pheromone communication in insect pests -- have been used widely by farmers for decades, Science explains, to trap insects or confuse them enough so they can’t breed. 

As pesticides, pheromones are nontoxic and biodegradable, and small amounts (just tens of grams per hectare) are needed to be effective -- making them an environmentally-friendly alternative to traditional pesticides for trapping bugs. But the commercial production of large amounts of synthetic pheromones requires the use of harmful chemicals (such as neurotoxins hexane and dichloromethane) and generates dangerous waste byproducts. 

So, a team led by Christer Löfstedt from Lund University, Sweden, created a plant factory for producing moth pheromone:

  • They isolated four key genes involved in the production of natural sex pheromones of two moths: the bird cherry ermine moth (Yponomeuta evonymella) and the orchard ermine moth (Yponomeuta padella). In the wild, females emit these pheromones to attract male suitors, Science explains.
  • Genes that code for pheromone biosynthesis were injected into the tobacco plant Nicotiana benthamiana via bacteria cultures (pictured). 
  • By doing so, the team got the tobacco plants to express genes for moth pheromone production.
  • The result was a fatty, alcohol-based product that closely mimics natural sex pheromones. 

Their plant-derived compounds were quite effective at trapping moths in the field -- attracting on average 130 male bugs per trap, approximately half that of commercially synthesized pheromones. 

No matter what you may think about GM crops, this is a cost-effective way to produce large amounts of a safer alternative to bug sprays with minimum amounts of hazardous waste. This is an especially important development because farmers have dramatically ramped up their use of pheromones to control pests. Löfstedt tells Science: "Total land area treated by pheromones has approximately doubled since the turn of the century."

Right now, the team still has to prepare baits for trapping insects using their plant-derived pheromone components. Their next goal is to develop GM plants that can release these pheromones into the environment.

The work was published in Nature Communications this week. 

[Via Science]

Image: Erling Jirle, Department of Biology, Lund University, Sweden

This post was originally published on Smartplanet.com

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