Scientists working at Rothamstead Research institute in the United Kingdom have genetically engineered wheat crops to release pheromones that insects release when they are attacked by predators.

High crop yields depend on the use of insecticides to control pests

Because of the need to use as little of the Earth’s surface for agriculture as possible, it is important that we maintain high crop yields. Today’s crops depend on the use of pest control strategies in order to maintain high yields.

Aphids constitute one of the biggest classes of plant-feeding insects. Different strategies to prevent aphids from feeding on crops have largely centred on targeting molecular components of their nervous system. DDT was the earliest example of an agent that disabled a neuronal ion channel, preventing electrical signalling in the insect nervous system.

Most other pest control strategies also target nervous system components, but pesticide resistance is becoming a growing problem. Resistance arises from mutations that either make the target of an insecticide insensitive, a trait which is then selected for by the evolutionary pressure created by the insecticide’s use, or via mutations to enzymes that mean that insects can better break down insecticide compounds. This second kind of resistance leads to cross resistance.

New approaches are needed

Despite new insecticides having improved target specificity – killing only pests as opposed to bees or pest predators –  resistance means there is a need for new strategies.

Some of the most successful recent pesticides targeted components of insect mechanosensory systems that prevented them from being able to insert their mouth into plant tissue. This process requires proprioceptive feedback in order to ‘balance’ the long mouth protrusion as it pierces the outer layer of plants.

A radical new approach being developed by scientists working at Rothamstead Research institute uses genetic engineering to create plants that can release pheromones that may be able to deter plant-feeding insects. Aphids release these pheromones when predatory insects approach.

The pheromones warn other nearby insects that a predator is threatening them, leading the insects to try and escape.

By modifying plant genomes to emit these pheromones it is hoped that they can deter plant-feeding insects without the need for insecticide nerve agents that can be deadly to bees or other organisms.

 

Future outlook

While is it necessary to use pest control products to keep food production efficient, and to thereby reduce the already massive impact of the agriculture industry on our planet, ideal pest-control products would prevent plant-feeding insects from eating crops but would otherwise not affect natural ecosystems.

It is widely understood today that the use of even the least harmful pesticide products available leads to a plethora of negative environmental effects. When insecticides kill entire classes of organisms from an ecosystem it results in corresponding perturbations.

At the crucial level of the many thousands of single cell microbes that live in soils, pesticides that wipe out species above them, whose waste certain classes survive off, can leads to die offs of some microbes and population explosions of others. This can in turn lead to a breakdown of normal nutrient cycling at a microscopic level.

If these pheromone-based approaches can be successful they could eliminate the need for pesticides, although the future of these strategies is still speculative with no success currently documented in real-world testing, although the concept has been proven in controlled tests.

Even if they are successful, life may adapt again. Plant-feeding species may evolve to ignore these warning pheromones, which in turn could lead to an explosion of predator species who can pray more easily on insects that no longer respond to the warnings of their neighbours.

The future of the food production industry will need constant innovation to stay ahead of the many problems our crops are facing today. //