As the EU continues to push towards pesticide use reduction, proof that its suggested alternative bio-based solutions offer a real alternative for field crops is very limited at best.

So we are left wondering if such stated solutions can or will offer real control options in field crops?

There is also a question as to how such products would be assessed in pesticide usage terms, as the volume of ‘active’ can be much higher.

Well, it seems that there is some scope for hope, at least for some parts of the world.

I read with interest that researchers in Brazil have field-tested a new approach for the control of a very big pest of maize – the fall armyworm.

Fall armyworm

This is a very important and devastating pest of maize crops, which is fast becoming a global threat.

It has traditionally been a problem in North and South America, but now it has advanced to parts of Africa and Asia. We might still be a bit cold for this problem in Ireland.

The fall armyworm is the caterpillar stage of the life cycle of a moth and it is a ferocious leaf feeder.

The closest we can come as a comparison are the caterpillars from the white butterfly that feed on brassicas such as cabbage.

Huge numbers can quickly defoliate plants. The pest is spread by the moths flying about and laying their eggs on susceptible hosts plants.

Most damaging pest

Brazil plants more than 40 million acres of maize annually and the fall armyworm is the most damaging pest of the crop there. So it was a good place to test the technology.

Being such a big pest, it is hardly surprising that GMO technology has been used for a long time now to control it.

This uses a bacteria gene inserted into the plant to provide a natural mechanism to kill the caterpillars as they eat the foliage.

But this technology has been used for some time and fears continue that resistance remains a possibility.

The threat is really about numbers building rapidly within a crop

The threat is really about numbers building rapidly within a crop, as it has three separate generations per year.

A single larva will cause no significant damage, but as numbers build in the generations, so does the damage. And they can attack the cobs as well as the leaf and stems.

The reproductive capacity of fall armyworm threatens the effectiveness of insecticides and also the biotech pest-resistant GMO varieties which farmers currently use.

So, alternative control options would be very welcome to help protect the existing methods used.

A self-limiting technology

As the pest problem becomes more international, so does the requirement for an alternative solution.

A unique collaboration between Oxitec in the UK and Bayer is doing just that.

The objective was to develop a Friendly™ fall armyworm to combat the pest and the initial validation focus was placed on Brazil. And unlike conventional pest control, the new technology is looking at a different approach.

Unlike using an insecticide, which controls pest multiplication by taking out a segment of the population, Oxitec’s Friendly™ technology (developed initially at Oxford University) uses the adult moth to help bring about the solution.


Control was based around the production of male self-limiting fall armyworm moths. These find and mate with female fall armyworm moths in maize fields, but the females produce no female offspring.

So the ability of the pest to multiply and cause damage is limited quite quickly and the population gradually shrinks. This means fewer caterpillars eating crop leaves and fewer female moths to lay eggs within those fields.

As well as acting to control the pest and protect the crop, the release of these self-limiting male moths will also offer protection to the insect-resistant GM crops against any potentially resistant fall armyworm caterpillars.

So, this technology would also help keep these other protection measures effective for longer.


The Oxitec Friendly™ fall armyworm technology is a safe, non-toxic and species-specific control tool.

It has no impact on beneficial insect species and it is self-limiting in the environment. And while this specific product is new, Oxitec’s Friendly™ technology is not.

It has already been tested in different parts of the world in trials of insects such as mosquito, the Mediterranean fruit fly and the diamondback moth. In these tests, the product was proven to be safe, effective and self-limiting.

The next stage

While of no direct benefit to the crops we grow, it is interesting to know that a technology is being developed that seems to have the potential to work and be effective in field crops and we look forward to hearing how this behaves when it goes to full field-scale use.

Releasing these moths in a single field could still do little for that field for a while, as they can fly to neighbouring fields to lay their eggs and that is where the caterpillars will be.

So information on the density of any release would be important, as the grower who pays the bill will want to see results in his/her fields.