Could Genomics Halt the Spanish Slug?

31 March, 2016

A team of British scientists hopes new genetic technology could be the solution to seeing off the invasive Spanish slug, Arion vulgaris.

First noticed by gardeners in 2012, the large and distinctive slugs were initially observed eating plants and vegetables usually avoided by smaller, native UK species. In the four years since, further research has shown how they are thriving in the UK climate, raising fears that they could pose a viable threat to the country’s arable crops.

“Whether it will out-compete our native species, we don’t know,” says Dr Jonathan Clarke, head of business development at the John Innes Centre. “But we need to be aware that they could cross-hybridise.”

According to the Eastern Daily Press the team has turned to a pioneering genetic-based solution, already used in other parts of the world to kill pests such as the Colorado beetle. Scientists hope they can first identify genes within the slug’s DNA that dictate its ability to feed or breed, so colleagues at the neighbouring Genome Analysis Centre are first to sequence the pest’s genome.

By interfering with these genes, it would be possible to disrupt those vital processes – either killing the slug outright, or reducing populations by smashing its breeding capacity. That gene interference is made possible by targeting a specific characteristic common to all living cells, which use a substance called ribonucleic acid (RNA) as a messenger to carry the DNA’s instructions. The technique is known as RNA interference, or RNAi.

“This is new technology that could have a positive impact on safeguarding crops,” says Dr Ian Bedford, head of entomology at the John Innes Centre. “By getting the slug to ingest this RNAi, we have a specific solution, targeted at a specific pest, that will deactivate essential genes within that pest.”

The ideal solution would to find a delivery method where the slug would eat the RNAi in a conventional bait pellet.

“There is an assumption that Spanish slugs are resistant to standard agrochemical solutions,” says Dr Bedford, “but we think that is purely because of the number that often invade the crop. However, we have shown that a single mature Spanish slug can consume up to 20 ferric phosphate pellets before it dies.”

In a bid to track the spread of the pest, which has also become a problem in several other European countries, researchers are asking British farmers to report major cases of slugs damage to their crops, in an effort to try to identify the species responsible.