Preparing for invasive pest introductions in advance could bring better results for farmers

Originally published on Farming Future Food

A more proactive approach to biological control would help stop invasive pests which threaten agriculture, according to a US expert.

Invasive pests pose a major economic threat to arable farming, with annual yield losses caused by these species of around 16% to the major global food crops of rice, wheat and maize alone.

Current attempts to curb the impacts of invasive pests using their natural enemies are reactive, waiting for species to arrive in new territories before potential controls are screened for potential release — but this approach is not nimble enough to stop damage, University of California entomologist Dr Mark Hoddle wrote in the journal Biocontrol.

Hoddle pointed to the invasion of the Asian citrus psyllid (Diaphorina citri) in California as an example of the sluggishness of reactive approaches. Years passed before two parasitoid wasps from the pest’s native range were ready to be released, by which time the species had made greater incursions and caused damage, due to its ability to vector a pathogen which causes a disease known as citrus greening.

The well-prepared approach to invasions

Instead of reactive action, potential invasive pests which pose the threat of economic damage and are unlikely to be easily eradicated should be identified in advance of their arrival, he urged, with natural enemies then assessed for the suitability to be introduced to new territories.

Such testing involves exploring how specific a predator or parasite is to the pest in question, and how effective they are in reducing its numbers. Once this is completed with satisfactory conclusions, such species can be cleared for release.

“Investment in proactive biological control research can be viewed as being analogous to an insurance policy, excellent to have, but something policy holders hope will not be needed. Proactive biological control research is a new twist on a classic approach to managing invasive pests,” he said.

Monitoring the obvious — and the wild cards

Identifying potential ‘incursion pathways’ for invasive species is crucial, he commented, which may be common trade routes for potentially-infested plant material or tourism links. There should also be attention paid to ‘wild cards’ or ‘emerging invasive species’, before they have clear routes of introduction to new areas.

Hoddle’s team have been involved in proactive preparations for the possible introduction of the avocado seed moth (Stenoma catenifer) from South America to the US, identifying the impacts of possible natural enemies and shedding light on the moth’s sex pheromone, which could be used in trapping and mating disruption.

“Rare events, for example pest introductions resulting in establishment, may not be so uncommon when the number of times the rare event could happen is very large, such as the importation of hundreds of millions of avocado fruit from areas with known fruit feeding pests over long periods of time,” he suggested.

In some cases, suitable natural enemies may not be found, he noted, but then, resources can be directed at other alternative control methods which could help protect valuable crops ahead of the arrival of their potential pests.