How thousands of stowaway pests are hitching a free ride into SA

The global Covid-19 pandemic has put human interactions with other animal species in the spotlight.

But what about our interaction with plants? Modern technology has enabled grains, fruits, vegetables and other plants to end up on the opposite side of the world from where they’re indigenous.

A growing awareness of these “alien invaders” has seen swathes of land cleared of trees in many provinces.

But to the untrained eye, on a microscopic level, there’s another whole alien invasion taking place: every imported agricultural product can unwittingly smuggle an insect, mite fungus or virus across SA’s borders.

And according to a recent study published, just under a third of products are contaminated by pests.

Davina Saccaggi, formerly of Stellenbosch University, and fellow researchers analysed an extensive data set of imported plant products that arrived in SA between 1994 and 2019.

These products, 25,279 in total, were inspected by the department of agriculture  and the study shows that “30% tested positive (meaning they had at least one contaminant) while 13% had multiple contaminants”. 

Of the 13,731 recorded contaminants, “fungi (41%), mites (37%) and insects (19%) were most common”. 

This data set and analysis “can inform strategies for risk assessment, pathway management and biosecurity protocols”, say the researchers, who identified a “major stumbling block” as being the absence of any “long-term record-keeping system”.

This has meant there’s been little idea of what to expect or look out for.

“Each inspection is a matter of personal knowledge and experience particular to that crop, commodity or entry point. Without generalised knowledge and long-term records, there is no way to analyse historical trends or predict future patterns,” said Saccaggi.

However, “tucked away in files, stored on stiffy disks or on CDs”, this information is now being recorded by the researchers in the hope of rectifying the situation.

“We’re now in the process of modelling these data to find consistent predictors of patterns which can be used to adjust sampling and inspection protocols. These will improve SA’s ability to find and stop any pests on imported goods,” she said.

TimesLIVE