Trialeurodes vaporariorum, or glasshouse whitefly, is the foremost pest for the UK’s tomato growers.

The pest damages the plant in three ways; by extracting sap and therefore vital nutrients, by creating a sticky ‘honeydew’ on the surface of the plant which attracts mould, and by transmitting damaging plant viruses through their saliva.

Currently, biocontrol methods are used to reduce the impact of the whitefly on tomato crops.  The parasitoid wasp lays its eggs in the young whitefly which are then eaten by the hatching larvae. However, for control to be effective, the wasps need to be released on a weekly basis which is costly and labour intensive.

As a result, most farmers also use chemical pesticides as a second line of defence.  This includes the widespread use of the controversial neonicotinoid pesticides which have been linked to dwindling bee populations.

Whitefly were 80% less likely to settle on the wild variety

By fitting gold wires to the back of individual whitefly and measuring the electro-chemical signals as they fed on the plant sap, the team found the insects spent more time ‘roaming’ and less time feeding on the wild varieties than those which settled on the commercial plants.

“One option would be to revert back to growing more of the older, wild varieties, and certainly we are already seeing a trend towards this, particularly on allotments and among smaller growers,” explains McDaniel.

“However, lower yields means the wild varieties are unlikely to be a viable option on a large scale.

“Our findings suggest that if we can breed the wild, whitefly resistant genes back into our tomatoes – either through a selective breeding programme or genetic engineering – then it offers a real solution for the commercial tomato industry.”

Project supervisor Dr Barry Brogan, also from Newcastle University, said the findings also highlighted the importance of maintaining biodiversity.

“There has been growing interest in traditional and wild varieties of fruit and veg, driven mainly by people wanting to re-capture the tastes of their childhood,” explains Dr Brogan.

“But actually it’s playing a vital role in protecting these older varieties and maintaining biodiversity. If we allow our wild species to be lost then we risk losing potentially useful traits that we might need at a later date.”