The Worrying Emergence of Insecticide Resistance in Crop Pests

Using their state-of-the-art diagnostic approaches the team at Rothamsted, who receive strategic funding from BBSRC, have identified the underlying mechanisms of this resistance, with a view to developing new advice and technologies to ensure farmers are able to continue protecting their crops against damage and disease.

The grain aphid, Sitobion avenae is an important pest of wheat and barley, reducing grain yield by transmitting Barley Yellow Dwarf Virus (BYDV). Until recently, growers had good control of this pest with pyrethroids. However, during summer 2011 there were reports of control failures which prompted Rothamsted scientists to test aphid samples for resistance to pyrethroids using scientific techniques such as topical bioassays and DNA diagnostics.

These techniques have allowed the Rothamsted scientists to look for a genetic mutation which occurs in other insect pests and is known to cause insecticide resistance. The target-site mutation, called "kdr", was identified in the grain aphid samples which were obtained from the Insect Survey, that Rothamsted Research has been running for nearly 50 years. The sample testing was funded by HGCA.

If farmers are to control for this alarming increase in aphid resistance then Professor Lin Field, Lead researcher at Rothamsted said "continued resistance monitoring is essential and growers will need rapid and clear feedback". She added "alternatives to pyrethroids also need to be evaluated in anticipation of increased resistance causing widespread spray failures and greater BYDV problems."

The scientific analysis conducted at Rothamsted has shown that the mutation was present in 2012 in some areas at high frequency (>50%) and was also present at low levels in 2009 but appeared to take hold in 2011 when pyrethroid control failures were first reported.