Resistant myzus persicae aphid threatens virus yellows control
COLD weather and widespread use of neonicotinoid seed treatments combined to limit virus yellows infection in the sugar beet crop in 2011 to the extent that just 0.5 per cent of the crop was affected.
Concern, however, is increasing over the developing risk of resistance to neonicotinoid insecticides used to control myzus persicae aphids, the virus yellows vector.
Resistance has been identified in France, Italy and Spain, in myzus persicae populations associated mainly with peach and nectarine trees, where topical applications of neonicotinoids are used for aphid control, said Dr Mark Stevens.
“If those aphids start moving north and adapt to colder climes then I worry because there is very little chemistry coming on stream to control them,” he said.
Rothamsted Research work had shown these aphids were also carrying MACE and kdr resistance mechanisms, conferring resistance to pirimicarb and pyrethoids. “We have little in the can to actually control them,” said Dr Stevens.
“There are no resistant varieties coming on stream in the immediate future and the problem we are faced with is we are not looking at one virus but a complex of up to four different viruses, making it a very difficult target to hit with a resistance gene,” he said.
He told sugar beet growers at the conference the situation was ‘one we need to keep an eye on’.