The attack of the clones: tracking the movement of insecticide-resistant peach–potato aphids Myzus persicae (Hemiptera: Aphididae)

Abstract

Myzus persicae (Sulzer) collected in Scotland were characterized for four microsatellite loci, intergenic spacer fingerprints and the resistance mechanisms modified acetylcholinesterase (MACE), overproduced carboxylesterase and knockdown resistance (kdr). Microsatellite polymorphisms were used to define a limited number of clones that were either fully susceptible to insecticides or possessed characteristic combinations of resistance mechanisms. Within these clones, intergenic spacer fingerprints could either be very consistent or variable, with the latter indicating ongoing evolution within lineages, most likely derived from the same zygote. Two clones (termed A and B) possessed all three resistance mechanisms and predominated at sites treated with insecticides. Their appearance on seed potatoes and oilseed rape in Scotland in 2001 coincided with extensive insecticide use and severe control failures. Clones C, I and J, with no or fewer resistance mechanisms, were found in samples from 1995 and were dominant at untreated sites in 2001. A comparison of Scottish collections with those from other UK and non-UK sites provides insight into the likely origins, distribution and dynamics of M. persicae clones in a region where asexual (anholocyclic) reproduction predominates, but is vulnerable to migration by novel genotypes from areas of Europe where sexual (holocyclic) reproduction occurs.

Spatial and temporal dynamics of Myzus persicae clones in fields and suction traps

“…An additional seven clones were collected in a single year, usually only once, and are the subject of a separate study. In accordance with the convention adopted by Fenton et al (2005) , the 14 clones were designated A -N ( Table 1 ).…”

“…Myzus persicae sexual populations are genetically diverse ( Wilson et al , 2002;Fenton et al , 2003;Guillemaud et al , 2003;Vorburger et al , 2003a ). Studies of long-term asexual populations of this aphid show instead an extreme effect of genetic bottlenecking ( Fenton et al , 1998( Fenton et al , , 2005Zamoum et al , 2005;Kasprowicz et al , 2007;van Toor et al , 2007 ). Asexual populations are particularly important in vectoring plant viruses when they move from plant to plant and crop to crop.…”

“…In M. persicae , the spread of insecticide resistance beyond sexual and into asexual populations is rapid and generally associated with expansion of resistant clones but not resistance genes. Resistant clones eventually become mixed with stable asexual populations ( Fenton et al , 2005 ) and these appear in waves, with new clones appearing in successive years . Three resistance mechanisms have been identified in M. persicae populations including elevated carboxylesterase, which sequester and degrade org anophosphates; modified acetylcholinesterase (MACE), which confers resistance to dimethylcarbamates; and knockdown resistance (kdr) and super-kdr (skdr), which modify the nerve sodium channels gating system, thereby rendering pyrethroids ineffective ( Foster et al , 2000 ).…”

“…Three resistance mechanisms have been identified in M. persicae populations including elevated carboxylesterase, which sequester and degrade org anophosphates; modified acetylcholinesterase (MACE), which confers resistance to dimethylcarbamates; and knockdown resistance (kdr) and super-kdr (skdr), which modify the nerve sodium channels gating system, thereby rendering pyrethroids ineffective ( Foster et al , 2000 ). The selective advantage conferred Spatial and temporal dynamics of Myzus persicae clones in fields and suction traps Louise Kasprowicz , Gaynor Malloch , Jon Pickup * and Brian Fenton by insecticide resistance is considerable and, under ideal conditions, resistant clones can multiply in sprayed crops to reach damaging levels ( Foster et al , 1998;Fenton et al , 2005 ) and these can be found in large quantities in suction traps ( Malloch et al , 2006 ). However, in the absence of insecticide selection, resistant clones appear to be at a considerable disadvantage both within and between seasons ( Foster et al , 2002;Fenton et al , 2005;.…”

“…The selective advantage conferred Spatial and temporal dynamics of Myzus persicae clones in fields and suction traps Louise Kasprowicz , Gaynor Malloch , Jon Pickup * and Brian Fenton by insecticide resistance is considerable and, under ideal conditions, resistant clones can multiply in sprayed crops to reach damaging levels ( Foster et al , 1998;Fenton et al , 2005 ) and these can be found in large quantities in suction traps ( Malloch et al , 2006 ). However, in the absence of insecticide selection, resistant clones appear to be at a considerable disadvantage both within and between seasons ( Foster et al , 2002;Fenton et al , 2005;.…”