Aphid, peach-potato

There are marked species differences in A-esterase activity. Birds have very low, often undetectable, levels of activity in plasma toward paraoxon, diazoxon, pirimi-phos-methyl oxon, and chlorpyrifos oxon (Brealey et al. 1980, Mackness et al. 1987, Walker et al. 1991 Figure 2.10). Mammals have much higher plasma A-esterase activities to all of these substrates. The toxicological implications of this are discussed in Chapter 10. Some species of insects have no measurable A-esterase activity, even in strains that have resistance to OPs (Mackness et al. 1982, Walker 1994). These include the peach potato aphid (Myzus persicae Devonshire 1991) and the... 

Metabolic resistance may be the consequence of the appearance of a novel gene on the resistant strain, which is not present in the general population it may also be due to the presence of multiple copies of a gene in different strains or clones as in the example of OP resistance in the peach potato aphid mentioned earlier. 

L. M. Field, A. L. Devonshire, B. G. Forde, Molecular Evidence that Insecticide Resistance in Peach-Potato Aphids (Myzus persicae Sulz.) Results from Amplification of an Esterase Gene , Biochem. J. 1988, 257, 309-312. 

Susceptible plants Most plants may be attacked by aphids. Many aphid species are plant-specific, such as the lupine aphid, while others, such as the peach potato aphid, will attack hundreds of different types of plants. Aphids may spend the summer on certain plants, moving to a different host species for the winter. 

Chang, T., Chen, L., Chen, S., Cai, H., Liu, X., Xiao, G., and Zhu, Z., Transformation of tobacco with genes encoding Helianthus tuberosus Agglutinin (HTA) confers resistance to peach-potato aphid (Myzus persicae), Transgenic Res., 12, 607-614, 2003. 

Devonshire, A.L., The properties of a carboxylesterase from the peach-potato aphid, Myzuz persicae (Sulz.), and its role in conferring insecticide resistance, Biochem. J., 161, 675,1977. 

Sauvion, N., Rahbe, Y., Peumans, W.J., Van Damme, E., Gatehouse, J.A. and Gatehouse, A.M.R. (1996). Effects of GNA and other mannose binding lectins on development and fecundity of the peach-potato aphid. Entomol. Exp. Appl. 79, 285-293. 

Transgenic potato plants with enhanced resistance to the peach-potato aphid Myzus persicae. Entomol. Exp. Appl. 79, 295-307. 

Potato leaf roll virus - PLRV Virus Lower leaves are rolled upwards and inwards they feel brittle and crackle when handled. The other leaves are hghter green and more erect than normal. Yield is lowered. The virus is transmitted by aphids from plant to plant. Peach potato aphid is the main vector. Infected tubers (which show no signs of the disease) are planted and thus the disease is carried forward from year to year. (1) Resistant varieties (2) Use high grade seed (3) Ensure no aphids in the chitting house (4) Apply a suitable systemic insecticide to reduce the spread of the virus (5) Reduce sources of infection - dumps etc. 

Mosaics - potato virus Y (PVY) Virus May range from a faint yellow mottling on leaves to a severe distortion of the leaves and distinct yellow mottling. Yield can be seriously reduced by the severe forms. Peach potato aphid is the main vector of PVY. The virus is non-persistent on the aphid. Symptoms may not appear for 4 weeks after infection. (1) As for leaf roll (2) Some varieties resistant (3) Using aphicides can give variable results... 

The current insecticidal seed dressing are very effective at controlling peach potato aphids. Insecticide resistance is now a problem with some post emergence insecticides. 

The EU ban on neonicotinoids from December 2013 means that seed dressings containing clothianadin, imidacloprid and thiomethoxam can no longer be used for the control of cabbage stem hea beetle (CSFB) or the peach-potato aphid, a vector of turnip yellows virus. Fohar apphed pyrethroids ate now the only control for CSFB, but resistance is now widespread. 

Slugs may be a serious problem of winter oilseed rape, particularly in trashy or cloddy seedbeds or when late established. Metaldehyde or equivalent should be applied where there is a high risk, and method of establishment may influence the timing of this application. The peach-potato aphid may need a pyrethroid or pirimicarb spray in October/November, but populations of the aphid are highly resistant to both. 

Vims spread by peach potato aphid. Mild winters favour survival of aphid and disease spread. TuYV is a persistent vims. 

The crop is infected by aphids which have over-wintered mainly in clamps. Several green aphids carry the virus, particularly peach potato aphid. After a mild winter and warm spring aphid migration is early and the chances of an epidemic are increased. BMYV and BYV have a wide host range including some common weeds. 

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