Insecticide Resistance - M.persicae specific

Question 1

Additional Reading - Existing resistance

Answer 1

Nauen et al., 1996 + Devine et al., 1996

- Resistance to the secondary metabolite nicotine may be a problem due to structural similarities with neonicotinoids

Question 2

Additional Reading - Peach-potato aphid pest

Answer 2

Lojek and Orlob, 1972

• M.persicae is a vector of the tobacco mosaic virus
• pest of tobacco plants, peach trees etc

Question 3

Additional Reading - M.persicae cross resistance to neonics

Answer 3

Jenshke and Nauen 2008

- Imidacloprid, acetamiprid cross resistance observed

Question 4

Additional Reading - Genes associated with overexpression of detoxifying enzymes

Answer 4

Bass et al., 2013
M.persicae - CYP6CY3

Bass et al., 2015
B. tabaci - CYP6CM1

Bass et al., 2011
Niparavalta lugens - CYP6ER1

Ding et al., 2013
N. lugens - CYP6AY1

Question 5

Additional Reading - Resistance to other insecticides M.persicae versus B.tabaci

Answer 5

Foster et al., 2002
- M.persicae no resistance to Pymetrozine

Gorman et al., 2010
- B.tabaci cross resistance to Pymetrozine

Question 6

Additional Reading - CYP6CY3 resistant vs non

Answer 6

Peunean et al., 2010 + Bass et al., 2014

- gene expressed 22 fold more in resistant strains

Question 7

Additional Reading - Effectiveness of CYP6CY3 to neonics

Answer 7

Bass et al., 2014

- 22 fold difference made insect 30-60 fold more resistant

Question 8

Additional Reading - Human version of CYP6CY3

Answer 8

Bass et al., 2014

• CYP2A6
• main high-affinity nicotine metabolising gene in humans
• much less efficient

Question 9

Additional Reading - Cuticular thickening

Answer 9

Puinean et al., 2010

• Over expression of cuticular thickening genes (2-16 fold) in resistant
• Larger number of expressed sequence tag genes being transcribed that encode cuticular proteins (32)
• Using Imidacloprid recovery found that after 50 hours 56% of insecticide could be recovered from resistant cuticle versus 22% from non
• Feeding neonics rather than spraying resistant insects gave a LC50 17 times lower than spray vs 8 times lower in non-resistant

Question 10

Additional Reading - M.persicae Target site resistance

Answer 10

Bass et al., 2011

• Used piperonyl butoxide to determine if that was the main cause of resistance in French clones showing increased resistance - Found no difference in resistance
• Also found no real difference in CYP6CY3 expression in comparison to other resistant strains
• Found that the amino acid at loop D (very important to nicotine binding) argenine had changed to theronine
• Switch to threonine gives nAChR in insects a vertebrsate like quality thus reducing sensitivity to neonics

Question 11

Additional Reading - N.lugens target site

Answer 11

Liu et al., 2005

- target site mutation at gene location Y151S