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Insecticide resistance mechanisms in the green peach aphid Myzus persicae (Hemiptera: Aphididae) II: Costs and benefits.

Silva AX, Bacigalupe LD, Luna-Rudloff M, Figueroa CC - PLoS ONE (2012)

Bottom Line: As M. persicae feeds upon a huge diversity of hosts, it has been exposed to a wide variety of plant allelochemicals, which probably have promoted a wide range of detoxification systems.Our results show a significant interaction between host and IRM on the intrinsic rate of increase (r(m)).Hence, our results suggest that the trade-off among resistance mechanisms might be quite complex, with a multiplicity of costs and benefits depending on the environment.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.

ABSTRACT

Background: Among herbivorous insects that have exploited agro-ecosystems, the peach-potato aphid, Myzus persicae, is recognized as one of the most important agricultural pests worldwide. Uses over 400 plant species and has evolved different insecticides resistance mechanisms. As M. persicae feeds upon a huge diversity of hosts, it has been exposed to a wide variety of plant allelochemicals, which probably have promoted a wide range of detoxification systems.

Methodology/principal findings: In this work we (i) evaluated whether insecticide resistance mutations (IRM) in M. persicae can give an advantage in terms of reproductive fitness when aphids face two hosts, pepper (Capsicum annuum) a suitable host and radish (Raphanus sativus) the unfavorable host and (ii) examined the transcriptional expression of six genes that are known to be up-regulated in response to insecticides. Our results show a significant interaction between host and IRM on the intrinsic rate of increase (r(m)). Susceptible genotypes (not carrying insensitivity mutations) had a higher r(m) on pepper, and the transcriptional levels of five genes increased on radish. The r(m) relationship was reversed on the unfavorable host; genotypes with multiple IRM exhibited higher r(m), without altering the transcriptional levels of the studied genes. Genotypes with one IRM kept a similar r(m) on both hosts, but they increased the transcriptional levels of two genes.

Conclusions/significance: Although we have studied only nine genotypes, overall our results are in agreement with the general idea that allelochemical detoxification systems could constitute a pre-adaptation for the development of insecticide resistance. Genotypes carrying IRM exhibited a higher r(m) than susceptible genotypes on radish, the more unfavorable host. Susceptible genotypes should be able to tolerate the defended host by up-regulating some metabolic genes that are also responding to insecticides. Hence, our results suggest that the trade-off among resistance mechanisms might be quite complex, with a multiplicity of costs and benefits depending on the environment.

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Quantification of relative expression levels in four genotypes on suitable (pepper) and unfavorable (radish) hosts.The results represent the relative mRNA expression, with transcripts expressed by the aphids on pepper as calibrator and on radish as interest sample. Data were normalized for variation using GADPH expression. The green bars correspond to S genotypes (sensitive; N36-1 and Sur25A), the yellow bar corresponds to the SR genotype (simple resistant; Peralillo 1) and the red bar corresponds to the MR genotype (multiple resistant; 16A). Data represent mean ± SE of two different experiments, with three technical replicates each case.*p<0.05 and **p<0.01 indicate a significant difference compared to 1, used as a reference value for no change in expression using a t-test. Gene abbreviations: (A) cathepsin B-N, cathepsin B clade N; (B) HSP-70, heat shock protein 70; (C) GST, glutathione S-transferase; (D) Esterase E4/FE4, carboxylesterase type E or FE4; (E) CYP6CY3, cytochrome p450family CYP6CYP3; (F) CYP4, cytochrome p450 family CYP4.
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pone-0036810-g002: Quantification of relative expression levels in four genotypes on suitable (pepper) and unfavorable (radish) hosts.The results represent the relative mRNA expression, with transcripts expressed by the aphids on pepper as calibrator and on radish as interest sample. Data were normalized for variation using GADPH expression. The green bars correspond to S genotypes (sensitive; N36-1 and Sur25A), the yellow bar corresponds to the SR genotype (simple resistant; Peralillo 1) and the red bar corresponds to the MR genotype (multiple resistant; 16A). Data represent mean ± SE of two different experiments, with three technical replicates each case.*p<0.05 and **p<0.01 indicate a significant difference compared to 1, used as a reference value for no change in expression using a t-test. Gene abbreviations: (A) cathepsin B-N, cathepsin B clade N; (B) HSP-70, heat shock protein 70; (C) GST, glutathione S-transferase; (D) Esterase E4/FE4, carboxylesterase type E or FE4; (E) CYP6CY3, cytochrome p450family CYP6CYP3; (F) CYP4, cytochrome p450 family CYP4.

Mentions: The transcriptional level for all six of the selected genes depended on the genotype (Figure 2).


Insecticide resistance mechanisms in the green peach aphid Myzus persicae (Hemiptera: Aphididae) II: Costs and benefits.

Silva AX, Bacigalupe LD, Luna-Rudloff M, Figueroa CC - PLoS ONE (2012)

Quantification of relative expression levels in four genotypes on suitable (pepper) and unfavorable (radish) hosts.The results represent the relative mRNA expression, with transcripts expressed by the aphids on pepper as calibrator and on radish as interest sample. Data were normalized for variation using GADPH expression. The green bars correspond to S genotypes (sensitive; N36-1 and Sur25A), the yellow bar corresponds to the SR genotype (simple resistant; Peralillo 1) and the red bar corresponds to the MR genotype (multiple resistant; 16A). Data represent mean ± SE of two different experiments, with three technical replicates each case.*p<0.05 and **p<0.01 indicate a significant difference compared to 1, used as a reference value for no change in expression using a t-test. Gene abbreviations: (A) cathepsin B-N, cathepsin B clade N; (B) HSP-70, heat shock protein 70; (C) GST, glutathione S-transferase; (D) Esterase E4/FE4, carboxylesterase type E or FE4; (E) CYP6CY3, cytochrome p450family CYP6CYP3; (F) CYP4, cytochrome p450 family CYP4.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3369902&req=5

pone-0036810-g002: Quantification of relative expression levels in four genotypes on suitable (pepper) and unfavorable (radish) hosts.The results represent the relative mRNA expression, with transcripts expressed by the aphids on pepper as calibrator and on radish as interest sample. Data were normalized for variation using GADPH expression. The green bars correspond to S genotypes (sensitive; N36-1 and Sur25A), the yellow bar corresponds to the SR genotype (simple resistant; Peralillo 1) and the red bar corresponds to the MR genotype (multiple resistant; 16A). Data represent mean ± SE of two different experiments, with three technical replicates each case.*p<0.05 and **p<0.01 indicate a significant difference compared to 1, used as a reference value for no change in expression using a t-test. Gene abbreviations: (A) cathepsin B-N, cathepsin B clade N; (B) HSP-70, heat shock protein 70; (C) GST, glutathione S-transferase; (D) Esterase E4/FE4, carboxylesterase type E or FE4; (E) CYP6CY3, cytochrome p450family CYP6CYP3; (F) CYP4, cytochrome p450 family CYP4.
Mentions: The transcriptional level for all six of the selected genes depended on the genotype (Figure 2).

Bottom Line: As M. persicae feeds upon a huge diversity of hosts, it has been exposed to a wide variety of plant allelochemicals, which probably have promoted a wide range of detoxification systems.Our results show a significant interaction between host and IRM on the intrinsic rate of increase (r(m)).Hence, our results suggest that the trade-off among resistance mechanisms might be quite complex, with a multiplicity of costs and benefits depending on the environment.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile.

ABSTRACT

Background: Among herbivorous insects that have exploited agro-ecosystems, the peach-potato aphid, Myzus persicae, is recognized as one of the most important agricultural pests worldwide. Uses over 400 plant species and has evolved different insecticides resistance mechanisms. As M. persicae feeds upon a huge diversity of hosts, it has been exposed to a wide variety of plant allelochemicals, which probably have promoted a wide range of detoxification systems.

Methodology/principal findings: In this work we (i) evaluated whether insecticide resistance mutations (IRM) in M. persicae can give an advantage in terms of reproductive fitness when aphids face two hosts, pepper (Capsicum annuum) a suitable host and radish (Raphanus sativus) the unfavorable host and (ii) examined the transcriptional expression of six genes that are known to be up-regulated in response to insecticides. Our results show a significant interaction between host and IRM on the intrinsic rate of increase (r(m)). Susceptible genotypes (not carrying insensitivity mutations) had a higher r(m) on pepper, and the transcriptional levels of five genes increased on radish. The r(m) relationship was reversed on the unfavorable host; genotypes with multiple IRM exhibited higher r(m), without altering the transcriptional levels of the studied genes. Genotypes with one IRM kept a similar r(m) on both hosts, but they increased the transcriptional levels of two genes.

Conclusions/significance: Although we have studied only nine genotypes, overall our results are in agreement with the general idea that allelochemical detoxification systems could constitute a pre-adaptation for the development of insecticide resistance. Genotypes carrying IRM exhibited a higher r(m) than susceptible genotypes on radish, the more unfavorable host. Susceptible genotypes should be able to tolerate the defended host by up-regulating some metabolic genes that are also responding to insecticides. Hence, our results suggest that the trade-off among resistance mechanisms might be quite complex, with a multiplicity of costs and benefits depending on the environment.

Show MeSH
Related in: MedlinePlus