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What do spring migrants reveal about sex and host selection in the melon aphid?

Thomas S, Boissot N, Vanlerberghe-Masutti F - BMC Evol. Biol. (2012)

Bottom Line: Moreover, an analysis of the genetic composition of these alate and apterous populations in four geographic regions suggested differences in life-history strategies, such as host choice and reproductive mode, and questioned the common assertion that A. gossypii is an anholocyclic species throughout its distribution area, including Europe.Our results clearly demonstrate that the melon plant acts as a selective filter against the reproduction of non-specialised individuals.We showed that olfactory cues are unlikely to be decisive in natura for host recognition by spring-migrant aphid populations that are not specialised on Cucurbitaceae.

View Article: PubMed Central - HTML - PubMed

Affiliation: INRA, UMR1062 CBGP, F-34988 Montferrier-sur-Lez, France.

ABSTRACT

Background: Host plants exert considerable selective pressure on aphids because the plants constitute their feeding, mating and oviposition sites. Therefore, host specialisation in aphids evolves through selection of the behavioural and chemical mechanisms of host-plant location and recognition, and through metabolic adaptation to the phloem content of the host plant. How these adaptive traits evolve in an aphid species depends on the complexity of the annual life cycle of that species. The purpose of this field study was to determine how winged spring-migrant populations contribute to the evolution and maintenance of host specialisation in Aphis gossypii through host-plant choice and acceptance. We also assessed whether host-specialised genotypes corresponded exclusively to anholocyclic lineages regardless of the environmental conditions.

Results: The spring populations of cotton-melon aphids visiting newly planted melon crops exhibited an unexpectedly high level of genetic diversity that contrasted with the very low diversity characterising the host-specialised populations of this aphid species. This study illustrated in natura host-plant-selection pressure by showing the great differences in genetic diversity between the spring-migrant populations (alate aphids) and the melon-infesting populations (the apterous offspring of the alate aphids). Moreover, an analysis of the genetic composition of these alate and apterous populations in four geographic regions suggested differences in life-history strategies, such as host choice and reproductive mode, and questioned the common assertion that A. gossypii is an anholocyclic species throughout its distribution area, including Europe.

Conclusions: Our results clearly demonstrate that the melon plant acts as a selective filter against the reproduction of non-specialised individuals. We showed that olfactory cues are unlikely to be decisive in natura for host recognition by spring-migrant aphid populations that are not specialised on Cucurbitaceae. The agroecosystem structure and history of the four studied regions may have partially shaped the genetic structure of the spring-migrant populations of A. gossypii. Cucurbitaceae-specialised genotypes corresponded exclusively to anholocyclic lineages, regardless of the environmental conditions. However, some genotypes that were genetically close to the host-specialised genotypes and some genotypes that probably originated from wild plants had never been previously sampled; both were holocylic.

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Melon-growing areas and aphid-sampling sites in a. France and b. the Lesser Antilles.
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Figure 1: Melon-growing areas and aphid-sampling sites in a. France and b. the Lesser Antilles.

Mentions: To investigate the genetic diversity of A. gossypii, we sampled alate and apterous aphids from 2004 to 2009 in four locations in the southeast (SE) of France, one location in the southwest (SW) and west (W) of France and one location in the Lesser Antilles (LA) (Figure 1). The aphids were genotyped using eight microsatellite markers.


What do spring migrants reveal about sex and host selection in the melon aphid?

Thomas S, Boissot N, Vanlerberghe-Masutti F - BMC Evol. Biol. (2012)

Melon-growing areas and aphid-sampling sites in a. France and b. the Lesser Antilles.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368726&req=5

Figure 1: Melon-growing areas and aphid-sampling sites in a. France and b. the Lesser Antilles.
Mentions: To investigate the genetic diversity of A. gossypii, we sampled alate and apterous aphids from 2004 to 2009 in four locations in the southeast (SE) of France, one location in the southwest (SW) and west (W) of France and one location in the Lesser Antilles (LA) (Figure 1). The aphids were genotyped using eight microsatellite markers.

Bottom Line: Moreover, an analysis of the genetic composition of these alate and apterous populations in four geographic regions suggested differences in life-history strategies, such as host choice and reproductive mode, and questioned the common assertion that A. gossypii is an anholocyclic species throughout its distribution area, including Europe.Our results clearly demonstrate that the melon plant acts as a selective filter against the reproduction of non-specialised individuals.We showed that olfactory cues are unlikely to be decisive in natura for host recognition by spring-migrant aphid populations that are not specialised on Cucurbitaceae.

View Article: PubMed Central - HTML - PubMed

Affiliation: INRA, UMR1062 CBGP, F-34988 Montferrier-sur-Lez, France.

ABSTRACT

Background: Host plants exert considerable selective pressure on aphids because the plants constitute their feeding, mating and oviposition sites. Therefore, host specialisation in aphids evolves through selection of the behavioural and chemical mechanisms of host-plant location and recognition, and through metabolic adaptation to the phloem content of the host plant. How these adaptive traits evolve in an aphid species depends on the complexity of the annual life cycle of that species. The purpose of this field study was to determine how winged spring-migrant populations contribute to the evolution and maintenance of host specialisation in Aphis gossypii through host-plant choice and acceptance. We also assessed whether host-specialised genotypes corresponded exclusively to anholocyclic lineages regardless of the environmental conditions.

Results: The spring populations of cotton-melon aphids visiting newly planted melon crops exhibited an unexpectedly high level of genetic diversity that contrasted with the very low diversity characterising the host-specialised populations of this aphid species. This study illustrated in natura host-plant-selection pressure by showing the great differences in genetic diversity between the spring-migrant populations (alate aphids) and the melon-infesting populations (the apterous offspring of the alate aphids). Moreover, an analysis of the genetic composition of these alate and apterous populations in four geographic regions suggested differences in life-history strategies, such as host choice and reproductive mode, and questioned the common assertion that A. gossypii is an anholocyclic species throughout its distribution area, including Europe.

Conclusions: Our results clearly demonstrate that the melon plant acts as a selective filter against the reproduction of non-specialised individuals. We showed that olfactory cues are unlikely to be decisive in natura for host recognition by spring-migrant aphid populations that are not specialised on Cucurbitaceae. The agroecosystem structure and history of the four studied regions may have partially shaped the genetic structure of the spring-migrant populations of A. gossypii. Cucurbitaceae-specialised genotypes corresponded exclusively to anholocyclic lineages, regardless of the environmental conditions. However, some genotypes that were genetically close to the host-specialised genotypes and some genotypes that probably originated from wild plants had never been previously sampled; both were holocylic.

Show MeSH
Related in: MedlinePlus