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Spodoptera frugiperda (Lepidoptera: Noctuidae) host-plant variants: two host strains or two distinct species?

Dumas P, Legeai F, Lemaitre C, Scaon E, Orsucci M, Labadie K, Gimenez S, Clamens AL, Henri H, Vavre F, Aury JM, Fournier P, Kergoat GJ, d'Alençon E - Genetica (2015)

Bottom Line: We found a significant reduction of mating success in F1 in one direction of the cross and a high level of microsatellite markers showing transmission ratio distortion in the F2 progeny.Our results support the existence of post-zygotic reproductive isolation between the two laboratory strains and are in accordance with the marked level of genetic differentiation that was recovered between individuals of the two strains collected from the field.Altogether these results provide additional evidence in favor of a sibling species status for the two strains.

View Article: PubMed Central - PubMed

Affiliation: UM - UMR 1333 DGIMI, Université Montpellier, Place Eugène Bataillon, 34095, Montpellier, France, pascalinedumas@gmail.com.

ABSTRACT
The moth Spodoptera frugiperda is a well-known pest of crops throughout the Americas, which consists of two strains adapted to different host-plants: the first feeds preferentially on corn, cotton and sorghum whereas the second is more associated with rice and several pasture grasses. Though morphologically indistinguishable, they exhibit differences in their mating behavior, pheromone compositions, and show development variability according to the host-plant. Though the latter suggest that both strains are different species, this issue is still highly controversial because hybrids naturally occur in the wild, not to mention the discrepancies among published results concerning mating success between the two strains. In order to clarify the status of the two host-plant strains of S. frugiperda, we analyze features that possibly reflect the level of post-zygotic isolation: (1) first generation (F1) hybrid lethality and sterility; (2) patterns of meiotic segregation of hybrids in reciprocal second generation (F2), as compared to the meiosis of the two parental strains. We found a significant reduction of mating success in F1 in one direction of the cross and a high level of microsatellite markers showing transmission ratio distortion in the F2 progeny. Our results support the existence of post-zygotic reproductive isolation between the two laboratory strains and are in accordance with the marked level of genetic differentiation that was recovered between individuals of the two strains collected from the field. Altogether these results provide additional evidence in favor of a sibling species status for the two strains.

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Related in: MedlinePlus

Ratio of fertility in inter-strain crosses (light grey columns) in both directions of the cross. C/R (female corn with male rice) and R/C (female rice with male corn) cross direction. The within-strain crosses (dark grey columns) C/C (female and male corn) and R/R (female and male rice). Different letter above the bars means that the ratio of fertility were significantly different (p < 0.05)
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Fig2: Ratio of fertility in inter-strain crosses (light grey columns) in both directions of the cross. C/R (female corn with male rice) and R/C (female rice with male corn) cross direction. The within-strain crosses (dark grey columns) C/C (female and male corn) and R/R (female and male rice). Different letter above the bars means that the ratio of fertility were significantly different (p < 0.05)

Mentions: The statistical results showed that the cross direction was an important parameter of the statistical model. Indeed, the interaction between the female strains and male strains was significant (p < 0.0001). Among the 30 C/C crosses, 29 were fertile, while 25 of R/R crosses led to viable progeny (over 30 crosses, Fig. 2). Fertility between the two within strain crosses were not found significantly different (p value of 0.07). Unlike the within strain crosses, the fertility between the two among strain crosses were significantly different (p = 0.012). Indeed, only eight couples over 27 C/R crosses produced a viable progeny against 21 couples over 30 crosses for R/C crosses (Fig. 2). Comparison of the two within strain crosses C/C with C/R and R/R with C/R crosses evidenced the low fertility of among strain crosses (p < 0.0001 and p = 0.00025, respectively). Same results were observed between C/C and R/C crosses (p = 0.003) but no difference was found between R/R and R/C crosses (p = 0.219). Except for a longer egg incubation period, we did not notice any aberrant feature in the development of these C/R larvae. Though this asymmetry in fertility has already been described by Pashley (1988), it was not reported by Whitford et al. (1988).Fig. 2


Spodoptera frugiperda (Lepidoptera: Noctuidae) host-plant variants: two host strains or two distinct species?

Dumas P, Legeai F, Lemaitre C, Scaon E, Orsucci M, Labadie K, Gimenez S, Clamens AL, Henri H, Vavre F, Aury JM, Fournier P, Kergoat GJ, d'Alençon E - Genetica (2015)

Ratio of fertility in inter-strain crosses (light grey columns) in both directions of the cross. C/R (female corn with male rice) and R/C (female rice with male corn) cross direction. The within-strain crosses (dark grey columns) C/C (female and male corn) and R/R (female and male rice). Different letter above the bars means that the ratio of fertility were significantly different (p < 0.05)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4419160&req=5

Fig2: Ratio of fertility in inter-strain crosses (light grey columns) in both directions of the cross. C/R (female corn with male rice) and R/C (female rice with male corn) cross direction. The within-strain crosses (dark grey columns) C/C (female and male corn) and R/R (female and male rice). Different letter above the bars means that the ratio of fertility were significantly different (p < 0.05)
Mentions: The statistical results showed that the cross direction was an important parameter of the statistical model. Indeed, the interaction between the female strains and male strains was significant (p < 0.0001). Among the 30 C/C crosses, 29 were fertile, while 25 of R/R crosses led to viable progeny (over 30 crosses, Fig. 2). Fertility between the two within strain crosses were not found significantly different (p value of 0.07). Unlike the within strain crosses, the fertility between the two among strain crosses were significantly different (p = 0.012). Indeed, only eight couples over 27 C/R crosses produced a viable progeny against 21 couples over 30 crosses for R/C crosses (Fig. 2). Comparison of the two within strain crosses C/C with C/R and R/R with C/R crosses evidenced the low fertility of among strain crosses (p < 0.0001 and p = 0.00025, respectively). Same results were observed between C/C and R/C crosses (p = 0.003) but no difference was found between R/R and R/C crosses (p = 0.219). Except for a longer egg incubation period, we did not notice any aberrant feature in the development of these C/R larvae. Though this asymmetry in fertility has already been described by Pashley (1988), it was not reported by Whitford et al. (1988).Fig. 2

Bottom Line: We found a significant reduction of mating success in F1 in one direction of the cross and a high level of microsatellite markers showing transmission ratio distortion in the F2 progeny.Our results support the existence of post-zygotic reproductive isolation between the two laboratory strains and are in accordance with the marked level of genetic differentiation that was recovered between individuals of the two strains collected from the field.Altogether these results provide additional evidence in favor of a sibling species status for the two strains.

View Article: PubMed Central - PubMed

Affiliation: UM - UMR 1333 DGIMI, Université Montpellier, Place Eugène Bataillon, 34095, Montpellier, France, pascalinedumas@gmail.com.

ABSTRACT
The moth Spodoptera frugiperda is a well-known pest of crops throughout the Americas, which consists of two strains adapted to different host-plants: the first feeds preferentially on corn, cotton and sorghum whereas the second is more associated with rice and several pasture grasses. Though morphologically indistinguishable, they exhibit differences in their mating behavior, pheromone compositions, and show development variability according to the host-plant. Though the latter suggest that both strains are different species, this issue is still highly controversial because hybrids naturally occur in the wild, not to mention the discrepancies among published results concerning mating success between the two strains. In order to clarify the status of the two host-plant strains of S. frugiperda, we analyze features that possibly reflect the level of post-zygotic isolation: (1) first generation (F1) hybrid lethality and sterility; (2) patterns of meiotic segregation of hybrids in reciprocal second generation (F2), as compared to the meiosis of the two parental strains. We found a significant reduction of mating success in F1 in one direction of the cross and a high level of microsatellite markers showing transmission ratio distortion in the F2 progeny. Our results support the existence of post-zygotic reproductive isolation between the two laboratory strains and are in accordance with the marked level of genetic differentiation that was recovered between individuals of the two strains collected from the field. Altogether these results provide additional evidence in favor of a sibling species status for the two strains.

Show MeSH
Related in: MedlinePlus