Agricultural and Forest Entomology (2008) 10, 279-290

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A.B. Jensen, L.M. Hansen and J. Eilenberg (2008)
Grain aphid population structure: no effect of fungal infections in a 2-year field study in Denmark
Agricultural and Forest Entomology 10 (3), 279-290
Abstract: 1 Sitobion avenae (F.) is a serious pest in Danish cereal crops. To understand the population genetic structure, aphids were sampled in seven different winter wheat (Triticum sativum Lamarck) fields throughout Denmark. The aphids were genotyped with seven microsatellite markers. In total, 2075 aphids were collected and 1203 of these were genotyped.
2 The Danish S. avenae populations displayed very high genotypic diversity, high percentages of unique genotypes and low linkage disequilibria; this is likely to be a result of genetic recombination encompassed by their holocyclic lifestyle. The populations showed very limited differentiation and no sign of isolation by distance. Almost all the genetic variation was ascribed within the populations rather than between populations, probably due to a high migration rate at approximate 10% per generation.
3 Seasonal changes in clonal diversity and distribution of asexual summer generations of S. avenae within the infestation period in a single winter wheat field were followed over two consecutive years by weekly sampling from 60 plots each of 20 × 20 m. Clonal diversity was high in all samples with no dominant clonal lineages and no significant difference in the genotypic diversity between weeks or between years. However, a temporal genetic differentiation effect, throughout the infestation, suggests that selective factors or high temporal migration play an important role in shaping the genetic structure S. avenae.
4 Analyses of fungal infected and uninfected aphids were performed to test whether some clonal linage were more often infected by fungi from the Entomophthorales under field conditions. In total, 54 progeny from aphids with Entomophthorales were genotyped and compared with 422 uninfected aphid genotypes. The Entomophthorales-infected aphid genotypes did not cluster out together, suggesting that these fungal pathogens did not affect the population differentiation or clonal distribution of S. avenae in a Danish agroecosystem.
5 Our findings indicate that S. avenae populations can be controlled using conservation biological control.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Annette Bruun Jensen, Jørgen Eilenberg

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
population dynamics/ epidemiology
Research topic(s) for beneficials or antagonists:
population dynamics/epizootiology

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Sitobion avenae Wheat (Triticum) Denmark
Entomophthora planchoniana (entomopathogen) Sitobion avenae Wheat (Triticum) Denmark
Pandora neoaphidis (entomopathogen) Sitobion avenae Wheat (Triticum) Denmark