Articles
SIMPLE IS BEAUTIFUL: A NEW BIOTEST FOR THE APHID TOLERANCE ASSESSMENT OF DIFFERENT HOP GENOTYPES
Article number
1010_10
Pages
97 – 102
Language
English
Abstract
A cornerstone of integrated pest management in hops is the breeding of cultivars that are tolerant or resistant to Phorodon humuli infestation.
During 2010, 2011 and 2012 we have developed a bioassay to assess the aphid susceptibility of different hop genotypes.
We chose for these tests the susceptible cultivars Hallertauer Magnum (HM) and Herkules (HS), the aphid-tolerant or-resistant cultivars Spalter Select (SE) and Boadicea (BO), and two apparently resistant genotypes from our germplasm the male accession 3W and the breeding line 2005/034/022. Rooted cuttings of these six genotypes were produced immediately after winter dormancy and planted in 2.5 L preserving jars in 12 replications, respectively.
Each jar was equipped with one cutting and one aphid larva with the same day of birth, closed with a sheet of gauze and then stored in a climate chamber for 22-28 days.
All enclosures of a series were opened synchronously and the aphids in each jar were counted.
Altogether 11 test series were conducted.
HS was the genotype found to have the highest and a rather even infestation level, and was chosen as standard cultivar (100%) to assess relative infestation levels of the other genotypes.
BO revealed by far the lowest infestation levels, emphasizing its very good aphid resistance. 3W also showed a very good resistance level and yielded even results.
The proven aphid tolerance of SE was reflected in oscillating infestation levels of lower than 50% of HS. The breeding line 2005/034/022 displayed very heterogeneous infestations between the single series and its susceptibility level is unclear.
HM was similarly susceptible as HS, but the results from single series were more uneven.
It is recommended to conduct according bioassays as early as possible during the vegetation period, and to avoid trials later than mid-June.
As a result of our trials, we come to the conclusion that the intended development of a simple laboratory bioassay was successful and with it now it will be possible to quickly separate new genotypes into the three classes resistant, tolerant and susceptible to aphid infestation.
During 2010, 2011 and 2012 we have developed a bioassay to assess the aphid susceptibility of different hop genotypes.
We chose for these tests the susceptible cultivars Hallertauer Magnum (HM) and Herkules (HS), the aphid-tolerant or-resistant cultivars Spalter Select (SE) and Boadicea (BO), and two apparently resistant genotypes from our germplasm the male accession 3W and the breeding line 2005/034/022. Rooted cuttings of these six genotypes were produced immediately after winter dormancy and planted in 2.5 L preserving jars in 12 replications, respectively.
Each jar was equipped with one cutting and one aphid larva with the same day of birth, closed with a sheet of gauze and then stored in a climate chamber for 22-28 days.
All enclosures of a series were opened synchronously and the aphids in each jar were counted.
Altogether 11 test series were conducted.
HS was the genotype found to have the highest and a rather even infestation level, and was chosen as standard cultivar (100%) to assess relative infestation levels of the other genotypes.
BO revealed by far the lowest infestation levels, emphasizing its very good aphid resistance. 3W also showed a very good resistance level and yielded even results.
The proven aphid tolerance of SE was reflected in oscillating infestation levels of lower than 50% of HS. The breeding line 2005/034/022 displayed very heterogeneous infestations between the single series and its susceptibility level is unclear.
HM was similarly susceptible as HS, but the results from single series were more uneven.
It is recommended to conduct according bioassays as early as possible during the vegetation period, and to avoid trials later than mid-June.
As a result of our trials, we come to the conclusion that the intended development of a simple laboratory bioassay was successful and with it now it will be possible to quickly separate new genotypes into the three classes resistant, tolerant and susceptible to aphid infestation.
Publication
Authors
F. Weihrauch, A. Baumgartner, M. Felsl, J. Kneidl , A. Lutz
Keywords
Humulus lupulus, Aphididae, damson-hop aphid, Phorodon humuli, aphid susceptibility, aphid resistance
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