Effect of plant traits on host selection and performance of rape stem weevil (Ceutorhynchus napi Gyll.) (Col.: Curculionidae) on resynthesized lines and cultivars of oilseed rape (Brassica napus L.)

by Heike Lena Schäfer-Kösterke
Doctoral thesis
Date of Examination:2014-07-24
Date of issue:2015-06-25
Advisor:Prof. Dr. Stefan Vidal
Referee:Prof. Dr. Stefan Vidal
Referee:Prof. Dr. Heiko C. Becker
Referee:Dr. Bernd Ulber
Persistent Address: http://dx.doi.org/10.53846/goediss-5156

 

 

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Abstract

English

During its long growing season oilseed rape is attacked by a wide range of insect pests. Infestation by rape stem weevil (Ceutorhynchus napi Gyll.) and cabbage stem weevil (Ceutorhynchus pallidactylus (Marsh.)) can cause major economic damage. There is an urgent need for oilseed rape cultivars that are genetically resistant to C. napi, C. pallidactylus and other insect pests as part of integrated pest management systems to minimize the number of insecticide applications. The main objective of the study was to determine the susceptibility of 30 B. napus genotypes, showing a broad genetic variability, for infestation by the specialist stem weevils C. napi and C. pallidactylus. High antixenosis resistance to C. napi in the resynthesized line S30 has been identified. In addition, in S30 a low level of C. pallidactylus infestation was found. To identify plant factors determining host location, host acceptance and larval performance of C. napi and C. pallidactylus, morphological plant traits and metabolic plant compounds were assessed. Oviposition by C. napi was dependent upon the length of stems of genotypes. The number of eggs deposited by C. napi was associated with the content of individual glucosinolates, while the number of C. napi and C. pallidactylus larvae in stems was not associated with the glucosinolate profiles of stems. There was no evidence that the carbon and nitrogen contents in stems affected the host acceptance and larval performance of C. napi and C. pallidactylus. This study has successfully demonstrated the potential of resynthesized lines of B. napus as potential sources of resistance against the stem-mining pest C. napi. The resynthesized line S30 can provide a potential genetic source for breeding oilseed rape cultivars with resistance to C. napi.
Keywords: host plant resistance; resynthesized lines; glucosinolates; larval instar index; nitrogen
 
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