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Influence of glandular-haired perennial Medicago species on the alfalfa weevil (Hypera postica (Gyllenhal);) (Coleoptera: Curculionidae)
Abstract
Laboratory and greenhouse studies were conducted to evaluate glandular-haired perennial Medicago species as potential germplasm sources for alfalfa weevil (Hypera postica (Gyllenhal)) resistance. M. prostrata and M. glandulosa had the highest degree of resistance to the weevil, while M. glutinosa had intermediate resistance. Larval development studies indicated that perennial diploids M. prostrata and M. glandulosa were highly resistant, and were comparable with a resistant annual M. disciformis. Number of eggs oviposited into stems of M. prostrata and M. glandulosa was low in both free-choice and no-choice tests. In the no-choice test, oviposition was higher in susceptible M. sativa (alfalfa) than in perennial tetraploid M. glutinosa, however, no difference between these entries was evident in the free-choice test. In feeding tests, dry matter consumption, leaf damage ratings, and numbers of weevils on the entries were all lower for M. prostrata and M. glandulosa than for susceptible M. sativa. M. glutinosa did not appear to be consistently resistant to adult weevil feeding. Adult feeding damage ratings, leaf dry matter consumption, and oviposition did not vary with glandular hair density on the stems of M. glutinosa. The relative number of adults present on M. glutinosa did vary inversely with glandular hair density on stems. Weevil oviposition appeared to be associated with stem toughness, with fewest eggs deposited into relatively tough stems of M. prostrata and progeny of M. prostrate x M. sativa (diploid) crosses. Oviposition was highest into the least tough stems of tetraploid M. sativa. A field study compared weevil abundance and damage on four perennial, glandular-haired lines and four commercial cultivars. The glandular-haired M. glandulosa entry tended to have the lowest number of larvae and the least stem tip damage, when differences were indicated among entries. The M. prostrata x M. sativa cross progeny had moderate damage similar to the commercial cultivar 'Team' and to the M. glandulosa entry on one sample data. M. glandulosa had the shortest growth habit while the commercial cultivars were taller than the remaining glandular-haired entries.
Subject Area
Entomology
Recommended Citation
Danielson, Stephen Dale, "Influence of glandular-haired perennial Medicago species on the alfalfa weevil (Hypera postica (Gyllenhal);) (Coleoptera: Curculionidae)" (1987). ETD collection for University of Nebraska-Lincoln. AAI8803747.
https://digitalcommons.unl.edu/dissertations/AAI8803747