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United States Department of Agriculture

Agricultural Research Service

Title: Influence of Plant Ontogeny and Abiotic Factors on Resistance of Glandular-Haired Alfalfa to the Potato Leafhopper (Hemiptera: Cicadellidae)

Authors
item Casteel, Clare - UNIV OF CALIF-RIVERSIDE
item Ranger, Christopher - RUTGERS UNIVERSITY
item Backus, Elaine
item Ellersieck, Mark - UNIV OF MISSOURI-COLUMBIA
item Johnson, David - CAL/WEST SEEDS-W SALEM WI

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 26, 2005
Publication Date: April 1, 2006
Citation: Casteel, C.L., Ranger, C.M., Backus, E.A., Ellersieck, M.R., Johnson, D.W. 2006. Influence of Plant Ontogeny and Abiotic Factors on Resistance of Glandular-Haired Alfalfa to the Potato Leafhopper (Hemiptera: Cicadellidae). Journal of Economic Entomology. 99(2):537-543.

Interpretive Summary: Laboratory experiments were conducted to characterize the trichome-based defense of glandular-haired alfalfa, Medicago sativa L., against the potato leafhopper, Empoasca fabae (Harris). Within-plant variability in leafhopper resistance was examined by caging adult leafhoppers to either basal or apical stem internodes, or under varying light and temperature conditions, on either the leafhopper-resistant, glandular-haired M. sativa cv. ‘G98A’ or the susceptible, nonglandular-haired M. sativa cv. ‘Ranger’. Young, actively secreting glandular trichomes are located on apical internodes of G98A, while senesced gland heads are found on older, basal internodes of G98A. After 96 hrs, the highest cumulative leafhopper mortality and lowest number of excretory droplets were associated with apical internodes of G98A, as well as when plants were held in high light and high temperature conditions, respectively. These results indicate that certain regions of M. sativa G98A are better protected against the potato leafhopper than others, and that temperature and light also influence resistance levels.

Technical Abstract: Laboratory experiments were conducted to characterize the trichome-based defense of glandular-haired alfalfa, Medicago sativa L., against the potato leafhopper, Empoasca fabae (Harris). Within-plant variability in leafhopper resistance was examined by caging adult leafhoppers to either basal or apical stem internodes of the leafhopper-resistant, glandular-haired M. sativa cv. ‘G98A’ or the susceptible, nonglandular-haired M. sativa cv. ‘Ranger’. Young, actively secreting glandular trichomes are located on apical internodes of G98A, while senesced gland heads are found on older, basal internodes of G98A. After 96 hrs, the highest cumulative leafhopper mortality and lowest number of excretory droplets were associated with apical internodes of G98A. No difference was detected in mortality and feeding levels among insects caged on basal internodes of G98A and basal and apical internodes of Ranger. The influence of abiotic factors on leafhopper resistance was evaluated by caging adult leafhoppers on either G98A or Ranger under four combinations of low and high light and temperature regimes. After 96 hrs, the highest cumulative mortality was associated with leafhoppers confined to G98A under high light and high temperature conditions. These results indicate that certain regions of M. sativa G98A are better protected against the potato leafhopper than others, and that temperature and light also influence resistance levels.

Last Modified: 4/16/2014
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