6 October 2019 Resistance of Fruits from a Mandarin Cultivar to Feeding by Fork-Tailed Bush Katydids
Bodil N. Cass, Elizabeth E. Grafton-Cardwell, Jay A. Rosenheim
Author Affiliations +

Plants use a variety of mechanisms to defend against herbivore damage, each with different consequences for agricultural production. Crops relying on tolerance strategies may need different pest management approaches versus those relying on resistance strategies. Previous work suggested that densities of fork-tailed bush katydids (Scudderia furcata Brunner von Wattenwyl [Orthoptera:Tettigoniidae]) that generated substantial scarring on cultivars of sweet oranges (Citrus sinensis, (L.) Osbeck [Sapindales: Rutaceae]) produced only low levels of scarring on cultivars of Citrus reticulata Blanco mandarins. We used field experiments in representative cultivars of these species to test non-mutually exclusive hypotheses regarding the mechanisms underlying this observation: 1) katydids are averse to feeding on mandarin fruits, 2) damaged mandarin fruits preferentially abscise, 3) damaged mandarin fruit tissue recovers during development, and 4) katydid scars on mandarins have a different morphology that may result in misclassification. We found strong support for the first hypothesis, demonstrating that katydids reject opportunities to feed on C. reticulata fruit. Instead of chewing deep holes in the fruit, as was commonly observed for C. sinensis, the katydids only scratched the surface of the C. reticulata fruits.The hypotheses of preferential abscission of damaged fruits and of recovery of damaged tissue were not supported. The low incidence of damage to the mandarins prevented a comprehensive assessment of the scar morphology; however, at harvest, the superficial cuts in C. reticulata were not easily distinguishable from background damage. This indicates that in contrast to C. sinensis, C. reticulata has substantial natural resistance to fork-tailed bush katydids making them a non-pest in this crop.

© The Author(s) 2019. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Bodil N. Cass, Elizabeth E. Grafton-Cardwell, and Jay A. Rosenheim "Resistance of Fruits from a Mandarin Cultivar to Feeding by Fork-Tailed Bush Katydids," Journal of Economic Entomology 112(6), 2861-2871, (6 October 2019). https://doi.org/10.1093/jee/toz241
Received: 8 June 2019; Accepted: 31 July 2019; Published: 6 October 2019

This article is only available to subscribers.
It is not available for individual sale.

citrus species
cultivar effect
Get copyright permission
Back to Top