Artificial rainfall increases herbivory on an externally defended forb
Plants have a variety of herbivore resistance traits, including a diverse array of chemicals, either inside plant tissues or on plant surfaces. External chemical defenses are common and widespread, though understudied as a class. One potential selective force on these defenses is their potential for abiotic dislodgement given their exposed position. I tested whether abiotic removal (artificial rainfall) leads to increased herbivory in the annual chenopod Atriplex rosea. This plant, like other chenopods, has specialized secretory trichomes, which secrete water-soluble herbivore resistance compounds onto the plant’s surfaces. Consistent with this hypothesis, I found significantly greater chewing herbivory in plants which received artificial rainfall compared to no-rainfall controls and a below-leaf water control. This simple experiment demonstrates that abiotic factors can directly change the efficacy of a resistance trait.
KeywordsExternal chemical defenses Herbivore resistance Salt bladders Atriplex Diabrotica
Cathy Koehler and Paul Aigner supported this work at the McLaughlin reserve, as did the staff of Homestake Mining Company. Charley Eiseman identified Monoxia angularis. Rick Karban read and gave insightful comments on the manuscript. This work was funded by the Jastro-Shields fund through the graduate group in ecology at UC Davis.
- Baldwin BC, Goldman D, Keil D, Patterson R, Rosatti T, Wilken D (2012) The Jepson manual: vascular plants of California, 2nd edn. University of California Press, BerkeleyGoogle Scholar
- Elle E, van Dam N, Hare J (1999) Cost of glandular trichomes, a “resistance” character in Datura wrightii Regel (Solanaceae). Evolution (NY) 53:22–35Google Scholar
- Thompson JN (2005) The geographic mosaic of coevolution. University of Chicago Press, ChicagoGoogle Scholar