N addition suppresses the performance of grassland caterpillars (Gynaephora alpherakjj) by decreasing ground temperature. Issue 3 (28th March 2017)

• Record Type: Journal Article
• Authors: Yang, Yangheshan; Xi, Xinqiang; Zhong, Xintong; Eisenhauer, Nico; Sun, Shucun
• Is Part Of: Ecosphere. Volume 8:Issue 3(2017)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2017-03-28
• Subjects: feeding activity -- global change -- grassland caterpillar -- Gynaephora alpherakjj -- N deposition -- Tibetan Plateau; Ecology -- Periodicals; Ecology; Periodicals; 577.05
• DOI: 10.1002/ecs2.1755
• Languages: English
• ISSNs: 2150-8925

Abstract

Abstract: Nitrogen deposition may stimulate plant biomass production and improve the quality of plant tissue, with both effects potentially facilitating herbivore growth and development. We hypothesized that simulated N deposition (N addition) would facilitate the growth and development of the grassland caterpillar Gynaephora alpherakjj, a notorious pest species in the alpine Tibetan meadow. We tested this hypothesis in two complementary experiments. The first field experiment tested N (ambient N levels vs. N addition) and caterpillar effects (caterpillar absence vs. presence) on plant community and sedge (major food plant species for caterpillars) biomass, growth, and development rate of the caterpillars, and microhabitat temperature. The second chamber experiment tested N addition effects through plant tissue quality on caterpillar performance. Results show that N addition increased the biomass and leaf N concentration of the sedge species, but decreased the feeding time, growth, and development rate of the caterpillars in the field experiment. The independent chamber experiment showed that increased leaf N facilitated the caterpillar growth and development. These results suggest that the reduced performance of caterpillars was not caused by an N addition‐induced change in food quality. By contrast, N addition significantly reduced the ground surface temperature presumably because of canopy shading, as indicated by increased plant height and biomass in the N addition treatment. A significant quadratic relationship between ground surface temperature and the number of feeding caterpillars in the field experiment explained the difference in feeding time between the N addition and ambient N treatments. It can thus be concluded that N addition reduced caterpillar performance by stimulating plant growth leading to reduced ground surface temperatures, which decreased caterpillar feeding activity. Our results suggest that the effect of N deposition on abiotic factors could be critical to the growth, development, and survival of immobile herbivore species or the individuals at immobile stages that cannot quickly respond to changing microclimatic environments.