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Effects of Long-term Experimental Warming on Aphid Density in the Field
 

Summary: Effects of Long-term Experimental Warming on Aphid Density
in the Field
LYNN S. ADLER,1,
* PERRY DE VALPINE,2
JOHN HARTE,3
AND JESSICA CALL
4,5
ABSTRACT: Global warming is generally predicted to increase the intensity of herbivore
pressure on plants. Support for this prediction often comes from short-term studies, or studies
conducted in controlled laboratory settings. We examined the effect of long-term experimental
warming on an aphid-sagebrush interaction (Obtusicauda coweni and Artemisia tridentata) in
natural field plots in the Rocky Mountains. In no year did we find support for the prediction
that warming increased aphid abundance or population growth. In fact, warming decreased
aphid density on sagebrush in one year, tended to decrease aphids in a second year, and had no
effect in a third year. In enclosures that excluded predators, warming decreased aphid
population growth by an amount consistent with observed field density differences. Warming
increased sagebrush carbon:nitrogen (C:N) ratio and plant size, but there was no significant
correlation between these variables and aphid growth or density. In a separate snow-
manipulation experiment in unwarmed plots, the timing of snowmelt did not affect aphid
density. In conclusion, warming reduced or did not affect aphid density in each of three years,

  

Source: Adler, Lynn - Department of Plant, Soil and Insect Sciences, University of Massachusetts at Amherst

 

Collections: Environmental Sciences and Ecology