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Elevated CO 2 levels and herbivore damage alter host plant preferences
Author(s) -
Agrell Jep,
Anderson Peter,
Oleszek Wieslaw,
Stochmal Anna,
Agrell Cecilia
Publication year - 2006
Publication title -
oikos
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.672
H-Index - 179
eISSN - 1600-0706
pISSN - 0030-1299
DOI - 10.1111/j.0030-1299.2006.13614.x
Subject(s) - spodoptera littoralis , herbivore , biology , larva , host (biology) , medicago sativa , insect , bioassay , plant tolerance to herbivory , botany , malvaceae , hatching , noctuidae , agronomy , horticulture , zoology , ecology
Interactions between the moth Spodoptera littoralis and two of its host plants, alfalfa ( Medicago sativa ) and cotton ( Gossypium hirsutum ) were examined, using plants grown under ambient (350 ppm) and elevated (700 ppm) CO 2 conditions. To determine strength and effects of herbivore‐induced responses assays were performed with both undamaged (control) and herbivore damaged plants. CO 2 and damage effects on larval host plant preferences were determined through dual‐choice bioassays. In addition, larvae were reared from hatching to pupation on experimental foliage to examine effects on larval growth and development. When undamaged plants were used S. littoralis larvae in consumed more cotton than alfalfa, and CO 2 enrichment caused a reduction in the preference for cotton. With damaged plants larvae consumed equal amounts of the two plant species (ambient CO 2 conditions), but CO 2 enrichment strongly shifted preferences towards cotton, which was then consumed three times more than alfalfa. Complementary assays showed that elevated CO 2 levels had no effect on the herbivore‐induced responses of cotton, whereas those of alfalfa were significantly increased. Larval growth was highest for larvae fed undamaged cotton irrespectively of CO 2 level, and lowest for larvae on damaged alfalfa from the high CO 2 treatment. Development time increased on damaged cotton irrespectively of CO 2 treatment, and on damaged alfalfa in the elevated CO 2 treatment. These results demonstrate that elevated CO 2 levels can cause insect herbivores to alter host plant preferences, and that effects on herbivore‐induced responses may be a key mechanism behind these processes. Furthermore, since the insects were shown to avoid foliage that reduced their physiological performance, our data suggest that behavioural host plant shifts result in partial escape from negative consequences of feeding on high CO 2 foliage. Thus, CO 2 enrichment can alter both physiology and behaviour of important insect herbivores, which in turn may to impact plant biodiversity.