Roles of food quality and enemy-free space in host use by a generalist insect herbivore

被引:114
作者
Singer, MS
Rodrigues, D
Stireman, JO
Carrière, Y
机构
[1] Univ Arizona, Dept Entomol, Tucson, AZ 85721 USA
[2] Univ Arizona, Ctr Insect Sci, Tucson, AZ 85721 USA
[3] Univ Fed Rio Grande Sul, PPG Biol Anim, Dept Zool, BR-91501970 Porto Alegre, RS, Brazil
[4] Univ Arizona, Dept Ecol & Evolutionary Biol, Tucson, AZ 85721 USA
关键词
Arctiidae; diet choice; enemy-free space; Estigmene acrea; generalist insect herbivore; host preference; parasitoids; polyphagy; Senecio longilobus; Tachinidae; tritrophic interactions; Viguiera dentata;
D O I
10.1890/03-0827
中图分类号
Q14 [生态学(生物生态学)];
学科分类号
071012 ; 0713 ;
摘要
The relative importance of food quality vs. enemy-free space remains an unresolved but central issue in the evolutionary ecology of host use by phytophagous insects. In this study, we investigate their relative importance in determining host-plant use by a generalist caterpillar, Estigmene acrea (Lepidoptera: Arctiidae). In nature, E. acrea late-instar caterpillars preferred Senecio longilobus (Asteraceae), which contains pyrrolizidine alkaloids that the caterpillars sequester, over Viguiera dentata (Asteraceae), a natal host, and typically suffered a 28% mortality risk from parasitoids. We hypothesized that the natural, mixed diet of caterpillars provides high-quality food via hosts like Viguiera as well as antiparasitoid defense via sequestered toxins from Senecio. We found that a pure Viguiera diet provides superior growth performance over a pure Senecio or mixed diet in the absence of parasitism. However, when parasitism risk is at least moderate, the mixed diet provides a survival advantage over the pure diets of Viguiera or Senecio. We therefore conclude that the balance between benefits of growth (food quality) and defense (enemy-free space) maintains the use of a mixed diet in nature. Furthermore, the value of enemy-free space supercedes the value of food quality in determining the host-plant preference of late-instar caterpillars.
引用
收藏
页码:2747 / 2753
页数:7
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