Summary: 518
Ecology, 80(2), 1999, pp. 518­523
1999 by the Ecological Society of America
INFLUENCE OF PREY AVAILABILITY AND INDUCED HOST-PLANT
RESISTANCE ON OMNIVORY BY WESTERN FLOWER THRIPS
ANURAG A. AGRAWAL,1
CHRIS KOBAYASHI,2
AND JENNIFER S. THALER
Department of Entomology and Center for Population Biology, University of California­Davis,
One Shields Avenue, Davis, California 95616-8584 USA
Abstract. Theory predicts that the balance of nutritional needs, food availability, and
the quality of particular food items are important factors in the feeding decisions of om-
nivorous animals. In this study we investigate factors that affect the feeding decisions of
an omnivorous thrips (Frankliniella occidentalis) that eats both animal prey and plant
foliage. In the presence of prey (mite eggs), adult and larval thrips consumed nearly half
the amount of plant tissue as did thrips without prey. We manipulated host-plant quality
by exposing plants to spider mite feeding. In the absence of prey, systemically induced
plant responses following herbivory reduced the amount of feeding by thrips compared to
that on uninduced control plants. In the presence of prey, induced responses caused a shift
in the feeding preferences of thrips: thrips consumed half the amount of plant material and

Source: Agrawal, Anurag - Department of Ecology and Evolutionary Biology & Entomollogy, Cornell University

Collections: Environmental Sciences and Ecology