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Dr. Vamsi Nalam
Department of Biology
Indiana University – Purdue University Fort Wayne
It is widely accepted that plant defense responses vary with insect host plant specialization and feeding guilds. Generalists are thought to be more susceptible to a given plant defense compound compared to specialists that may use these same defensive compounds to their own advantage. Feeding guilds are also a strong indicator of differential induction of plant responses. Insect herbivores can be classified into several feeding guilds. Example- leaf chewers, phloem feeders, xylem feeders, leaf miners, fruit and flower chewers, gall-inducing, and root chewers. Studies examining the mechanisms underlying plant defense responses to insect herbivore attack have identified the role of two major phytohormones- salicylic acid (SA), jasmonic acid (JA). We investigated how soybean plants tailor their defense against insect herbivores from two feeding guilds: phloem feeding aphids and cell content feeding thrips. Gene expression analyses indicated that SA pathway was induced in response to aphids whereas JA was activated against thrips feeding. Exogenous application of SA and JA confirmed gene expression results in that SA application lowered aphid numbers and JA application reduced thrips population. In the short-term, results of this study will shed light on the ecological and molecular interactions of plant and insects, and in the long-term this research can be applied to ecologically based management programs of the insect herbivores.
Biology | Life Sciences
Selig, Patrick; Keough, Stacy; Nachappa, Punya; and Nalam, Vamsi J., "Interactive Effects of Jasmonic Acid and Salicylic Acid on Induction of Host Defenses in Soybean (Glycine max) against two insect herbivores, Soybean Aphid and Soybean Thrips" (2015). 2015 IPFW Student Research and Creative Endeavor Symposium. 60.