Resistance Mechanisms Against Arthropod Herbivores in Cotton and Their Interactions with Natural Enemies

Abstract

Abstract Cotton plants (genus Gossypium) are grown on more than 30 million hectares worldwide and are a major source of fiber. The plants possess a wide range of direct and indirect resistance mechanisms against herbivorous arthropods. Direct resistance mechanisms include morphological traits such as trichomes and a range of secondary metabolites. The best known insecticidal compounds are the terpenoid gossypol and its precursors and related compounds. Indirect resistance mechanisms include herbivore-induced volatiles and extrafloral nectaries that allow plants to attract and sustain natural enemy populations. We discuss these resistance traits of cotton, their induction by herbivores, and their impact on herbivores and natural enemies. In addition, we discuss the use of genetically engineered cotton plants to control pest Lepidoptera and the influence of environmental factors on the resistance traits. Keywords: Bt-cotton Gossypium gossypolhost plant resistanceoptimal defense theoryplant defense ACKNOWLEDGMENTS We thank Ursus Kaufmann (Agroscope) for the drawing of Figures 2 and 4 and Steven E. Naranjo (USDA-ARS) and Michael Meissle and Jana Collatz (Agroscope) for their thorough review of an earlier draft of the manuscript.