Comparative Effectiveness of Potential Elicitors of Plant Resistance against Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) in Four Crop Plants.
Feeding by insect herbivores activates plant signaling pathways, resulting in the enhanced production of secondary metabolites and other resistance-related traits by injured plants. These traits can reduce insect fitness, deter feeding, and attract beneficial insects. Organic and inorganic chemicals applied as a foliar spray, seed treatment, or soil drench can activate these plant responses. Azelaic acid (AA), benzothiadiazole (BTH), gibberellic acid (GA), harpin, and jasmonic acid (JA) are thought to directly mediate plant responses to pathogens and herbivores or to mimic compounds that do. The effects of these potential elicitors on the induction of plant defenses were determined by measuring the weight gains of fall armyworm, Spodoptera frugiperda (J. E. Smith) (FAW) (Lepidoptera: Noctuidae) larvae on four crop plants, cotton, corn, rice, and soybean, treated with the compounds under greenhouse conditions. Treatment with JA consistently reduced growth of FAW reared on treated cotton and soybean. In contrast, FAW fed BTH- and harpin-treated cotton and soybean tissue gained more weight than those fed control leaf tissue, consistent with negative crosstalk between the salicylic acid and JA signaling pathways. No induction or inconsistent induction of resistance was observed in corn and rice. Follow-up experiments showed that the co-application of adjuvants with JA failed to increase the effectiveness of induction by JA and that soybean looper [Chrysodeixis includens (Walker)], a relative specialist on legumes, was less affected by JA-induced responses in soybean than was the polyphagous FAW. Overall, the results of these experiments demonstrate that the effectiveness of elicitors as a management tactic will depend strongly on the identities of the crop, the pest, and the elicitor involved.
Texas A&M Agrilife Extension, Rosenberg, Texas, United States of America.
John W
JW
Gordy
Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America.
B Rogers
BR
Leonard
Department of Experimental Statistics, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America.
David
D
Blouin
Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America.
Jeffrey A
JA
Davis
Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America.
Michael J
MJ
Stout
D000818:Animals; D018556:Crops, Agricultural / Q000187:drug effects* / Q000276:immunology / Q000469:parasitology*; D003517:Cyclopentanes / Q000276:immunology; D003998:Dicarboxylic Acids / Q000276:immunology; D060467:Disease Resistance / Q000187:drug effects*; D005875:Gibberellins / Q000276:immunology; D003368:Gossypium / Q000187:drug effects / Q000276:immunology / Q000469:parasitology; D060434:Herbivory / Q000187:drug effects*; D012275:Oryza / Q000187:drug effects / Q000276:immunology / Q000469:parasitology; D054883:Oxylipins / Q000276:immunology; D013025:Glycine max / Q000187:drug effects / Q000276:immunology / Q000469:parasitology; D018411:Spodoptera / Q000254:growth & development / Q000502:physiology*; D013830:Thiadiazoles / Q000276:immunology; D003313:Zea mays / Q000187:drug effects / Q000276:immunology / Q000469:parasitology
D003517:Cyclopentanes; D003998:Dicarboxylic Acids; D005875:Gibberellins; D054883:Oxylipins; D013830:Thiadiazoles; C015700:benzo-1,2,3-thiadiazole; C011006:jasmonic acid; C007842:gibberellic acid; C010038:azelaic acid