Whiteflies interfere with indirect plant defense against spider mites in Lima bean.
Plants under herbivore attack are able to initiate indirect defense by synthesizing and releasing complex blends of volatiles that attract natural enemies of the herbivore. However, little is known about how plants respond to infestation by multiple herbivores, particularly if these belong to different feeding guilds. Here, we report the interference by a phloem-feeding insect, the whitefly Bemisia tabaci, with indirect plant defenses induced by spider mites (Tetranychus urticae) in Lima bean (Phaseolus lunatus) plants. Additional whitefly infestation of spider-mite infested plants resulted in a reduced attraction of predatory mites (Phytoseiulus persimilis) compared to attraction to plants infested by spider mites only. This interference is shown to result from the reduction in (E)-beta-ocimene emission from plants infested by both spider mites and whiteflies. When using exogenous salicylic acid (SA) application to mimic B. tabaci infestation, we observed similar results in behavioral and chemical analyses. Phytohormone and gene-expression analyses revealed that B. tabaci infestation, as well as SA application, inhibited spider mite-induced jasmonic acid (JA) production and reduced the expression of two JA-regulated genes, one of which encodes for the P. lunatus enzyme beta-ocimene synthase that catalyzes the synthesis of (E)-beta-ocimene. Remarkably, B. tabaci infestation concurrently inhibited SA production induced by spider mites. We therefore conclude that in dual-infested Lima bean plants the suppression of the JA signaling pathway by whitefly feeding is not due to enhanced SA levels.
Zhang
Peng-Jun
PJ
Laboratory of Entomology, Wageningen University, PO Box 8031, 6700 EH Wageningen, The Netherlands.
Zheng
Si-Jun
SJ
van Loon
Joop J A
JJ
Boland
Wilhelm
W
David
Anja
A
Mumm
Roland
R
Dicke
Marcel
M
D000818:Animals; D003517:Cyclopentanes / Q000037:antagonists & inhibitors; D004478:Ectoparasitic Infestations / Q000276:immunology; D007887:Fabaceae / Q000276:immunology* / Q000469:parasitology; D006430:Hemiptera / Q000472:pathogenicity*; D054883:Oxylipins / Q000037:antagonists & inhibitors; D020156:Salicylic Acid / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D040102:Tetranychidae / Q000472:pathogenicity*
D003517:Cyclopentanes; D054883:Oxylipins; C011006:jasmonic acid; D020156:Salicylic Acid