Caterpillar saliva beats plant defences

Abstract

Blood-feeding arthropods secrete special salivary proteins that suppress the defensive reaction they induce in their hosts. This is in contrast to herbivores, which are thought to be helpless victims of plant defences elicited by their oral secretions. On the basis of the finding that caterpillar regurgitant can reduce the amount of toxic nicotine released by the tobacco plant Nicotiana tabacum, we investigate here whether specific salivary components from the caterpillar Helicoverpa zea might be responsible for this suppression. We find that the enzyme glucose oxidase counteracts the production of nicotine induced by the caterpillar feeding on the plant.

Induction of plant responses to oviposition and feeding by herbivorous arthropods: a comparison

“…Another way to deal with the feeding induced increase of toxins has recently been shown for larvae of Helicoverpa zea feeding upon tobacco plants. These larvae release a glucose oxidase that down-regulates the wound-induced increase of nicotine (Felton & Eichenseer, 1999;Musser et al, 2002).…”

Lessons from the Far End: Caterpillar FRASS-Induced Defenses in Maize, Rice, Cabbage, and Tomato

“…The repertoire of plant defense compounds that are induced in response to herbivory on tobacco from the tobacco hornworm (Manduca sexta) and beet armyworm (Spodoptera exigua) are different (Voelckel and Baldwin 2004). Alternatively, herbivore cues such as saliva from the same insect TFW suppresses herbivore defenses in tobacco, but induces them in tomato (Musser et al 2002;Tian et al 2012). Although, most of these studies are focused on caterpillar oral secretions or saliva, little is known about frassinduced plant defenses in various host-herbivore systems.…”

“…Plant defense responses to insect herbivory have been attributed to several insect behaviors such as feeding, crawling, oviposition, and even defecation (Alborn et al 1997;Felton and Tumlinson 2008;Hilfiker et al 2014;Kim et al 2012;Mithöfer et al 2005;Peiffer et al 2009;Ray et al 2015). Insect feeding is associated with deposition of oral secretions and/ or saliva on plant tissue, which leaves chemical cues of et al 2013b;Musser et al 2002;Tian et al 2012). Furthermore, insect secretions contain a blend of various molecules that differentially affect plant defense responses.…”

Ungulate saliva inhibits a grass–endophyte mutualism

“…By contrast, populations adapted to more favourable sites invest more in growth, diverting resources towards defence production only when induced by damage [19]. Although the same biochemical pathway underlies alkaloid synthesis in both populations [12], the inducible response in European plants would require a signal to upregulate alkaloid production and this additional step may be altered by salivary components [8][9][10].…”

“…Limited evidence of antifungal activity in herbviore saliva, primarily through lactoferrin peptides and lysozymes [6,7], suggests that this may arise if compounds reduce fungal growth and subsequently lower alkaloid production. Defences may also be mitigated if salivary enzymes directly inhibit signals that activate induced wound responses [8][9][10]. Although fungal inhibitors and disruptors of defence signalling may have also arisen independently of endophytes [9,11], this does not detract from their potential impact on plant -herbivore interactions.…”