The multiple strategies of an insect herbivore to overcome plant cyanogenic glucoside defence

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Stefan Pentzold, Mika Zagrobelny, Pernille Sølvhøj Roelsgaard, Birger Lindberg Møller, Søren Bak

Cyanogenic glucosides (CNglcs) are widespread plant defence compounds that release toxic hydrogen cyanide by plant bglucosidase
activity after tissue damage. Specialised insect herbivores have evolved counter strategies and some sequester
CNglcs, but the underlying mechanisms to keep CNglcs intact during feeding and digestion are unknown. We show that
CNglc-sequestering Zygaena filipendulae larvae combine behavioural, morphological, physiological and biochemical
strategies at different time points during feeding and digestion to avoid toxic hydrolysis of the CNglcs present in their Lotus
food plant, i.e. cyanogenesis. We found that a high feeding rate limits the time for plant b-glucosidases to hydrolyse CNglcs.
Larvae performed leaf-snipping, a minimal disruptive feeding mode that prevents mixing of plant b-glucosidases and
CNglcs. Saliva extracts did not inhibit plant cyanogenesis. However, a highly alkaline midgut lumen inhibited the activity of
ingested plant b-glucosidases significantly. Moreover, insect b-glucosidases from the saliva and gut tissue did not hydrolyse
the CNglcs present in Lotus. The strategies disclosed may also be used by other insect species to overcome CNglc-based
plant defence and to sequester these compounds intact.
Original languageEnglish
Article numbere91337
JournalPLOS ONE
Volume9
Issue number3
Number of pages8
ISSN1932-6203
DOIs
Publication statusPublished - 2014

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