title: Entomotoxic action of Sambucus nigra agglutinin I in Acyrthosiphon pisum aphids and Spodoptera exigua caterpillars through caspase-3-like-dependent apoptosis.
abstract: In this project, the toxicity and mechanism of action of the ricin-B-related lectin SNA-I from elderberry (Sambucus nigra) in the pea aphid (Acyrthosiphon pisum) and the beet armyworm (Spodoptera exigua), two important pest insects in agriculture, were studied. SNA-I is a chimeric lectin belonging to the class of ribosome-inactivating proteins and consists of an A-chain with N-glycosidase activity and a carbohydrate-binding B-chain. Incorporation of 2 mg/ml of SNA-I in the diet of neonates and adults of A. pisum caused 40-46% mortality within 2 days, while in third instars of S. exigua, the larval biomass was significantly reduced by 12% after feeding for 3 days on a diet containing 5 mg/g of SNA-I. Interestingly, extracts of the (mid)gut of treated A. pisum and S. exigua demonstrated DNA fragmentation and this was accompanied with an increase in caspase-3-like activity. The involvement of cell death or apoptosis in the entomotoxicity of SNA-I through induction of caspase-3-like activity was also confirmed by addition of the permeable caspase-3 inhibitor III in the diet, leading to a rescue of the treated aphid neonates. Finally, similar to the chimeric lectin SNA-I, the hololectin SNA-II, consisting of two carbohydrate-binding B-chains caused high mortality to neonate A. pisum aphids with an LC₅₀ of 1.59 mg/ml, suggesting that the entomotoxic action of the lectins under study mainly relies on their carbohydrate-binding activity.
authors.affiliation: Department of Crop Protection, Ghent University, Belgium.
authors.forename: Shahnaz
authors.initials: S
authors.lastname: Shahidi-Noghabi
authors.forename: Els J M
authors.initials: EJ
authors.lastname: Van Damme
authors.forename: Kamran
authors.initials: K
authors.lastname: Mahdian
authors.forename: Guy
authors.initials: G
authors.lastname: Smagghe
mesh_terms: D000818:Animals; D001042:Aphids / Q000187:drug effects*; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism*; D053938:DNA Fragmentation / Q000187:drug effects; D007300:Insect Control / Q000379:methods*; D007814:Larva / Q000187:drug effects; D007928:Lethal Dose 50; D037121:Plant Lectins / Q000633:toxicity*; D054788:Ribosome Inactivating Proteins / Q000633:toxicity*; D027924:Sambucus nigra / Q000737:chemistry*; D018411:Spodoptera / Q000187:drug effects*; D016019:Survival Analysis
chemical_list: D037121:Plant Lectins; C050600:Sambucus nigra lectins; D054788:Ribosome Inactivating Proteins; D053148:Caspase 3