title: Aphicidal efficacy of scorpion- and spider-derived neurotoxins.
abstract: Insect-specific neurotoxins that act within the insect hemocoel (body cavity) represent an untapped resource for insect pest management. On the basis of recent advances made in development of appropriate delivery systems for transport of these toxins from the insect gut, across the gut epithelium to their target site, we screened neurotoxins derived from scorpion or spider venom for efficacy against the pea aphid, Acyrthosiphon pisum, and the green peach aphid, Myzus persicae. Toxins were selected to represent different modes of electrophysiological action, including activity on voltage-gated calcium channels (ω-TRTX-Gr1a, ω-agatoxin Aa4a, ω-hexatoxin-Hv1a), calcium- and voltage-activated potassium channels (charybdotoxin, maurotoxin), chloride channels (chlorotoxin) and voltage-gated sodium channels (LqhαIT). The Bacillus thuringiensis-derived toxin Cyt1Aa was also tested as a positive control for toxicity. In per os bioassays with both aphid species, toxicity was only seen for ω-TRTX-Gr1a and Cyt1Aa. On injection into the hemocoel of A. pisum, LD₅₀ values ranged from 1 to 8 ng/mg body weight, with ω-hexatoxin-Hv1a being the most toxic (1.02 ng/mg body weight). All neurotoxins caused rapid paralysis, with charybdotoxin, maurotoxin and chlorotoxin also causing melanization of injected aphids. These data represent the first comprehensive screen of neurotoxins against aphids, and highlight the potential for practical use of the insect-specific toxin ω-hexatoxin-Hv1a in aphid management.
authors: Department of Entomology, Iowa State University, Ames, IA 50011, USA.
authors: Narinder
authors: N
authors: Pal
authors: Takashi
authors: T
authors: Yamamoto
authors: Glenn F
authors: GF
authors: King
authors: Clement
authors: C
authors: Waine
authors: Bryony
authors: B
authors: Bonning
mesh_terms: D000818:Animals; D001042:Aphids / Q000187:drug effects*; D001413:Bacillus thuringiensis / Q000378:metabolism; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000378:metabolism; D061046:Biological Control Agents; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D018999:Charybdotoxin / Q000633:toxicity*; D004731:Endotoxins / Q000378:metabolism; D006460:Hemolysin Proteins / Q000378:metabolism; D007300:Insect Control / Q000379:methods; D007928:Lethal Dose 50; D009498:Neurotoxins / Q000633:toxicity*; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D012604:Scorpion Venoms / Q000633:toxicity*; D012605:Scorpions; D015222:Sodium Channels / Q000187:drug effects / Q000378:metabolism; D013111:Spider Venoms / Q000633:toxicity*; D013112:Spiders
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D061046:Biological Control Agents; D015220:Calcium Channels; D004731:Endotoxins; D006460:Hemolysin Proteins; D009498:Neurotoxins; D015221:Potassium Channels; D012604:Scorpion Venoms; D015222:Sodium Channels; D013111:Spider Venoms; C030956:insecticidal crystal protein, Bacillus Thuringiensis; C104498:maurotoxin; C091539:Chlorotoxin; D018999:Charybdotoxin