Enhanced Resistance to Four Species of Clypeorrhynchan Pests in Neotyphodium uncinatum Infected Italian ryegrass

Particular alkaloids produced by Neotyphodium</it> endophytes show toxicity to invertebrates. Italian ryegrass (Lolium multiflorum</it> Lamarck) cultivars and strains that are symbiotic with Neotyphodium</it> endophytes have been recently established in Japan. N. uncinatum</it>-infected Italian ryegrass lines accumulate N</it>-formylloline, a type of loline alkaloid (1-aminopyrrolizidine) showing neurotoxicity to herbivorous insects. This study investigated the toxicity of N</it>-formylloline and resistance of N. uncinatum</it>-infected Italian ryegrass to vascular-sap feeding Clypeorrhynchan pests. When four vascular-sap feeding insects: Laodelphax striatellus</it> (Fallén) (Homoptera: Delphacidae), Sogatella furcifera</it> (Horváth) (Homoptera: Delphacidae), Cicadulina bipunctata</it> (Melichar) (Homoptera: Cicadellidae), and Nephotettix cincticeps</it> (Uhler) (Homoptera: Cicadellidae) fed on N. uncinatum</it>-infected Italian ryegrass, significant decreases in survival rate were observed for three phloem-sap feeders but not for a xylem-sap feeder, N. cincticeps</it>. This result suggests an uneven distribution of N</it>-formylloline among plant tissues. A potency assay for N</it>-formylloline using a Parafilm feeding sachet and a quantitative analysis of N</it>-formylloline in plant showed a concentration-dependent lethal effect of N</it>-formylloline on all four tested vascular-sap feeders. Our results strongly suggest that N. uncinatum</it>-infected plants can control some Clypeorrhynchan pests in crop fields.