Evaluating the fungal endophyte Neotyphodium occultans for resistance to the rice leaf bug, Trigonotylus caelestialium, in Italian ryegrass, Lolium multiflorum

Abstract

Fungal endophytes of the genus Neotyphodium (Ascomycota: Clavicipitaceae) form symbiotic associations with many grass species of the subfamily Pooideae, including some important forage and turf grasses from the genus Lolium. Some Neotyphodium-infected grasses have enhanced resistance to the rice leaf bug, Trigonotylus caelestialium (Kirkaldy) (Heteroptera: Miridae), one of the major pests in rice production in Japan. The insects can grow on Lolium grasses and thus cause a conflict of interest between production of forage and rice. Endophyte-mediated resistance to T. caelestialium is likely to be conferred by N-formylloline, one of the major loline alkaloids (saturated 1-aminopyrrolizidines) observed in some grass-Neotyphodium associations. We checked the feasibility of using Neotyphodium occultans, the native endophyte of Italian ryegrass (Lolium multiflorum Lam.), to reduce T. caelestialium, as this endophyte produces N-formylloline, but no known mammalian toxins. To this end, we conducted choice and no-choice feeding assays using T. caelestialium first instars and 35 N. occultans-infected Italian ryegrass plants with different in planta N-formylloline concentration. Some N. occultans-infected ryegrass showed significant resistance to T. caelestialium. The preference and the survival of this insect were considerably lower on infected plants, and the higher the in planta N-formylloline concentration, the greater the adverse effects on the insect. The incremental risk of death of the insect was assumed to be due to intake of the chemical, and in addition, to the decreased amount of feeding caused by its insect-deterrent effect. These results indicated that the use of the N. occultans-grass associations has potential to reduce T. caelestialium propagation in ryegrass crops. The breeding of N. occultans-infected Italian ryegrass cultivars with high N-formylloline concentrations should be an effective way to develop pasture grasses with a greater protective effect against T. caelestialium.

Host Plant Resistance of Cool-Season (C3) Turfgrasses to Above- and Belowground Feeding by <I>Tipula paludosa</I> (Diptera: Tipulidae)

“…Endophyte infection, which signiÞcantly decreased larval weight gain in young grasses, was correlated with decreased emigration. Increased emigration away from Eϩ plants has been detected with both chewing and sucking insects in turfgrasses (Richmond and Shetlar 1999, 2000, while avoidance of Eϩ plants is often associated with movement toward E-plants (Carriere et al 1998, Clement et al 2011, Shiba et al 2011. Other turf feeding insects are not affected by endophyte-mediated defenses (Williamson and Potter 1997).…”

Endophytic fungi alter sucking bug responses to cotton reproductive structures

“…Our study extends these previously reported facultative endophyte-mediated negative effects on aphids more broadly to other hemipterans to include L. hesperus plant bugs (Miridae) and N. viridula stink bugs (Pentatomidae). To our knowledge, the only other evidence to date of fungal endophyte-mediated effects on nonaphid hemipterans involves the obligate clavicipitaceous Neotyphodium-Lolium fungus-ryegrass system (Shiba & Sugawara, 2005;Shiba et al, 2011). For example, Shiba & Sugawara (2005) showed that the presence of N. lolli as an endophyte in perennial ryegrass, Lolium perenne, deterred feeding on inflorescences by both first instar and adult rice leaf bugs, Trigonotylus caelestialium Kirkaldy (Heteroptera: Miridae).…”

Potential antagnosim of cultivated and wild grass–endophyte associations towards Meloidogyne incognita

“…In turn, these endophytes often confer tolerance to abiotic (Kannadan and Rudgers, 2008) and biotic (Elmi et al, 2000;Shiba et al, 2011) sources of stress. In the present study, the decrease in the number of M. incognita J2 moving towards E+ plants and in the number of J2 penetrating the roots of E+ plants suggests that presence of the endophyte N. coenophialum might partly contribute to the anti-nematode properties of endophyte-host associations.…”

“…increasing resistance to insect pest, being more competitive and thriving better with limited resources (Malinowski and Belesky, 2000;Shiba et al, 2011). It suggests that the endophytic fungi can play important ecological roles in plant communities (Clay and Holah, 1999).…”