Lolium perenne is a major forage and turf grass, which is often naturally infected with a "wild-type" strain (E(WT)) of the fungal endophyte Neotyphodium lolii , establishing a symbiotic relationship. In this study, the impacts of different strains wild type E(WT), AR1 (E(AR1)) and AR37 (E(AR37)), of N. lolii on the phenolic profile, phenolic content, and antioxidant capacity of L. perenne were examined. Samples could be ranked according to their phenol content as follows: E(AR1) > E(AR37) ≥ E(-) > E(WT). Radical-scavenging assays showed the same relative ranking of extracts. Flavonoid glycosides and hydroxycinnamic acids were the most abundant polyphenols in L. perenne extracts. Chlorogenic acid and its derivatives were the major compounds responsible for the antioxidant activity. Infection with N. lolii significantly influenced L. perenne phenolic content and antioxidant activity. In conclusion, changes in phenolic composition were merely quantitative. Endophyte infection can have zero, positive, or negative effect on phenol content depending on the endophyte strain.

Perennial ryegrass (Lolium perenne) is often infected with the fungal‐endophyte Neotyphodium lolii. In addition to the ‘wild‐type’ strain (EWT), several ‘selected’ strains of N. lolii are now being marketed as AR1 (EAR1) and AR37 (EAR37). Each of these strains impact positively on L. perenne's resistance against many insects, including the African black beetles (Heteronychus arator). The impact of volatile oils produced specifically by each strain in the endophyte–grass association in enhancing the grass's resistance to insects is still largely unknown. Keeping these in view, we determined the volatile oil profiles produced by L. perenne infected with either EWT or EAR1 or EAR37 and determined the impacts of these volatiles on the host‐selection behaviour of H. arator adults. In the absence of endophyte infection (E–), L. perenne produced 18 different volatile oils. In L. perenne EWT, quantities of 2‐ethyl‐1‐hexanol acetate (Rt = 14.5 min), (Z)‐2‐octen‐1‐ol (Rt = 22.2 min), and butylated hydroxyl toluene (Rt = 23.2 min) were 24, 16 and 26%, respectively, greater than L. perenne E–. The strains EAR1 and EAR37 affected differently the quantities of the volatile compounds but not their identity. In the four‐choice bioassay, males and females of H. arator were equally attracted to each strain. In Y‐tube olfactometer, compared against E–, H. arator adults were less attracted to L. perenne EWT and EAR1. The attractiveness of EAR37 was similar in effect to E– to H. arator. The results indicate that each strain of N. lolii alters the profile of volatile oils in L. perenne differently and that alteration can influence H. arator adult‐host selection.

No abstract

Herbivorous insects use sensory cues to choose their host plants for feeding and/or oviposition by assessing host quality. Olfactory, contact and visual cues of the host mediate such choices. The right-host choice for oviposition by a lepidopteran is essential for the performance of its progeny. In natural conditions, plants are often and concurrently attacked by both herbivorous insects and pathogenic fungi. In such a three-way relationship, the interaction between the plant and insect is usually influenced by the fungal population, and such an influence can be either mutualistic or antagonistic. In the present study, we tested the three-way relationship using the system, Epiphyas postvittana-Vitis vinifera-Botrytis cinerea. We sought answers to the questions: (1) whether the females of E. postvittana prefer to oviposit on V. vinifera leaves infected by B. cinerea; and (2) whether the larvae of E. postvittana prefer to feed on V. vinifera leaves infected by B. cinerea. We found that the host-seeking gravid females of E. postvittana 'tested' the infection status of the host plant using olfactory, visual, and tactile cues; in consequence, they laid significantly fewer eggs on the moderately (30-60%) and intensely (90-100%) infected leaves of V. vinifera. The neonate larvae preferred to feed on mildly (5-10%) and moderately (30-60%) infected leaves, as against the uninfected (control) leaves, and showed no preference for intensely (90-100%) infected leaves. External and internal examination of the larvae established that the larvae fed on B. cinerea-infected leaf because viable conidia of B. cinerea occurred on the body surface and within the gut of the neonate larvae.

No abstract