Argentine stem weevil adults are affected by meadow fescue endophyte and its loline alkaloids

Abstract

Responses of adult Argentine stem weevil (ASW) to meadow fescue infected with the endophyte Neotyphodium uncinatum and to two loline alkaloids produced by the fungus were investigated Endophyte in two different meadow fescue seedlines did not affect adult ASW feeding scores but reduced oviposition compared with endophytefree controls In a nochoice experiment adult ASW were given artificial diets containing Nformyl loline (NFL) or Nacetyl norloline (NANL) at three concentrations or a control diet with no lolines Mortality was significantly higher at the highest rate of NFL than for lower rates and the control For NANL mortality was increased at both the lowest and the highest concentrations Feeding scores were higher on control than loline diets but only after 4 weeks In a choice experiment NFL appeared to have no effect on ASW feeding preference whereas there was less feeding at the highest concentration of NANL compared with the control diet

Feeding and oviposition by Argentine stem weevil on <i>Epichlo uncinata</i>infected lolinecontaining <i>Festulolium</i>

“…Furthermore, in the case of oviposition, the level of protection afforded to this plant material was similar to that of Samson AR37 and Samson WT. The absence of a reduction in ASW feeding in E. uncinata infection in Festulolium in the present work is consistent with the results obtained by Jensen et al (2009) with E. uncinata infected meadow fescue plants and artificial diets containing different loline concentrations. The reduction of feeding and oviposition of ASW on Samson AR37 recorded in the present work was contrary to earlier studies by Popay & Wyatt (1995) and A.J.…”

“…That grasses favourable for adult feeding are favourable for oviposition does however not always apply, as some grasses, for example, are rejected as oviposition hosts despite being utilized Visual score of feeding (0-10 scale) Barrier Nil 6.5 1 6.0 6.9 Barrier U2 6.1 6.3 1 6.5 G. Samson AR37 4.4 4.8 4.1 G. Samson WT 3.5 3.7 4.0 G. Samson Nil 6.9 6.5 7.2 1 G. Wana cocksfoot 8.5 8.7 8.9 LSD (P=0.05)=1.40; P <0.0001 for feeding by gravid female weevils (Firth et al 1993;Barker & Firth 1994). The results of Jensen et al (2009) and the present study suggest that E. uncinata infection in meadow fescue and Festulolium leads to a further case where the correlation between susceptibilities to feeding and oviposition breaks down -that is, the high susceptibility of E. uncinata-infected meadow fescue and Festulolium to feeding by ASW does not predict the low susceptibility to ASW oviposition.…”

“…because of potential agronomic advantages, not least pest resistance and tolerance. Earlier research at Cropmark Seeds (Patchett 2007;Patchett et al 2008) and elsewhere (Jensen et al 2009;Popay & Lane 2000;Popay et al 2009) indicated some level of resistance to Argentine stem weevil (ASW) (Listronotus bonariensis (Kuschel)) is afforded to meadow fescue and to meadow fescue-perennial ryegrass (Lolium perenne L.) hybrids (Festulolium) when plants are infected with E. uncinata. Further, data are becoming available from field situations to suggest that E. uncinata infected Festulolium supports lower ASW populations (Barker 2013).…”

Ovipositional preferences and larval survival of annual bluegrass weevil, Listronotus maculicollis, on Poa annua and selected bentgrasses (Agrostis spp.)

“…Often females created ovipositional probes but did not deposit eggs in them. A feeding score was determined on a 0-9 scale that took into account number and size of feeding scars, with 0 being assigned when no feeding was observed and 9 if more than 135 feeding scars were found (modified from Jensen et al, 2009). The experiment was conducted with overwintering adults (collected February-March 2011) (four experiment runs with three replications per run of each of the nine grasses) and spring-generation adults (collected June-July 2011) (three runs with three replications per run of each of the nine grasses).…”

Anti‐insect defenses of Achnatherum robustum (sleepygrass) provided by two Epichloë endophyte species

“…However, Epichlo€ e species are also well renowned for producing a variety of alkaloid compounds that may be toxic to, or deter, insect herbivores (Cheplick & Faeth, 2009;Schardl et al, 2013;Panaccione et al, 2014). Direct protection against insect herbivores may be due to insecticidal compounds such as loline alkaloids Nformylloline, N-acetylnorloline, and the ergot alkaloid ergovaline or due to insect-deterring alkaloidal compounds such as peramine (Rowan et al, 1986;Potter et al, 2008;Jensen et al, 2009;Popay et al, 2009). Specific fungal alkaloid compounds from all four classes may cause delayed development and reduced mass and fecundity, which may decrease insect fitness and therefore indirectly reduce insect population sizes and densities (Braman et al, 2002;H€ arri et al, 2008;Dmitriew & Rowe, 2011;Saari et al, 2014;V elez et al, 2014).…”