Effect of &lt;i&gt;Epichlo&lt;/i&gt; endophyte strains in &lt;i&gt;Lolium&lt;/i&gt; spp cultivars on Argentine stem weevil parasitism by &lt;i&gt;Microctonus hyperodae&lt;/i&gt;

Goldson, S. L.; Tomasetto, Federico; Popay, Alison J.

doi:10.30843/nzpp.2015.68.5807

Cited by 7 publications

(11 citation statements)

References 13 publications

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“…Finally the results presented here are consistent with those in earlier studies where parasitism rates was found to be higher in tetraploid L multiflorum than diploid L. perenne (Goldson et al, 2015;Goldson and Tomasetto, 2016). Should selection pressure be the underlying mechanism for this decline, we should expect its expression to be most apparent in L. perenne, this species being the most common pasture grass in New Zealand.…”

Section: Discussionsupporting

confidence: 92%

“…As a possible mechanism for this, it has been posited that the tendency for tetraploid L. multiflorum to have fewer and larger tillers may offer less opportunity to behavioral-based escape responses by the weevil (Tomasetto et al, 2017b). Such behaviourallymediated resistance to M. hyperodae by ASW was originally suggested by Goldson et al (2015) based on the observation that the weevils tended to move off the foliage toward the soil when parasitoids were introduced (Gerard, 2000). It is further hypothesized that this sort of response has become enhanced through consistent parasitoid selection pressure and is under investigation elsewhere.…”

Section: Discussionmentioning

confidence: 99%

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Biological Control Success of a Pasture Pest: Has Its Parasitoid Lost Its Functional Mojo?

et al. 2018

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Sustainable and integrated pest management often involves insect parasitoids. However, the effectiveness of parasitoids biocontrol has often failed, frequently for obscure reasons. A parasitoid's success is partly due to its behavioral response to pest density, i.e. its consumer functional response. For many years in New Zealand, a braconid parasitoid, Microctonus hyperodae successfully suppressed a severe ryegrass weevil pest, Listronotus bonariensis. However, there is now evidence that this has severely declined, but that the extent of decline can depend on the pasture species. Here, we tested whether the current functional responses of M. hyperodae to L. bonarensis in two of the most common New Zealand pasture grasses (Lolium multiflorum and L. perenne) reflect observed differences in field parasitism and whether this functional response has changed over time. Our analysis involved data from 1993 and 2018. We found a type I functional response in L. multiflorum in both years, but the slope of the relationship declined over time. There was no evidence for any type of functional response in L. perenne. This lack of response in L. perenne coincided with consistently found lower parasitism rates on this host plant than in L. multiflorum; both in the field and laboratory. Here, we found that apparently declining searching efficiency was correlated with the decline in parasitism. This observation supports the hypothesis that parasitism decline could be the result of evolution of resistance based on enhanced evasive behavior by L. bonariensis.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Biological Control Success of a Pasture Pest: Has Its Parasitoid Lost Its Functional Mojo?

et al. 2018

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“…Depending on the strain they also reduce the impacts of other ryegrass pests such as black beetle, Heteronychus arator (Fabricius), and the root aphid Aploneura lentisci (Passerini) (Popay & Thom, ). In New Zealand a parasitoid has also been introduced to control ASW, but endophyte appears to have little impact on parasitism levels (Goldson et al., ). Thus, the two pest management mechanisms conjointly assist with reducing the economic impact of this insect pest.…”

Section: Discussionmentioning

confidence: 99%

Impact of Epichloë endophytes on adult Argentine stem weevil damage to perennial ryegrass seedlings

Ruppert

Matthew

McKenzie

et al. 2017

Entomologia Exp Applicata

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In New Zealand, the fungal endophyte Epichlo€ e festucae var. lolii Latch, Christensen & Samuels (Hypocreales) is widely used to enhance productivity and survival of mature perennial ryegrass, Lolium perenne L. (Poaceae) plants. These endophytes produce alkaloids that reduce damage by insect pests, such as Argentine stem weevil (ASW), Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae). However, knowledge of the effect of these fungi on seedlings is limited. High concentrations of grass-endophyte-derived alkaloids occur in endophyte-infected seed and can be translocated into seedlings to provide early protection from insect herbivory. A glasshouse experiment was conducted in which adult ASW were given a choice between perennial ryegrass cultivar 'One50' without endophyte (Nil) or containing endophyte strains AR1, AR37, or NZ CT , and cv. 'Trojan' containing strain NEA2, in three post-sowing time periods. ASW feeding damage was assessed together with plant survival and dry weight production. Plant survival and dry matter production was reduced in all treatments with mortality highest in endophyte-free and AR37 treatments, especially in the first and second time period. Strongest adult ASW deterrence occurred on seedlings infected with endophyte strains that produce peramine (AR1, NZ CT , and NEA2). Strain NZ CT was virtually undamaged in the third time period whereas damage initially increased in AR1 and NEA2 up until day 50-53 post-sowing and then declined. Endophyte-free and AR37 treatments were significantly more damaged than AR1, NZ CT , and NEA2. This research indicated there is a period of seedling vulnerability to adult ASW attack during germination, even for strains producing peramine. Possible explanations for these results are discussed.

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“…This study has highlighted an effect on L. bonariensis parasitoidavoidance behaviour and parasitism rates based on the influence of tetraploidy in L. multiflorum such as Tama. Unlike the other grasses, there was minimal weevil parasitoid-avoidance behaviour and no parasitism decline (e.g., Goldson et al, 2015;Goldson and Tomasetto, 2016;Tomasetto et al, 2017a). Conversely, reduced parasitism rates have indeed been found in diploid L. multiflorum to a similar extent to that found in both diploid and tetraploid L. perenne (Goldson and Tomasetto, 2016;Tomasetto et al, 2017b).…”

Section: Varying Effects Of Ploidy On Parasitism Ratesmentioning

confidence: 99%

Plant-Mediated Behavioural Avoidance of a Weevil Towards Its Biological Control Agent

et al. 2022

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New Zealand pastures largely comprising Lolium ryegrass species (Poales: Poaceae) are worth $19.6B and are subject to major pest impacts. A very severe pest is the Argentine stem weevil Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae). This has been previously suppressed by the importation biological control agent, Microctonus hyperodae Loan (Hymenoptera: Braconidae). However, this suppression has recently declined and is subject to investigation. It has been hypothesised that grass type influences the parasitism avoidance behaviour by the weevil and thus parasitism rates. This study explored the hypothesis using three common pasture grasses: a diploid Lolium perenne x Lolium multiflorum hybrid ryegrass (cv. Manawa), a tetraploid Italian ryegrass L. multiflorum Lam. (cv. Tama), and a diploid perennial ryegrass L. perenne L. (cv. Samson). The described laboratory-based microcosm methodology determined the extent of weevil avoidance behaviour on each of these three grasses when subjected to the parasitoid. Such reaction was gauged by the extent of reduced weevil on-plant presence and feeding compared to the control populations. In the absence of the parasitoid, the hybrid cv. Manawa ryegrass is as highly favoured by the weevil as the tetraploid cv. Tama. On diploid cv. Samson, feeding is considerably less. In the presence of the parasitoid, weevils on the tetraploid cv. Tama plants showed little avoidance activity in response to the parasitoid and it can be argued that the benefits of staying on this plant outweighed the possibility of parasitism. Conversely and surprisingly, in the parasitoid’s presence, weevils on diploid cv. Manawa showed very strong avoidance behaviour leading to levels of exposure similar to those found on the less-preferred diploid cv. Samson. These findings reflect how weevil parasitism rates have declined in most Lolium grasses, particularly diploids, since the 1990s, but not in the tetraploid L. multiflorum. This contribution supports the hypothesis that the decline in weevil parasitism rates has been the result of rapid evolution arising from parasitoid-induced selection pressure and the countervailing effect of the nutritional quality of the host plants.

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Effect of <i>Epichlo</i> endophyte strains in <i>Lolium</i> spp cultivars on Argentine stem weevil parasitism by <i>Microctonus hyperodae</i>

Cited by 7 publications

References 13 publications

Biological Control Success of a Pasture Pest: Has Its Parasitoid Lost Its Functional Mojo?

Biological Control Success of a Pasture Pest: Has Its Parasitoid Lost Its Functional Mojo?

Impact of Epichloë endophytes on adult Argentine stem weevil damage to perennial ryegrass seedlings

Plant-Mediated Behavioural Avoidance of a Weevil Towards Its Biological Control Agent

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