Impact of clover root weevil<i>Sitona lepidus</i>(Coleoptera: Curculionidae) larvae on herbage yield and species composition in a ryegrass‐white clover sward

Gerard, P.J.; Hackell, D. L.; Bell, N.L.

doi:10.1080/00288230709510306

Cited by 29 publications

(30 citation statements)

References 18 publications

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“…At the Northland site, clover root weevil ( Sitona obsoletus , formerly S. lepidus ) populations increased after sowing, with populations towards the end of the fourth year (191 per m 2 ) approaching damaging levels (~300 per m 2 ; Gerard, Hackell, & Bell, ). Towards the end of the fourth year, the population of root‐knot nematodes ( Meloidogyne spp.…”

Section: Resultsmentioning

confidence: 99%

High perennial ryegrass seeding rates do not negatively impact pasture sward persistence

Lee

Thom

Chapman

et al. 2017

Grass and Forage Science

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Poor persistence of perennial ryegrass swards is a common problem; however, there is a lack of long‐term studies to understand the mechanisms associated with poor persistence. This study describes an experiment to test the hypothesis that high ryegrass seeding rates (>18 kg seed per ha) reduce long‐term population persistence because of smaller plant size and poorer survival during the first year after sowing. Four cultivars, representing four functional types of perennial ryegrass, were sown at five seeding rates (equivalent to 6, 12, 18, 24 and 30 kg seed per ha) with white clover in three regions of New Zealand. Swards were monitored for 5 years. No evidence was found to indicate a lack of persistence of ryegrass‐based swards sown at higher seeding rates. During the first year, swards sown at higher seeding rates had greater herbage accumulation (except at the Waikato site), greater ryegrass tiller density and greater ryegrass content. This initial impact of high seeding rates had largely dissipated by the fourth year, resulting in swards with similar annual herbage accumulation, tiller density and botanical composition. Similarly, there were relatively few differences among cultivars for these variables. Although high seeding rates did not negatively impact sward persistence, geographical location did, with strong evidence of ryegrass population decline at the Waikato site for all treatment combinations, some decline in Northland, and stable populations in Canterbury. It is possible that productive perennial ryegrass pastures can only be sustained for 4–5 years in some situations, even when the best ryegrass technology and management practices are used.

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Section: Resultsmentioning

confidence: 99%

High perennial ryegrass seeding rates do not negatively impact pasture sward persistence

Lee

Thom

Chapman

et al. 2017

Grass and Forage Science

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“…Factors contributing to this enhanced rate of parasitism could be that M. aethiopoides releases were made in summer, allowing the parasitoid to multiply through at least one generation before diapause. The background host densities at time of release (5-19 m -2 ) were 3-30 times lower than typical L. bonariensis adult densities (Barker and Addison 1992;Barker and Addison 1994) and that more than one M. aethiopoides larva can complete development in a single host (Gerard et al 2007b).…”

Section: Discussionmentioning

confidence: 98%

“…On completion of development, the larvae emerge as prepupae and pupate in the soil and pasture litter. The parasitoid is summer active and overwinters as diapausing 1st instars (Gerard et al 2007b).…”

Section: Introductionmentioning

confidence: 99%

Field release, establishment and initial dispersal of Irish Microctonus aethiopoides in Sitona lepidus populations in northern New Zealand pastures

2011

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The clover root weevil Sitona lepidus Gyllenhal (Coleoptera: Curculionidae) became an economically important pasture pest in New Zealand shortly after it was discovered in the Waikato region in 1996. A classical biological programme was initiated and an Irish biotype of Microctonus aethiopoides Loan (Hymenoptera: Braconidae) was released at four sites in the North Island in late summer 2006. These sites in Waikato, Hawke's Bay and Manawatu (two sites) regions were monitored monthly and parasitoid establishment confirmed at all sites within four months. In the winter of 2007, parasitism exceeded 70%. A widespread North Island drought in summer 2008 had a severe impact on S. lepidus populations at the Waikato and the two Manawatu release sites, resulting in parasitism below detection levels in the following summer. However, populations recovered by autumn. Within three years at the Hawke's Bay site, M. aethiopoides appears to be suppressing S. lepidus populations and has dispersed naturally over 60 km.

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“…Although the individual CRW treatment effects are not statistically significant, the prevalence of positive effects of CRW inoculation on these particular clover populations suggests they were exhibiting a compensatory growth response to larval feeding. Compensatory nodule growth after nodule feeding by CRW larvae has been reported for white clover in field plots (Gerard et al 2007) and for Sitona hispidulus larval feeding on lucerne (Quinn & Hall 1992), but in neither case did the compensatory response lead to larger plants than weevil-free controls. Positive effects on shoot growth of larval herbivory on roots have been reported in some turf grasses (Crutchfield & Potter 1995).…”

Section: Discussionmentioning

confidence: 94%

Effect of clover root weevil larval feeding on growth of clover progenies from parents selected for tolerance in field trials

Crush

Gerard

Ouyang

et al. 2010

New Zealand Journal of Agricultural Research

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The effects of larval herbivory by clover root weevil (CRW, Sitona lepidus) on seven white clover (Trifolium repens) and two red clover (Trifolium pratense) progenies from plants showing tolerance of CRW in field trials were tested in two controlled glasshouse experiments. CRW larvae recovered from red clover plants were, on average, fewer (6.3 larvae/g root dry weight) and shorter (5.7 mm/g root dry weight) than those from white clover (16.7 larvae, 7.1 mm length).This confirmed previous findings that red clover is an inferior host for this pest. In the first experiment, progeny of four of the white clover selections for CRW tolerance showed high tolerance (shoot dry weights (2.9% to '3.1% different from their respective weevil-free controls) compared with a 13Á24% shoot weight loss for two white clover cultivars. These results confirm field trial observations that there is variation for CRW tolerance in white clover and also that CRW tolerance is hereditable in at least some populations. The second experiment, on a smaller subset of white clovers, showed little effect of CRW on either the tolerant clover selections or the cultivar controls. An index of larval feeding pressure (larval numbers)larval projected areas/root dry weight) gave much lower values for the second experiment (12Á78 mm 2 / g) than for the first (69Á102 mm 2 /g). The absence of negative effects of CRW on the cultivar controls in experiment 2 was assumed to result from low CRW feeding pressure, allowing compensatory growth responses. A small but consistent increase in shoot: root ratio in the 'CRW treatment in experiment 1 provided supporting evidence for increased allocation to shoots as a mechanism for plants to reduce the impact of root herbivory. IntroductionEvaluations of white clover (Trifolium repens) and red clover (T. pratense) cultivars and experimental lines in on-farm trials in Northland (Cooper et al. 2003) and the Waikato (Crush et al. 2004 in the presence of clover root weevil (CRW, Sitona lepidus) showed differences among plant types. Vigorous, well-adapted white clovers are more tolerant of CRW than are less vigorous or poorly adapted white clovers, and red clover is more tolerant of

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Impact of clover root weevilSitona lepidus(Coleoptera: Curculionidae) larvae on herbage yield and species composition in a ryegrass‐white clover sward

Cited by 29 publications

References 18 publications

High perennial ryegrass seeding rates do not negatively impact pasture sward persistence

High perennial ryegrass seeding rates do not negatively impact pasture sward persistence

Field release, establishment and initial dispersal of Irish Microctonus aethiopoides in Sitona lepidus populations in northern New Zealand pastures

Effect of clover root weevil larval feeding on growth of clover progenies from parents selected for tolerance in field trials

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