Effect of clover root weevil larvae on four annual forage legumes

Abstract

The effect of clover root weevil (Sitona lepidus) (CRW) larval feeding on subterranean, suckling, striated and clustered clovers was compared with white clover in a glasshouse experiment. Growth of suckling, striated, and clustered clover was significantly reduced by CRW, approaching the levels of damage recorded in white clover. N fixation in suckling and clustered clovers was also reduced. Growth and nitrogen fixation of two subterranean clovers (cv. Denmark, cv. Leura) were changed relatively little by CRW larval feeding. The relatively high level of the isoflavonoid biochaninA that was present in subterranean clover roots may explain the species' tolerance of CRW. These results suggest that CRW may not pose a major threat to dryland farming systems based on subterranean clover. Keywords: annual clover, clover root weevil, roots, Trifolium dubium, Trifolium glomeratum, Trifolium striatum, Trifolium subterraneum

Effects of clover root weevil and moisture stress on subterranean, balansa, Persian, arrowleaf and white clovers

“…The highest number of CRW larvae recovered was from white clover, confirming its status as the preferred host of CRW, and relatively few larvae were recovered from sub clover. The results confirm earlier evidence for the relative tolerance of sub clover to CRW (Hardwick 1998;Crush et al 2007). Roots of Leura sub clover contain high levels of the isoflavone biochaninA that has been implicated in the CRW tolerance of this cultivar (Crush et (Crush et al 2006).…”

“…Comparatively little research has been done on the impact of CRW on annual legumes which are important where regular moisture deficits limit persistence of white clover. Crush et al (2007) reported the effect of CRW larval feeding on roots and nodules of subterranean clover (Trifolium subterraneum), suckling clover (T. dubium), clustered clover (T. glomeratum) and striated clover (T. striatum), that are naturalised on shallow, stony lowland soils, dry north-facing hills and the inland South Island arid soils (Boswell et al 2003). Growth of suckling, striated and clustered clover was significantly reduced by CRW, approaching levels of damage recorded in white clover.…”

Clover root weevil tolerance of clover cultivars

“…Within Trifolium spp. it feeds on white clover (T. repens), red clover (T. pratense), strawberry clover (T. fragiferum), alsike clover (T. hybridum), caucasian clover (T. ambiguum), crimson clover (T. incarnatum), subterranean clover (T. subterraneum), suckling clover (T. dubium), clustered clover (T. glomeratum) and striated clover (T. striata) (Murray 1996a;Hardwick 1998;Crush et al 2007Crush et al , 2008.…”

The bionomics of an invasive speciesSitona lepidusduring its establishment in New Zealand

“…It is likely that some plant defence or tolerance attributes, present in original genotypes from European and Mediterranean countries where Sitona spp. are endemic, have been lost, resulting in the high vulnerability of New Zealand white clover cultivars to S. lepidus compared to some other clover species (Gerard et al , 2005; Crush et al , 2007). In addition, while generalist predators and pathogens cause some mortality (Willoughby et al , 1998), there has been no evidence of any density-dependent interactions, presumably because of the presence and abundance of alternative hosts.…”