Response to clover root weevil outbreaks in South Canterbury, Otago and Southland; the agricultural sector and government working together

Abstract

<jats:p>Clover root weevil was first discovered in the northern South Island in 2006, and an introduced biocontrol agent the parasitoid wasp Microctonus aethiopoides, was immediately released there in response. As the weevil spread southwards, ongoing releases and natural parasitoid dispersal generally supressed it to economically tolerable levels. However, mild winters in the southern South Island during 2013 and 2014 allowed weevil populations to grow and spread quicker than the parasitoid. This severely impacted white clover production and farm profitability in parts of South Canterbury, Otago and Southland, thus, scientists and industry conducted 18 months of intensive parasitoid releases of ca. 1.1 million parasitised weevils at 6000 sites. The parasitoid rapidly established at all 50 monitored release sites and dispersed from them. The biocontrol agent now occurs at all locations in South Canterbury, Otago, Southland, and elsewhere in New Zealand, where clover root weevil is present. Keywords: biological control, pest spread, parasitic wasp, Sitona obsoletus, Microctonus aethiopoides, South Canterbury, Southland, Otago</jats:p>

Olfactory Receptor Neurons for Plant Volatiles and Pheromone Compounds in the Lucerne Weevil, Sitona discoideus

“…It has a strong preference for white clover (Trifolium repens L.) (Crush et al 2010;Murray and Clements 1994), but elsewhere has also been reported as a pest of red clover (T. pratense L.) (Murray et al 2007). The weevil is now widely established across New Zealand (Hardwick et al 2016). Both S. discoideus and S. obsoletus commence egg laying in autumn (March) in New Zealand which continues through winter into early spring (November).…”