Resistance-breaking currant-lettuce aphid biotype discovered in Australia

A new biotype of the currant-lettuce aphid (Nasonovia ribisnigri), capable of colonising Nr:0-resistant lettuce varieties, has been discovered in Victoria.  

Until recently, there was only one known biotype of currant-lettuce aphid in Australia, Nr:0. Growers have primarily controlled the aphid by using lettuce varieties containing a gene which confers resistance to this biotype.

However, following reports by consultants and growers of currant-lettuce aphid colonising Nr:0-resistant lettuce varieties, initial testing by plant breeding company, Rijk Zwaan, has confirmed the presence of a new biotype.

Currant-lettuce aphid is a pest of lettuce, endive and chicory, but is most problematic in traditional head lettuce varieties where it colonises rosettes and hearts, impacting the produce’s marketability.

The new biotype, Nr:1, cannot be distinguished visually from Nr:0. Determining the resistance status requires testing through laboratory bioassays.

cesar is working with Stuart Grigg Ag-Hort Consultanting and RMCG to identify the biotypes of further populations of currant-lettuce aphid from Victoria.   

Growers who suspect that they may have currant-lettuce aphid in their crop can contact Dr Siobhan de Little to discuss options for identification of the biotype on their properties. 

Dr Siobhan de Little, cesar

sdelittle@cesaraustralia.com

+61 3 9349 4723