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New Zealand Plant Protection 66 (2013): 385

Farm-scale assessments of natural enemies for controlling Bactericera cockerelli in potatoes with Phacelia tanacetifolia as a border planting

F.H. MacDonald, G.P. Walker, P.G. Connolly and B. Hart

ABSTRACT

AS Wilcox & Sons are investigating planting Phacelia tanacetifolia (phacelia) alongside commercially grown potatoes to attract natural enemies into the crop to control Bactericera cockerelli, the tomato potato psyllid. Using the validated method of 'middle leaf ' sampling in potatoes to assess crop infestations and predator numbers, assessments were conducted from November 2012 to January 2013 in Wilcox crops at Pukekohe, Waiuku and Matamata. Insect numbers with and without phacelia plantings, and over differing distances from the phacelia, were compared. At sites with phacelia, Melanostoma fasciatum (small hover fly) numbers were significantly increased when compared to the site without, while the other common predator found on potatoes, Micromus tasmaniae (brown lacewing), was generally unaffected. The number of hover flies (eggs and larvae) at phacelia sites ranged from almost 4/middle leaf at 5 m from the planting to <1/middle leaf at 100 m away, compared with a maximum of 0.15/ middle leaf at the site with no phacelia. Phacelia tanacetifolia plantings are an important reservoir for hover flies and are likely to be a useful IPM tool in potatoes.

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