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New Zealand Plant Protection 64 (2011): 293

Could Harmonia conformis be an important predator of Bactericera cockerelli?

N.J. Larsen, F.H. MacDonald, P.G. Connolly and G.P. Walker


The tomato-potato psyllid (TPP), Bactericera cockerelli, is a new major pest of solanaceous plants in New Zealand. Both nymphs and adults may cause damage to plants by feeding on leaves and stems, and by also transmitting a bacterial pathogen, Candidatus Liberibacter solanacearum. TPP infestations affect the quality and yield of important crops such as potatoes, tomatoes, capsicums and tamarillo. Existing natural enemies of insect pests in these crops may be important in controlling TPP, particularly in winter and spring when TPP populations are low. In confined no-choice cage tests in the laboratory, it was established that all life stages of Harmonia conformis readily eat all life stages of TPP. Harmonia conformis was tested in choice trials to assess predation of TPP when offered an alternative food source, green peach aphid (GPA), Myzus persicae. Predators were offered equal numbers of TPP and GPA, ranging from 25 to 50 per species. Larvae and adults of H. conformis ate all life stages of TPP, even when other food (GPA) was available. This study is part of a larger project, partly funded by Horticulture Australia (HAL), investigating the potential effectiveness of selected predators against TPP.

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