Establishment, dispersal and impact of the flower-galling mite Aceria lantanae (Acari: Trombidiformes: Eriophyidae) on Lantana camara (Verbenaceae) in South Africa

Abstract

The flower-galling mite, Aceria lantanae (Cook) (Acari: Trombidiformes: Eriophyidae), was released as a biological control agent of Lantana camara L. (Verbenaceae) in the Limpopo, Mpumalanga, Gauteng and KwaZulu-Natal provinces of South Africa, between 2007 and 2012. Flower galls were subsequently observed at several sites where the mite had not been released, providing evidence of dispersal. This study was therefore conducted to determine the establishment, seasonal performance and dispersal rate of A. lantanae in the aforementioned South African provinces and neighbouring Swaziland. The effect of A. lantanae along with the other previously-established biological control agents on inflorescence and seed production of susceptible L. camara varieties was determined by insecticide exclusion experiments in the field. Aceria lantanae became established at 58.6% of the original release sites located in the four provinces. The mite has also established widely within the geographic range of L. camara in South Africa and Swaziland, with dispersal rates of up to 40.6km per annum. Infestations of inflorescences varied substantially between sites, provinces and seasons and ranged from 2.7% to 97%. Inflorescence and seed production declined significantly by up to 97% and 94%, respectively, on untreated biological control stands compared to the insecticide-treated exclusion stands. Although A. lantanae has become widespread within the geographic range of L. camara in South Africa, different L. camara plants appeared to vary in their susceptibility to A. lantanae, suggesting that genetic differences among plants may have affected the performance of the mite. If this is true, additional mite strains will be required to control resistant varieties.