Suppression of growth and reproductive capacity of the weed Lantana camara (Verbenaceae) by Ophiomyia camarae (Diptera: Agromyzidae) and Teleonemia scrupulosa (Heteroptera: Tingidae)

Abstract

An 8-month study was conducted to determine the effect of herbivory by the herringbone leafminer Ophiomyia camarae Spencer (Diptera: Agromyzidae) and the lace bug Teleonemia scrupulosa Stål (Heteroptera: Tingidae) on growth and reproductive capacity of their host plant, Lantana camara L. (Verbenaceae). Ophiomyia camarae adults were released into field cages at two population densities while T. scrupulosa, a widespread and naturalised biocontrol agent in South Africa, colonised and attacked uncaged plants of similar size grown under similar field conditions. At lower initial density, O. camarae reduced stem height, stem diameter, leaf density, flower density and above-ground biomass by 5, 22, 54, 100 and 41%, respectively. At higher initial density of O. camarae, stem height, stem diameter, leaf density, flower density and above-ground biomass were substantially reduced by 19, 28, 73, 99 and 49%, respectively. Teleonemia scrupulosa also reduced stem height, stem diameter, leaf density, flower density and above-ground biomass by 37, 34, 75, 100 and 50%, respectively. The root development was less affected by both O. camarae and T. scrupulosa. Whilst higher densities of O. camarae exerted noticeable herbivore pressure, T. scrupulosa herbivory substantially hampered plant growth and reproductive capacity even at lower population levels. These findings suggest that O. camarae, released in 2001 for the control of lantana, would be effective as part of a complementary guild of biological control agents. The profound effect of herbivory by T. scrupulosa on plant growth and reproductive capacity suggests that it is making a much greater contribution to the biological control of lantana in South Africa than was previously thought.