Co-existence between two leaf-feeding biological control agents of Lantana camara alters their herbivory under semi-field conditions

Abstract

Interaction between two biological control agents released against Lantana camara L. (sensu lato) (Verbenaceae) was studied in replicated semi-field plots. Caged plants under semi-field conditions were inoculated with Uroplata girardi Pic (Coleoptera: Chrysomelidae) and Ophiomyia camarae Spencer (Diptera: Agromyzidae), either alone or in combination, to investigate the extent to which co-infestation of the two agents affects the reproductive capacity and growth of their host. At the end of the trial, both single and combined attacks by the two agents had no effect on stem diameter, stem height, and canopy width. However, uncaged control plants were heavily attacked by Teleonemia scrupulosa Stål (Hemiptera: Tingidae), and therefore became significantly shorter than all the caged plants in all the treatments. When confined alone, feeding damage by O. camarae resulted in higher reduction of fruit and flower biomass relative to that caused by U. girardi alone. However, when confined alone, U. girardi caused higher reductions in leaf density and fruit biomass than when combined with O. camarae. Single attack by O. camarae caused higher reduction in flower biomass than simultaneous attack by both agents. Above-ground biomass of all single and combined treatment plants were significantly lower than those of the caged control plants. Uncaged control plants exposed to heavy attack by T. scrupulosa did not produce flowers and fruits, and their above-ground biomass was significantly lower than those of caged control plants. Overall, the study showed that simultaneous attack by the two herbivores alters their herbivory, thereby affecting reproductive capacity and growth of their host.