Differences between sun and shade habitats on the invasive shrub Lantana camara and its biocontrol agent Teleonemia scrupulosa

Abstract

The sap-sucking lace bug, Teleonemia scrupulosa (Hemiptera: Tingidae), was released as a biocontrol agent against the invasive shrub Lantana camara (Verbenaceae) in South Africa in 1961. Like many agents released against the weed in South Africa, success has been varied, largely attributed to the sheer number of L. camara varieties involved and the habitat types they invade. This study assessed the effects of L. camara variety (floral colour) and light microhabitat (sun/shade) on the preference, proliferation and feeding damage of T. scrupulosa. Using a cage choice test, varietal preference of T. scrupulosa between two of the most abundant (invasive) L. camara varieties (pink and orange) was assessed under both shaded and well-lit conditions. Secondly, the effect of T. scrupulosa chlorotic feeding damage on leaf physiology was evaluated. Results indicated that T. scrupulosa preferred the orange flower variety in high light environments but did not proliferate on either variety in the shade. At approximately 20% herbivory damage, photosynthesis declined by 90%, which was primarily attributed to the rapid increase in stomatal resistance. These results indicate that microhabitat, particularly sunlight intensity, is more important than L. camara variety to T. scrupulosa host preference. Mass release strategies should therefore consider microhabitat, prioritising releases on plants in open sunny locations to encourage agent persistence and proliferation.