Impact of biocontrol agents on Lantana camara in an inland area of South Africa

Abstract

Lantana camara L. (Verbenaceae) is a weed of significant concern in many tropical and subtropical countries. This work aimed to quantify the combined impact of the established suite of lantana biocontrol agents on plant growth under field conditions in an inland area with a continental climate in South Africa. An insecticidal exclusion method was employed to compare plant growth parameters and agent damage between exclusion plants and biocontrol plants. Despite failing to maintain exclusion plants completely biocontrol agent-free, leaf damage was 44% greater, and side-stem production 16% less, in biocontrol compared to exclusion plants. There was a positive relationship between leaf damage and reduction in side-stem production over the study period. Overall, insecticidal exclusion, though only partially effective, showed that the established suite of lantana biocontrol agents is having a measurable growthinhibitory impact on the target weed. Keywords Agent damage Á Carbofuran Á Insecticidal exclusion Á Invasive alien plants Á Teleonemia scrupulosa Handling Editor: S. Raghu.

Effects of Carbofuran on Lantana camara and its biocontrol agent, Teleonemia scrupulosa

“…An alternative explanation would be the reduction in leaf palatability as a result of chemical application, but this aspect was not investigated in the present work. These findings corroborate field results which showed that the number of leaves, inflorescences and infructescences damaged by the suite of biocontrol agents present in a study area in Mpumalanga, South Africa, was generally greater in biocontrol compared to exclusion plants (Katembo, 2018). In another field study, carbofuran was used in an exclusion experiment at a rate of 1 g/m 2 (10% a.i.)…”

“…Carbofuran levels in L. camara leaves peaked two weeks after it was applied onto the soil, but then declined significantly afterwards. A similar trend was observed on plants obtained from a field experiment (Katembo, 2018). The current study showed a very short time effect of carbofuran on the number of leaves damaged by T. scrupulosa (Figure 3.d); nevertheless leaf damage was still significantly greater (45.9%) on the biocontrol compared to the exclusion plants throughout the study period, suggesting that even at trace levels carbofuran had a suppressing effect on T. scrupulosa feeding.…”

Unsuitability of the gall‐inducing fly Eutreta xanthochaeta for biological control of Lantana camara in presence of other native hosts in nature

“…Some authors have shown a positive relationship between leaf damage and a reduction of lateral stems (Katembo et al, 2020). However, there is scarce information of the damage caused by gall inducers on stems, even though such structures act like a sump of nutrients formerly used by the plant to generate new tissues, flowers, seeds, or fruits (Stone & Schönrogge, 2003).…”