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

Abstract

The biological control of weeds requires the successful introduction and establishment of natural enemies into other regions, to reduce population densities of target species. Potential biocontrol agents are sought in the native region of target weed and should be highly specialized. The gall‐inducing fly Eutreta xanthochaeta Aldrich (Diptera: Tephritidae) is native to Mexico and has been brought into other regions of the world – such as Hawaii (USA), South Africa, and Australia – for the biological control of Lantana camara L. (Verbanaceae), although this not always proved to be successful. Here we investigate the trophic interactions of this fly species with two host plants inhabiting in sympatry, L. camara and Lippia myriocephala Schltdl. & Cham. (Verbenaceae), evaluating its preference through infestation rates, the gall distribution in the plant architecture, as well as the indirect impact upon production of inflorescences affecting the reproductive capacity of the plants. We found that the fly was not monophagous in its native range, and under natural conditions it preferred the wild host L. myriocephala in the presence of L. camara. Moreover, we found that gall formation was linked to changes in the host architecture along with the potential for reproduction, leading to increased terminal buds and a reduction in the inflorescences produced on the twigs where galls develop. Lantana camara consists of both horticultural hybrids and wild varieties resulting in unresolved taxonomic ambiguities. Hence, there may be adaptive limitations of this fly to distinct geographic races or climatic conditions in the various regions, which needs further investigation.

Biological control of weeds – Context dependency matters

“…Hernández‐López et al. (2023) investigated the use of host plants by an oligophagous gall‐inducing fly. The species is used for the control of an invasive herb of ambiguous taxonomy that includes many ornamental varieties and has become naturalized worldwide.…”