Biology, host specificity and varietal preference of the lantana gall fly: lessons learnt in time

Abstract

Lantana camara L. (Verbenaceae) is a Weed of National Significance in Australia. This aggressive perennial woody shrub invades national parks, forestry, grazing lands, and riparian areas, displacing native species and reducing productivity. Effective control using mechanical or chemical means is both difficult and costly. Lantana was one of the first weeds to be targeted for classical biological control. Thirty agents were deliberately introduced to Australia, of which twenty agents, including a mite and a fungal pathogen, have become established and contribute to seasonal damage of the weed. Despite this, control of the lantana is still not adequate.
The lantana gall fly, Eutreta xanthochaeta Aldrich (Tephritidae), which aids control in Hawai’i, was field released in Australia in 1914, and again in 1971. This fly forms monothalamous galls on young shoots of lantana, significantly reducing the production of inflorescences on galled branches. Historically, difficulties mass rearing this agent resulted in only a very limited number of flies ever being released, and at only two locations in Queensland. Ultimately the agent failed to establish, and it was deemed a low priority to pursue further, as other potential agents were investigated. In 2022, E. xanthochaeta was re-imported into quarantine at the Ecosciences Precinct in Brisbane. A colony was successfully established from one female fly and five male flies, the only survivors from imported galls from Hawaii. This paper reports on the optimisation of rearing methods, biology of the lantana gall fly, and preliminary results of supplementary host specificity testing being undertaken.