Factors influencing the biological control of Lantana camara in Australia and South Africa.

The insect species introduced into Australia and South Africa as potential biological control agents of Lantana camara (lantana) were reviewed to determine factors that may have contributed to the high proportion of candidates that failed to establish on the plant. Fourteen of the 25 candidates deliberately introduced into Australia and five of the 15 introduced into South Africa have established. A greater proportion of candidates that were collected from L. urticifolia or L. tiliifolia established in Australia and South Africa than those collected from other Lantana species. DNA studies suggest that L. urticifolia and L. tiliifolia are more closely related to L. camara than other species of Lantana and therefore a candidate’s natural host may influence its establishment on L. camara. Some preference towards different lantana phenotypes has been observed in eight species, while there appeared to be no preference towards phenotypes in three species. Climate appears to be an influencing factor in the distribution of agents with only two species in Australia and South Africa being found in all lantana regions. The remaining species have distributions ranging from very localised to more widespread. The release methods used and the numbers of individuals released may have contributed to at least five species in Australia and up to eight in South Africa not establishing. The main factors influencing the establishment of agents on lantana appear to be: (a) the identity of the plant from which the potential agent had been collected; (b) the phenotype of lantana on which it had been released; (c) the climate of the area where it had been released and; (d) the release procedures used. Future research into the biological control of L. camara should consider addressing these areas which may result in greater establishment rates of candidates and better control of lantana.