Potential for Integrated Control of Horehound Marrubium vulgare L. by the Plume Moth Wheeleria spilodactylus (Curtis) and 2,4-D

Abstract

Marrubium vulgare is an introduced perennial herbaceous weed of pastures and natural ecosystems in southern Australia. The moth Wheeleria spilodactylus has recently been established as a biocontrol agent and is spreading widely; its larvae feed on shoots and later leaves of M. vulgare. Glasshouse experiments were carried out to examine how eggs, larvae and adult W. spilodactylus might be affected by herbicide treatment of M. vulgare and thus to determine whether the two control techniques were compatible. Survival and development of larvae was generally little affected by herbicide treatments that were sufficient to damage the weed severely. Adult moths showed large reductions in longevity and fecundity in response to loss of M. vulgare flowers as a food source. Female moths offered a choice of treated or untreated plants as oviposition sites strongly avoided herbicide-treated M. vulgare. The results justify further investigation of the combined effects of herbicide and W. spilodactylus in the management of M. vulgare infestations.