Vagility as a Liability: Risk Assessment of the Leaf-Blotching BugEucerocoris suspectus(Hemiptera: Miridae), A Prospective Biological Control Agent of the Australian TreeMelaleuca quinquenervia

Abstract

Melaleuca quinquenervia (Cav.) S.T. Blake (Myrtales: Myrtaceae) forms dense monocultures that displace native vegetation in wetlands of southern Florida, USA. Faunal studies in the tree's native Australian range revealed several prospective biological control agents, including the leaf-blotching bug, Eucerocoris suspectus Distant (Hemiptera: Miridae). This herbivore was imported into quarantine to assess risk to Florida native and ornamental species after preliminary Australian studies had indicated that it might be useful. Ornamental Melaleuca spp. suffered heavy feeding in no-choice adult feeding trials, with moderate feeding on some native Myrtaceae. Native species sustained light to heavy feeding in multichoice adult feeding trials and in a no-choice nymphal feeding trial. Feeding increased on native species in a large enclosure after M. quinquenervia was cut, allowed to dry, and then removed. Nymphs completed development only on M. quinquenervia and ornamental bottlebrushes, Melaleuca spp. However, inability to fully develop on non-target species is of limited importance as a criterion for release of insects with highly mobile immature stages as compared to less vagile species. Local movement from the host to other plant species could result in unacceptable non-target damage despite seemingly adequate developmental specificity. This insect would clearly harm native and ornamental Myrtaceae and should therefore not be released.