Kunzea ericoides

Abstract: Three different species of Myrtaceae growing in Australia and New Zealand are known as 'Tea-tree': the Australian Tea tree (Melaleuca alternifolia), the New Zealand Manuka (Leptospermum scoparium) and Kanuka (Kunzea ericoides). All three essential oils are used by aromatherapists, although only Melaleuca has been tested for toxicity, and its antimicrobial effects studied. The pharmacology and antimicrobial activity of the three 'tea-tree' oils was determined using guinea-pig ileum, skeletal muscle (chick biventer muscle and the rat phrenic nerve diaphragm) and also rat uterus in vitro. Differences were shown between the three essential oils in their action on smooth muscle: Manuka had a spasmolytic action, while Kanuka and Melaleuca had an initial spasmogenic action. Using the diaphragm, Manuka and Melaleuca decreased the tension and caused a delayed contracture; Kanuka had no activity at the same concentration. The action on chick biventer muscle was, however, similar for all three oils, as was the action on the uterus, where they caused a decrease in the force of the spontaneous contractions. The latter action suggests caution in the use of these essential oils during childbirth, as cessation of contractions could put the baby, and mother, at risk. The comparative antimicrobial activity showed greater differences between different samples of Manuka and Kanuka than Melaleuca samples. The antifungal activity of Kanuka was inversely proportional to its strong antibacterial activity, whilst Manuka displayed a stronger antifungal effect, though not as potent as Melaleuca. The antioxidant activity of Manuka samples was more consistent than that of Kanuka, while Melaleuca showed no activity. The variability in the Manuka and Kanuka essential oils suggests caution in their usage, as does the fact that the oils have not been tested for toxicity.

Abstract: The essential oils of seven Myrtaceae species were investigated for its chemical composition and antibacterial activity. The volatile oils were characterized by a high content of monoterpenoids of which 1,8-cineole (88.0, 65.0 and 77.0% for Melaleuca hypericifolia, Callistemon viminalis and Callistemon citrinus respectively), terpinen-4-ol (47.0 and 49.8% for Melaleuca thymifolia and Callistemon polandii respectively) and α-pinene (54.5% for Kunzea ericoides) were the major components. The oil from M. linariifolia was characterized by a high concentration of methyleugenol (87.2%). The oil from Melaleuca thymifolia was the most active, exhibiting high antimicrobial activity against all tested bacteria.

Abstract: Summary • Pisolithus is a common ectomycorrhizal (EcM) associate of prostrate kanuka Kunzea ericoides var. microflora (Myrtaceae) in New Zealand geothermal areas. Here, we report the genetic diversity and phylogeny of Pisolithus and interpret the results in relation to the origin of this fungus in New Zealand. • We determined the genetic variation of Pisolithus on the basis of ITS gene sequences and spore morphology. • We identified three Pisolithus species in New Zealand, each matching Australian species associated with eucalypts and acacias. All three species co-occurred locally in thermal areas, with two species sometimes colonizing root tips in the same soil volume, indicating co-occurrence of species on a smaller scale. • We propose that Pisolithus fungi were introduced to New Zealand from Australia by trans-Tasman airflow during recent geological times. The success of this long-distance dispersal of EcM fungi may be related to the capacity of kanuka to act as a ‘nurse plant’ for wind-blown spores.

Abstract: The Canterbury Plains in the eastern South Island is one of the most modified regions of New Zealand with less than 2% of indigenous vegetation cover remaining. The critically endangered ground beetle Holcaspis brevicula Butcher, a local endemic known only from a small area in that region, is thought to be threatened by the loss and fragmentation of the formerly widespread forest and shrubland habitat. Previously, only the two type specimens, both male, were known to science. From 2000-2005, we conducted a survey for H. brevicula, using pitfall traps and active searching, in four of the largest remnants of the once extensive low forest and shrubland of kanuka, Kunzea ericoides, each covering less than 20 ha. In addition we conducted extensive trapping in an adjacent 7000 ha plantation forest of exotic Pinus radiata, in grassland and pasture areas, exotic shrubland, and in the nearest mountain beech (Nothofagus solandri var. cliffortioides) forest in the foothills of the Southern Alps. A total of 8658 carabids representing 47 species were collected over 57 494 trap-days, including five specimens of H. brevicula, all found in the pine plantation. A search of all major New Zealand collections for this species revealed three additional specimens, bringing the overall total of known specimens to ten, all of which were collected in this plantation forest. We propose that the exotic plantation forest inadvertently provides an important substitute habitat for this forest carabid, whereas the few small and fragmented native kanuka remnants appear to be insufficient to maintain populations of this species.