Steinbauer M.J.,La Trobe University |
Sinai K.M.J.,La Trobe University |
Anderson A.,Cesar Pty Ltd |
Taylor G.S.,University of Adelaide |
Horton B.M.,Office of Environment and Heritage
Austral Ecology | Year: 2015
Coteries of the meliphagid bird Manorina melanophrys are associated with a form of eucalypt defoliation and recovery called bell miner-associated dieback (BMAD). Through their defence of cooperative colony boundaries against other insectivorous birds, bell miners may foster greater abundances of lerp-forming psyllids (Hemiptera: Aphalaridae), some of which reduce the lifespan of leaves. Trophic cascades in BMAD forests need to be understood to have a complete picture of regulatory processes. We studied relationships between leaf quality, psyllid and Psyllaephagus parasitoid/hyperparasitoid abundances within the Gondwana Rainforest World Heritage Area, NSW, Australia; our focal tree species were Eucalyptus propinqua and E. biturbinata. Eucalyptus biturbinata had tougher leaves than E. propinqua; leaf toughness of both species varied with site and tree. We found a statistically significant, negative relationship between toughness (surrogate for leaf age) and foliar nitrogen content; younger leaves had higher nitrogen contents. Both bell miner abundance and foliar nitrogen were positively correlated with psyllid abundance. The abundance of Glycaspis species (the psyllid that produces lerps with the highest sugar content) was more closely correlated with foliar nitrogen content than was the abundance of all five psyllid genera combined. We identified 14 Psyllaephagus spp./morphospecies, comprising 11 primary parasitoids and three hyperparasitoids. The abundance of all Psyllaephagus combined was positively correlated with the abundance of lerps. However, psyllid parasitism was not correlated with the abundance of lerps. The abundance of the three hyperparasitoids was positively correlated with the abundance of Psyllaephagus hosts. The availability of epicormic foliage (young, morphologically juvenile leaves produced following defoliation) is likely to alter the nutritional ecology underpinning the diversity and abundance of psyllid populations. Higher quality epicormic foliage should favour populations of Glycaspis species (by enhancing nymphal survival) creating lerp hotspots that induce residency by opportunistic bell miners. The positive contribution of induced amelioration, interacting with feedbacks from parasitoids and hyperparasitoids, to BMAD requires longitudinal investigation. © 2014 Ecological Society of Australia.
Tingley R.,University of Melbourne |
Weeks A.R.,University of Melbourne |
Weeks A.R.,Cesar Pty Ltd |
Smart A.S.,University of Melbourne |
And 3 more authors.
Biological Invasions | Year: 2014
We document the successful establishment of a European newt (Lissotriton vulgaris) in south-eastern Australia, the first recorded case of a caudate species establishing beyond its native geographic range in the southern hemisphere. Field surveys in south-eastern Australia detected L. vulgaris at six sites, including four sites where the species had been detected 15 months earlier. Larvae were detected at three sites. Individuals had identical NADH dehydrogenase subunit 2 and cytb mtDNA gene sequences, and comparisons with genetic data from the species’ native range suggest that these individuals belong to the nominal subspecies L. v. vulgaris. Climatic conditions across much of southern Australia are similar to those experienced within the species’ native range, suggesting scope for substantial range expansion. Lissotriton vulgaris had been available in the Australian pet trade for decades before it was declared a ‘controlled pest animal’ in 1997, and thus the invasion documented here likely originated via the release or escape of captive animals. Lissotriton vulgaris is the sole member of an entire taxonomic order to have established in Australia, and given the potential toxicity of this species, further work is needed to delimit its current range and identify potential biodiversity impacts. © 2014, Springer International Publishing Switzerland.
Umina P.A.,University of Melbourne |
Umina P.A.,Cesar Pty Ltd |
Jenkins S.,University of Melbourne |
McColl S.,Cesar Pty Ltd |
And 2 more authors.
Insects | Year: 2015
Shifts to Integrated Pest Management (IPM) in agriculture are assisted by the identification of chemical applications that provide effective control of pests relative to broad-spectrum pesticides but have fewer negative effects on natural enemy (beneficial) groups that assist in pest control. Here, we outline a framework for identifying such applications and apply this framework to field trials involving the crop establishment phase of Australian dryland cropping systems. Several chemicals, which are not presently available to farmers in Australia, were identified as providing moderate levels of pest control and seedling protection, with the potential to be less harmful to beneficial groups including predatory mites, predatory beetles and ants. This framework highlights the challenges involved in chemically controlling pests while maintaining non-target populations when pest species are present at damaging levels. © 2015 by the authors; licensee MDPI, Basel, Switzerland.