Anatomy of an outbreak: the biology and population dynamics of a Cardiaspina psyllid species in an endangered woodland ecosystem

Climate, resource availability and natural enemies are pivotal factors influencing population fluctuations of insects. However, the principal factors underlying insect outbreaks, particularly in natural ecosystems, are still debated and may vary between species. We assessed the role of these factors...

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Published inAgricultural and forest entomology Vol. 17; no. 3; pp. 292 - 301
Main Authors Hall, Aidan A. G, Gherlenda, Andrew N, Hasegawa, Shun, Johnson, Scott N, Cook, James M, Riegler, Markus
Format Journal Article
LanguageEnglish
Published Oxford, UK Blackwell Publishing Ltd 01.08.2015
Subjects
Animal populations
Cardiaspina
climate
defoliation
developmental stages
ecosystems
Endangered & extinct species
endangered species
Entomology
eucalypts
Eucalyptus
grey box
heat
insect outbreak
insects
leaves
natural enemies
parasitoids
population
population dynamics
Psyllidae
resource availability
summer
temperature
trees
woodlands
Australia
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Summary:Climate, resource availability and natural enemies are pivotal factors influencing population fluctuations of insects. However, the principal factors underlying insect outbreaks, particularly in natural ecosystems, are still debated and may vary between species. We assessed the role of these factors on psyllid population dynamics during the peak and decline of a Cardiaspina psyllid outbreak in a critically endangered eucalypt woodland in Australia. Initially, this involved describing the field biology and ecology of a newly reported Cardiaspina species on grey box (Eucalyptus moluccana Roxb.). Within 1 year, the psyllid completed four generations. Its biology and parasitoid complex were similar to other Cardiaspina species during outbreaks. Minimum winter temperature was a key driver of psyllid development and density. Natural enemies did not prevent or control this outbreak. The outbreak resulted in area‐wide and chronic defoliation of host trees. Resource depletion and summer heat waves impacting critical developmental stages of psyllids were the major factors responsible for the significant reduction of psyllid populations in early 2013. However, ongoing regeneration of trees in the highly fragmented woodlands may allow recolonization of new foliage and chronic infestations to continue.
Bibliography:http://dx.doi.org/10.1111/afe.12106
NSW Environmental Trust
UWS Research Partnership Project
ArticleID:AFE12106
ark:/67375/WNG-S106KK09-K
Fig. S1. Nearmap image of a section of the Plumpton Park study site in February 2014, with Cardiaspina defoliated Eucalyptus moluccana that can be differentiated from nonhost Eucalyptus.Fig. S2. Abundance of grey box Cardiaspina adults averaged across the five study sites (square-root values), scored fortnightly on yellow sticky traps; the sex ratio was 1 : 1.Fig. S3. Mean ± SE eggs laid per grey box Cardiaspina female for the winter generation revealed that there was no significant difference between study sites.Fig. S4. Mean ± SE percentage mortality of grey box Cardiaspina eggs and nymphs on Eucalyptus moluccana leaves during the survey period.Fig. S5. Leaf of Eucalyptus moluccana infested by grey box Cardiaspina with 1611 nymphs (mostly fourth instar) on both sides of the leaf.Fig. S6. Mean ± SE percentage parasitism of grey box Cardiaspina nymphs on Eucalyptus moluccana leaves during the survey period.Table S1. GenBank accession numbers for the cytb gene from three parasitoid species of the grey box Cardiaspina obtained from five study sites in the Cumberland Plain Woodland of Western Sydney.Table S2. Number and density of Eucalyptus moluccana and other Eucalyptus species in study sites.
istex:41C161B832589C42F744B5F6BDADDD037C44E73C
Blacktown City Council
ISSN:1461-9555
1461-9563
DOI:10.1111/afe.12106