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Avila G.A.,University of Auckland | Withers T.M.,Better Border Biosecurity | Withers T.M.,New Zealand Forest Research Institute | Holwell G.I.,University of Auckland
Entomologia Experimentalis et Applicata | Year: 2016

There is a growing body of evidence that many hymenopteran parasitoids make use of olfaction as the primary mechanism to detect and locate hosts. In this study, a series of bioassays was conducted to investigate the orientation behaviour of the gum leaf skeletonizer larval parasitoid Cotesia urabae Austin & Allen (Hymenoptera: Braconidae) in both Y-tube and four-arm olfactometers. In a Y-tube olfactometer, male C. urabae were attracted only to virgin conspecific females. Host-plant leaves, damaged leaves, host larvae, and host larvae feeding on leaves were highly attractive to female C. urabae, whereas host frass and conspecific males were not. The multiple-comparison bioassay conducted in a four-arm olfactometer clearly indicates that C. urabae females were significantly more attracted to the host Uraba lugens Walker (Lepidoptera: Nolidae) larvae feeding on Eucalyptus fastigata H Deane & Maiden (Myrtaceae) leaves than to any other of the odour sources tested. The results of this study show that C. urabae individuals responded to chemical cues specific to the host plant and target host insect, and support hypotheses that unreliable cues are not utilized for host location by specific natural enemies. © 2016 The Netherlands Entomological Society. Source


Avila G.A.,University of Auckland | Withers T.M.,Better Border Biosecurity | Withers T.M.,New Zealand Forest Research Institute | Holwell G.I.,University of Auckland
Austral Entomology | Year: 2015

Retrospective host specificity testing of the recently introduced biological control agent Cotesia urabaeAustin & Allen, 1989 against Uraba lugensWalker, 1863 was conducted to assess the potential risk posed to the endemic nolid moth Celama parvitisHowes, 1917. The effect that different periods of host deprivation and prior host exposure ('experience') had on the parasitoid's readiness to attack a non-target species was examined in a sequence of consecutive no-choice tests. Even though C.urabae was observed to oviposit on C.parvitis in 91% of the no-choice tests, no parasitoids emerged from the 52% of larvae that survived to complete larval development. Host larvae that died during the laboratory rearing were dissected revealing that 63% contained a parasitoid larva, none of which had developed beyond the second instar within the larvae of C.parvitis. These results show a high level of developmental failure of C.urabae within C.parvitis, confirming that it is not a suitable physiological host. Therefore, potential negative impacts of C.urabae on C.parvitis in the wild are likely to be negligible. Significant differences were found in the attack times between parasitoids with different levels of host deprivation, with younger parasitoids taking longer to initiate attack behaviour. Also, it was observed that the lag until first attack decreased significantly after previous experience with the same host in a succession of no-choice tests. These results suggest that host deprivation and experience may play an important role in increasing the responsiveness to non-target species by C.urabae. © 2015 Australian Entomological Society. Source


Barratt B.I.P.,Agresearch Ltd. | Todd J.H.,Better Border Biosecurity | Todd J.H.,Plant and Food Research | Malone L.A.,Plant and Food Research
Biological Control | Year: 2016

Regulators often require risk assessment to ascertain biosafety of biocontrol agents before approval for release. Selecting the most informative non-target species for host range testing can be challenging. Here we compare traditional test list selection with a more objective method that selects species from a dataset of invertebrates from the receiving environment. A model, PRONTI (priority ranking of non-target invertebrates) ranks species using five criteria: hazard, exposure, potential ecological impacts from exposure, anthropocentric value and testability. For a case study, we used the braconid parasitoid Microctonus aethiopoides Loan released in New Zealand in 1982 for biocontrol of the pest weevil Sitona discoideus Gyllenhal. We compared species prioritised by PRONTI as worthy of testing with those selected prior to release. Several species which have been attacked in the field by M. aethiopoides since its release ranked highly suggesting that if PRONTI had been available pre-release, better predictions of non-target attack might have been made. The investment in time needed to adopt PRONTI needs to be balanced against its objectivity when comparing it with current conventional methods. © 2015. Source


Goldson S.L.,Better Border Biosecurity
Journal fur Verbraucherschutz und Lebensmittelsicherheit | Year: 2011

The term 'biosecurity', in New Zealand, broadly refers to the need to prevent the establishment and/or the impact of unwanted organisms in all ecosystems. The New Zealand Ministry of Agriculture and Forestry (MAF) has operational and policy responsibility for biosecurity across all of the major sectors of the economy and environment. Science is recognised as essential to advancing New Zealand's biosecurity capability beyond that which can be gained via organisational revision and optimisation. A multi-organisational research group known as 'Better Border Biosecurity' was established in 2005 specifically to provide the necessary strategic research to underpin MAF's and other 'end-users' operational and policy requirements. However, this can only work if there is a strong partnership between the contributing parties. Biosecurity in New Zealand is not without its issues. There is a varyingly asserted expectation that there should be readily available biosecurity measures that, while having no effect on trade, will work flawlessly. An unfortunate corollary of this is that the system may be thought of as having 'failed' when incursions occur or they cannot be effectively eradicated. Further, there remains an abiding issue for all in biosecurity around how to measure success in terms of incursions averted. Also, there is now community resistance to some measures taken to eradicate incursions, particularly after two (successful) aerial spraying programmes in Auckland against lymantriid moths. Care is needed to define what biosecurity covers in an international sense and New Zealand's legislative framework for biosecurity bears ongoing scrutiny if clarity of operational responsibility between MAF and the New Zealand Environmental Risk Management Authority is to continue to progress. © 2011 Bundesamt für Verbraucherschutz und Lebensmittelsicherheit (BVL). Source


Avila G.A.,University of Auckland | Withers T.M.,Better Border Biosecurity | Withers T.M.,New Zealand Forest Research Institute | Holwell G.I.,University of Auckland
BioControl | Year: 2016

The larval parasitoid Cotesia urabae Austin and Allen (Hymenoptera: Braconidae) is known to be attracted to odours of its target host Uraba lugens Walker (Lepidoptera: Nolidae), host plant (Eucalyptus species), and target plant-host complex. Cotesia urabae females were tested in both a Y-tube and four-arm olfactometer to further investigate these attractions as well as their attraction to three non-target Lepidoptera (two in the family Erebidae and one in the family Geometridae), and their corresponding host plants and plant-host complexes. In a Y-tube olfactometer, wasps were attracted to the odours of the non-target Erebidae larvae when tested on their own and when feeding on their host plants, but not to their non-target host plants alone, suggesting some rare circumstances in the field these non-targets could be attacked by C. urabae. The multiple-comparison bioassay conducted in a four-arm olfactometer indicates that target plant-host complex odours invariably produced the strongest attraction compared with any other of the non-target plant-host complex odours tested. Cotesia urabae females that were given prior exposure and the opportunity to oviposit within either non-target species were not subsequently more attracted to the Erebidae odours, suggesting that associative learning is unlikely to increase non-target attack. Such olfactometer assays could be a very useful addition to the host specificity testing methods able to be conducted within quarantine facilities, prior to the release of candidate biological control agents. We urge other biocontrol scientists to undertake similar assays to assist with non-target risk assessments. © 2016 International Organization for Biological Control (IOBC) Source

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