Post-release assessment of Aphalara itadori (Hemiptera: Psyllidae) as a classical biological control agent of Fallopia japonica (Polygonaceae)
File(s)
Author(s)
Clewley, Gary
Type
Thesis
Abstract
Fallopia japonica is a damaging invasive weed that is difficult to control in the UK. In
2010, Aphalara itadori (Hemiptera), an insect herbivore native to Japan, was
released in the UK as a biocontrol agent. Classical biocontrol of weeds has a long
history across the world but this is an unprecedented type of release for the
European Union. This provided the opportunity to investigate the conditions for
establishment and the potential impacts of A. itadori under semi-natural conditions
awaiting the potential establishment of large field populations in the UK.
A meta-analysis, using global data, was carried out to see if classical biocontrol is an
effective method of weed management. Field cage trials were then used to assess
some life-history traits of A. itadori, including fecundity and longevity. Factors
influencing establishment, including rainfall, competition and the role of generalist
predators were investigated. The ability to cause damage to F. japonica is essential
for a successful programme and this was tested, both directly and indirectly
considering the performance of native plant species grown with F. japonica with and
without biocontrol. Finally, the integration of biocontrol with existing control methods
and preliminarily with another biocontrol agent, Mycosphaerella polygoni-cuspidati, a
leaf-spot pathogen was investigated.
Aphalara itadori showed the potential to be an effective biocontrol agent with the
capacity to successfully reproduce outside, with potentially two generations per year
in some areas of the UK. There were demonstrable impacts of A. itadori herbivory on
F. japonica within a single growing season. Nonetheless, there was a discrepancy
between the predicted performance from this study and what has been observed at
the open field release sites. This is possibly a result of the effect of predation on A.
itadori survival so recommendations, such as the use of protective cages, are
suggested to inform the release strategy.
2010, Aphalara itadori (Hemiptera), an insect herbivore native to Japan, was
released in the UK as a biocontrol agent. Classical biocontrol of weeds has a long
history across the world but this is an unprecedented type of release for the
European Union. This provided the opportunity to investigate the conditions for
establishment and the potential impacts of A. itadori under semi-natural conditions
awaiting the potential establishment of large field populations in the UK.
A meta-analysis, using global data, was carried out to see if classical biocontrol is an
effective method of weed management. Field cage trials were then used to assess
some life-history traits of A. itadori, including fecundity and longevity. Factors
influencing establishment, including rainfall, competition and the role of generalist
predators were investigated. The ability to cause damage to F. japonica is essential
for a successful programme and this was tested, both directly and indirectly
considering the performance of native plant species grown with F. japonica with and
without biocontrol. Finally, the integration of biocontrol with existing control methods
and preliminarily with another biocontrol agent, Mycosphaerella polygoni-cuspidati, a
leaf-spot pathogen was investigated.
Aphalara itadori showed the potential to be an effective biocontrol agent with the
capacity to successfully reproduce outside, with potentially two generations per year
in some areas of the UK. There were demonstrable impacts of A. itadori herbivory on
F. japonica within a single growing season. Nonetheless, there was a discrepancy
between the predicted performance from this study and what has been observed at
the open field release sites. This is possibly a result of the effect of predation on A.
itadori survival so recommendations, such as the use of protective cages, are
suggested to inform the release strategy.
Version
Open Access
Date Issued
2014-06
Date Awarded
2015-02
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Leather, Simon
Sponsor
Biotechnology and Biological Sciences Research Council (Great Britain)
Publisher Department
Life Sciences
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)