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The oviposition and movement behaviour of
Bt-resistant and Bt-susceptible Helicoverpa
armigera (Hübner) (Lepidoptera: Noctuidae)
on Bt cotton and non-Bt cotton plants
Luong, Thi Anh Tuyet
A thesis submitted for the degree of Doctor of Philosophy at
The University of Queensland in 2016
The School of Biological Sciences
Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) has caused poor yields to a range of
agricultural crops, particularly to cotton. Pesticides have been used to control this pest with serious
undesirable side effects, including the rapid development of high levels of resistance. Since 1996,
genetically modified cotton (Bt cotton) has been planted to control H. armigera in Australia.
However, it is reported that surviving larvae of all sizes can be found in fields from time to time in
all growing regions. Research has shown that the survival of these larvae on Bt cotton is not
necessarily due to physiological resistance, and behavioural resistance has been inferred. Extensive
work on various aspects of behaviour of H. armigera in Australian has been conducted; however, to
date those experiments were carried out using a Bt-susceptible H. armigera strain. Experiments in
this thesis were undertaken with both physiologically Bt-resistant and Bt-susceptible lines of H.
armigera. One might expect larvae that are susceptible to Bt to show differences in behaviour in
comparison to Bt-resistant larvae.
Oviposition choice experiements consistently showed that both Bt-resistant and Bt-susceptible
moths did not choose plants or plant parts that were less toxic in terms of Bt toxin on which to lay
eggs. There was one exception in that Bt-susceptible moths were more likely to lay eggs on squares
of Bt cotton plants than those of non-Bt cotton. As expected the mortality of Bt-susceptible H.
armigera larvae was significantly higher on structures of Bt cotton plants than on those structures of