Electrical signalling on Bt and non-Bt cotton plants under stress by
Aphis gossypii
Abstract
Bt cotton is a genetically modified pest-resistant plant that produces
an insecticide from Bacillus thuringiensis (Bt) to control Lepidopteran
species. Surprisingly, there is no study – yet, that characterizes the
signalling mechanisms in transgenic cotton plants attacked by non-target
insects, such as aphids. In this study, we characterized the production
of electrical signals on Bt and non-Bt cotton plants infested with Aphis
gossypii and, in addition, we characterized the dispersal behaviour of
aphids to correlate this behaviour to plant signalling responses.
Electrical signalling of the plants was recorded with an extracellular
measurement technique. Impressively, our results showed that both Bt and
non-Bt cotton cultivars, when attacked by A. gossypii, emitted potential
variation-type electrical signals and clearly showed the presence of
distinct responses regarding their perception and the behaviour of
aphids, with evidence of delay, in terms of signal amount, and almost
twice the amount of Cry1F protein was observed on Bt cotton plants at
the highest density of insects/plant. We present in our article some
hypotheses that are based on plant physiology and insect behaviour to
explain the responses found on Bt cotton plants under aphid stress