Aphis gossypii
Jéssica K. S Pachú1*, Francynes C.O.
Macedo2, José B Malaquias3, Wesley
A. C. Godoy1, Francisco S. Ramalho4and Ricardo F. Oliveira2
1*Corresponding author: Jéssica K. S Pachú, Rua Dr
Alvim, 2227, Piracicaba, 13418-060, São Paulo, Brazil, Email:
jessikapachu@gmail.com.1Department of Entomology and Acarology, Luiz de
Queiroz College of Agriculture (ESALQ), University of São Paulo (USP),
Av. Pádua Dias 11, Piracicaba, 13418-900, São Paulo, Brazil.2Department of Plant Physiology and Biochemistry, Luiz
de Queiroz College of Agriculture (ESALQ), University of São Paulo
(USP), Av. Pádua Dias 11, Piracicaba, 13418-900, São Paulo, Brazil.3Department of Biostatistics, São Paulo State
University (UNESP), Botucatu, Brazil. 4Biological
Control Unit ⁄ Embrapa Algodão, Av. Osvaldo Cruz, 1143 Campina Grande,
Paraíba 58107-720, Brazil.
ABSTRACT Plants have developed various mechanisms to respond
specifically to each biotrophic attack. It has been shown that the
electrical signals emitted by plants are associated with herbivory
stress responses and can lead to the activation of multiple defences. 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.
KEYWORDS : biotic, response, plant, insect, interaction.