Observations on neurophysiological pattern and behavioural traits as death-feigning mechanism in Eucryptorrhynchus scrobiculatus (Coleoptera: Curculionidae).

In adaptation to surrounding environmental stimuli, most insects exhibit defense behaviour (death feigning) to improve survival rates in the wild. However, the underlying mechanism of death feigning remains largely unknown. Here, we test the neurophysiological pattern and behavioural traits of death-feigning mechanism in the forestry pest, Eucryptorrhynchus scrobiculatus. Using neuroanatomy, LC-MS/MS target metabolomics detection technology and qRT-PCR, we investigated the effects of neurochemicals and metabolic pathways in experimental weevils. The excision and drug tests were conducted to verify the key regulatory body parts involved in regulating the central nervous system in death feigning. Our results reconstructed the death-feigning mechanism of E. scrobiculatus: when the effective stimuli point of arousal weevil received mechanical stimulation, the thoracoabdominal ganglion transmitted signals into the brain through the ventral nerve cord, and then the brain regulated DA and 5-HT metabolic pathways, reducing the expression of dopamine (dar2), octopamine (oar1, oab2) receptor genes, finally inducing death feigning. This study suggested the variation of neurotransmitters in the brain was an important indicator to evaluate the physiological response of death feigning and provided ecological and theoretical information for future investigation to reveal key behaviour and target genes for pest control.