Behaviour and metabolism during tonic immobility (death-feigning) in Eucryptorrhynchus scrobiculatus and E. brandti (Coleoptera: Curculionidae)

• Published in: European journal of entomology Vol. 118; no. 1; pp. 322 - 329
• Main Authors: LI, Huijuan, WEN, Junbao
• Format: Journal Article
• Language: English
• Published: Ceske Budejovice Institute of Entomology 01.01.2021; Institute of Entomology, Biology Centre, Czech Academy of Science
• Subjects: Anti-predator behavior; anti-predator behaviour; coleoptera; curculionidae; death-feigning; defence strategy; Energy consumption; Environmental factors; eucryptorrhynchus; Eucryptorrhynchus scrobiculatus; Insect ecology; Insects; Laboratories; Light; Males; Mechanical properties; Mechanical stimuli; Metabolic rate; Metabolic response; Metabolism; Physiology; Sexes; Sound; Stimulation; Temperature effects; thanatosis; Tonic immobility
• ISSN: 1210-5759; 1802-8829
• DOI: 10.14411/eje.2021.033

The antipredator behaviour, tonic immobility (TI) is a valuable defence that enables insects to increase their chance of survival and is a trade-off between fl eeing and protection. How the TI strategies of insects respond to environmental factors, however, remains a largely understudied subject. In this paper the effect of four factors (mechanical stimulation, light, sound and temperature) and metabolic responses were used to evaluate TI behavioural and physiological adaptions in Eucryptorrhynchus scrobiculatus (ESCR) and Eucryptorrhynchus brandti (EBRA). In the behavioural experiment, the metaventrite, which is the stimulus-sensing region in ESCR and EBRA, was subjected to mechanical stimulation. Light lengthened the TI duration in ESCR males, while sound had the opposite effect in ESCR and EBRA. The effect of temperature on the duration of TI was variable: in ESCR, the duration was shorter at low (15°C) and high (32°C) temperatures, but in EBRA, it was longer at the low (15°C) temperature. In the metabolism experiment, ESCR and EBRA metabolic rates (MR), was significantly dependent on whether they were in a state of TI or not. The TIMR declined to 76.90% in ESCR and 71.40% in EBRA. These results indicate that TI in ESCR and EBRA differed under different external conditions and contributes to the understanding of the physiological regulation of ecological traits of insect TI.