Post-Moult Behaviour in the Water-Stick Insect Ranatra Linearis

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Abstract
The four hour period in Ranatra nymphs between moulting and cuticle darkening is characterized by particular foreleg movements: (i) slow opening and closing of claws (OCT); (ii) moving foreleg femur tips towards the head (B2F). Post-moult behaviour has been divided into three phases: phase 1, lasting about 25 min, claws usually closed, few OCT movements and few B2F movements occur; phase 2 with claws open and forelegs stretched out in front, lasts on average 25 min; during longer phase 3 (205 min on average) many OCT and B2F movements occur. Age does not influence the duration of phases. The number of OCT and B2F movements during phase 3 increases significantly with age. An environmental factor such as presence of potential prey can influence this behaviour. Phases 1 and 3 last longer in absence of prey items than in their presence. The rates of B2F and OCT movements during phase 3 are significantly higher in the presence of prey, for all instars. The four hour period in Ranatra nymphs between moulting and cuticle darkening is characterized by particular foreleg movements: (i) slow opening and closing of claws (OCT); (ii) moving foreleg femur tips towards the head (B2F). Post-moult behaviour has been divided into three phases: phase 1, lasting about 25 min, claws usually closed, few OCT movements and few B2F movements occur; phase 2 with claws open and forelegs stretched out in front, lasts on average 25 min; during longer phase 3 (205 min on average) many OCT and B2F movements occur. Age does not influence the duration of phases. The number of OCT and B2F movements during phase 3 increases significantly with age. An environmental factor such as presence of potential prey can influence this behaviour. Phases 1 and 3 last longer in absence of prey items than in their presence. The rates of B2F and OCT movements during phase 3 are significantly higher in the presence of prey, for all instars.