Abdominal movements, heartbeats and gas exchange in pupae of the Colorado potato beetle, Leptinotarsa decemlineata

The rhythms of abdominal movements, heartbeats and gas exchange in the pupa e of Leptiontarsa decemlineata (Say) were recorded simultaneously using an electrolytic respirometer and infrared gas analyser, both combined with con tact thermography. Abdominal pulsations and heartbeat occurred periodically with little varian ce among individuals. The abdominal pulsations and heartbeat pauses varied individually within large limits, with the frequency of abdominal pulsation s being six to seven times lower than that of the heart pulses. A proportion of the pupae (20%) showed discontinuous gas exchange with larg e, actively ventilated CO2 bursts, whereas others (approximate to 25%) exhi bited continuous regular microcycles (flutter) with abrupt intake of air in to the tracheae before discrete microbursts of carbon dioxide. The abdomina l pulsations exerted only a minor influence on ventilation during the micro cycles. More than 90% of the bursts of abdominal movement coincided with a series o f forward directed heartbeats, but interspersed between the bouts of abdomi nal movement commonly two to three heartbeat pulses were observed that were not associated with abdominal movements. A period of abdominal movement as sociated with a heartbeat pulse was commonly initiated by one or two vigoro us strokes of abdominal rotation.