Patterns of respiration in Locusta migratoria nymphs when feeding

Flow-through respirometry was used to investigate patterns of respiration o f fifth-instar Locusta migratoria L. nymphs fed a chemically defined, synth etic food. Each animal was recorded for up to 2.7 h, during which they had access to food and water ad libitum, and at least one meal was taken. The s tart of feeding was coincident with a sudden and rapid rise in respiration. Both carbon dioxide (CO2) production and oxygen (O-2) consumption rose, th e traces for the two gasses showing a high degree of alignment. The end of a meal correlated with a sudden and rapid decrease in respiratory rate towa rds resting levels. When feeding was interrupted by an intra-meal pause, re spiratory rate tended to drop marginally and then stabilize, before rising rapidly upon the resumption of feeding within the meal. Maximal rates of re spiration during feeding represented a 3-4-fold increase over those at rest . Walking and climbing within the chamber were not associated with any noti ceable change in respiratory rate above baseline. When locusts were quiesce nt between feeding episodes, respiration was steady and continuous, rather than discontinuous. Possible causes for large changes in respiration during feeding are discussed.