Oxygen consumption of engorged nymphs and unfed adults of Hyalomma asiaticum ticks (Acari: Ixodidae) exposed to various photoperiods.

The oxygen consumption of engorged nymphs of Hyalomma asiaticum was measured at various intervals after drop-off from mice hosts. Duration of nymphal development to the emergence of adults was 25-32 days at 25 degrees C. The oxygen consumption was high immediately after completing the blood meal (193-248 mm3 g-1 h-1 but decreased significantly 18 days later (at 25 degrees C) to 45-65 mm3 g-1 h-1. It increased again before ecdysis (81-102 mm3 g-1 h-1, and also after ecdysis in freshly moulted adults (177-220 mm3 g-1 h-1. The oxygen consumption in 8-month-old adult ticks was very variable ranging from 40-42 to 172 mm3 g-1 h-1. Neither engorged nymphs nor unfed adult ticks showed any dependence of their respiratory metabolism on the photoperiodic regimes tested (LD 20:4 and LD 12:12, with or without transfer to an alternative photoperiod after engorgement of nymphs).