title: Respiratory gas exchange in the desert flea Xenopsylla ramesis (Siphonaptera: Pulicidae): response to temperature and blood-feeding.
abstract: Xenopsylla ramesis is a flea species parasitizing gerbilline rodents in the deserts of the Middle East. This study was undertaken to determine metabolic requirements of the different developmental stages of the flea-life cycle as well as to investigate the metabolic response to temperature and starvation after blood feeding. A high resolution respirometry system was used to measure CO2 emission of fleas ranging in size from 0.166+/-0.006 mg (larvae) to 0.263+/-0.009 mg (adults). The free-living stages (larvae and adults) had significantly higher metabolic rates than the cocooned stages (pupae). CO2 emission rates of the larvae exceeded that of the adults by 2.6-fold and the pupae by 7.3 times. In the adults, both temperature and blood feeding significantly affected starvation-level metabolism. Metabolism was temperature dependent with an average Q10 of 2.57 for females and 2.55 for males over the temperature range of 10-30 degrees C. No consistent decline in thermal sensitivity at higher ambient temperatures was evident. Fleas that had a blood meal prior to starvation had significantly higher metabolic rates (0. 86 +/- 0.008 x 10(-3) ml mg(-1) h(-1)) than fleas, which were newly emerged unfed adults (0.56 +/- 0.1 x 10(-3) ml mg(-1) h(-1)). Water content also differed between fed (range approx. 67-69% body mass) and newly emerged adults (range approx. 73-75% of body mass). Feeding may stimulate some as yet undetermined physiological process that causes differential metabolic response in starving, fed and unfed fleas. Characteristics of gas exchange in desert-dwelling fleas are reflective of the off-host life style in the protected microenvironment of the host nest or burrow, rather than as a response to any type of environmental extreme.
authors.affiliation: Science Division, 100 East Normal, Truman State University, Kirksville, MO 63501, USA. Lfielden@truman.edu
authors.forename: L J
authors.initials: LJ
authors.lastname: Fielden
authors.forename: B R
authors.initials: BR
authors.lastname: Krasnov
authors.forename: I S
authors.initials: IS
authors.lastname: Khokhlova
authors.forename: M S
authors.initials: MS
authors.lastname: Arakelyan
mesh_terms: D000367:Age Factors; D000821:Animal Feed; D000818:Animals; D001769:Blood; D001835:Body Weight; D002245:Carbon Dioxide / Q000378:metabolism; D003889:Desert Climate; D005260:Female; D008297:Male; D011659:Pulmonary Gas Exchange / Q000502:physiology*; D005423:Siphonaptera / Q000254:growth & development / Q000502:physiology*; D013217:Starvation; D013696:Temperature
chemical_list: D002245:Carbon Dioxide