DESICCATION TOLERANCE OF MUELLERIUS CF. CAPILLARIS (NEMATODA, PROTOSTRONGYLIDAE) FIRST-STAGE LARVAE

Muellerius cf capillaris is the most common lung worm of wild Nubian i bex (Capra ibex nubiana) in the northern Negev desert, Israel. The cap acity of the free living stages (L1) of the parasite to survive extrem e desiccation was tested under 2 different dehydration regimes at 23 C : rapid dehydration through direct exposure to 0% relative humidity (R I-I), and a slow dehydration regime of preconditioning at 33% RH for 7 days prior to exposure to 0% RH for a further 21 days. In direct expo sures to 0% and 33% RH, by day 11 survival rates of L1 were significan tly higher than when stored in water and in 97% RH (P < 0.05). The slo w dehydration regime enhanced the survival of L1 up to 10-fold by day 28 as compared with direct exposure to 0% RI-I. The same mean numbers of larvae were recovered from the land snail Theba pisana infected wit h L1 exposed for 21 days at 33% RH and from T. pisana infected with no ndesiccated L1 (P > 0.1). LI surviving after 21 days of desiccation at 0% RH were, on the other hand, less infective to T. pisana. The perce ntage of such postdesiccated L1 reaching infective stage (L3) was, how ever, the same as that of the control group. The ability of M. cf. cap illaris LI to survive anhydrobiosis and retain infectivity to land sna ils after extreme desiccation enables their coexistence with the Nubia n ibex in desert habitat.