REMARKS 



Environmental Adaptability 



The xeric environment in which 0, moubata is capable of sur- 

 vival is best explained by two physiological studies by Lees (19^6A, 

 19/i-7). In his research on water balance in ticks. Lees (19A-6A) 

 found that among the species studied, _0. moubata shows the greatest 

 ability in limiting evaporation from its own body. In this species, 

 the critical temperatiire at which water loss increases through the 

 superficial waxy epicuticvilar layer is also high (Lees 19/k7). This 

 resistaince to desiccation at temperatures within its biological 

 range may be correlated broadly with the argasids* choice of dry, 

 dusty ecological niches. 



Lees summarized his 194-6A studies , in which Ixodes ricinus 

 was the principal species for research and 0. moubata was one of 

 eight other species used for comparative purposes, as follows: 



"The unfed tick gains water from humid air or from 

 water in contact with the cuticle, and loses water by 

 evaporation. Whilst attached to the host the tick is 

 gaining water from the ingested blood and losing water 

 in the excrement. The engorged tick usually lacks the 

 ability to take up water from humid air. 



"The exchange of water takes place mainly through 

 the cuticle. Reg\ilation of the water balance is there- 

 fore brought about by the activity of the epidermal 

 cells. 



'"The cuticle comprises two principal layers, the 

 epicuticle and endocuticle. The epicuticle is overlaid 

 by a lipoid possessing important waterproofing proper- 

 ties. The pore canals, which traverse the endocuticle, 

 are occupied by cytoplasm, and may in consequence play 

 an importaxit role in the active transfer of water through 

 the cuticle; they do not penetrate the epicuticle. 



"Water loss from the unfed tick is not closely re- 

 lated to saturation deficiency, particularly at high 



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