Abiotic factors influencing the ecology of wild rabbit fleas in north‐eastern Spain

Abstract

During 1992, the population dynamics of rabbit fleas were compared at two sites in north-eastern Spain. The sites differed mainly in terms of annual rainfall and soil type. All flea species showed seasonal cycles of abundance, although peaks in numbers occurred at different times, reflecting their specific adaptations for coping with climatic variables. Adult Spilopsyllus cuniculi (Dale) (Siphonaptera: Pulicidae) were found largely parasitizing rabbits in spring and adult Caenopsylla laptevi (Beaucournu etal.) (Siphonaptera: Ceratophyllidae) in the autumn. In contrast, monthly flea indices of Xenopsylla cunicularis (Smit) (Siphonaptera: Pulicidae) and Echidnophaga iberica (Ribeiro et al.) (Siphonaptera: Pulicidae) peaked in summer. Spilopsyllus cuniculi was present at both sites, but was less common on the drier site, where monthly mean temperature and annual rainfall approached the flea's physiological limits. By contrast, E. iberica, X. cunicularis and C. laptevi, known to be better adapted for dryness, showed the opposite patterns of abundance. Nevertheless, even these arid-adapted species took advantage of the milder and wetter spring (X. cunicularis and E. iberica) or autumn (C. laptevi) for breeding and larval development. Although environmental temperature, rainfall and soil texture will influence the microclimate of the burrows where the flea larvae develop, burrow humidity seems to be more dependent on soil characteristics and past rainfall rather than the humidity of the external air.

Plague and Climate: Scales Matter

“…But, the underground location of most burrows implies that conditions inside these structures fluctuate only moderately [49], [50]. In fact, temperatures inside and outside burrow systems are highly correlated, but inside humidity is a complex function of past rainfall and soil characteristics [51] rather than of present ambient humidity [52]. Note that investigations on burrow micro-climate have been conducted in different parts of the world [51], [53], [54], including in plague-endemic regions, but these measurements were generally obtained from only a small number of natural or, in some instances, artificial burrows, allowing investigators to draw only tentative conclusions from the results of these studies [49], [55].…”

Interannual Variability of Human Plague Occurrence in the Western United States Explained by Tropical and North Pacific Ocean Climate Variability

“…79 In burrows, soil moisture could be a better indicator of humidity, because it affects fleas, rather than above-ground measures of humidity. 80 Contrary to air (above-ground) and burrow temperatures that exhibit strong coherent correlations, burrow humidity depends more on past rainfall and soil type than on the humidity of the air outside the burrow. 80,81 In this study, we have described how seasonal precipitation is instrumental in understanding the association between PDO/ENSO and human plague.…”

“…80 Contrary to air (above-ground) and burrow temperatures that exhibit strong coherent correlations, burrow humidity depends more on past rainfall and soil type than on the humidity of the air outside the burrow. 80,81 In this study, we have described how seasonal precipitation is instrumental in understanding the association between PDO/ENSO and human plague. Precipitation in winter and early spring mainly falls as snow in the elevated plague areas.…”

Effectiveness of habitat management in the recovery of low-density populations of wild rabbit

“…We suspect that wild rabbits avoid these slopes because they tend to be wet and cold (less sun exposure), and such environments favor litter mortality (Rödel et al 2009). In addition, according to GarciaBocanegra et al (2010), the Spilopsyllus cuniculi flea, which finds its physiological optimal conditions in wet sites (Osácar-Jimenez et al 2001), is an important disease vector in the European wild rabbit.…”