Differing ectoparasite loads, sexual modes, and abundances of whiptail lizards from native and non-native habitats

We investigated ectoparasite loads between two syntopic species of whiptail lizards (Teiidae) which differ in reproductive modes and occur in native and non-native riparian forests. Tiger Whiptails (Aspidoscelis tigris) reproduce sexually and Sonoran Spotted Whiptails (A. sonorae) are an all-female parthenogenic species. Both lizards carry ectoparasites and reside in riparian habitats. Our objectives were to compare ectoparasitic mite loads between whiptail species and compare mite loads on whiptails from three habitat types; native cottonwood (Populus) forests and mesquite (Prosopis) woodlands, and non-native saltcedar (Tamarix). We quantified mite loads during dry, hot, summer months and the wetter monsoon season. We captured whiptails from trap arrays and photographed their ventral side. We calculated mite infestation by dividing the number of scales with mites present by the total number of ventral scales. Sonoran Spotted Whiptails had higher mite loads than Tiger Whiptails, but the best predictors of mite load were the type of riparian habitat and seasonality. Whiptails from native vegetation forests had six times higher mite loads compared to non-native saltcedar sites. Mites were most abundant on whiptails during cooler early summer and during humid monsoon months. Although non-native habitats had a similar microclimate to native habitats, the ectoparasite loads on lizards were much lower, perhaps related to the low abundance of lizard hosts in the non-native habitat. Our results suggest that environmental factors such as habitat and climate may be better predictors of ectoparasitism than host reproductive mode when comparing sexual and unisexual species of lizards.