Immune response of lizards and rodents to larval Ixodes scapularis (Acari: Ixodidae)

The house mouse (laboratory strain), Mus musculus (L.), the cotton mouse, Peromyscus gossypinus (LeConte), the broad-headed skink, Eumeces laticeps (Schneider), and the guinea pig, Cavia porcellus (L.), were successively infested five times with larvae of the blacklegged tick, Ixodes scapularis Say. Tick feeding success, engorgement weight, and subsequent molting success were measured after each infestation. A greater percentage of ticks (P less than 0.05) fed on M. musculus and E. laticeps than on P. gossypinus or C. porcellus. P. gossypinus expressed a transitory partial resistance, measured in percentage of ticks feeding, during the third infestation but showed increased tolerance during the fourth and fifth infestations. Ticks fed on E. laticeps were heavier than those fed on any other host (P less than 0.05). Those fed on M. musculus were heavier than those fed on P. gossypinus, but the difference was not statistically significant. On C. porcellus, only 1.6% of larvae from the third infestation and none thereafter engorged; weights of larvae from first and second infestations were higher (P less than 0.05) than those fed on M. musculus and P. gossypinus and lower (P less than 0.05) than those fed on E. laticeps. A greater percentage of larvae from E. latticeps and M. musculus (P less than 0.05) molted to nymphs compared with those from P. gossypinus and C. porcellus. Molting success was the same for ticks fed on P. gossypinus and on C. porcellus during the first and second infestations. M. musculus, P. gossypinus, and E. laticeps expressed no resistance (measured as percentage feeding, engorgement weight, and molting) to feeding by I. scapularis larvae after five infestations. Host serum was tested using an ELISA for detection of antibodies against I. scapularis salivary gland antigens before and after each infestation. Antibodies were detected after the second infestation and thereafter in C. porcellus, the only species to show antibodies or to express and maintain an acquired resistance to tick feeding throughout five infestations.