The environmental influences in selected vegetation microhabitats on the various life stages of Amblyomma Maculatum Koch (Acari, Ixodidae)

Abstract

Analysis of the meterological data showed a high degree of accuracy was obtained from microclimate data for predicting biological events of Amblyomma maculatum Koch. The main factor affecting developmental and survival times of A. maculatum life stages were temperature and saturation deficit (SD) related to vegetation type and release date. A. maculatum microclimate developmental temperature threshold was determined to be 9(DEGREES)C. While the critical saturation deficit (CSD) was 4mm of Hg. The activity periods for the various life stages of A. maculatum were determined from ectoparasite surveys and confined tick studies. Male activity began in April while females were not observed until mid-June. Both sexes reached their peak activity levels in mid-September. Peak larval populations on meadowlarks occurred in January while the nymphal activity was highest in February and continued through April. These activity periods allowed the immature stages, most susceptible to water stress, to avoid the high SD's, above the CSD, of the summer and early fall months. Thus, these stages are able to survive longer at higher activity levels, increasing their potential to encounter a suitable host. From this information models were developed to use as a tool to estimate the death point and activity periods of various tick species which could be used in tick control strategies. These strategies would include: (1) timing of control applications; (2) fencing to change cattle graving patterns; or modifying pasture improvement practices to include ectoparasite control.