Behavior of nymphs and adults of the black-legged tick Ixodes scapularis and the lone star tick Ambylomma americanum in response to thermal stimuli

Authors: OTALORA-LUNA, FERNANDO - University Of Richmond; DICKENS, JOSEPH C. - University Of Richmond; BRINKERHOFF, JORY - University Of Richmond; Li, Andrew

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/19/2022
Publication Date: 1/26/2022
Citation: Otalora-Luna, F., Dickens, J., Brinkerhoff, J., Li, A.Y. 2022. Behavior of nymphs and adults of the black-legged tick Ixodes scapularis and the lone star tick Ambylomma americanum in response to thermal stimuli. Insects. https://doi.org/10.3390/insects13020130.
DOI: https://doi.org/10.3390/insects13020130

Interpretive Summary: The blacklegged tick and the lone star tick are among serious vector tick species that transmit pathogens that cause diseases in humans and animals in the United States. Both are three-host tick species that require one bloodmeal for each of the three parasitic developmental stages - larva, nymph, and adult. Ticks are known to use body heat and odors/breaths of humans or animals as cues to locate hosts in environment. Although substantial efforts have been made in understanding ticks' responses to chemical odors associated with hosts, little progress has been made in characterizing and understanding the roles of radiative heat associated with vertebrate hosts. Such information would help develop better personal protection measures / products to reduce the risk of tick bites and pathogen transmission. The USDA-ARS scientists collaborated with university researchers in a tick research project to characterize behavioral responses to radiative heat through carefully designed laboratory studies. The study revealed differences between the two tick species in orientation and locomotive behavior toward the heat sources. Results obtained from this study are of interest to entomologists, behavioral biologists, sensory physiologists, and researchers who work in the fields of tick repellents, personal protections, and public health.

Technical Abstract: Ticks use heat radiation emitted by warm-blooded animals to orient to potential hosts for blood-feeding. As sources of radiative heat produce convective heat as well, it is difficult to separate their effects of tick behavior. Here we study the behavior of the black-legged tick Ixodes scapularis and the lone star tick Amblyomma amercanum to sources of heat radiation representative of a human host (32º C). While speed, walking distance, displacement and linearity measured on a servosphere were unaffected by a source of the heat radiation, walking trajectories of females were aimed toward this thermal source. In a different walking bioassay, both nymphs and adults of both sexes of A. americanum, but not I. scapularis, oriented to a thermal source. We discuss our results in the context of the ecology of both tick species and their potential in tick survey and management.