Abstract
Simple SummaryTicks use heat emitted by warm-blooded animals to orient to potential hosts for blood-feeding. Here we study the behavior of two species, the black-legged tick and the lone star tick, to sources of heat emissions representative of a human host. First, we offered a heat source to females walking on a locomotion compensator (servosphere). While speed, walking distance, displacement and linearity were unaffected by the source of heat, walking trajectories of ticks were aimed toward this thermal source. In a double-choice walking bioassay, both nymphs and adults of both sexes of the lone star tick, but not the black-legged tick, oriented to a thermal source. From a practical standpoint, a source of heat might be used in combination with other, e.g., chemical or visual, signals in strategies aimed at the survey or control of targeted tick species.Ticks use chemical and thermal signals emitted by humans and other vertebrates to locate suitable hosts for a blood meal. Here, we study the behavior of black-legged Ixodes scapularis and the lone star ticks Amblyomma americanum exposed to heat sources held at temperatures near those of vertebrate hosts (32 °C). First, we used a locomotion compensator to test behavioral responses of ticks to an infrared light emitting diode (LED). The servosphere allowed us to measure parameters such as velocity, acceleration, linearity, and orientation. Then a heating element (Peltier) located in one of the extremes of a double-choice vertical rod (flying T), was employed to observe upward movement of the ticks toward such a heat source. While both species oriented toward the LED, only lone star ticks were attracted to the Peltier element while climbing upward. In conclusion, we showed that heat attracted ticks from short distances up to several centimeters on a the servosphere, and those responses differed between the two species of ticks on the flying T. We discuss our results in the context of the ecology of both tick species and their potential in tick survey and management.
Highlights
The black-legged tick Ixodes scapularis and the lone star tick Amblyomma americanum are hard tick species (Acari: Ixodidae) that parasitize vertebrates including white-tailed deer and humans
Speed, walking distance, displacement and linearity did not differ between control, test and end-control period for either of the two tick species
The cosines of mean direction and upward straightness were affected by thermal stimulation of both ticks, an effect that remained latent during end-control (Table 1)
Summary
The black-legged tick Ixodes scapularis and the lone star tick Amblyomma americanum are hard tick species (Acari: Ixodidae) that parasitize vertebrates including white-tailed deer and humans The distribution of both species is expanding in North America with the subsequent geographic expansion of tick-transmitted epidemics [1,2,3]. The dynamics of this expansion is due mostly to climate and landscape changes produced by anthropic activities [7,8] Both the black-legged tick and the lone star tick are three-host ticks, so each parasitic stage (larva, nymph and adult) normally feeds on a different individual host in a life cycle spanning 2 to 3 years on average [9].
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