Egg hatching success is significantly influenced by the time of thermal stress in multiple hard tick species

Abstract

Worldwide, ticks are blood-feeding arthropods responsible for the transmission of disease-causing pathogens to a wide range of vertebrate hosts, including livestock and humans. Tick-borne diseases have been implicated in significant economic losses to livestock production, and this threat will increase as these obligate parasites widen their geographical ranges. Just like in other ectotherms, thermal stress due to changing global temperatures has been shown to influence tick survival and distribution. However, the influence of extreme temperatures in ticks focused on advanced, mobile stages, ignoring stages that are immobile and cannot move to more favorable microhabitats. In this study, low- and high-temperature regimens were assessed in relation to egg viability for hard tick species. Tick eggs exposed early in development were significantly more susceptible to thermal stress when compared with those exposed later in development. In our tested models, treatment was more important for egg hatching than species differences. Lastly, there was evidence of extreme thermal exposure significantly altering the hatching times of tick eggs for specific treatments. These results provide insights into the critical period for tick egg viability and potential tick control strategies as the globe continues to experience climate change.

Developmental stage and level of submersion in water impact the viability of lone star and winter tick eggs during flooding

“…As previously seen with thermal tolerance (Ajayi et al, 2024), the developmental stage of the egg had a major effect on survival after water submersion. Submersion in water was detrimental even after a single day.…”

“…This is critical as disturbing egg clusters reduces viability (Benoit et al, 2007; Yoder et al, 2012; Ramos et al, 2013). Furthermore, the egg stage, whether early or late in development, is important to stress tolerance (Ajayi et al, 2024), which was not previously examined in relation to water submersion.…”

“…As tick eggs, specifically when in clusters, float on the surface of the water, we measured viability of partially submerged (floating on the surface) egg clusters compared to those that are fully submerged in water. Furthermore, we have recently established that stress tolerance in tick eggs is dependent on the process of embryo and larval development within the eggs (Ajayi et al, 2024). As such, we determined whether or not the developmental stage of the tick eggs has a direct impact on egg survival in relation to water submersion.…”