Liquid water intake of the lone star tick, Amblyomma americanum: Implications for tick survival and management

Abstract

ixodid ticks are ectoparasites that feed exclusively on blood as their source of nutrients. Although ticks spend most of their life off the host, until now it has been assumed that the blood and the water vapor are the only sources of water to maintain water balance and prevent desiccation. Here we report for the first time that adult lone star ticks, Amblyomma americanum, also actively drink nutrientfree water, which greatly increases their survival. the volume of ingested water is greater in females than males (0.55 ± 0.06 vs 0.44 ± 0.07 µl) and most likely due to differences in tick size. Water uptake occurs through mouthparts and it can be later observed in the salivary glands and the midgut. We also exploited this behavior by adding a variety of inorganic compounds and microorganisms to water. Addition of inorganic salts to drinking water such as KH 2 po 4 + nacl+Kno 3 resulted in 100% tick mortality within 3 days. As a proof of concept for using the water drinking as a delivery route of toxic reagents for ticks, we also show that adding Pseudomonas aeruginosa to drinking water quickly leads to tick death. this tick behavior can be exploited to target important physiological systems, which would make ticks vulnerable to dehydration and microbial dysbiosis. Ticks are obligate blood feeding ectoparasites and one of the most important arthropod groups that vector pathogens to people and other animals worldwide 1-5. Hard ticks have to survive extended periods off the host (~ 90% of their lifetime) throughout their development. Therefore, tick survival is dependent on their ability to maintain water balance, as they have to overcome fluctuating environmental conditions, primarily temperature and relative humidity (RH) 6,7. Ticks maintain water balance by water vapor uptake. Water vapor uptake directly depends on the Critical Equilibrium Activity (CEA), which is the minimum RH required for water uptake and maintaining the water balance in the body 8-10. In most ixodid ticks the CEA is close to 90% RH 10 ; in Amblyomma americanum water vapor uptake is between 85% and 93% RH and accounts for up to 77% of the water taken in 11. Water vapor uptake was first reported in Amblyomma variegatum with the mouthparts as the main site of this uptake 12. It was demonstrated that the salivary glands secrete to the mouthparts a hygroscopic solution high in chlorine, potassium, and sodium 6,13 which absorbs water vapor that is then ingested by the tick 6. Off host ticks could also actively drink water to maintain water balance, whereas several studies reported no water drinking behavior in Ixodes ricinus, Dermacentor marginatus, and D. reticulatus 14-16. Our recent study demonstrated that I. scapularis can approach and touch water droplets and occasionally insert the hypostome and drink water (5% of ticks tested) 17. Drinking-like behavior was also observed for several Rhipicephalus species, Dermacentor nuttalli, Amblyomma hebraeum, and larvae of A. americanum 18-20. However, the significance of liquid water drinking in tick biolo...

Early onset of pre-lethal effects of lotilaner (Credelio®) on Amblyomma americanum ticks on experimentally infested dogs

“…The mean weight of ticks taken from control dogs did not increase significantly between 2 and 24 h post attachment. This is consistent with published literature on the early stage of tick feeding where imbibing blood and injecting saliva is approximately equivalent and overall blood intake is minimal [ 21 , 22 ]. In contrast, at 24 h post attachment ticks collected from lotilaner-treated dogs had lower mean weights than those from control dogs and lower mean weights than at 2 h post-attachment.…”

“…To our knowledge, this is the first study using EthoVision XT software to analyze tick movements post-exposure to acaricidal products. This software has been used to monitor attractant behaviors in ticks and insects and to document the responses to insecticidal products in a variety of insects [ 22 ‒ 26 ]. The software was able to accurately detect tick movement with sufficient accuracy to allow analysis of distance and velocity parameters but was inaccurate in assigning directional and angular movements.…”

The bacterial community of the lone star tick (Amblyomma americanum)

“…The majority of the bacterial taxa were representative of soil-and plantassociated bacteria. This is not surprising since A. americanum has been shown to actively ingest liquid water from the environment to recuperate the imminent water losses occurring through excretion mechanisms [37][38][39], and it this therefore likely that these bacteria were ingested along with water [10]. The soil and plant origin of the midgut bacteria was also suggested for I. ricinus [10,40].…”

Applications of Blocker Nucleic Acids and Non-Metazoan PCR Improves the Discovery of the Eukaryotic Microbiome in Ticks

“…Although the possibility of contamination from the body surface of ticks with these microbial DNA cannot be completely excluded, the body surfaces were thoroughly cleaned by washing with 10% sodium hypochlorite and 70% ethanol in the preliminary stages of DNA extraction [64]; it is likely that the origin of the detected protists was mainly internal. Ticks obtain water transdermally from water vapor when not attached to a host [65,66]; however, Amblyomma americanum feeds not only from water vapor but also from liquid water and takes up water in its salivary glands and intestinal tract [67]. The frequent detections of taxa that appear to be from the environment may indicate that other ticks also consume liquid water.…”