Food is necessary for survival, but an East African species of ticks adapted
to survive without feeding for eight years. Not only did they live for a
total of 27 years, but they healthily reproduced long after the last male
tick died.
Julian Shepherd, associate professor of biological sciences, discovered the
longevity and reproduction abilities of the Argas brumpti after running out
of a suitable food source for the species. He received the ticks as a gift
in 1976 and decided to observe them in his lab in a habitat with stable
conditions. Little did he know the original group of ticks would survive
until the next century, with offspring alive and reproducing today.
The more commonly known species of ticks have a hard plate in their skin,
but Argas brumpti have soft and leathery skins. Besides their shells, the
biggest difference between the two are their eating patterns. A. brumpti
ticks bloat less, eat faster and eat more frequently. When Shepherd no
longer had lab rabbits, mice and rats for the ticks to feed on, the A.
brumpti’s ability to survive with longer breaks in between meals turned out
to be more significant than he first realized.
After 45 years of researching the ticks, Shepherd published his findings in
the Journal of Medical Entomology. In the paper, “Record Longevity and
Reproduction of an African Tick, Argas brumpti,” Shepherd observed the
record adaptability and survival of the tick.
“I am always enthralled by the adaptations of organisms to their environment
– in this case, a dry environment with virtually no access to water for long
periods of time and a lifestyle that must wait for very long intervals of no
food between encounters with host animals,” Shepherd said.
Shepherd was originally given six adult females, four adult males and three
nymphs of the species. The ticks fed on the lab’s rabbits, mice and rats
until 1984, when Shepherd decided to stop using the animals and no longer
had an available food source.
The ticks, however, survived without feeding until the last original male
tick died four years later, but the females continued to live for another
four years. Shepherd then reintroduced feeding to the female ticks and
discovered another surprising attribute of A. brumpti.
At least one of the original females reproduced and laid a batch of eggs.
Asexual reproduction in ticks is rare, which means the species can store
viable sperm for long durations of time. This longevity and long-term
storage of sperm is a record compared to any other tick species.
The batch of eggs contained male and female offspring, which are still alive
in 2022. Further research could be conducted on these offspring to discover
more information about A. brumpti’s survivability and ability to conserve
water and energy. These findings could be extended beyond the ticks in
Shepherd’s lab.
“Research on how organisms master such challenges can inform understanding
of how other organisms, including us, might manage similar challenges,”
Shepherd said.
However, Shepherd’s time with the species has come to an end. The ticks are
now being sent to scientists in South Africa for further research.
“I have more ideas for work with ticks, but I am now concentrating on a
separate line of research working with moths on the physiology of sperm,”
Shepherd said. “I was very glad that the South African researchers could use
the ticks.”
Reference:
Julian G Shepherd, Record Longevity and Reproduction of an African Tick,
Argas brumpti (Ixodida: Argasidae), Journal of Medical Entomology,
tjab205,
DOI: 10.1093/jme/tjab205