Ticks survive for 27 years in entomologist's lab
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."