The giant longhorn beetle is not the most outgoing of suitors. The male spends his adult life in a hole at the base of a ghaf tree, waiting for love to come along.
Instead, his late-night encounter is with the Zayed University entomologists Brigitte Howarth and Janine Tan.
Dr Howarth crawls through the thorny branches around the ghaf tree where he lives, coaxing him from his hole. She speaks with affection, as if to a pet kitten. “Come on little fellow.”
Anthracocentrus arabicus spreads his mandibles, ready for battle. When she pokes her tweezers into the hole the beetle grabs them and holds on for dear life, landing in a small plastic box.
The scientists measure him, record the GPS coordinates and place him back in the tree where he continues to wait for a mate.
It could be a long wait. The mark, release and recapture study has shown that there may be more than 10 males to every female.
“I would say it’s easily one to 10 or possibly even higher than that, and that alone will give us food for thought in terms of thinking about the life strategies and the trade-offs,” Dr Howarth says. “This is what we’re going to have to speculate on, why the species is doing this.”
The five-month study, which concludes this month, is the first time scientists have systematically tracked the movement and ecology of beetles on a weekly basis.
It is one of the first studies in the UAE to look into the life cycle of an endemic insect.
Many are unaware that the UAE is home to the world's largest beetle outside the Brazilian rainforest.
As Dr Howarth and Dr Tan move in the darkness from tree to tree, they find males lurking just a few centimetres from where they saw them a week before.
Females are altogether more elusive. The entomologists found live males in abundance, eight to 10 on every visit, but only one living female was seen this season.
“We don’t know what’s happening with these females,” Dr Tan says.
They may simply be harder to locate, but another possibility is that they have a much shorter life. The lifespan of an adult is probably two to three weeks, possibly four at most.
Females emerge from underground, mate, lay eggs and die. It would be beneficial to have several males around so she can make the most of her time.
Egg production has a large expenditure. The large male to female ratio would ensure that every female is fertilised.
For their part, the males do not waste their energy moving. They are territorial and predictable. Dr Howarth and Dr Tan find the same beetles at the same tree week after week. Dr Howarth recognises beetles at a glance and knows which tree they “belong” to.
So far, each tree has one beetle and the farthest a beetle has ventured is 30 metres.
It appears males do not move far from their underground site, but emergence has not been observed.
The male’s reluctance to move may be to conserve energy for what is truly important: procreation. Energy conservation is vital because it is believed that longhorn beetles feed only as underground larvae and emerge to the surface fully grown with enough fat to last them a lifetime.
“That may explain why they’re not leaving the release sites. If you’re a species that doesn’t feed as an adult it would pay off not to wander too far and to concentrate on your real purpose, which is to find a mate.”
But there must be some interaction because males are built to fight. The warrior beetle has evolved over millions of years of desert survival and ghaf-tree battles with male competitors.
They grow up to 12 centimetres long, have 5cm antennae, strong legs and mandibles that can draw blood. Dr Howarth has studied the nocturnal beetles for more than a decade and she has the scars to prove it.
So how are they finding mates?
“It’s not like one is just going to pop up and say, ‘hello, I’m here!’,” Dr Howarth says.
“There is a precedence in the insect world that the females don’t fly and the males are the ones who disperse themselves, but we do know that females are seen in the same places as the male and we have seen carcasses.”
The sites at the base of the tree where female carcasses have been found may be where the males and females merge.
Only two of the males were found to be active. Dr Tan found one halfway up a tree one night, the first time they’d seen movement more than a few centimetres from the release site.
Evidently, not all beetles behave the same way and this will require continuing study.
“It also brings in a lot of questions on how to manage the conservation of the species,” Dr Tan says. “What impact does that have on the fitness of the population? If a large number of them aren’t [moving far], what affect is that having?”
By midnight, the two have amassed a box of dead beetles. Carcasses and live specimens build a picture of population size, longevity, niche requirement and how the species interacts with others.
Baseline data has been collected on much of the UAE insects, but little about life cycles.
Dr Michael Gillet, a former professor at UAE University, found two dead beetles in the desert outside Al Ain in the 1990s. Dr Howarth discovered the first live specimen in 2003. Its life and times are still a mystery.
“We’re still working on baseline data for a lot of biodiversity in the UAE without knowing how destruction and fragmentation of habitats will affect some of these species,” Dr Howarth says. “What are the requirements of that species? Is that species now on the brink of extinction? Does it have an effect on other species? Would the loss of that species have a devastating effect on other species?”
Research on the beetle resumed when Dr Tan, an associate instructor at Zayed University, came from the UK where she researched the life cycle of pine weevils in the coniferous forestry industry for her PhD.
Dr Howarth brought her to the Wadi Al Towayya site where she and Dr Gillet found the first longhorn beetle, and the pair have begun to collaborate on a growing number of research projects.
Last month Dr Tan discovered the beetle at Mushrif Park in Dubai, debunking the theory that they could not inhabit irrigated ghaf plantations, where trees have shorter roots.
“Janine found something that has completely devastated one of my theories and that’s nice. This is part of what needs to happen,” Dr Howarth says.
“Having found them in an irrigated park we’re now going to be looking in far more places for evidence.”
Future studies will establish whether shorter roots affect larval habits.
On a recent Friday visit to the ghaf grove at Wadi Al Towayya, outside Al Ain city, Dr Howarth and Dr Tan introduced the beetles to families who shared their picnic space. Reaction was divided between wonder and apathy.
“Some of the families were incredibly curious and when we produced some of these beetles their eyes almost dropped out of their heads,” Dr Howarth says.
“Not everybody was impressed but there were some families that were in awe. They don’t understand the desert is living.”
The beetle’s health reflects the ecosystem, even though the extent of its role in the food web remains under study. The best ecological studies take decades.
The longhorn beetle's predators are known to include owls and gerbils, and ecological studies such as this one will establish whether it is a keystone species whose disappearance would greatly impactaffect many others.
“Where they fit in terms of food webs and food chains is quite important for the rest of the environment,” Dr Howarth says.
“I would ask that we consider more studies such as these, carried out by PhD students living in the UAE and so on, to try to capture as much as possible of the biodiversity while we still have some, because it’s rapidly declining.”
Dr Howarth insists that although a warrior beetle may not have the obviously adorable traits of a leopard or sandcat, they should be loved in their own right.
“Insects are not always terribly popular because people think they are not particularly cuddly, although I think they’re awfully cute,” she says.
“ We are so quick to make decisions about organisms and their value based on our own needs rather than others.”
azacharias@thenational.ae