The madayaw weevil of Maragusan, Davao de Oro, and Caraga, Davao Oriental, is now among the growing number of weevils in Mindanao that are now described.
The name is derived from the Mandaya Indigenous people’s word, which means good, pleasant or beautiful that aptly describes the new weevil species and the Mandaya people of Eastern Mindanao. It is dedicated to the Mandaya of Davao Oriental for having pleasantly welcomed the efforts that contribute to environmental sustainability and regeneration in Davao region.
Flightless beetle
Much smaller than the May beetles, the most common mango-dwelling “salagubang” that kids love to play with, this tiny beetle species—Metapocyrtus (Artapocyrtus) madayaw sp., or simply madayaw weevil—is a flightless creature, which means it survives and can thrive within a restricted range.
While they may have been in existence for the longest time in parts of Eastern Mindanao, it was only discovered recently as a new species, thanks to a group of researchers who spotted the uniqueness of these amazing wingless leaf-eating beetles.
Published in the Far Eastern Entomologist, a paper authored by Dr. Analyn Anzano Cabras, Milton Norman Medina, Amy G. Ponce and Jhonnel P. Villegas described in full the madayaw weevil—a species not known to science until their recent discovery.
The weevil specimens—14 females and 5 males—were collected in two separate locations, at a forest patch near a banana plantation in Maragusan and the riparian ecosystem of Kapuka Falls in Barangay Laiwawan in the town of Carago, Davao Oriental via “opportunistic sampling.”
Declining weevil diversity
In their paper, the authors cited the diversity of plants and animals species in the Philippines. But among the taxa that recently gained momentum in discovering new species is the genus Metapocyrtus Heller, 1912 (Coleoptera: Curculionidae, Entiminae, Pachyrhynchini).
“Due to their flightless ability, this genus has a narrow and restricted biogeographic distribution,” the paper said.
According to them, known for their association with forested habitats, the denudation and fragmentation of Philippine forests may have inadvertently led to the increasing decline of weevil diversity, especially endemic ones.
They said only around 25 percent of the country’s forest cover remains, which may have caused many species to be lost to science even before taxonomists could describe them.
Moreover, they said that weevil research in the country is still in the taxonomic stage, with many species remaining undescribed and there’s very scarce information about their ecology and conservation, making species management and protection difficult.
Massive land conversion
Many forested areas in Mindanao have been converted or transformed into food-production areas, including massive plantations for agro-industrial products like rubber and cash crops, such as pineapple, palm oil and cavendish bananas.
Besides habitat loss, the use of agrochemicals to boost plant growth, increase yield and neutralize pests by operators of big plantations makes insects, bugs and beetles—particularly the flightless ones‚highly vulnerable to species extinction.
Significant discovery
Interviewed by the BusinessMirror via Messenger, Villegas described the significance of the discovery of the new species:
“This gives us scientific knowledge about a previously unknown species. It gives a glimpse of how biodiverse the Philippines is,” he said.
Moreover, Villegas, a Master of Science in Biology graduate from Ateneo de Davao University, said their discovery in slightly disturbed areas provides insights into biodiversity-friendly agriculture and tourism.
He said the discovery presents the primordial importance of underfunded insect taxonomy in the country, adding that most species become extinct even before taxonomists can describe them.
According to Villegas, given that some of the specimens they collected survived in slightly disturbed areas near a banana plantation, studying their biology may provide valuable insights into what agricultural practices, as in the case of banana plantations, would allow them to thrive in their natural habitat.
For the specimens collected in the Kapuka Falls, which is a tourist site, the researchers said they can help devise policies to maintain biodiversity and, at the same time, promote tourism development.
Newly evolved species?
For her part, Cabras, an Associate Professor at Davao Oriental State University and a Research Associate at the Philippine National Museum, believes that the new species has always been in the locality.
“We found the first specimen back in 2019. And I’m sure they have been there already for a long time. But it was only described recently because studies of weevils in the country have only intensified in the last decade,” Cabras added.
According to Cabras, the Madayaw weevil’s closest relative is Metapocyrtus (Artapocyrtus) pardalis from Butuan.
Due to geographic isolation, she believes the new population in the Davao region has evolved to become a new species, which is often the case in the Philippines when populations get isolated geographically either by mountains or waters.
Just one of many
Flightless weevils are common in the Philippines.
“There are lots of flightless weevils in the Philippines including the tribe Celeutherini, and many leaf litter weevils,” Cabras said, who is also the editor-in-chief of the Journal of Tropical Coleopterology.
“Beetles in the world comprises 400,000 species of which 8,000 are in the Philippines. They come in various sizes ranging from the size of a palm to less than 1 mm,” she said.
Unique weevil
But other than being flightless, the Madayaw weevil is unique because of its natural color and design .
“Their behavior is also unique because they fall intentionally every time there is disturbance,” she said partly in Filipino.
According to Cabras, the Madayaw weevil displays unique iridescent colors to ward off predators—its defense mechanism.
“They can also camouflage with the dead leaves and making them hard to find,” she added.
Ultimate survivors?
As the weevil species was found thriving in patches of forest near disturbed areas—such as a banana plantation, which makes use of environmentally harmful pesticides and other chemicals, and a tourism site frequented by local and foreign tourists—it only suggests that it is a hardy species that can survive anthropogenic (environmental change caused or influenced by people) threats.
“This indicates that the species may be able to tolerate certain levels of anthropogenic disturbance as long as their habitat vegetation is not eliminated,” the authors observed.
Nevertheless, the authors said a proper environmental management plan must be put in place to protect and conserve the weevil species.
Image credits: Analyn Cabras