TOKYO -- An aphid native to Japan uses fluid from its own body to seal up holes in its nest, according to findings by a team of researchers from the National Institute of Advanced Industrial Science and Technology (AIST) and others published on April 16.
The aphids, Nipponaphis monzeni, manipulate the tissues of a host plant to create a microhabitat known as a gall. The insects, each measuring 0.5 millimeters long, live collectively inside the gall, which can function as a food source, as protection from predators, and as a nest. From the outside it looks like an irregular or heavily altered area on a plant's exterior.
The team behind the research says around 100 aphid larvae working together can use the liquid to close a 2-millimeter-square hole in the structure within 30 minutes. The findings were published in the U.S.-based National Academy of Sciences (NAS) electronic journal Proceedings of the National Academy of Sciences (PNAS) on April 16.
Of the approximately 5,000 types of known aphid, some 80 of them including the Nipponaphis monzeni live in social insect colonies with defined roles in reproduction, defense and others. They make their galls on the evergreen tree Distylium racemosum, which is found in Japan from the southwest in Kyushu to the east in the Kanto region. If the gall is breached by a threat, like a moth grub, aphid soldier larvae excrete fluid with a high coagulant factor from their bodies to then stop up the hole.
Analyzed on a molecular level, the melanin produced by the aphids contains tyrosine, enzymes necessary for melanin synthesis, and large amounts of a protein thought to be specific to the aphids. The fluid it secretes is highly concentrated with lipids. Once ejected the lipids congeal together and re-cover the hole. Proteins then bond in the process of melanin synthesis to harden into a crust, completing the rebuilding process.
The fluid is also used to heal wounds sustained on their bodies. However, if a larva releases too much of the multipurpose gunk, it ceases to grow and dies. AIST senior researcher Mayako Kutsukake, a member of the team behind the discovery, told the Mainichi Shimbun her plans for the future of the study. "There are still lots of things we don't know about the abilities of insects like the soldier aphid because they're difficult to rear in a lab. We next want to investigate how they store the tyrosine and other elements used to create a crust."
(Japanese original by Ai Oba, Science & Environment News Department)