When did the beetle begin to incarnate as the "red lady moon" of the angiosperm? On April 12, a new discovery was published in the top journal of botany, Nature-Botany, nanjing institute of geology and paleontology: a short-winged flower beetle, pollen and feces wrapped in a 99 million-year-old amber fossil provides direct evidence for the establishment of an ecological relationship between Cretaceous beetles eating pollen.
Figure 1. Pelretes vivificus found in Burmese amber in the middle Cretaceous period and their pollination-related adaptive features (laser confocal in green). (Courtesy photo)
Angiosperms (also known as flowering plants) dominate terrestrial ecosystems, and most angiosperms rely on pollination by insects or other animals to sustain plant populations. Pollinators of angiosperms are vital in terrestrial ecosystems, and visiting insects such as bees, butterflies, moths, beetles, and flies play an irreplaceable role. However, little is known about the origins of the insect-borne pollination pattern of angiosperms.
Cai Chenyang, a researcher at the Nanjing Institute of Geology and Paleontology of the Chinese Academy of Sciences, mentored Erik tihelka, a student at the University of Bristol, and collaborated with Dr Liqin Liqin and others to discover an extremely rare and exquisitely preserved beetle fossil in Burmese amber in the middle of the Cretaceous period through systematic collection and research of a large number of Mesozoic beetle fossils. The fossil was identified as a new genus and 1 new species of the family Brachycephalus, the Neonocene Pink Beetle.
Figure 2. Three-ditch pollen clusters preserved in Burmese amber with the neonatal pink beetle and two fossils of beetle feces composed of the same pollen (laser confocal in green). (Courtesy photo)
The neonatal pollen carapace found in amber is very similar to the living type, and has evolved characteristics in its body structure that are suitable for flower visiting and pollen feeding, such as the receptors at the end of the jaw whiskers, the soft hairs used for climbing on the ventral surface of the tarsal joint, and the soft hairs on the back of the abdomen that can carry pollen. The researchers also found many pollen and pollen clusters of higher angiosperms on and near the body of the beetle.
After polishing the amber specimens, the research team used solid microscopes, biological fluorescence microscopes and laser confocal microscopes to observe and study, and found that the beetles were surrounded by more than 100 pollen particles, and there were four pollen clusters near the beetles. These pollens are typical of the three-groove type of pollen. It has been identified as a true dicotyledonous plant, close to the pollen of plants of the suborder Asteraceae and Rosaceae.
More importantly, the researchers found for the first time two three-dimensional preserved long columnar feces composed of three-groove pollen in amber fossils, less than 2 millimeters closest to the beetle fossils. Through the comprehensive study of the shape, size and composition of fecal fossils, it is very similar to the feces of living beetles.
The above series of evidence provides direct and reliable evidence for the establishment of the ecological relationship between the mid-Cretaceous beetle eating pollen, which proves that the pollination relationship between the mid-Cretaceous beetle and the higher true dicotyledonous plant has been established to this day, revealing the diversity of the pollinator beetle of the upper angiosperm in the middle of the Cretaceous Period, and providing a key example for studying the evolution of the co-evolutionary relationship between insects and angiosperms in modern terrestrial ecosystems.
Figure 3. Beetles are ecological restorations of pollination of early higher angiosperms. (Courtesy photo)
Source: Science and Technology Daily