There is fossil evidence that insects lay eggs and eat eggs in plants

200 million years of insects feed on the ecological reconstruction of eggs in the leaves Courtesy of the research group

The team of Professor Feng Zhuo, Dean of the Institute of Paleontology of Yunnan University, provides direct fossil evidence for the reproductive biology and behavior of egg-laying insects in plants during geological history, which was published online in Current Biology on November 8. This research department provides direct fossil evidence for the insect’s intraplant spawning and egg-eating behavior during geological history.

Insect insect egg-laying behavior is a very specific reproductive strategy, in which insects use specialized ovipositors to lay eggs into plant tissues such as leaves or bark. This reproductive strategy allows the eggs to be effectively protected, thereby improving the survival rate of the offspring. Due to the lack of direct evidence of solid fossils, we currently do not understand the biology and evolution of egg-laying insects in ancient plants.

Feng Zhuo’s team collected a large number of beautifully preserved plant fossils in the Upper Triassic Xujiahe Formation about 207-201 million years ago in the Sichuan Basin. Through meticulous comparative anatomical studies, Feng Zhuo’s team found a large number of solid fossils of insect eggs inside the leaves of Dorebyra. These fossilized insect eggs have an average diameter of about 200 microns and are round to oblong in shape, clinging to the inside of the upper epidermis of the leaf blade and arranged neatly between parallel veins.

They found that these fossil eggs are very similar to the structure of living insect eggs, with layered egg shells, conical egg pore processes, egg pore air chambers, egg orifices and other structures. These fossil eggs are closest to living dragonfly eggs, but the range of variation is more pronounced, suggesting that the eggs may be in a more primitive stage of evolution. The upper epidermis of the leaves of the host plant has a thicker cuticle than the lower epidermis, which is a good thermal insulation and protection against ultraviolet radiation; Between the veins are soft mesophyll tissues that facilitate insertion into the ovipositor and laying eggs. Repeated observations have verified that fossil eggs only appear in the leaves of Dorebyra. This evidence suggests that in order to achieve effective protection for future generations, insects 200 million years ago not only carried out specific screening of host plants, but also had obvious favorable choices for spawning locations.

An interesting finding is that these eggs were actually fed by egg-eating insects. These ovophilous insects use stinging mouthparts to pierce the eggshell to feed on the egg fluid, leaving feeding holes about 1-3 microns in diameter on the eggshell. Since eggs are rich in lecithin and protein, egg fluid is a very efficient way to take in nutrients. However, how to accurately find these eggs “hidden” inside the leaves requires a very special olfactory or visual nervous system.

Intra-plant spawning represents an “advanced” survival strategy, and egg feeding is also an efficient nutrient acquisition strategy, both of which are conducive to the reproduction of species. Current fossil specimens confirm that the two opposing strategies appeared in the late Triassic period more than 200 million years ago, which can be described as “the devil is one foot high, and the road is one foot high”. (Source: China Science News, Wen Caifei)

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