Assistant Professor Shuichi Yano and Kaoru Fukusei (currently Saitama Prefectural Agricultural Technology Research Center) of Kyoto University hatch when a predator with a body length of 0.5 mm continues to touch the egg with the tip of a brush, imitating the movement of attacking a tick egg. It was discovered that hatching resumed when the egg stopped and stopped touching.This research is based on Mr. Fukuse's bachelor thesis research in his fourth year.
Kaburidani are beneficial insects that prey on agricultural pests and do not bite humans.They live on plants and cannibalize with each other as soon as there is a shortage of food pests.At this time, the larvae that have just hatched from the eggs are most likely to be predated, and the larvae try to prey on the eggs as well, but the shells of the eggs are strong and roll without teeth.If the egg is aware of this attack, it should stop hatching during the attack and wait until it is safe before hatching.Therefore, it was examined whether the hatching was delayed by touching the eggs of the Kenagakaburidani.
In the experiment, a population of eggs laid in a short time was used to know that they were about to hatch.If nearly half of these eggs are used when they hatch, the remaining eggs are near hatching.Predators do not attack eggs very often.So, imitating the attack of the predator, I touched the egg that was about to hatch with a fine brush and rotated it a quarter.It took less than 4 minutes to finish rolling half of the eggs that were about to hatch, so I kept touching them every 1 minutes for 5 minutes.Then, the eggs stopped hatching while they continued to touch, and when they stopped touching, the hatching resumed, catching up with the hatching rate of the eggs that did not touch.In addition, it was confirmed by experiments that rolling alone does not cause a delay in hatching.
This result is the first example to show that arthropod eggs change the timing of hatching depending on the risk of predation.Similar bargaining may be widespread in terrestrial animals that lay sturdy eggs individually.
Paper information:[Scientific Reports] Delayed mite hatching in response to mechanical stimuli simulating egg predation attempts
