There praying mantis (Mantis religion), one of the most common species of the order Mantodea, is an insect “famous” for its behavior cannibal who often adopts the female, devouring the male during mating. In reality, the phenomenon does not always occur, but in approximately the 30% of pairs and it is an evolutionary adaptation that is effective especially in conditions of malnutrition and scarcity of prey. For males, getting close to females is an advantage, but also a risk: to limit the danger of being devoured due to hunger, they tend to choose well-nourished females over thinner ones, but sometimes sacrifice is necessary. Autumn is the right time to observe this phenomenon, considering that the praying mantis mates precisely in this period ensure the birth of a new generation in spring.
The biological reasons for mantis cannibalism
Although it is a very “famous” behavior, scientific field studies show that, in natural conditions on average, no more than 30% Some females cannibalize the male, but sometimes it is useful to do so. The praying mantis it does not survive the low temperatures of late autumn and before dying it reproduces. Mating is obviously the crucial moment to ensure the survival of the species and it is necessary to adopt the most effective strategies for maximum egg production, such as cannibalism.
There poor availability of prey in certain environmental conditions and the effort necessary to carry out theoogenesis (process of maturation of egg cells) push the female to look for one protein source available and “ready to use”: the best option is to use the male himself as food. On the other hand, in a certain sense, the male sacrifices himself willingly… or almost! In a cost-benefit balance, male mantises during their lifetime they can fertilize multiple females if they encounter a large number of potential partners or sacrifice themselves by fertilizing only one female, but obtaining the result that as a benefit the female who devoured them produces a greater number of eggs, thanks to the abundant meal and with a protein content coming from the male himself. In essence, he invests his life by increasing the production of eggs in the female he has fertilized: the new generation will be his children.
In our latitudes, every female, in autumn, before dying it lays eggs fertilized within aootecaa sort of cylindrical case that is fixed to walls and trunks in protected and sunny places. If you’re familiar with polyurethane foam that you spray to seal cracks, you can imagine a mantis ootheca. As soon as it is emitted by the female through particular glands, it has a consistency fluid. The fluid is worked by a rhythmic movement of the female to make it thick and frothy. In a short time, the foam dries and hardens, taking on a spongy, laminated appearance, capable of protecting the inside about 300 eggs.
How your partner eats
The female generally devours the male immediately before or during mating. The female begins to consume the male starting from the head: this strategy, although frightening in our eyes, is also a winner, given that by decapitating him it blocks the cerebral ganglion that regulates the partner’s movements. In this way, the inhibition of movements is interrupted and thus the abdominal nervous ganglia, now without brakes, uncontrollably amplify the reproductive movements in the male making mating more effective.
Cannibalism is a widespread behavior in most mantis species: for example, a study conducted on a population of Chinese mantis (Tenodera sinensis) found that males constituted 63% of the diet of adult females.
Why it is called a praying mantis: the characteristics
Mantis religion belongs to the Mantoidei, an Order that matters around 2000 species mostly tropical or in any case adapted to warm-temperate climates. Originally from Central-Southern Europe, Asia and North Africa, it was introduced into North America and Canada, and is now widespread everywhere up to 50° North latitude, where the climate becomes inhospitable for it. Despite its diffusion, since 2015, it has been included in the IUCN Red List as threatened species though at minimal risk. Mantises are absolutely insects harmless to humans and petsthey are not poisonous and can be excellent allies even in the home and garden since they feed on insects.
Let the name of the genus be Mantisboth that of the species “M. religious“, they recall something connected to the sacred: the word Mantis means prophet. These names are due to the particular posture of the forelimbs, which make the animal always appear in an attitude of prayer. In reality, these are so-called arts raptors, because they serve to grab prey: insects and sometimes even small reptiles. The stretch of the tibia and femur are particularly robust and equipped with spines and a terminal hook to hold the prey during the meal.
The body also presents another peculiarity: the praying mantis possesses a single hearing organa sort of “ear” positioned in the ventral portion of the thorax. It is a very sensitive, specialized organ and mainly picks up ultrasound between 25 and 45 kilohertz. It has been observed that some mantises are capable of making rapid deviations in flight when stimulated by ultrasonic pulses, perhaps to escape insectivorous bats that emit ultrasound.
