BIONICS

Gryllus Campestris bioacoustic research

What is known


Gryllus campestris or the field cricket


Animalia - Artropode - Hexapoda - Insecta - Ortopter - Grullidae


Grillus campestris, also known as the field cricket, can be found in Central, Southern and Western Europe, Western Asia and Northern Africa. As a habitat, it prefers south oriented pastures. Taxonomies can be found on many websites, as well as in specialized literature. We will briefly present a few pieces of information about this species. There are about 900 species of crickets. According to studies, in Romania there are 9 species. In terms of food, they are necrophagous and omnivorous organisms. They feed with organic, as well as decomposing materia, vegetable materia, mushrooms, plants and some saplings. Furthermore, during the fights that take place between them, the wounded or dead ones are eaten. In terrariums, great numbers lead to cannibalism especially when lacking protein based foods. Reproduction takes place between May and June. The field cricket builds a tunnel of about 20 cm in length, and 1,2-1,5 cm in diameter. At the entrance, it creates a terrace which is cleaned of any vegetation. This terrace is the place where he sings. They live in colonies consisting of up to tens of individuals. Studies have shown that field crickets have 4 songs, which consist of trains of impulses on frequencies of 4,9 kHz. In 1897, Amos Dolbear in an article entitles „The cricket as a thermometer” wrote of the presence of a link between temperature and the number of chirps (impulses). It is not exact, as it depends on other parameters as well, but it approximates temperature fairly well. Dolbear expressed in the following relation his formula, which offers a way to estimate TF, the temperature in degrees Fahrenheit, from the number of chirps per minute N:

This formula has a precision of approximately 1 degree when it is applied to the song of the field cricket. The counting can be accelerated by simplifying the formula and the number of chirps produced in 15 seconds( N’) as follows:


To offer the temperature in degrees Celsius, the formula becomes:


Studies made in the bioacoustic field have observed frequency, sound intensity (approximately 74dB at a distance of 74dB), the way that females locate the source and the parameters from the song that attract her. Studies refered to circadian cicles, behavioral and anatomical habitat have been made. Despite all these studies, in 2011 new information has been found regarding the way that male crickets take care of the attracted females. The way that crickets hear is very interesting. They have their ears situated on the front legs, in addition to the two spiracle tubes with a role in hearing.

When it sings, the cricket rubs together his wings, which have a different structure one from the other, generating that specific song. It’s song is amazingly similar to the echolocator’s signal, or that of the radar. In the animal kingdom, similar forms of signal have been found at dolphins and bats.

 


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