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Characteristic behavior of crickets


Hitoshi Aonuma (University of Hokkaido)


1. Phonotaxis of crickets

Male cricket stridulates 3 different types of noises that are called as calling song, courtship song and aggressive song. “Calling song” is stridulated when a male is to attract female. When male notice a female approaching, it changes the stridulating pattern to “courtship song”. It continues stridulating courtship song until female accepts copulation. “Aggressive song” is stridulated when it fights toward conspecific males. During a fight, a male stridulates aggressive song for threatening the opponent, and after wining, it also stridulates aggressive song to scare away the opponent.

Male cricket generates songs by rapidly opening and closing its forewing with scraping. The sound-producing apparatus is composed by scraper and file. A scraper is comprised by specialized cuticle and the underside of the forewing has a rough surface called “file”. A scraper on the tip of the opposite forewing runs across the file to generate chirp. The sound generated by one rub of the apparatus is called a syllable. A number of syllable arrangements make up a chirp. A song is composed of a continuous series of chirps and intervals.



Fig. 1. A: Location of tympanic organs in a female cricket. The tympanic organs are located on each side at the base of the tibia in the forelimbs (arrows). B, C: Expanded views of the tympanic organs.
B shows the lateral side, and C shows the medial side. Arrows represent the tympanic organ. Scale, 1 mm. The female shows phonotaxis to the “calling song”.


2. Cricket courtship behavior

Only among vertebrates and insects have tympanic organ as a sound receptor. The male cricket stridulated calling song in order to call female as a mating partner. When the male notice a female approaching, it stridulates courtship song until the female accepts the male as a mating partner. The male turn its abdomen toward the female so that the female can climb up the male to recieve a spermatophore. Spermatophore contains sperms. In copulation, some male insects pass spermatophore to female, and the other insects put the sperm in the female body directly. All male insects of the order orthoptera pass spermatophores to females (video link
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Once the male cricket succeeds in mating, it needs to prepare another spermatophore for subsequent mating. During this preparation time, the male expresses feeding, drinking, and fighting behavior but wouldn’t express further courtship behavior for 1 hr. The interval time between 2 behavior, spermatophore protrusion and courtship stridulation, is about 1hr and is fixed. Regulation of the mating behavior periods is mediated through the action of two biogenic amines, octopamine and serotonin.


Cricket mating behavior


3. Fighting behavior of crickets

Many insects use sounds and chemicals for intraspecific communication. For example, the crickets’ calling song that we hear in the evening of autumn is the sound communication between male and female crickets. If the male notice female approaching, it starts stridulating courtship song. In this case male touches the body surface of a female, before starting courtship song. The male detects chemical substances composed by hydrocarbons on the body surface of female. In crickets, sex discrimination by male cricket is based on the cuticular chemical substances on the body surface. This means crickets also use chemicals for intraspecific communication. If the male cricket notice a cricket approaching is a male, the it starts aggressive behavior, and if female, it starts courtship behavior. Thus the chemical substances on the body surface are called cuticular pheromones. Male crickets exhibit intensive aggressive behavior when they encounter another male. Male cuticular pheromones induce aggressive behavior in male crickets. A fight consists of a sequentially escalating series of behaviors beginning with antennal fencing, which leads to the spreading and finally the engaging of the mandibles. The crickets continue fighting until one of them gives up attacking and fleeing from the opponent. Then the winner starts stridulating aggressive song. The duration of the fight is usually within several seconds. After the fight is settled, the losers depress the motivation of aggression for more than 3 hr although winners keep aggressiveness.



Fighting behavior between male crickets


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