Navigation and Courtship



Download 18.56 Kb.
Date conversion20.07.2018
Size18.56 Kb.
Navigation and Courtship

  • All insects spend their entire lives mating, and the mating process for most insects is generally the same. They use various skills to track down a mate: For instance, insects like the fly rely on their navigation system. Flies have compound eyes and very good eyesight, as well as a strong sense of smell. When these senses reveal the presence of a potential mate, a male fly will fertilize the female in the air (during flight). Some insects display mating behaviors also seen in the animal world. Dragonflies are very aggressive and territorial when they are mating. They will defend their mate and the site in which they choose to lay their eggs. Some dragonflies have also been seen attacking humans if they feel that their mate or eggs are in danger. Other insects like the honeybee will spend time courting a particular mate by flying around this potential partner in a rhythmic fashion. There are also rare cases in which the female will reject the male insect during courtship if she doesn't want to mate with him. It is unknown why some insects are rejected, but this seldom happens in the insect world.

Attraction: Sounds, Visual Signals and Pheromones

  • Most insects spray their scent in order to attract a mate directly to them. Nearly all insects use pheromones to make themselves more appealing to a potential mate. Butterflies--who spend a great deal of time, day in and day out, looking for a partner--attract a mate with visual signals that make them appear more beautiful to another insect. Female fireflies also use visual signals like flashing light to let males know they are available to mate. Other insects like the cricket use sound to attract a partner. Have you ever heard a cricket chirping all night long just outside your door, or even underneath your couch? Crickets chirp and make sounds in order to call a mate to them. They will continually chirp and call until they are paired up.



Fertilization and Egg Laying

  • Female insects of several different species mate with several different partners during their lifetime. Some female insects, like the black widow spider, will even attack and eat the male soon after mating with him. These male black widows are generally much smaller than the females as well. The majority of insects need a male to fertilize eggs. The eggs (larva) are usually laid within the same day of fertilization. The average male insect will fertilize a female by injecting his sperm directly inside her through a small opening. A strange-looking insect called the rotting banana mates by mounting the female from behind and inserting its penis inside her. Other insects like the robber fly mate by turning their backs to each other and connecting from behind, becoming intertwined until fertilization happens. Standard houseflies will lay their eggs soon after fertilization takes place. After the eggs hatch, maggots emerge, and later mature into adult flies. For flies, the process happens rather quickly; they have a very short life span.

Insects communicate by means of scents - pheromones:- chemicals used for 'signalling'. With these they both locate and identify their mates. Pheromones are communication chemicals. They are natural chemicals emitted in tiny quantities in the form of a vapour by virtually all known insects. They are frequently concerned in the mating process. Each insect species has its own unique signature scent. In fact, sex provides us with a powerful means of surveillance and control in the insect world.



Insects


Insect species make up more than two-thirds of all extant animal species, and most insect species use sex for reproduction, though some species are facultatively parthenogenetic. Many species have sexual dimorphism, while in others the sexes look nearly identical. Typically they have two sexes with males producing spermatozoa and females ova. The ova develop into eggs that have a covering called the chorion, which forms before internal fertilization. Insects have very diverse mating and reproductive strategies most often resulting in the male depositing spermatophore within the female, which stores the sperm until she is ready for egg fertilization. After fertilization, and the formation of a zygote, and varying degrees of development; the eggs are deposited outside the female in many species, or in some, they develop further within the female and live born offspring are produced.

Love at First Sight – Insects that Use Visual Signals to Attract a Mate:

Some insects begin their search for a sexual partner by looking for or giving visual cues or signals. Butterflies, flies, odonates, and luminous beetles use visual signals most often.

In some butterfly species, males spend much of the afternoon patrolling for receptive females. Anything that looks like a female may be inspected, especially if the object is a desired color and "floats like a butterfly," to borrow a phrase from Muhammed Ali.

Many species of flies perch in a place that provides a clear view of the area. The fly sits, watching for any flying object that might be a female. If one appears, he quickly takes flight and makes contact. If his quarry is indeed a female of his own species, he escorts her to an appropriate place for mating – perhaps a leaf or a twig nearby.

Fireflies may be the most famous insects that flirt using visual signals. Here, the female sends the signal to lure a male. She flashes her light in a specific code that tells passing males her species, her sex, and that she is interested in mating. A male will reply with his own signal. Both male and female continue to flash their lights until they have found each other.

Serenades of Love – Insects that Use Auditory Signals to Find a Mate:

If you've heard the chirp of a cricket or the song of a cicada, you've listened to insects calling for a mate. Most insects that makes sounds do so for the purpose of mating, and males tend to be the crooners in species that use auditory signals. Insects that sing for a partner include Orthopterans, Hemipterans, and Coleopterans.

The best known singing insects must be the male periodical cicadas. Hundreds or even thousands of male cicadas congregate in an area after emerging, and produce an ear-splitting chorus of song. The cicada chorus usually includes three different species, singing together. Remarkably, the females respond to the song and are able to find mates of the same species from within the chaotic choir.

Male crickets rub their forewings together to produce a raspy and loud song. Once he lures a female close to him, his song changes to a softer courtship call. Mole crickets, which are ground dwellers, actually construct special entrance tunnels shaped like megaphones, from which they amplify their calls.

Some insects simply tap on a hard surface to produce their love calls. The death-watch beetle, for example, bangs his noggin against the roof of his tunnel to attract a mate. These beetles feed on old wood, and the sound of his head tapping resonates through the wood.

Love is in the Air – Insects that Use Chemical Cues to Find a Mate:

French naturalist Jean-Henri Fabre discovered the power of the insect sex pheromones quite by accident in the 1870's. Male peacock moths came flitting in the open windows of his laboratory, landing on the mesh cage of a female. He tried to fool the males by moving her cage to different locations, but the males always found their way back to her.

As you might suspect from their plumose antennae, male moths search for suitable female mates by sensing sex pheromones in the air. The female cecropia moth emits a scent so powerful it attracts males from miles around.

A male bumble bee uses pheromones to lure a female to a perch, where he can mate with her. The male flies along, marking plants with his perfume. Once he sets his "traps," he patrols his territory waiting for a female to land on one of his perches.



Unmated Japanese beetle females release a strong sex attractant, which quickly draws the attention of many males. Sometimes, so many male suitors appear at one time that they form a crowded cluster referred to as a "beetle ball."


The database is protected by copyright ©dentisty.org 2016
send message

    Main page