Ovipositor

Ovipositor is in the animal kingdom generally the name given to a trained females at oviposition apparatus. Although there are similar structures in different groups of animals ( for example, when bitterling ), this term is, however, generally used, especially when the ovipositor of insects. He is referred to according to its very different configurations as ovipositor, ovipositor ovipositor or ovipositor. Functionally, it serves the females to deposit eggs in various substrates.

Design and function

The ovipositor is formed as a tube of the paired Gonapophysen that form in the area of the genital segments ( 8th and 9th abdominal segment ) as training on the front edge of the Coxopodite the two genital segments ( Valvifer ). They are derived from the corresponding developments of the cliff divers, which form a simple laying pipe. Is the genital opening from which the eggs are pressed into the lumen of the tube at the base of the laying pipe.

Higher insects such as dragonflies, Spring terror, thrips, Hemiptera and Hymenoptera have a more developed ovipositor ( orthopteroider ovipositor ). Here, the second Valvifer carries a further Gonapophysenpaar which forms a double pipe together with the two Ursprungsvalvulae. In this case, both the third and also the second valvulae a folding strip in a corresponding groove of the first crimped, wherein the second valvulae usually be the middle of the upper delimitation of the lower half tube. The base of the Gonapophysen is ( pro-and retractor ) equipped with muscles against each other allows movement of the valvulae both sides. Through the alternating movement of a building under egg laying pipe to the top of the laying pipe can be conveyed.

Transformations

Some representatives of Hymenoptera, especially bees and wasps, a poison sting has emerged from this original ovipositor. In this case, the lumen of the original laying pipe ( spine) carries the poison from a poison sac.

With many other subgroups of the ovipositor can be changed. Some Grasshopper the Gonapophysen are heavily regressed and seamed together. They are short and hook-shaped, sharply formed the middle valvulae. The Real Grilling the middle valvulae are completely absent and the laying pipe is formed of only the first and third valvulae.

Atypical oviposition apparatus

In addition to this basic type of ovipositor are numerous atypical oviposition devices that have probably evolved independently in insects. So diving beetles have a the ovipositor described functionally very similar ovipositor, which, however, can not be deduced from this. Even with different Netzflüglern and snakeflies exist tubular formations on the ventral side of the genital segments. In many groups of insects, the posterior abdominal segments are instead of laying pipe is tapered and take over the function of the egg-laying; these can be everted and usually retracted into the front segments.

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