Insect reproductive system

Sperm, produced by the male in one testicle or more commonly two, is transmitted to the female during mating by means of external genitalia.

[1]: 880 Accessory glands or glandular parts of the oviducts produce a variety of substances for sperm maintenance, transport, and fertilization, as well as for protection of eggs.

The more primitive apterygote insects have a single testis, and in some lepidopterans the two maturing testes are secondarily fused into one structure during the later stages of larval development, although the ducts leading from them remain separate.

However, most male insects have a pair of testes, inside of which are sperm tubes or follicles that are enclosed within a membranous sac.

[1]: 885 The ground plan of the abdomen of an adult insect typically consists of 11–12 segments and is less strongly sclerotized than the head or thorax.

If the Apterygota are considered to be indicative of the ground plan for pterygotes, confusion reigns: adult Protura have 12 segments, Collembola have 6.

Apterygotes possess a pair of styles; rudimentary appendages that are serially homologous with the distal part of the thoracic legs.

A pair of appendages, the cerci, articulates laterally on segment 11; typically these are annulated and filamentous but have been modified (e.g. the forceps of earwigs) or reduced in different insect orders.

An annulated caudal filament, the median appendix dorsalis, arises from the tip of the epiproct in apterygotes, most mayflies (Ephemeroptera), and a few fossil insects.

[2]: 49 The organs concerned specifically with mating and the deposition of eggs are known collectively as the external genitalia, although they may be largely internal.

[3] The components of the external genitalia of insects are very diverse in form and often have considerable taxonomic value, particularly among species that appear structurally similar in other respects.

Mutants of D. melanogaster that are defective in genes mei41 and mei9 that encode products employed in meiosis were found to display decreased meiotic recombination and also to have increase sensitivity to the DNA damaging agents x-rays, UV, methyl methanesulfonate and nitrogen mustard.