Insect Abdomen












































INSECT ABDOMEN AND ITS MODIFICATIONS

·         Abdomen is the largest, eleven segmented (Uromers) posterior tagma.
·         Eleventh segment, being reduced and divided into three lobes namely a dorsal epiproct and a pair of paraproct that surrounded the anus.
·         The terminal segments may bear a pair of cerci.
·         Spiracles are present on each side of the first eight abdominal segments.
·         8th and 9th segments are known as genital segments.
·         Female genitalia (ovipositor) present in 8th and 9th segment.
·         Male genitalia present in 9th segment.
·         Abdomen is the centre for reproduction and metabolism.
Modifications of ovipositor
  • Short & horny. Eg: Short horned grass hopper
  • Sward like. Eg:  Long horned grass hopper
  • Needle like. Eg:Ichneumon wasps.
  • Sting: Honey bee workers
  • Telescopic. Eg:Diptera
  • Rigid blade like. Eg: Cicadas
Modifications of abdomen
    1. In ants, bees and wasps, the first abdominal segment is fused with the metathorax and is called as propodeum. The second segment forms a narrow waist called petiole and the remaining segments are collectively called gaster.
    2. In queen termites, after mating the abdomen becomes swollen due to enlargement of ovaries. The abdomen becomes bloated and this obesity is called physogastry.
Abdominal appendages
Appendages
Description
Example
Styli
Paired tube like outgrowth on the ventral side of the first three segments 
Silverfish, proturans
Collophore
Cylindrical adhesive tube in the venter of first segment (also called ventral tube or glue peg)
Springtails
Retinaculum
Posterior hook like structures in the venter of third segment (also called tenaculum or hamula)
Springtails
Furcula
Springing organ in the venter of fifth segment
Springtails
Prolegs
Five pairs of unsegmented lobes in third to sixth and tenth segments each
Catepillars
Tracheal gills
Lateral outgrowth of the body wall enriched with tracheae, filamentous (mayfly) or lamellate (damselfly)
Damselfly, mayfly naiads
Anal papillae
Four papillae surrounding the anus
Mosquito larvae




Appendages
Description
Example
Dolichasters
Segmental protuberance fringed with setae
Antlion grubs
Cornicles
Pairs of short tubes in fifth or sixth segment, concerned with honeydew secretion
Aphids
Caudal breathing tube
Hollow tube at apex
Water scorpion
Cerci
A pair in eleventh segmented, much varying in from, long and many segmented in manyfly, long but unsegmented in cricket, short and many segmented in cockroach, short and unsegmented in grasshopper, sclerotized and forcepslike in earwings, asymmentrical in male web spinners.
Earwigs
Median caudal filament
Epiproct elongated into a circus like structure.
Mayfly and silverfish
Pygostyles
Short unsegmented cerci like structures
Scoliid wasps
Anal styli
Pair of short unsegmented structures
Male cockroach

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