Insect Abdomen - Insect Anatomy Exam 1

How many total segments in the insect abdomen?

11 or 12

How many segments does the pre-genital abdomen have in both males and females?

Females: 1-7 segments

Males: 1-8 segments

True or False: generally no appendages in the abdomen of adults and larvae

False. No appendages in adults, but many larvae have prolegs

What types of sclerites are found in the pre-genital abdomen?

Dorsal tergum (tergites when subdivided)

• mediotergite (dorsal) and laterotergite (lateral)

Vental sternum (sternites when subdivided)

Membranous pleuron (pleurites when sclerotized)

How many segments does the genital abdomen have in both males and females?

Males: 9

Females: 8 or 9

How many segments does post-genital abdomen have

10+

What is terminalia?

When an abdomen has 8+ segments collectively

What are the structures of post-genital segment 11 in adults and nymphs?

1 Epiproct

2 Paraprocts

2 Cerci

What is subgenital plate?

The last visible sternum

How was the ovipositor derived?

From legs

What does the general form of the ovipositor include?

2 pair basal sclerites (valvifers)

• 1st and 2nd gonacoxites

3 pair processes (valvulae)

• 1st and 2nd gonapophyses

• Gonoplac

What are 2 modern leg remants?

Abdominal styli and cerci

What is eusternum?

Definitive sternal plate

What does the insect sternum consist of?

Derived from fusion of the eusternum and the coxa of ancestral legs (coxosterna - coxal bases)

Appears to be 1 plate

What are 3 terminal appendages in holometabolous larvae?

Pygopods - segment 10 (ventral)

Urogomphi - outgrowths of tergum of segment 9 (dorsal)

Prolegs

How many abdominal segments do holometabolous larvae have?

10

What are the hooks at the end of prolegs called?

Crochets

What order has an abdomen comprised of 6 segments?

Collembola

What is the organ for water balance? What order is it found in?

Collophore

What is furcular and where is it found?

Found in Collembola. Basal manubrium, bearing 2 arms, each with a dens and a mucro

What is retinaculum?

Clasp for furcula found in Collembola

Which group of insects has up to 6 segments visible and 6-9 segments not apparent because they are telescoped?

Holometabolous adults

What is the 1st and 2nd abdominal segment in hymenoptera?

Propodeum and petiole

What is metasoma or gaster?

The functional abdomen in ants

What is the mesosoma? What is included in the mesosoma?

The functional thorax of hymenoptera. The propodeum in included in the fuctional thorax but it is the 1st abdominal segment.

What does intersegmental relations have to do with adult insects and nymphs?

Their abdominal segments telescope

What is primary segmentation?

Muscles on intersegmental folds

True or False: primary segmentation works on sclerotized insects?

False. Works by longitudinal muscles shortening the actual segment on soft bodied insects like larvae

What is secondary segmentation?

Telescoping on any sclerotized insect because sclerotization means the segment cannot shorten

In the membranous area, muscles on intersegmental folds, slight offset between true and apparent segmental division

What is the tergum?

Antecostal cuture - internal ridge

Anterior pentecostal suture to posterior membrane

The _____ is the narrow lip between membrane and posterior pentecostal suture

Acrotergite (ventral and dorsal)

List the 5 sets of muscles in the abdoment by Snodgrass

Dorsal longitudinal (internal and external)

Ventral longitudinal (internal and external)

Lateral (compress segment)

Transverse muscles (alary muscles on diaphragms)

Spriacular muscles

True or False: Exterior dorsal muscles are longer than interior dorsal muscles

False

What is the function of dorsal and ventral muscles?

Telescope

What is the function of lateral muscles?

Compression

Dorsal longitudinal interior muscles _____ the abdomen and exterior muscles ____ protract the abdomen

Retract

Protract