Lecture 4 - Reproduction Embryology and post-embryonic development in insects

Question 1

Mate location

Answer 1

Females and Males need to be in the same place at the same time

Question 2

Mate location: On host

(Eg + 4 description)

Answer 2

Strepsiptera (twisted - wing parasites)

Females are legless and wingless

They mate on the tip of the abdomen of bees

This occurs when the male find the tip of the abdomen of the bee and this is where mating occurs with the female parasite

Question 3

Mate location: at a food source
(Eg + 1)

Answer 3

Face Flies

Both males and females are attracted by the olfactory eminations of cow feces (this is where they mate and female oviposit)

Question 4

Mate Location: Lek Behavior

Eg (3) + 1

Answer 4

Eg. Dragonflies, Moths, Bees

This occurs when the male arrives first, female chooses the mate and find the opportunity to choose male based on their dance or other characteristics (to defend the territories)

Question 5

Mate Location: Hilltop Behaviour

Eg (5) + 1

Answer 5

Dragonflies, wasp, beetles, butterflies, flies

males often found flying up and staying on a hilltop waiting for the female (male dash to the top competing for the best territory would have a better chance of mating)

Question 6

Mate Location: Visual Displays

Eg (3) + Description (3)

Answer 6

Eg: Butterfly courtship (This occurs when the female butterfly require the male to dance)

Eg: Fireflies (This occurs when the male and female produces flash)

Eg: Fruit flies (This occurs when the fruit flies move their wings in a rhythmic way to attract the female fruit flies)

Question 7

Mate Location:
Chemical attractants (Pheromones)

Answer 7

This occurs when the female moth releases pheromones (long term) to attract male moth, then perform tactile stimulation that causes the male to release pheromones via short range

Question 8

Mate Location: Sound Production (Stridulation)

Eg (2)

Answer 8

Sound production is usually produced by the male

Eg: Crickets (Orthoptera) rub their forewings together so that there is a scrapper present on one wing and a file present on the other wing

Eg: Male mosquitoes also attracted to the specific frequency of the female mosquito wingbeats

Question 9

Courtship

Answer 9

release of chemical and auditory signals to bring mates close to proximity

Question 10

The different techniques of courtship is known as:

(2)

Answer 10

A) Tactile Stimulation

B) Combined with short-range chemical stimulation

Question 11

Example of Courtship

Answer 11

This occurs when the balloon flies (male) wrap their gift in silk, the male will trick the female by offering them an empty balloon

Question 12

Post-Copulatory behaviors

Eg. Dragonflies

(2)

Answer 12

Males often take female on a prolong tandem flight to ensure no other males can mate with it

The male hold the female and this causes the female to bend their abdomen in order to transfer the sperm in the second abdominal segment

Question 13

Post-Copulatory behaviors

Eg: Male Moth

(2)

Answer 13

Male moth often consist of accessory gland that make the female unreceptive to further male

This can inhibit the secretion of pheromone by the female so that no additional males are attracted to the female

Question 14

Post-Copulatory behaviors

Eg. Orthoptera

Answer 14

Male Orthoptera will produce a gential plug and insert that plug into the female genital part to prevent other males from mating with the female

Question 15

Fertilization

Answer 15

There are different forms of fertilization but it usually occurs at the ova pass through the oviduct

Question 16

Types of Fertilization

Non-insect hexapods thysanura) and primitive insects

(2)

Answer 16

This occurs when there is an indirect sperm transfer, the male will deposit a package of sperm known as spermatophore onto the substrate

This causes the female to pick up that package and fertilizes it

Question 17

Types of Fertilization

In higher order of insects (3)

Answer 17

The fertilization is internal

The sperm are stored in the female’s spermatheca (pouch storing sperm of male)

This pouch is connected to the median oviduct and can be stored for months (moth) or years (ant queen)

Question 18

Types of fertilization

Eg. Praying Mantids (2)

Answer 18

Since female praying mantids are larger than the male and thus are prone to getting eaten, therefore the male will bring a nuptial gift to the female

This causes the male to get the job done

Question 19

Types of Fertilization

Eg. Scorpionflies (2)

Answer 19

The male will bring the female a nuptial gift to occupy her

*** Studies have shown a positive correlation b/t the size of the gift and the mating success

Question 20

Embryology

Answer 20

Is defined as the development of the fertilized egg

Question 21

Meroblastic

Answer 21

Insect embryologic development where there is only partial cleavage

Question 22

Steps of Meroblastic

(6) + Description

Answer 22

Zygote will undergo nuclear cleavage
- This is not a cell division but instead known as holoblastic

Once nuclear cleavage occurs, the zygote produces daughter nuclei known as energids
- These energids will migrate to the outside of the egg known as blastoderm

There is a thickened area known as primitive streak that forms known as the primordium
- primordium will develop into the embryo

Once this occurs, there is an invagination of the medial plate to form the mesoderm and endoderm

This causes the lateral plate to fuse forming the ectoderm

There is an invagination that forms the stomodeum (mouth) and proctodeum (anus)

Question 23

Longitudinal Section of the Embryo (2)

Answer 23

Ectoderm invaginates at front and rear end of the embryo’s body to form the foregut and the hindgut

The midgut will develop from the endoderm to fuse with the foregut and the hindgut to to form the alimentary canal

Question 24

Fate of cell layers (3)

Answer 24

a. Endoderm

b. Mesoderm

c. Ectoderm

Question 25

Endoderm

Answer 25

Midgut

Question 26

Mesoderm (3)

Answer 26

Musculature, fat body

Circulatory system

Gonads - Lateral oviducts, vas deferens

Question 27

Ectoderm

(6)

Answer 27

Exoskeletal epidermis *

Tracheal system *

Nervous system

Foregut and hindgut (including the Malpighian tubules, excretory organs)

Median oviduct

Spermatheca

• Shed with each olt

Question 27

Ectoderm

(6)

Answer 27

Exoskeletal epidermis *

Tracheal system *

Nervous system

Foregut and hindgut (including the Malpighian tubules, excretory organs)

Median oviduct

Spermatheca

• Shed with each molt

Question 28

In terms of the ecotderm layer, which one will shed with each molt

(2)

Answer 28

Ecoskeletal epiderm

Tracheal system

Question 29

Larval Development

(2)

Answer 29

Larval Development is strongly influence by the temperature and nutrition

However the course is governed by the hormonal factors

Question 30

Types of Larval Development

(3) + Eg

Answer 30

a. Ametaboloous (Thysanura)

b. Hemimetabolous (Orthoptera and Hemiptera)

c. Holometabolous (Eg. Lepidoptera, Coleoptera, Diptera)

Question 31

Ametabolous

(Eg) + 2

Answer 31

(Eg. Thysanura)

The only difference b/t the immatures and adult is the size, and the development of the gonads

These insects are often wingless

Question 32

Hemimetabolous

Eg + 3

Answer 32

Eg: Orthoptera, Hemiptera

This occurs when there is a gradual change through each molt (this leads to the development of external wing, external genitalia and adult structure)

The immatures are known as nymphs and the aquatic immature stage are known as naiads

Wing development occurs in stage 3 but only is it functional in the adult form

Question 33

Holometabolous

Eg + 2

Answer 33

(eg. Lepidoptera, Coleoptera, Diptera)

These insects consists of internal wing development where the insect will develop into a larva → Pupa → Adult

The pupa is the intermediate stage and the immature is the larvae stage

Question 34

The Major Function of the Pupa

(2)

Answer 34

a. Permite the larvae to diverge into adult form

b. Overwinterring stage

Question 35

The Major Function of the Pupa : Permit the larva to diverge into adult form

(2)

Answer 35

The larva and adult can occupy completely different ecological niches and have different diet (The larva is concerned with feeding, whereas the adult is concerned with mating, dispersal and oviposition)

The body is rebuilt during the pupa stage

Question 36

The Major function of the Pup: Overwintering Stage

Answer 36

This occurs when it remain dormant and withstand environmental extremes

Question 37

Some Modification of Normal Development: Tse Tse Fly

(2)

Answer 37

These flies are viviparous meaning that they give birth to live ones

The larvae are retained w/ in the oviduct and then displaced into the soil to mature to pupates

Question 38

Some Modification of Normal Development: Aphids

(2)

Answer 38

Can alternate throughout generation meaning that the: Wing form alternate with wingless + sexual alternate with asexual

Question 39

Aphid Cycle: Fall

Answer 39

This occurs when alate (Wing formed) oviparous (egg laying) female and alate males mate

Question 40

Aphid Cycle: Winter

Answer 40

The female aphid will lay the eggs in the winter

Question 41

Apid Cycle: Spring

(3)

Answer 41

The egg hatch into female known as apterous (wingless) and viviparous

Females are known as stem mother

Once 10 days of being born, the female will give birth to spring dispersers (that are alate and viviparous)

Question 42

Aphid Cycle: Summer

(2)

Answer 42

These spring dispersers will give birth to apterous and viviparous female

As a result of crowding and declining food quality these apterous vicarious female will give birth to alate viviparous females