Lecture 4 - Reproduction Embryology and post-embryonic development in insects Flashcards
Mate location
Females and Males need to be in the same place at the same time
Mate location: On host
(Eg + 4 description)
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
Mate location: at a food source
(Eg + 1)
Face Flies
Both males and females are attracted by the olfactory eminations of cow feces (this is where they mate and female oviposit)
Mate Location: Lek Behavior
Eg (3) + 1
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)
Mate Location: Hilltop Behaviour
Eg (5) + 1
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)
Mate Location: Visual Displays
Eg (3) + Description (3)
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)
Mate Location:
Chemical attractants (Pheromones)
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
Mate Location: Sound Production (Stridulation)
Eg (2)
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
Courtship
release of chemical and auditory signals to bring mates close to proximity
The different techniques of courtship is known as:
(2)
A) Tactile Stimulation
B) Combined with short-range chemical stimulation
Example of Courtship
This occurs when the balloon flies (male) wrap their gift in silk, the male will trick the female by offering them an empty balloon
Post-Copulatory behaviors
Eg. Dragonflies
(2)
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
Post-Copulatory behaviors
Eg: Male Moth
(2)
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
Post-Copulatory behaviors
Eg. Orthoptera
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
Fertilization
There are different forms of fertilization but it usually occurs at the ova pass through the oviduct
Types of Fertilization
Non-insect hexapods thysanura) and primitive insects
(2)
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
Types of Fertilization
In higher order of insects (3)
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)
Types of fertilization
Eg. Praying Mantids (2)
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
Types of Fertilization
Eg. Scorpionflies (2)
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
Embryology
Is defined as the development of the fertilized egg
Meroblastic
Insect embryologic development where there is only partial cleavage
Steps of Meroblastic
(6) + Description
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)
Longitudinal Section of the Embryo (2)
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
Fate of cell layers (3)
a. Endoderm
b. Mesoderm
c. Ectoderm
Endoderm
Midgut
Mesoderm (3)
Musculature, fat body
Circulatory system
Gonads - Lateral oviducts, vas deferens
Ectoderm
(6)
Exoskeletal epidermis *
Tracheal system *
Nervous system
Foregut and hindgut (including the Malpighian tubules, excretory organs)
Median oviduct
Spermatheca
- Shed with each olt
Ectoderm
(6)
Exoskeletal epidermis *
Tracheal system *
Nervous system
Foregut and hindgut (including the Malpighian tubules, excretory organs)
Median oviduct
Spermatheca
- Shed with each molt
In terms of the ecotderm layer, which one will shed with each molt
(2)
Ecoskeletal epiderm
Tracheal system
Larval Development
(2)
Larval Development is strongly influence by the temperature and nutrition
However the course is governed by the hormonal factors
Types of Larval Development
(3) + Eg
a. Ametaboloous (Thysanura)
b. Hemimetabolous (Orthoptera and Hemiptera)
c. Holometabolous (Eg. Lepidoptera, Coleoptera, Diptera)
Ametabolous
(Eg) + 2
(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
Hemimetabolous
Eg + 3
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
Holometabolous
Eg + 2
(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
The Major Function of the Pupa
(2)
a. Permite the larvae to diverge into adult form
b. Overwinterring stage
The Major Function of the Pupa : Permit the larva to diverge into adult form
(2)
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
The Major function of the Pup: Overwintering Stage
This occurs when it remain dormant and withstand environmental extremes
Some Modification of Normal Development: Tse Tse Fly
(2)
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
Some Modification of Normal Development: Aphids
(2)
Can alternate throughout generation meaning that the: Wing form alternate with wingless + sexual alternate with asexual
Aphid Cycle: Fall
This occurs when alate (Wing formed) oviparous (egg laying) female and alate males mate
Aphid Cycle: Winter
The female aphid will lay the eggs in the winter
Apid Cycle: Spring
(3)
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)
Aphid Cycle: Summer
(2)
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
