W9: Invertebrate Physiology (Reproduction, Forensics & SIT) [Dr. Blair]

Question 1

Kinds of insect reproduction/Insect reproductive strategies? (3) HOP

Answer 1

• Haplodiploidy.
• Oviparous.
• Parthenogenesis.

Question 2

Haplodiploidy attributes? (3)

Answer 2

• Sexual reproduction.
• No fertilisation (haploid) (ie, eggs develop without fertilisation).
• Seen in eusocial insects (bees & ants).

Question 3

Oviparous attributes? (3)

Answer 3

• Sexual reproduction.
• Fertilisation of eggs occurs & produces diploid (2n) offspring.
• Seen in most insects (flies, mosquitoes).

Question 4

Parthenogenesis attributes? (3)

Answer 4

• Asexual reproduction.
• No fertilisation (ie, eggs develop without fertilisation).
• Seen in aphids, wasps & stick insects.

Question 5

Egs of oviparous insects? (2)

Answer 5

• Bees.
• Ants.

Question 6

Egs of parthenogenetic insects? (3)

Answer 6

• Wasps.
• Aphids.
• Stick insects.

Question 7

Eg of haplodiploidy insects?

Answer 7

Flies.

Question 8

Diptera attributes? (3)

Answer 8

• Order of flies.
• Two wings.
• Part of the important species in medical & applied entomology.

Question 9

Family under Diptera to focus on?

Answer 9

Calliphoridae.

Question 10

Calliphoridae is AKA?

Answer 10

Blow flies.

Question 11

Blow flies attributes? (2)

Answer 11

• Over 1100 species.
• Important in forensics as they often found on dead, often bloated, bodies upon which these flies/larvae are found.

Question 12

Fly life cycle layout in order? (6)

Answer 12

• Eggs.
• 1st larval stage.
• 2nd larval stage.
• 3rd larval stage.
• Pupa.
• Adult.
• Repeat process.

Question 13

Why are maggots eyes positioned where they are positioned?

Question 13

Blow flies courtship process: Finding Ms. Right? (5)

Answer 13

• Males will find a female (7 day old females).
• Courtship process is initiated by the male.
• Done by mating with the female and spreading her wings.
• Female’s eggs are fertilised provided she is accepting of the male.
• Females mate once, while males mate multiple times.

Question 14

Myiasis?

Answer 14

= the invasion of vertebrate tissues/organs (dead or living) by Dipteran larvae.

Question 15

Flies that cause myiasis in South Africa? (2)

Answer 15

• Tumbu flies.
• Screw-worm flies.

Question 16

Tumbu flies?

Answer 16

= under Calliphoridae family.

Question 17

Screw-worm flies attributes? (4)

Answer 17

• Under the Calliphoridae family.
• Have a rapid life cycle (3 weeks).
• Partake in obligate myiasis.
• Cause significant damage by laying eggs in vertebrate tissues, affecting livestock and sometimes humans.

Question 18

Economic impact of myiasis?

Answer 18

Infestation leads to secondary infections & significant economic losses, especially in livestock farming.

Question 19

What happens when they get into vertebrate tissue: Larvae in livestock? (4)

Answer 19

• More than just painful wounds.
• Secondary infection (death).
• Economic losses (livestock farming).
• Attracts more flies (feedback: outbreak).

Question 20

Screw-worm flies myiasis affects who? (2)

Answer 20

• Larvae in livestock.
• Larvae in humans.

Question 21

Screw-worm flies distribution attributes? (5)

Answer 21

• Severe losses to the livestock brought pressure to control/eradicate these flies (1900s-1930s).
• Pesticides & pheromone traps were unsuccessful in controlling this beast.
• Approached entomologists, Bushland & Knipling, who initiated research in 1930.
• Bushland suggested using chemicals on cattle (perhaps to make them unpalatable to the flies?).
• Knipling suggested breaking the insect life-cycle (sterile insect technique).

Question 22

Sterile Insect Technique (S.I.T)?

Answer 22

= genetic control programme that releases very high numbers of artificially sterilised males into the population, resulting in sterile matings & consequently a reduction in population size.

Question 23

S.I.T is AKA?

Answer 23

Sterile Male Release.

Question 24

S.I.T process (lay it out for me in order)? (7)

Answer 24

• Mass rearing of insects.
• Sterilise males with radiation, but ensure no noticeable change (eg, sickly, etc).
• Release millions of sterile males to significantly alter the sex ration (males : females).
• Sterile males mate with wild females.
• Eggs fail to develop, leading to decreased progeny & decreased population.
• Repeat the process.

Question 25

Did the S.I.T work?

Answer 25

YES, IT WORKED!

Question 26

Explain how the S.I.T worked? (4)

Answer 26

• Started in Curacao in Venezuela & screw-fly populations were eliminated (7 weeks).
• Controlled in the USA (1960s-1970s).
• Eliminated in Mexico (1980s).
• Eliminated in Libya (1991).

Question 27

What is key to the S.I.T working?

Answer 27

The female needs to mate once because if females mate multiple times it makes the …..

Question 28

Forensic entomology: Role of blow flies? (3)

Answer 28

• Able to sense freshly dead organic matter.
• Are first to arrive (<10 mins).
• Lay egg batches.

Question 29

Particular types of blow flies in Forensic entomology? (2)

Answer 29

• Green bottles.
• Blue bottles.

Question 30

Green bottles scientific name?

Answer 30

Lucilia cuprina.

Question 31

Blue bottles scientific name?

Answer 31

Calliphora vomitoria.

Question 32

Green bottles attributes? (3)

Answer 32

• Smaller.
• Maggots.
• Compete with blue bottles for food (carrion, excreta & nectar).

Question 33

Blue bottles attributes? (3)

Answer 33

• Larger.
• Maggots.
• Compete with green bottles for food (carrion, excreta & nectar).

Question 34

Forensic entomology: In the field? (4)

Answer 34

Forensic entomologists:

• Collect as much data as possible such as,
• Flies, maggots & pupae.
• Ambient weather conditions (temperature affects the rate of development of flies).
• Position of the body (outdoors, shade, buried).

Question 35

Forensic entomology: In the lab? (3)

Answer 35

Forensic entomologists:

• Determine the developmental stage & species collected from the field.
• Calculate the development rate of the stages.
• Data are compared against weather conditions to estimate the time of oviposition (Post Mortem Interval).

Question 36

Explain the graph of Temperature & fly development? (9)

Answer 36

• Graph illustrates the importance of temperature for fly development from an egg to adult.
• x-axis = Temperature.
• y-axis = Developmental time (days).
• Flies fail to develop at 10-13 degrees celsius.
• As temperature increases, the developmental time decreases exponentially from egg to adult.
• At 20C, eggs take about 25 days to develop into an adult & that decreases as it develops into an adult with increasing temperature.
• At 25C, it took about 15 days to develop from egg to adult.
• At 30C, it took about 12 days to develop from egg to adult.
• At 35C, it took 10 days to develop from egg to adult.

Question 37

PMI stands for?

Answer 37

Post Mortem Interval.

Question 38

Forensic entomology: PMI? (2)

Answer 38

• PMI graph.
• Forensic entomologists work backwards when determining the PMI.

Question 39

Explain the PMI graph?

Question 40

Forensic entomology: Added benefits from flies? (4)

Answer 40

• Locality, through the potential movement of the victim or locality of their death (eg, dumping).
• Trauma, through the presence & abundance of maggots within a corpse being used as a trauma guide.
• Toxins, through flies/maggots being examined for the presence of drugs/toxins (entomotoxicology).
• DNA identification, through the fact that maggots feeding on a corpse may retain testable DNA.

Question 41

Types of entomology covered? (2)

Answer 41

• Forensic entomology.
• Medical entomology.

Question 42

Medical entomology: Benefits from flies?

Answer 42

Sterilised blow flies, particularly green bottles, are used in Maggot therapy.

Question 43

Maggot therapy?

Answer 43

= where sterilised blow flies, especially green bottles, are used in medicine to help clean wounds by removing dead tissue, promoting healing & reducing infection.

Question 44

Maggot therapy benefits? (3)

Answer 44

• Aid in removal of damaged tissue.
• Regeneration of new cells.
• Decreasing infection by microbes.

Question 45

Super summary? (3)

Answer 45

• Reproduction (majority of insects are oviparous, asexual reproduction is possible in some).
• Life cycle (understanding the reproductive cycle, larva to adult).
• Useful applications (sterile insect technique, forensic entomology, medical uses via maggot therapy).