Blood feeding and mosy immunity

Question 1

Name the three stages of bloodfeeding and describe

Answer 1

1) Appetitive searching-driven by hunger, usually occurs at a specific time of the day regulated by the insects internally programmed activity cycle
2) Activation and orientation- a range of stimuli are used for this stage, mainly olfaction and vision
3) Attraction- decision as to whether and where to land on the host e.g. vision odours and heat

Question 2

what two ways do insects bloodfeed?

Answer 2

pierce or cut and rip

Question 3

what layer of skin do haematophagous insects need to get to in order to feed

Answer 3

inner dermis

Question 4

what mouthparts are modified to pierce bloodfeed?

Answer 4

mandibles/ maxillae

Question 5

Describe piercing bloodfeeding

Answer 5

long, piercing stylets interconnected to form a long tube through which blood can be sucked, take blood directly from a blood vessel that has been lanced by the mouthparts

Question 6

describe the mouthparts of piercer

Answer 6

The piercing structures, labrum and lacunae protrude beyond the labella. the tips of the lacuna and mandibles are finely serated.

Question 7

Describe cutting/tearing/ripping mouthparts

Answer 7

the skin is cut and then the blood is either sucked or lapped up from the resulting pool, maxillae are like scissors

Question 8

What 3 ways does the host circulatory system respond to gain homeostasis.

Answer 8

1) vasoconstriction -reduced blood flow
2) Platlet activity-plugs the wound within seconds of injury
3) coagulation- stabilises the plug

Question 9

Describe haematophagus insect saliva and what does it contain?

Answer 9

Lubricates the mouthparts, contains sialome; an array of components that aids feeding and overcomes coagulation and pain response to minimise host contact time

Question 10

What is unusual about haematophagus saliva?

Answer 10

does not contain digestive enzymes

Question 11

What do all haematophagus salivas contain? 3

Answer 11

1) an anti-coagulant- coagulated blood could kill the insect
2) an anti-platlet compound
3) a vasodilator

Question 12

Describe anti-haemostatic factors in salivary secretions

Answer 12

High diversity, closely related species often use quite separate molecular mechanisms

Question 13

Name 4 vasoconstrictors secreted by blood feeders and the species.

Answer 13

Nitric oxide-rhodnius prolixus
maxadilan-lutzomyia longipalpis
adenosine-phlebotomus papatasi
peroxidase/catechol oxidase- anopheles albimanus

Question 14

Name 3 anticoagulants and the spp.

Answer 14

Anti-thrombin- glossina morsitans
Prolixin S- Rhodnius prolixus
Hamadarin-Anopheles stephensi

Question 15

Name an anti-platlet compound and describe

Answer 15

Apyrase- hydrolyze ADP and consequently inhibit ADP-induced platlet aggregation
atleast 23 spp. have these with 3 families of apyrase
Apyrase speeds up blood feeding

Question 16

How could you characterise salivary gland gene function?

Answer 16

RNAi- inject dsRNA matching your target gene-> target gene degraded-> measure impact on the ability to blood feed

Question 17

What is the problem with bloodfeeding why?

Answer 17

extremely dangerous, host pain and itch poses a threat by swatting

Question 18

What is the safe feeding period for mosquitoes and triatomine bugs

Answer 18

wild mosquitoes=3 minutes

adult triatomine bugs = 20 minutes

Question 19

Describe the progression from tissue damage

Answer 19

tissue damage -> inflammation ->1) redness+ heat-increased blood flow 2) pain- swat response 3) swelling

Question 20

Describe host pain response 3

Answer 20

1) ATP released from damaged cells
2) release of serotonin and histamine from platelets and mast cells
3) Bradykinin following factor x11 activation

Question 21

Describe four suppressors expressed by spp. to avoid host pain response
suprressor->target-> species

Answer 21

Adenosine deaminase-> adenosine -> aedes aegypti
Anti-histamine-> histamine ->Rhodnius prolixus
Hamadarin-> bradykinin -> anopheles stephensi
Apyrase-> ATP-> many insects

Question 22

What are the five stages of a vert host itch response from no bite history to after many bites

Answer 22

1) no response
2) A delayed type IV immune response +itch
3) An immediate type I immune response +itch ->24-48 hours later a delayed type IV immune response + itch
4) only the immediate type 1 response and itch
5) no response

Question 23

What is blood meal size affected by? 6

Answer 23

ambient temperature, insect age, mating status, stage in gonotrophic cycle, previous feeding history and source of blood meal

Question 24

how much of the blood meal is made up of water? %

Answer 24

80%

Question 25

What is the peritrophic matrix?

Answer 25

A extracellular layer made up of glycosaminoglycans and chitin which separates the blood meal from the gut epithelium, semi permeable

Question 26

how many types of peritrophic matrix are there?

Answer 26

Type 1 and type 2