Lecture 29 - Lice, Fleas And Keds

Front 1

Phylum arthropods

Back 1

jointed appendages, exoskeleton, bilateral, metameric segmentation, metamorphosis
Insecta class: 3 pairs jointed legs, 3 regions of body, one pair antennae, hemimetabolous/holometabolous

Front 2

Lice

Back 2

Evolved from free-living insects resembline Pscoptera
Bark/dust lice small winged/wingless, no sucking mouthparts
Sipunculata/Anoplura: sucking lice (blood)
Mallophaga: chewing lice (hair, feathers)
Permanent ectoparasites of birds/mammals
Special legs for grasping, grooming kills

Front 3

Louse biology

Back 3

Hemimetabolous: gradual metamorphosis
Eggs - nymphs that resemble adults
Entire life on host
Transmitted directly between hosts, host specific, die when host dies or on unnatural host = co-speciation
Head, thorax, abdomen, 1 pair antennae, 3 pairs legs
Wingless, dorso-ventrally flattened

Sucking: head narrower than thorax
Chewing: head wider than thorax

Front 4

Order Sipunculata

Back 4

Chewing lice
Mammals, no monotremes/marsupials, not carnivores except canids and marine pinnipeds, species specific, diameter of hair shaft must be able to clasp, hold on with gonopods whilst eggs stick to hairs
Vectors of human diseases, head and body human lice
Enabled to survive aquatic lifestyle on marine mammals

Front 5

Family Echinophtiridae

Back 5

Seals and walruses
Respire air, able to survive when hosts in sea
Lepidophinus macrorhini: elephant seals, body covered in scales, bristles trap air when dives, valves close thoracic and abdominal spiracles
Echinophtirus horridus: seals, near nostrils and enter when dives, protects when closes nostrils

Front 6

Mallophaga

Back 6

Chewing lice, birds, few mammals, not humans, host specific
Hemimetabolous, ornate/sculpted eggs, head rounded
Suture between thorax and prothorax, chewing mandibles (feathers, hair, wool), feed on scurf
Epidermal scales, may pierce and ingest blood, eye reduced

Front 7

Mallophaga suborder Rhynchophthirina

Back 7

Haematomyzus elephantis
Few African and Indian elephants
Hopkinsis: warthogs, chewing parts on end of proboscis, very long legs

Front 8

Mallophaga suborder Amblycera

Back 8

Birds, some mammals, roam over body
Antennae not obvious, short/club-shaped and in groove on side of head
Palps visible from above, long tarsi to climb on smooth surfaces

Front 9

Mallophaga suborder Ischnocera

Back 9

Birds/mammals, 3/5 segmented antennae, no maxillary palps, horizontal mandibles hold onto and chew hairs

Front 10

Pocket gopher co-speciation

Back 10

122 louse species, cheek pockets carry food and bedding
Isolated burrows, colonies in 1 burrow to mate/breed
1 louse species per 1 gopher species
Mother to offspring when suckling
Rostral groove clamps onto hair
Avoids competition on hosts, spatial partitioning due to micro-environment differences in body sites

Front 11

Order Siphonaptera

Back 11

Fleas
Diverse, 239 genera, 800 species with subspecies, holometabolous, egg/larva/pupa/adult in different environments, wingless, very small, birds and lairing mammals, not host specific, streamlined head, small antennae in groove, mouthparts in groove, laterally compressed, combs (ctdenidum) to attach to hair, leathery tegument, difficult to crush, specialised jumping

Front 12

Flea feeding

Back 12

Adults feed on mammals with lairs and nesting birds
Not on primates with temporary shelters as nowhere for immature fleas to develop
Mouthpiece sucks blood in both sexes (f for eggs), 2-3 minutes, may overfeed and discharge blood for larva as fleadirt, iron for cuticles
Resistant to starvation, remain unfed for months

Front 13

Flea's holometabolous life cycle

Back 13

Adults lay eggs in hosts lair, hatch, larvae feed on organic material (remains of host food, flea dirt), 3 larval instars followed by pupates in a silk cocoon, covered with debris for camouflage, adult emerges when vibrations caused by host arrival

Front 14

Go to host only to feed
Leave dying/cooling host
Feed continuously
Burrow into host

Back 14

Pulex irrilans (humans)
Ctenocephalides felis (cats, most common form)
Spilopsyllus caniculi (rabbits)
Uropsylla tasmanica (Tasmanian devil)

Front 15

Spilosyllus cuniculi rabbit flea

Back 15

Attach to ears, use hormones to synchronise, adults to offspring when suckling
Fleas mature sexually ~10 days before rabbit birth, flea ovaries develop spontaneously due to rise in cortisol and cortisone in rabbit, more fleas, more firmly fixed, ears ripe when rabbits born, detach and move to face to be passed on
Feed on newborns, adults squirt blood, growth hormone (somatotrophin) stimulates mating and laying eggs
~12 days adults return to female for breeding cycle on next litter
Synchrony allows eggs to be deposited in nest with food and flea dirt

Front 16

Keds: diptera
Suborder: Brachcera

Back 16

Mammals and birds ectoparasites
Some prolonged on one host, others whole life
Blood sucking holometabolous flies on ungulates
Dorsoventrally flattened, leathery integument, large recurred claws, eyes reduced, antennae in pit, piercing/sucking, abdomen reduced, laviparous/pupi/vivparous, females lay single larva, prepupa, immobile and turn into puparium, kept in uterus longer

Front 17

Hippobosca equina

Back 17

Winged horse fly
Temperate and tropical, 1cm, winged, crawl on thin skin between legs/udders/tail/ears, skuttle, single prepupa in humus at plant base, almost spherical, hatches and seeks

Front 18

Lipoptena cervi

Back 18

Deer fly, female loses wings on host, wing stubs attached to thorax, 1 larva/pupa in uterus, pupariates and drops to ground, hatches and seeks host

Front 19

Melophagus ovinus

Back 19

Sheep ked, both sexes wingless, small eyes, no ocelli, no arista on antenna, female deposits larva on sheep, sticky puparium, keds transfer in summer when temperature higher than 60 degrees F and come to surface, burrow deeper at lower temp