This document provides an overview of arthropods and their medical significance. It discusses the phylum Arthropoda and some of its key characteristics. Specific sections cover arachnids like ticks and mites, and the orders they belong to. Life cycles and images of various arachnid species are presented, including Ixodes ricinus, Ornithodoros papillipes, and Sarcoptes scabiei. The document also discusses insects of medical importance, including lice species like Pediculus humanus capitis, fleas like Pulex irritans, and the diseases they can transmit. In summary, the document presents information on medically relevant arthropods like arachnids and insects,

1. Kursk State Medical University
department of biology, medical genetics and ecology
Lecture 5
Medical Arachnoentomology.
Phylum Arthropoda.
Yelena Novikova, PhD of Biology,
Associate Professor

2. • 1,5 million species;
• Bilateral symmetry;
• Tripoblastic animals;
• Protostomes;
• Coelomates;
• Metamerism;
• They range in size from
microscopic plankton up to
forms a few meters long;
• They occupy the different
ecological area.
The characters of Phylum Arthropoda

3. Insects
3
Body parts of Arthropods
Arthropod’s segments are grouped into body regions

4. Body parts of Arthropods
Some Arthropods have the cephalothorax (head and thorax)
and abdomen
Crustaceans
Arachnidea

5. 5
Some Arachnidae have the cephalothorax and abdomen separate,
while others have the cephalothorax and abdomen fused

6. Appendages of Arthropods
• Jointed appendages
• Specialization of appendages

7. Exoskeleton
• Exoskeleton- body covered with a hard external
skeleton (chitin)
• Exoskeleton good for small things, protects body
from damage (rainfall, falling, etc.).
• Striated muscles are attached to the exoskeleton

8. is the manner in which an animal routinely casts off a part of its
body
Molting
Timing of molting.
Throughout life - crustaceans.
Periodically until certain size -
copepods.
During metamorphosis -
insects.

9. Complete digestive system with regional specialization.
mouth
esophagus
gizzard
cecum rectum
anus
foregut midgut hindgut
Digestive glands: salivary glands and hepatopancreas.

10. Open Circulatory System
Open hemocoel as a result of hard exoskeleton and lack of internal
segmentation.
Muscular heart required since body movements can’t move blood.
Hemolymph has amebocytes, pigments, and some have clotting
factors.

11. RESPIRATORY SYSTEM
Respiratory structures depend on habitat.
Gills in aquatic animals.
Arachnid book lung.
Trachea in terrestrial insects.

12. EXCRETORY SYSTEM
Malpighian tubules in
arachnids and insects.
Blind tubes extend into
hemocoel and empty into
gut.
Malpighian tubules
Antennal and maxillary
glands in crustaceans.
Produce ammonia with
some urea and uric
acid.

13. NERVOUS SYSTEM OF ARTHROPODS
Primitive brain and Ventral Nerve Cord

14. General
• most arthropods are gonochoric
• fertilization may be external or internal in aquatic arthropods
• always internal in terrestrial species
Ontogenesis:
• Direct and indirect development (with complete and
incomplete metamorphosis).
REPRODUCTION AND ONTOGENESIS

15. CLASSIFICATION OF ARTHROPODS
Phylum
ARTHROPODA
Subphylum
Branchiata
Subphylum
Chelicerata
Subphylum
Tracheata
Class
Crustacea
Class
Insecta
Class
Arachnida

16. Medical Arachnology

17. ORDER ACARINA
The branch of biology studying of mites and ticks is called acarology
Ticks and mites are included in the order Acarina

18. The characters of order Acarina
 About 50000 species;
 Most are minute to small 0.08–1.00 mm, the largest Acari
may reach lengths of 10–20 mm;
 Body is complete fused or consists of two parts.
 Sucking and chewing mouth apparatus;
 Respiratory organs are absent or tracheal system;
 Types of nutrition: heterotrophs (predators, saprophytes,
parasites);

19. Sucking mouth apparatus
hypostome
It consists of a central hypostome, usually bearing recurved teeth, on
each side a chelicera with cutting digits, and palps.
chelicera
palps

20. Sucking mouth apparatus of tick
hypostome

21. 21
There are four stages in the life history of a tick: eggs, larva,
nymph and adult (complete metamorphosis).
Some ticks have but one nymphal stage, while others have
several nymphal stages.
The stages of the life-cycle

22. 22
- 3 pairs of legs;
- sexually immature;
Larva and nymph and adult stages
 4 pairs of legs;
 sexually immature;
 having no genital opening on the
ventral surface.
- 4 pairs of legs;
- sexually immature;
- the genital opening is located on
the ventral surface between the legs.

23. Classification of Class Arachnida
Class
ARACHNIDA
ORDER
SCORPIONES
ORDER
ARANEI
ORDER
ACARI
FAMILY
IXODIDEA (HARD TICKS)
FAMILY
ACARIFORMES
FAMILY
ARGAZIDEA
(SOFT TICKS)
SPECIES
SARCOPTES SCABIEI
SPECIES
IXODES RICINUS
SPECIES
ORNITHODOROS PAPILLIPES

24. 24
There are two families of ticks: the hard ticks, family
Ixodidae, and the soft ticks, family Argasidae

25. 25
Hard ticks covered by a hard integument. A dorsal shield or scutum is present.
Soft ticks covered by soft integument. The dorsal shield or scutum is absent

26. 26
Hard ticks have the spiracular plates located behind the 4th leg.
Soft ticks have the spiracular plates located behind the 3rd leg.

27. FAMILY IXODIDEA (HARD TICKS)

28. Morphology of Ixodes ricinus
Female, 3-4 mm
Male, 2,5 mm
Scutum

29. Female of Ixodes ricinus after feeding
1
2
1- scutum; 2 – mouth apparatus.

30. LIFE-CYCLE OF IXODES RICINUS

31. Feeding of female

32. MEDICAL SIGNIFICANCE OF IXODES TICKS
Ticks vectors of pathogens:
A) rickettsioses:
-Marseilles fever;
-Q fever;
-borne typhus in Central Asia;
B) viral infections:
- Spring-summer encephalitis
- Hemorrhagic fever;
- Scottish sheep encephalitis;
B) bacterial infections:
-tularemia;
-brucellosis;
-plague.

33. FAMILY ARGASIDAE (SOFT TICKS)

34. Ornithodoros papillipes
 temporary ectoparasite;
soft tick;
 the body of longitudinal or oval,
egg-shaped;
dark-grey color;
Size : female - 8,2 mm,
male— 5,8 mm;
4 pairs of legs;
 eyes are reduced;
characteristic welt on the edge
of the body;
sexual dimorphism is weak;
able to starve up to 11-13 years;

35. Ornithodoros papillipes
mouth apparatus
reproductive opening
Dorsal side Ventral side
The capitulum (mouthparts-bearing structure) is located on the
underside of the animal's body and is not readily visible

36. 36
In Ornithodoros the hypostome is toothed. The integument of
the body has elevations known as mammillae

37. Life-cycle of
Ornithodoros papillipes (1-2 years)
Female imago
Egg
(1000 in a life)
larva Nymph 1 Nymph 2
Nymph 3
Nymph 4
female male
Nymph 5
female
female male
male
Because of the ability for long-term fasting (10 years)

38. Ticks carry pathogens:
- Tick-borne relapsing fever;
- Q fever.
Medical significance of Ornithodoros papillipes

39. FAMILY ACARIFORMES
SARCOPTES SCABIEI
- obligatory ectoparasite;
-name of disease – scabies;
- cosmopolitan;
-Transmission:
person-to-person.

40. SARCOPTES SCABIEI (female)
Ventral side Dorsal side
size: 0,3 – 0,4 х 0,2 – 0,3 mm
legs legs
legs
legs
Mouth apparatus

41. SARCOPTES SCABIEI in a human epidermis
1 3
2 4
1- male; 2- egg; 3 - female; 4 – epidermis.

42. Life-cycle
Female imago
male
female
nymph I I
larva
nymph I
egg
Complete life-cycle - 9 – 14 days

43. LOCALIZATION OF SARCOPTES SCABIEI
IN A HUMAN BODY

44. Moves in the epidermis

45. Scabies disease

46. Scabies disease
Erythema and secondary
infection with scabies
Scabies disease

47. MEDICAL ENTOMOLOGY

48. Classification of Insects
Class INSECTA
ORDER
ANOPLURA
(Lice)
GENUS PULEX
GENUS PEDICULUS
ORDER
APHANIPTERA
(Fleas)
ORDER
DIPTERA
GENUS PHTHIRUS
GENUS CULEX
GENUS ANOPHELES
Sub-order
Hemopteroidea
(with incomplete
metamorphosis)
Sub-order
Holometabola
(with complete
metamorphosis)

49. ORDER
ANOPLURA

50. PEDICULUS HUMANUS CAPITIS – head lice
(It can only survive on human heads)
Name of disease: pediculosis
• Cosmopolitan;
• Obligatory ectoparasite;

51. • Size is about 3 mm (male 1– 2 mm,
female – 3 mm)
• It has three parts of the body:
- head;
- thorax;
- abdomen;
It has 6 legs with strong claws
which are designed for holding
tightly onto hair - these claws also
prevent the lice from jumping -
HEAD LICE DO NOT JUMP!!
It has simple eyes and no wings.
PEDICULUS HUMANUS CAPITIS – head lice

52. MORPHOLOGY OF PEDICULUS HUMANUS CAPITIS
FEMALE – 2,4 – 4 mm. MALE – 1 – 3 mm.

53. The stages of life-cycle of head lice
Imago–
Females deposit
about 140
eggs per life.
Optimal t=28 - 290С.
1-st larva stage 2-nd larva stage
Imago
Eggs (nit, size 0,6-1mm). Optimal temperature
for the larva development is 30 - 360.
The larva stages are not developed,
if the t<22 и >450С.

54. Life-cycle of head lice –
indirect development
(with incomplete metamorphosis)
Egg - nit A - 1-st larva stage; B - 2-nd larva stage
А
B

55. PEDICULUS HUMANUS CAPITIS – head lice

56. Head pediculosis

57. Pediculosis eyelashes

58. Head lice eggs on hair and head louse on fingernail
Photo courtesy of Foundation Studios

59. A head louse using its powerful claws to grasp a hair shaft
Source: Sally Speare and Rick Speare ©, School of Public Health and Tropical Medicine, James
Cook University, Townsville, 1998.

60. • Size is about 3,5 mm
(male 2-3 mm, female –
4 mm)
• It has 6 legs,
• It is tan to grayish-white.
• If separated from their
hosts, lice die at room
temperature.
PEDICULUS HUMANUS HUMANUS – body louse

61. PEDICULUS HUMANUS HUMANUS
Female– 2,2 – 4,7 mm.
Male – 2,1 – 3,7 mm.
Name of disease: pediculosis

62. Places of biting of P. humanus humanus

63. Phthirus pubis – pubic louse (crab louse)
Female – 1,5 mm; Male – 1,0 mm
1. The crab louse is found in the person's pubic hair.
2. An adult crab louse is about 1.3–2 mm long (slightly smaller than the body
louse and head louse).
3. It can be distinguished from those other species by its almost round body.
4. It has four pairs of the legs, two pairs of legs are much thicker than the front
legs and have large claws.
Disease - phthiriasis

65. Medical significance of lice
• The body louse and head louse cause the Pediculosis disease.
• The crab louse causes the Phthiriasis disease.
• The body louse is the vector of epidemic typhus,
relapsing fever, and trench fever.
• The head louse and the crab louse have never been
incriminated in disease transmission.

66. ORDER APHANIPTERA

67. PULEX IRRITANS
1. Facultative ectoparasite;
2. Brown, wingless insects;
3. Size - 2.0 to 2.5 mm;
4. Laterally compressed body;
5. Three parts of the body: head, thorax and abdomen;
6. The head has eyes and combs;
7. It has antennae and suctorial mouth parts.
8. Each segment of the three-segmented thorax bears a pair of powerful
legs terminating in two curved claws.

68. PULEX IRRITANS
The vector for plague

69. Life Cycle of Pulex irritans
• Complete metamorphosis
• Egg  Larvae  Pupa  Adult
– 18 days to 20 months
• Eggs (3-18 at one time in several batches)
• Larvae need high humidity
– 9-15 days optimal (up to 200 days)
• Pupa
– 7 days to 1 year
• Adult
– Live up to 4 years.

70. Life-cycle of Pulex irritance
imago
egg
imago
larva
pupa

72. PLAGUE CORK
1
2
3
1- pharynx; 2 – stomach; 3 – plague cork

73. ORDER - DIPTERA
FAMILY - CULICIDAE

74. Family
Anopheles and Culex
Anopheles Culex

75. Anopheles Culex
Landing of females
Anopheles и Culex

76. Heads of females ANOPHELES И CULEX
1
2
3
Anoph. Culex
1 – proboscis; 2 – antennae; 3 – palps; 4 - eyes
4

77. Heads of females ANOPHELES И CULEX
Anopheles Culex

78. EGGS OF ANOPHELES И CULEX
Anopheles Culex
-single;
- boat shaped;
- lateral floats;
-Small clusters - raft;
- cigar shaped;
- no lateral floats;

79. LARVAE OF ANOPHELES И CULEX
1 – head; 2 – thorax; 3 – abdomen;
4 - spiracles
1 – head; 2 – thorax; 3 – abdomen;
4 – respiratory siphon
Anopheles Culex
-free swimming;
- body consists of head, thorax, abdomen;
- it is vegetarian;
- floats horizontally surface feeder;
- very active – swift movement;
- no respiratory siphon;
- head downwards;
- slower with snake like movement;
- long narrow respiratory siphon;

80. Landing of larvae
Larva of Culex
Larva of Anopheles

81. Pupae of Culex и Anopheles
Culex Anopheles
1- spiracles; 2 – cephalothorax; 3 - abdomen
Culex
1
2
3
-Resting stage, does not feed, prefer stay quite at water surface;
- body consists of cephalothorax and narrow abdomen;
Respiratory spiracles are tubular shaped Respiratory spiracles are funnel shaped

82. FLIES

83. MUSKA DOMESTICA
Mechanical carrier of protozoan and helminthes
• Size – 6-9 mm
• Dark grey color
• The head of the adult fly has
reddish-eyes and sponging
mouthparts.
• The thorax bears four narrow
black stripes and there is a
sharp upward bend in the
fourth longitudinal wing
vein.
• The abdomen is grey or
yellowish with dark midline
and irregular dark markings
on the sides.

85. Morphology of Muska Domestica

86. Life-cycle of Muska Domestica
(complete metamorphosis)