1. Invertebrate diseases Pathology approached P. Zwart

2. Approach to invertebrates
The basic principle is: apply your usual professional skills and techniques
anamnesis taken as detailed as possible.
Animals kept individually or as a colony?
Number of animals per cage?
Course of the disease in the individual and/or in the colony

3. Approach to invertebrates
Signs that disease may be present (Individual insects):
Not feeding
Poor coordination
Jerky movements
Excessive grooming
Loss of orientation
Insects may climb high in the plant, expose themselves or hide

4. Approach to invertebrates
Inanition, vomiting and/or diarrhea.
change in color (melanization), or paleness.
swelling of the body
abnormal growth on the cuticula
deformations
missing or deformed limbs
poorly stredged wings
broken teeth
abnormal filling of bloodvessels (Lugworm, Arenicola marina).

5. Approach to invertebrates
Collect abnormal products and examine these under the microscope
Send materials to the laboratory

6. The invertebrate organism
Invertebrates are capable of combating infections.
Cellular defence
Humoral immunity
Fever (aquired) is known in some invertebrates

7. Viral diseases Polyhedrosis
Infection is by oral uptake of crystalline particles present in droppings
During infection, polyedric crystal-like inclusion bodies are produced in the host-cell

8. Viral diseases Polyhedrosis (Polyhedra-Infection) Nuclear polyhedrosis
virus (NPV)
Cytoplasmic
virus (CPV)
These viruses are host-specific !!
Core
Shell
Spikes

9. Polyhedrosis virus
Dead larvae hang as semi-liquified, black decomposing sacs.
Quarantaine: keep purchased caterpillars at least 3 days apart.

10. Polyhedrosis Virus Prevention:
Remove and destroy any infected caterpillars
Rinse all leaves used for food with a weak (<10%) chlorine bleach solution. After that, rinse with clean water to remove the bleach.
Clean all utensils and your hands with the bleach solution.
Avoid the build up of condensation on any surface which larva may come into contact with.

11. Iridescent virus Iridescent virus (a DNA virus)
Related viruses are ranavirus (frogs) and lymphocystis virus (fishes)
Special attention has been given to Chlor-iridovirus, which is transmittable from insects to poikilothermic vertebrates (especially lizards).

12. Iridescent virus
In a colony of crickets elderly females developed an enlarged abdomen.
Egg laying was minimal
Abdominal fat cells were enlarged and filled a homogenous basophilic mass.
an iridescent virus
infection occurred.

13. Bacterial infections
Bacteria like Aeromonas spp. and Pseudomonas spp. can act as pathogens (esp. in breeding colonies).
Susceptible are: Migratory locusts, snails and many other invertebrates.
Corals are susceptible to cyanobacteria like Phormidicum corallyticum and Oscillatoria sp.
Therapy requires isolation and antibiotic sensitivity tests.
Therapy should be guided intensively and not be left in the hands of the owner (risk of resistance)

14. Bacillus thuringiensis
A spore producing, Gram positive rod, which is distributed widely in nature.
Next to the spores, the bacterium contains a proteinaceous toxin in crystalline form.
It differs from Bacillus cereus and B. anthracis by the presence of specific plasmids.

15. Bacillus thuringiensis
Bacillus cereus
Spore
Plasmids
Bacillus thuringiensis
Bacillus anthracis

16. Bacillus thuringiensis
If crystals are eaten, this endotoxin binds to specific receptors present in the intestinal tract.
Within hours, the intestinal tract is paralyzed and the infected larva stops feeding
Occasionally the normal intestinal contents spread in the coelomic cavity, causing death by septicaemia.

17. Bacillus thuringiensis
Endotoxin from B. thuringiensis
Domain I can insert into the gut cell membrane, creating a pore through which ions can pass freely.
Domain II binds to receptors in the gut.
Domain III protects the exposed end (C-terminus)
of the active toxin, preventing further cleavage by gut proteases.

18. Bacillus thuringiensis
There many different strains
Each with its specific group or species of hosts.
Clinical symptoms: The toxins are lethal for larvae. Within minutes after ingestion, eating stops. The animal dies in 1 to 4 days by starvation or by sepsis.
Prophylaxis: Careful cleaning with water made alcaline by adding ammonia or Na-bicarbonate to reach a pH of
The indicator Phenolphthaleine turns violet if pH is > 8.2.

19. Fungal infections
Invertebrates, especially insects are susceptible to fungi.
Most frequent are strains of the Genera Beauveria, Verticillium, Aspergillus, Paecilomyces and many others
Entomopathogenic fungi can maintain themselves in a colony
Finally may lead to enzooties.
Penicillium
Paecilomyces

20. Fungal infections Fungi are contact pathogens
Spores adhere to the cuticula.
At optimal temperature and humidity they germinate, produce a tube, which penetrates the body wall and enters the tissues.
Finally, hyphi grow back through the body wall and emerge on the cuticula; spores are produced.
Toward the end of the season, or if environmental conditions are unfavorable for conidia production, “resting spores” are produced.

21. Fungal infections Symptoms reduced feeding,
lethargy; dead insects swell,
may be covered with fungi.
Production of melanin; black spots or areas on the cuticula.

22. Fungal infections
In the final stage, incoordinate or spastic movements, hypertrophy of body care and loss of orientation may be noted.
incubate in a humid chamber
hyphi and spores are produced on the cuticula.
Histopathology is useful.

23. Fungal infections
Combat is by immediate removal of all diseased and dead specimens. Raise the temperature to 38 – 40 °C (artificial fever)
The use of Imidazole and other antimycotics is still in an experimental phase.
Gentiana violett has been applied topically.
Stick insects with external fungal infection have been cured by spraying them with F 10 (Diluted 1 : 200).

24. Protozoan infections Microsporidiosis
Etiology: Many species: Some examples
Nosema locustae: migratory locusts and crickets
Orthosoma operophterae: winter moth
Nosema scripta: cottonwood leaf beetle
Spore-forms:
ellipsoid forms with a birefringent outer membrane.

25. Protozoan infections Clinical symptoms Migratory locust
(L. m. migratorioides)
INFECTION GRADE
Minimal
% fat cells
Moderate
% cells
Severe
% cells
Activity
Inactivity
Lethargy
Color
normal
Folded upper wings
Swollen abdomen

26. Protozoan infections Pathology Fat cells Malpighian tubes: Oocytes
Invaded and destroyed
Malpighian tubes:
A) thickening of tubes
B) destruction of epithelium
Oocytes
resorbtion of egg cells
invasion in the egg

27. Helminth (Nematode) infections
In Bird eating spiders, the Nematode Panagrolaimus sp.collects around cheliceres
Symptoms
Restlessness
spinning unusual amounts of silk
spending long periods around the water dish
a sweet smell coming from the container
wet sternum
white sticky mass around the mouth
holding the palps permanently under the chelicerae

28. Nematode infections Mermithidae-infection in migrating locust
Larvae in the haemocoel
Larvae emerge, moult and maturate.
Eggs eaten by the new host.
Larvae penetrate the intestinal wall (eventually peritonitis) and reach the haemocoel.
Larvae grow; insect’s abdomen enlarges.
Host dies at the moment the larvae leave it.

29. Nematode infections Mermithidae-infection Egg
Coelom of infected locust
Larva climbing
in grass
Worm dissected
from locust

30. Nematode infections Larvae of unidentified Nematodes in the
Hepatopancreas of a
naked snail (Arion
sp.).

31. Mite infections
Mould mites (Storage mite). I.e. Tyrophagus putrescentiae can damage a breeding colony.
Mass multiplication of such mites generally occurs when ventilation is insufficient and humidity is high.
Mites can cover the animals, slow down movements, hamper feeding
Removal: washing or (short) submersion in plain water.

32. Mite infections Mealmite (Tyroglyphus farinae)
A pest in breeding colonies of mealworms (T. molitor), king mealworms (Zophobas morio) fruit flies (D. melanogaster) and others eating mealy food
Create a draught (Ventilation)

33. Mite infections
The itch mite (or straw itch mite) (Pyemotes herfsi) infects all stages of the mealworm (T. molitor).
If added to small (<1 cm) larvae of the mealworm, these are dead within 4-5 days.

34. Mite infections On occasion, mites may enter the tracheae.
Dead mites are encapsulated by connective tissue

35. Mite infections
Lung mites (Riccardoella limacum) in Helix aspersa and H. pomatia
Lungmites live in the booklung and roam around the respiratory opening.
Heavy infestation slows growth and delays maturation.

36. Pests Scuttle fly (Megaselia scalaris) Megaselia scalaris
A small, fly moving with jerky movements
The larvae are carnivorous they live on dead insects and other organic materials
Emerging larvae feed on eggs and larvae of insects as well as on young ones of bird spiders
Full grown, healthy invertebrates are less likely to be attacked.
Megaselia scalaris
Drosophila

37. Megaselia trap Opening Water + Detergent Water + Detergent Water +
Bait
Water +
Detergent
®P.Debatist

38. Pathology of organs

39. The skin (cuticula) Melanizatio n in disease generalized darkening
affected area blackened

40. The skin (cuticula)
Defective development of wings, generally is a sign of malaise in the larval stage

41. The skin (cuticula) A Ruptures and traumata occur
If a bird eating spider falls to the ground, the abdomen may rupture
B) Spontaneous intestinal fistula A B

42. The eyes Note: Many mantides have a pigmented spot on their eyes.
The eyes of fast flying insects (dragon flies) can be damaged by traumata.
Note: Many mantides have a pigmented spot on their eyes.

43. Respiratory tract
In pulmonate snails pneumonias in lungmite infection and
bacterial and
protozoan infections.
Chlamydia?
Snail Lung normal
Protozoa?
Proliferation resp. epithel.

44. Urinary tract Malpighian tubules
Cilated Flame cells
Malpighian tubules
Ciliated (flame) cells at the top of tubule
Degeneration (A)
Calcium deposit (B) A B

45. Genital tract I
Degeneration of the ovary in mantides (Hierodula membranacea)
Normally the egg cases (ootheca) are barrel shaped.

46. Genital tract II
Clinics: the eggs were deposited in irregular clumps. In the ovary, the egg cells showed a severe degeneration.
Vitellin changed into a mass of birefringent crystals (A).
In surrounding vitellin cells (B), such crystals were present (+ inflammation) A B

47. Metabolic Diseases Inanition I
Mealworms which have been kept for a longer period on bran, stay small and hardly pupate.
If, in addition, the bran is infested by grain mites (Tyroglyphus farinae) the protein content of food diminishes
Therapy is by providing sufficient food and water
Inanition
Well fed

48. Metabolic Diseases Inanition II Poor growth, diminishing fertility.
Shortage in fat tissue.

49. Metabolic Diseases
Deciccation
Water deprivation
-> Shrinkage

50. Metabolic Diseases Calcium deficiency in snails
Develop a very thin shell or
Produce mill holes and lines in the shells of cage mates.
Therapy is by enriching the food with calcium
Insect-eating invertebrates, i.e. scorpions should be fed with gut-loaded or calcium-dusted insects.

51. I thank you for your attention