This document discusses the relationship between insect endosymbionts and the insect immunity system. It describes how endosymbionts like Wolbachia and Spiroplasma can provide benefits to insects like increased resistance to pathogens. The document outlines the types of immunity in insects and how endosymbionts can enhance both humoral and cellular immunity through increased antimicrobial peptide production and immune gene expression. Several studies are cited showing endosymbionts reduce susceptibility of insects to bacterial, viral, parasitic and parasitoid infections. The conclusion discusses using endosymbionts to help control mosquito-borne diseases and illnesses in beneficial insects.

2. RELATION OF INSECT
ENDOSYMBIONTS WITH
IMMUNITY SYSTEM
Presented by :
Thakur Mandar Vijay,
Jr. MSc Entomology,
Department of Entomology,
PG College of Agriculture,
RPCAU, Pusa.
Submitted to :
Dr. M. S. Sai Reddy,
Assistant Professor,
Department of Entomology,
PG College of Agriculture,
RPCAU, Pusa.
ENT 502 – Insect Anatomy, Physiology and Nutrition

3. CONTENT
1) Introduction
2) Types of Endosymbionts
3) Benefits of Endosymbionts
4) Insect Immunity System
5) Types of Immunity
6) Defence Mechanism

4. 7) Effect of Endosymbionts on Bacterial Infections
8) Effect of Endosymbionts on Viral Infections
9) Effect of Endosymbionts on Parasitic Infections
10) Effect of Endosymbionts on Parasitoid Attacks
11) General Effect of Endosymbionts on Insect
Immunity System
12) Conclusions and Future Prospects

5. An endosymbionts is any organism that lives within
the body or cells of another organism.
Endosymbionts are the microorganism that lives
within the cells of an insect
Endosymbiosis (Greek:endon= ‘within’,
sym=’together’, biosis=’living’)

6. Obligate, mutualistic interactions with bacteria
have a profound effect on various physiological
functions of the host.
Insects have co-evolved with their primary
endosymbionts for several million years.
Insects lacking their bacteria are unable to grow
and reproduce.
The symbiotic bacteria are not viable in the
absence of their host

7. Types of Endosymbionts

8. Wigglesworthia
glossinidia
(Bacteria)
Mother Glossina morsitans
Tsetse fly (Glossina morsitans)
Produce essential
vitamins that are
not present in the
vertebrate blood
meal .
Mother Pea aphid
Buchnera
aphidicola
(Bacteria)
synthesize
essential
amino
acids
Primary endosymbionts are vertically
transmitted from mother to offspring
Pea aphid

9. Secondary endosymbionts can be
transmitted horizontally, vertically or
via the environment.
Mother
Glossina
morsitans
Sodalis glossinidius
(Bacteria)
Sodalis was the first insect endosymbiont that was
reported to be successfully isolated and cultured in
vitro.
Same
generation
Glossina
morsitans

10. Benefits of Endosymbionts
1) Defence towards pathogens
2) Influence on insect plant interaction
3) Adaptation to Environment
4) Impact on population dynamics
5) Pesticide detoxification
6) Behavioural manipulation

11. Insect Immunity System
The insect immune system consists of a wide
variety of defence mechanisms.
 It act individually or in combination to prevent
foreign organisms from entering the insect body.
It suppress the growth and replication of
pathogens once they gain access to host tissues.

12. Types of Immunity
Immune response of insects includes humoral
immunity and cellular immunity.
1) Humoral immunity mainly produces
antibacterial peptides from fat bodies to resist
the reaction of invading pathogenic
microorganism.
2) Cellular immunity mainly kills invasive
pathogenic microorganisms through the activity
of immune cells, including phagocytosis, nodule
and cyst.

13. Defence Mechanism
The first line of defence -
 The first line of defence is represented by the
insect’s epithelia.
 It serves as a barrier against biotic and abiotic
factors.
 Produce local antimicrobial peptides (AMP)
upon infection or wounding.

14. The second line of defence -
The second line of defence is represented by the
innate immune system.
 It responds through a series of mechanisms.
It is non specific resistance.
 That destroy invaders in a generalized way
without targeting specific individual.

15. For checking the effect of endosymbionts
on insect immunity system two bacteria
used by all the scientists-
1) Wolbachia
2) Spiroplasma

16. Why these two only ?
Most commonly found
facultative endosymbiotic
bacteria.
Most common reproductive
parasite in the biosphere.

18. Effect of Endosymbionts On
Bacterial Infections
Drosophila melanogaster and
D. simulans flies with
Wolbachia bacteria.
Infected by three gram-
negative bacterial
pathogens -
1)Pseudomonas aeruginosa
2)Serratia marcescens
3) Erwinia carotovora
Did not affect survival ability of flies compared to
Wolbachia-free control flies.

19. D. Melanogaster carrying
the Spiroplasma
strain- MSRO
More
susceptible to
septic injury
Not
susceptible to
septic injury
When injury with the Gram-
negative bacteria -
1)Erwinia carotovora
2) Enterobacter cloacae
When injury with Gram-positive
bacterium- Enterococcus faecalis
The fungus -Beauveria bassiana

20. Effect Of Endosymbionts On
Viral Infections
D. melanogaster wild type and D. simulans adult
flies naturally infected with the Wolbachia strains
wMelCS and wMelPop survive longer on infection
by the RNA viruses Drosophila C Virus (DCV),
Flock House Virus (FHV) and Cricket Paralysis
Virus (CrPV)
Strain with anti-viral protection Strain without anti-viral protection
I. wMel I. wHa
II. wRi II. wNo
III. wAu

21. Effect Of Endosymbionts On
Parasitic Infections
Lower number of Plasmodium berghei (Protozoa)
oocyets in the Wolbachia-infected mosquitoes
Similar experiments also showed reduced numbers
of Brugia pahangi (Nematodes) parasites in A.
aegypti somatically infected with Wolbachia.
In tsetse fly, numbers of trypanosome parasites
(Protozoa) increases in absence of native
Wigglesworthia endosymbionts

22. Mosquito
Aedes aegypti
wMelPop-CLA
Wolbachia strain
wMelPop
Wolbachia strain
Reduces the ability of two
arboviruses (dengue virus
and Chikungunya virus)
and the avian malaria
parasite (Plasmodium
gallinaceum) to establish
infection in the mosquito
Changes in virulence
that lead to behavioral
effects that in turn
reduce blood-feeding
efficiency.

23. Effect Of Endosymbionts On
Parasitoid Attacks

24. Spiroplasma endosymbionts Wolbachia endosymbionts
Drosophila hydei and Drosophila simulans
Parasitoided
by
Leptopilina
heterotoma
(wasp)
Increases the ability to
survive infection
More susceptible to
parasitoid

27. General Effect of Endosymbionts
on Insect Immunity System
Endosymbionts effects more on humoral
immunity but also have impact on cellular
immunity.
Generation of high levels of reactive oxygen
species (ROS) and AMP in epithelial cells as well as
nitric oxide (NO) that is also involved in the
regulation of innate immune responses to bacteria
and parasites.

28. Increase in transcriptional levels of melanization
genes as well as AMP and Toll related genes.
Replication of the endosymbionts in the new host that
could result in immune priming.

29. Conclusions And Future
Prospects
Using endosymbionts you can control –
I. Natural populations of mosquitoes.
II. Human viral diseases such as Dengue and
Chikungunya.
III. Poultry malaria.
IV. Diseases of beneficial insects.
Conclusions And Future
Prospects