INTRODUCTION TO MEDICAL ENTOMOLOGY; CLASSIFICATION OF ARTHROPODS

Entomology

The study of insects, arachnids, and other arthropods that directly or indirectly affect humans.

TRUE

TRUE OR FALSE. Medical Entomology focuses on the biology and control of arthropods that impact public and individual health.

70%

Insects make up — of all known species of animals on Earth.

Public Health Entomology

Application of entomological knowledge to prevent and protect against vector-borne diseases.

Public Health Entomology

Uses biological insights on life cycles and control strategies to reduce harm to humans.

Medical Arthropodology

A broader study of both insect and non-insect arthropods in biomedical contexts

Dr. Tyagi

Medical Arthropodology is coined by —-

• Taxonomy & biodiversity

• Forensic entomology

• Biotechnology

• Integrated vector management

Medical Arthropodology includes topics such as

Arthropods

vectors of major diseases like malaria, filariasis, dengue, chikungunya, Zika, and Japanese encephalitis

Bites and stings
Allergic reactions
Ectoparasitism
Myiasis
Envenomation

Pathological conditions caused directly by arthropods are

indirect effects

Arthropods serve as vectors of pathogens via mechanical or biological transmission.

direct effects

Pathological conditions caused directly by arthropods

Mechanical transmission

Passive carriage of pathogens (e.g., houseflies carrying bacteria on their legs).

Biological transmission

The pathogen undergoes changes inside the vector before transmission.

Propagative
Cyclopropagative
Cyclodevelopmental

Types of Biological Transmission

Propagative

Pathogen multiplies inside arthropod but does not develop (e.g., Yersinia pestis in fleas).

Cyclopropagative

Pathogen multiplies and develops (e.g., Plasmodium in mosquitoes).

Cyclodevelopmental

Pathogen develops but does not multiply (e.g., Wuchereria bancrofti in mosquitoes).

biological vectors

Arthropods maintain pathogens inside their bodies and are essential in the disease cycle.

Bilaterally symmetrical bodies
Exoskeleton made of chitin (hard and rigid)
Segmented bodies with jointed appendages

What are the major morphological features of arthropods?

Major body divisions
Number of legs
Mouthparts

The identification of arthropods are based on:

Metamorphosis

Developmental changes in size, form, and structure.

Ametabolous (Direct Development)
Hemimetabolous (Simple/Gradual Metamorphosis)
Holometabolous (Complete Metamorphosis)

Types of Metamorphosis:

Ametabolous (Direct Development)

No change in form, only size (e.g., silverfish).

Hemimetabolous (Simple/Gradual Metamorphosis)

Gradual change from nymph to adult (e.g., cockroach).

Holometabolous (Complete Metamorphosis)

Distinct larval, pupal, and adult stages (e.g., mosquitoes, butterflies).

Class Insecta
Class Arachnida
Class Chilopoda
Class Diplopoda
Class Crustacea

What are the main classes of medically important arthropods?

Class Insecta

Three body segments: Head, thorax, abdomen.

Six legs & usually two pairs of wings (some wingless or single-winged).

mosquitoes, fleas, lice, cockroaches, flies

Class Insecta examples

ticks, mites, spiders, scorpions

Class Arachnida examples

Class Arachnida

Two body segments: prosoma & opisthosoma.
Eight legs, no antennae or wings.
1 pair of chelicerae and pedipalps

Class Chilopoda

Flattened body, venomous fangs, one pair of legs per segment.
Simple metamorphosis, piercing-chewing mouthparts

Centipedes

Class Chilopoda examples

Class Diplopoda

Cylindrical body, two pairs of legs per segment.
Each segment are made up of two segments fused together
Head contains a pair of antennae, simple eyes, and a single maxilla

Millipedes

Class Diplopoda examples

Class Crustacea

Primarily aquatic, two pairs of antennae.
Cephalothorax - fused head and thorax, which may be covered by a single large carapace

crabs, shrimps, copepods

Class Crustacea examples

carapace

The cephalothorax of a crustacean can be covered by a single large