Mosquitoes and Disease Transmission: Introduction and Classification

Mosquitoes are insects belonging to the family Culicidae, known as one of the most harmful insects to human health. They are dangerous disease vectors, causing numerous serious illnesses. This article provides detailed information about mosquitoes, their characteristics, development cycle, habits, and role in disease transmission.

1. Characteristics of Adult Mosquitoes

• Head: Has two compound eyes, the upper lip forms a feeding tube.

• Thorax: Three thoracic segments, each segment bears a pair of legs. Mosquito wings are membranous and supported by wing veins.

• Abdomen: 10 segments but only 8 are visible. It can swell when feeding.

2. Mosquito Larvae

Mosquito larvae go through four stages, differing only in size.

3. Development Cycle of Mosquitoes

Mosquitoes undergo complete metamorphosis, including four stages: egg, larva, pupa, and adult.

4. Flight Range of Mosquitoes

The flight range of mosquitoes depends on the species:

• Anopheles spp: 2-5km

• Culex spp and Aedes spp: Up to 16km

5. Factors Attracting Mosquitoes

Mosquitoes are attracted by:

• Dark colors

• CO2

• Some amino acids

• Warmth

• Humidity

Mosquitoes have varying preferences for humans and animals.

6. Purpose of Mosquito Blood Feeding

Mosquitoes feed on blood to provide nutrients for their egg development.

7. Identification and Differentiation of Mosquitoes

Differentiating and identifying mosquito species is based on the morphology of both larvae and adult forms.

8. Classification of the Family Culicidae

The family Culicidae consists of three subfamilies:

• Culicinae

• Anophelinae

• Toxorhynchitinae

9. Classification of the Subfamily Culicinae

The subfamily Culicinae comprises three genera:

• Aedes

• Culex

• Mansonia

10. The Genus Anopheles spp

The genus Anopheles spp is characterized by the absence of scales on their abdomen.

11. Characteristics of Adult Anopheles spp

• Long palps as long as the proboscis

• Wing margins with alternating black and white areas

• Pointed abdominal tip

12. Eggs of Anopheles spp

• Laid individually and float on the water surface

• Shaped like a boat with two floats on each side

13. Larvae of Anopheles spp

• Two respiratory siphons located near the dorsal surface of the 8th abdominal segment

14. Breeding Sites of Anopheles spp

Breeding sites are typically stagnant water with abundant aquatic plants on the surface.

15. Blood Feeding Habits of Anopheles spp

They usually attack at night, preferring to feed indoors.

16. Anopheles spp as Disease Vectors

Anopheles spp are vectors of:

• Malaria

• Some filarial worms

• Some forms of meningitis

17. Eggs of Aedes spp

Eggs are laid individually on the water surface, rhomboid-shaped, black or dark brown.

18. Egg Laying Sites of Aedes spp

Aedes spp usually lay their eggs in clean water.

19. Larvae of Aedes spp

Have short, wide respiratory siphons on the 8th segment, with a single tuft of hair at the end of the comb.

20. Adult Aedes Mosquitoes

• Short palps, long proboscis

• Black abdomen, often with two white stripes on the sides and white bands across the back of each segment

• Pointed abdominal tip

• The hind legs have five white bands

21. Activity Time of Aedes spp

Aedes spp usually bite during the morning or evening.

22. Aedes spp as Disease Vectors

Aedes spp are vectors of:

• Dengue fever

• Yellow fever

• Japanese encephalitis

• Zika

• Transmission of filarial worms

• Aedes aegypti is the most dangerous

23. Eggs of Mansonia spp

Eggs are spiky and adhere to the underside of aquatic plants in clusters.

24. Larvae of Mansonia spp

Have chitinous respiratory siphons with spiky projections that insert into the roots of aquatic plants for oxygen.

25. Adult Mansonia spp Mosquitoes

• Palps shorter than the proboscis

• Wing margins and veins have large yellowish-white scales

26. Activity Time of Mansonia spp

Mansonia spp usually bite at night, primarily outdoors.

27. Mansonia spp as Disease Vectors

Mansonia spp are vectors of filarial worms (Mansonia uniformis).

28. Eggs of Culex spp Mosquitoes

Eggs are cylindrical and laid in rafts that float on the water surface due to a small float at the end of each egg.

29. Egg Laying Sites of Culex spp

Culex spp usually lay eggs in dirty water with a high concentration of organic matter.

30. Appearance of Adult Culex spp Mosquitoes

Unlike the other three, they have a blunt abdominal tip.

31. Larvae of Culex spp

Respiratory siphon is rhomboid-shaped with multiple tufts of hair.

32. Habits of Culex spp

They live near humans and are active at night. They are common in newly developed urban areas.

33. Culex quinquefasciatus

It is the main nuisance mosquito and a vector of filarial worms.

34. Culex tritaeninorhynchus

It transmits Japanese encephalitis.

35. Sandflies

Sandflies are called Phlebotomus.

36. Appearance of Adult Phlebotomus

• They are small blood-sucking mosquitoes, 2-4mm long

• Pale yellow

• Humpbacked, long and pointed wings, the wings of sandflies have many hairs. Their bodies are also covered in hairs

• At rest, the wings remain upright on the back.

37. Biological Characteristics of Phlebotomus

• They live in hot climates or rodent burrows, wall crevices

• They are active at night, especially in warm and humid conditions. During the day, they rest in rock crevices, dense vegetation

• They do not fly far from their breeding sites.

38. Phlebotomus as Disease Vectors

Phlebotomus are vectors of:

• Leishmania

• Carrion’s disease

• Arboviruses

39. Consequences of Phlebotomus Bites

The bite site will be painful, causing urticaria, and may lead to fever.

Note: This article provides general information about mosquitoes and their role in disease transmission. To prevent diseases transmitted by mosquitoes, it is important to implement appropriate mosquito control measures.