Mosquitoes

mosquitoes and vector bionomics

1. By Dr Utpal Sharma Assistant Professor Department of Community Medicine SMIMS, Gangtok, Sikkim

2. Inroduction Derived from the spanish word “ Musketas ” in Spanish and Portugese it means “small fly” These arthropods have w orldwide distribution Species are grouped by genus according to their physical characteristics. More than 3450 species and subspecies found worldwide divided in 38 genera. Approximately 40 million years older than humans (fossils from Eocene)

3. Cont…. From the family Culicidae of the order Diptera and are similar in appearance to other flies There are three genera of medical importance: Culex - About 88 species Aedes - About 700 species Anopheles- About 460 species Great habitat diversity

4. Morphology Body : small, fragile, 3-6mm long Distinguishing of sexes: Antenna : plumose in male, pilose in female Palp External genitalia A long proboscis 3-5 times as long as head or about as long as head and thorax Mouthparts , piercing and sucking type. Proboscis and 6 needles.

5. Proboscis and palp ….

6. Antenna of mosquitoes Male (Plumose) Female ( Pilose )

7. Morphology of mosquito

8. Characteristics of mosquitoes Adult mosquitoes are terrestrial and capable of flight. With piercing-sucking mouthparts, the females feed mostly on animal blood and plant nectar Males mouthparts are modified to suck nectar and plant secretions. Eggs develop a few days after females take a blood meal. Females oviposit on the water, in crevices in the soil….. ….and also in special niches that are flooded such as natural and artificial containers or tree holes.

9. Habitat of mosquito

10. Habitat cont….

11. Life cycle of mosquito Egg Larva Pupa Adult

12. Life cycle of mosquito Like all flies, mosquitoes go through four stages in their lifecycles: egg, larva, pupa, and adult or imago. The first three stages—egg, larva, and pupa are largely aquatic. These stages typically last five to 14 days, depending on the species and the ambient temperature. Eggs hatch to become larvae, which grow until they are able to change into pupae. The adult mosquito emerges from the mature pupa as it floats at the water surface.  Depending on species, gender, and weather conditions, adult lifespan ranges from a week to several months.

13. Holometabola Larva (4 stages)— 7 days Pupa – 2-3 days Adult-10-14 days total. Egg — 1-4 days

14. Life cycle of mosquitoes Larva has a well-developed head with mouth brushes used for feeding.... ......a large thorax with no legs, and a segmented abdomen Larvae breathe through spiracles located on their eighth abdominal segments, or through a siphon.   Spends most of their time feeding on algae, bacteria, and other microbes in the surface  microlayer . Develop through four stages, or instars, after which they metamorphose into pupae At the end of each instar , the larvae molt, shedding their skins to allow for further growth.

15. Larva of mosquito Siphon tube

16. Larva… Palmate hair

17. Pupa of mosquito…. The mosquito pupa is comma-shaped. The head and thorax are merged into a  cephalothorax … …..with the abdomen curving around underneath.  Pupa swims actively by flipping its abdomen, and is called a "tumbler" because of its swimming action.  Comes to the surface frequently to breathe through a pair of respiratory trumpets on their cephalothoraces . Pupae do not feed during this stage. They pass their time hanging from the surface of the water by their respiratory trumpets.

18. Pupa to adult…. After a few days or longer, the pupa rises to the water surface…. ……….the dorsal surface of its cephalothorax splits, and the adult mosquito emerges. Development varies among species and is strongly influenced by ambient temperature.   Mosquitoes can develop from egg to adult in as few as five days to 40 days (in tropical conditions). Males typically live for about 5-7 days, feeding on nectar and other sources of sugar. The female will rest for a few days after the blood meal, while the blood is digested and eggs are developed. 

19. Pupa….transformation… Pupa Adult mosquito emerging from pupa

20. Difference between Male and female mosquitoes Female mosquito is the larger one. Female mosquito has longer proboscis Male mosquito has more bushy antenna   Male has palps as long as proboscis or even longer Low pitched whinny buzz indicates female mosquito.

21. Difference between different species of mosquitoes

22. Cont….

23. The adult mosquitoes Culex Aedes Anopheles

24. Mosquitoes and diseases Annoyance pest: A mosquito bite may induce local dermatitis or even systematic reaction in sensitive persons . Parasitic diseases: Malaria and filariasis . Virual diseases: Japanese encephalitis B, Dengue fever and yellow fever. Mechanical transmitter: Some mosquitoes may carry fly eggs to humans, inducing myiasis .