Lecture Notes: Engineering Mosquitoes to Be Less Harmful

Introduction

• Speaker: Daniel Whitefield
• Works in Dr. Zach Edelman's lab at A&M, Entomology Department
• No prior experience with entomology
• Topic: Engineering mosquitoes to be less harmful

Understanding Mosquitoes

Why Do Mosquitoes Suck Blood?

• Not for food: They feed on nectar.
• Blood is for egg production: Females need blood for its protein to produce eggs.

How Do Mosquitoes Suck Blood?

• Mouthparts
  • Labium: Flexible part that bends back during feeding
  • Labella: Pads that contact the skin
  • Maxilla: Have saw-like teeth that cut the skin
  • Mandibles: Hold the skin apart
  • Hypopharynx: Injects saliva containing anti-clotting factors and painkillers
  • Labrum: Forms the blood-feeding tube

Impact of Mosquitoes

• Malaria
  • Transmitted by mosquitoes
  • Killed 627,000 people in 2020
  • Symptoms: Splenomegaly, hepatomegaly
• Dengue Virus: 40,000 annual cases
• Other Diseases: Yellow fever, Zika virus, West Nile virus, Chikungunya virus, Heartworms in dogs
• Estimated that mosquitoes are the deadliest animals on the planet

Types and Behavior

• Species: 3,600 different species
• Human-Targeted Genera: Aedes, Anopheles, Culex
• Research Focus: Mostly Aedes aegypti for its ease of lab work

Mosquito Life Cycle

• Starts with a blood meal
• Lay 40-50 eggs per blood meal
• Eggs hatch into larvae then pupate into adults

Strategies to Make Mosquitoes "Suck" Less

Prevention and Control

• Public Sanitation and Health Education
  • Importance of infrastructure and community engagement
• Surveillance and Monitoring
  • Genetic testing and disease prevalence tracking

Control Strategies

• Mechanical Control: Mosquito nets, removing stagnant water, sealing buildings
• Chemical Control: Insecticides (larvicides and adulticides)
• Biological Control
  • Fish that eat larvae
  • Wolbachia bacteria: Can suppress or replace populations
  • Bacillus thuringiensis israelensis: Acts as a biological pesticide

Genetic Control

• Sterile Male Release: Use of irradiated sterile males
• Genetic Modification and Gene Drive
  • Gene Drive: Pushes genetically modified genes through population
  • Biodegradable Gene Drive: Designed to delete itself over time for safety

Scientific Background

DNA and Repair Mechanisms

• DNA stores information for proteins
• DNA Damage Causes: Replication errors, metabolism, radiation, chemicals
• Types of Damage: Single-strand breaks, double-strand breaks, crosslinks, modifications
• Repair Mechanisms: Single strand annealing, homologous recombination

CRISPR-Cas9 Technology

• Acts as molecular scissors with map (sgRNA) to target specific DNA sequences

Gene Drive Mechanism

• Normal Inheritance: Genetically modified genes diluted over generations
• Gene Drive: Ensures modified genes dominate through generations
• Biodegradable Approach: Uses single strand annealing to delete modifications over time

Research and Safety

• Importance of safety in genetically modifying mosquitoes
• Collaboration with local governments and communities

Published Research

• Papers on gene drive safety and mechanisms of making gene drive biodegradable
• Discoveries related to male and female determinants in mosquitoes
• Modifications for female flightlessness

Daily Lab Work

• Rearing and maintaining mosquito populations
• Techniques include injecting embryos, genotyping, and feeding mosquitoes

Conclusion

• Importance of interdisciplinary knowledge
• Open floor for questions