Poultry and Insect Labs

Insect Genetics for Agriculture and Human Health Applications

Basics of Insects

• Insects are classified as arthropods with distinct characteristics such as:

  • Chitin in exoskeletons

  • Segmented bodies

  • Compound eyes

• They represent the most diverse animal group, with over 1 million species documented.

• Insects play critical roles in ecosystems, particularly in pollination.

• While they are essential to ecological balance, some insects are pests and can transmit diseases.

Types of Insects

• Examples of different insect types include:

  • Stonefly (Plecoptera)

  • Dragonfly (Odonata)

  • Earwig (Dermaptera)

  • Tree cricket (Orthoptera)

  • Scale (Homoptera) and more.

Genetic Studies on Insects

• Genetic studies focus on:

  • Developmental genes leading to advancements in epigenetics understanding.

  • Inheritance, gene linkage, and the role of sex chromosomes.

  • Genes affecting disease transmission and lethality, particularly in pest populations.

  • Genes influencing social behavior in species like bees.

Model Organisms in Genetics

• The fruit fly (Drosophila melanogaster) serves as a primary model organism: - Short reproduction cycles and suitability for mutation studies.

  • Discovery of developmental (Hox) genes.

  • Provides examples for linkage labs.

Hox Genes in Fruit Flies

• Hox genes play crucial roles in development, determining body plan:

  • Specific genes expressed in corresponding chromosomal locations include genes such as Dfd, Scr, Antp, Ubx, Abd-A, and Abd-B.

Problematic Insects for Agriculture and Human Health

• Mosquitoes transmit diseases that infect over 700 million and kill more than 1 million people annually.

• Ticks, prevalent in areas like New York, cause diseases such as Lyme disease.

• Aphids can vector over 150 plant viruses, significantly impacting crops, e.g., cotton.

Other Harmful Insects

• Mealy bugs and the New World Screwworm (Cochliomyia hominivorax) pose threats through myiasis in humans and livestock.

Life Cycle of the New World Screwworm Fly

• The screwworm has a complex life cycle involving:

  • Gravid females laying eggs on wounds.

  • Larvae dropping to the ground and burrowing into soil for development.

Chemical Control Methods

• Use of insecticides has drawbacks:

  • Expensive and require frequent applications.

  • Can harm beneficial insects, such as honeybees.

  • Pest insects can develop resistance.

Biological Control

• Example: Aphidius colemani, a parasitoid wasp used to control aphids:

  • Wasps lay eggs inside aphids, ultimately leading to the aphid's death.

  • Results in sustainable pest management solutions.

Genetic Control Methods

• Genetic control methods are more complex but less frequent in application:

  • They cause no harm to off-target insects.

Sterile Insect Technique (SIT)

• A biological control method that involves:

  • Mass-rearing and sterilizing male insects using ionizing radiation.

  • Releasing them into wild populations to mate with females to reduce insect populations.

Gene Drives

• Involves releasing genetically modified insects that can alter wild populations:

  • Can introduce lethal genes or promote beneficial traits, like reduced disease transmission.

  • Small populations have the potential for significant ecological impact, raising concerns.

Honeybee Genetics

• Honeybee castes are determined by sexual reproduction:

  • Drones (haploid), queens (diploid), and worker bees (diploid).

• The haplodiploidy system allows unrecombined male production from unfertilized eggs.

  • Studies focus on genetics related to behavior and traits such as honey production or disease resistance.

Queen Life Cycle of Honeybees

• The queen lays fertilized and unfertilized eggs:

  • Fertilized eggs become diploid females (workers or queens).

  • Unfertilized eggs develop into haploid males (drones).

Summary of Insect Genetics

• Highlights the importance of insects in genetic research.

• Significant insects cause major issues in agriculture.

• Effective genetic techniques for controlling these insect populations are critical.

Poultry Genetics Overview

• The U.S. is the largest poultry producer globally, with chicken and turkey production valued over $75 billion in 2022.

• Breeds differ significantly between egg (such as White Leghorn) and meat (Cornish Cross) production.

Benefits of Poultry Production

• Poultry offers low-fat, high-protein, and rapidly produced meat compared to larger livestock.

• Growth rates vary: chickens mature in about 7 weeks, while turkeys take 14-18 weeks.

Current Poultry Production Methods

• Efficiency and space considerations:

  • Feed conversion rates: chickens (1.5-2.0), pork (5), beef (10).

  • The popularity of humane production practices like free-range systems is on the rise due to health and ethical concerns.

Genetics and Resistance in Chickens

• Genetic resistance to pathogens like salmonella is essential for chicken health.

• Vaccination and improved production conditions are potential solutions to emerging diseases.

Molecular Techniques in Poultry Genetics

• Use of CRISPR technologies to enhance genetic traits in poultry, focusing on disease resistance and growth rates.

Backyard Poultry

• Increased interest in backyard poultry suggests a cultural shift towards sustainable and personal food sources.

Types of Poultry

• Lesser-known poultry like quail, ducks, and guinea fowl have unique advantages or are gaining popularity in small-scale production.

Conclusion

• Poultry is a significant industry with ongoing challenges and opportunities for genetic advancements.

• Research continues to evolve in response to production needs and ethical considerations.