Lecture 2

IPM - Integrated Pest Management IPM - an ecologically based pest control strategy that maintains pest species below the economic injury level by use of the most appropriate and _________________ _____________ methods available.

Why are insects so abundant? Small _____ - takes little food to mature to reproductive age

Ability to ___- escape enemies, adverse environmental conditions Unique _____ - waxy layer, strong exoskeleton, jointed legs High __________ capacity- e.g. CPB female can lay 3000 eggs Metamorphosis

- adults and young use different resources

Facts you should know about insects World-wide entomologists have described about 1 million species, systematists estimate between 2 and 10 million

There are about 100,000 species described in the U.S. 15,000 - 20,000 insect species in Minnesota

Q: How many (%) are pests? < ______% are injurious - ca. 3,000 species worldwide _______ pest insects in the United States

Insect Abundance and Diversity

1. Insects live in every habitable place on earth except ____ ____ 2. Chief _____________ of plants on the planet 3. Major ____________ of plant eaters (herbivores) 4. Key role in _________ of organic matter 5. Key role as _________ for other organisms a) In some human cultures insects comprise 10% of the diet

How Do Insects Cause Damage? Injury to crops DIRECT or INDIRECT injury

Injury to Humans and animals Blood feeding - disease transmission Internal & External Parasites Annoyance

Injecting toxic substances Destroy stored products and possessions

Pest - A living organism that occurs in such numbers and places so that it _________ with the availability, quantity of value of a managed resource.

Beneficial - An insect which favorably affects humans with the result of its _______ or Insect _________.

Losses in Agriculture Preharvest

_____%

Postharvest

_____%

TOTAL

_____%

Annual loss in the U.S. about $7 billion annually to insects

Pest Control

The application of technology, in the context of biological knowledge, to achieve satisfactory reduction of pest numbers or effects.

Control Strategies 1. Natural 2. Biological 3. Cultural 4. Legislative and Regulatory 5. Mechanical and Physical

6. Genetic 7. Chemical

External and Internal Anatomy I.

External Anatomy a. Insect Exoskeleton

II. Metamorphosis III. Insect Phylogeny a. Assemblages of insect orders

Function of the Insect Cuticle • • • • •

Protection Retards ______ loss Muscle ________________ sites _____________ located in cuticle Contains _________ organs – mechanical – chemical

ORDER CLASSIFICATION - based primarily on 3 characters 1. Mouthparts, e.g., chewing, sucking, etc.

2. Wings a. Present or absent b. If present - specialization of wings 3. Type of metamorphosis a. No discernible metamorphosis b. Simple (gradual or hemimetabola) c. Complex (complete or holometabola)

Mouthparts

• Chewing or mandibulate: Orthoptera • Sucking: All Hemiptera and Siphonaptera » Many other insects within the higher orders

Mandibulate: Chewing

Haustellate: Piercing-sucking

Wing Modifications

Elytra – modified forewings (mesothoracic) of beetles - Coleoptera

Wing Modifications Hemelytra – modified forewings (mesothoracic) of true bugs - Hemiptera

Wing Modifications Hemelytra – modified forewings (mesothoracic) of true bugs - Hemiptera

All insects with hemelytra have sucking mouthparts

Metamorphosis - change in form Ametabola - no metamorphosis

Example: Silverfish - Thysanura

Simple (Gradual) Metamorphosis Each stage looks like a minature adult

Eample: true bug, Heteroptera

Complete (complex) Metamorphosis •Immature is unlike the adult •The largest & most diverse orders have complete metamorphosis

Example: Tobacco hornworm, Lepidoptera

Internal Anatomy & Physiology

•

Digestive System

•

Respiratory System

•

Circulatory System

•

Nervous System

•

Reproductive System

Digestive System – Generalized Insect Gut

Foregut and Hindgut – derived from integument – lined w/ chitin Midgut – single cell layer thick, all digestion/absorption in midgut Malpighian tubules – equivalent to our kidney (N waste) Drawing from Pedigo

Respiratory System

Cross section through an insect thorax

 Note – 1 cell layer thick midgut  Trachea helps support organs – acts like mesentery  Major tracheal trunks around key organ systems Drawing from Pedigo

Insect Respiration – Trachea and Spiracles

Drawing from Pedigo

Tracheae

Respiration

Circulatory System  Dorsal aorta – only ___________ and a series of “hearts”  Hemolymph (insect ____________)  ____________ (=white blood cells)

Functions include: 1. Delivers fresh _____________ to brain 2. Hemolymph transports ________, hormones, waste 3. Hemocytes involved in _____________ and form a primitive immune system (cellular and humoral) 4. Acts as ________ fluid to help extend limbs, organs NOTE: Hemolymph does ______ function in gas exchange (O2, CO2)

Circulation of hemolymph in an open circulatory system Hearts (Ostia)

From Elzinga, Fundamentals of Entomology

Insect Nervous System Components 1. Brain 2. Paired ventral ganglia 3. Peripheral nerves

CNS

Drawing from Pedigo

Sensory Structures • Mechanoreception • Chemoreception • Photoreception

Reflex Action

Nerve Transmission Action Potential

Adult Female Aphid Sensory Organs 1. Antennae 2. Compound eyes

3. Tip of mouth (Labium)

Drawing from Minks and Harrewijn, 1987

Compound Eye

Reproductive Organs

Male

Female

Soybean Aphids are Parthenogenic: All offspring are female, born pregnant, give live birth Birth rate: 3-8/day for 30 days Generation time 7-10 days, double in 2-3 days

Management implications Resurgence (moderate kill) Before spraying Day 1 Day 3 Day 5 Day 7

1000 aphids 150 300 600 1200 Drawings from Minks and Harrewijn 1987

What is a Land-Grant Institution? 1. Established by an act of Congress in 1862, known as the Morrill Act.

a. “Donating Public Lands to the several States and Territories which may provide Colleges for the Benefit of Agriculture and Mechanic Arts. …..an amount of public land …. equal to thirty thousand acres for each senator and representative in Congress.” b. Land sales funded establishment of the University of Minnesota. c. Mandate was to: “…teach agriculture, military tactics, and the mechanical arts as well as classical studies”.

2. Hatch Act – 1887, Established the Agricultural Experiment Stations 3. Extension Service – Smith-Lever Act, 1914,

“In order to aid in diffusing among the people of the United States useful and practical information on subjects relating to agriculture…..”

PHYLOGENY OF MAJOR GROUPS OF INSECTS Protura Diplura Collembola

Entognatha (Hexapoda) (Parainsecta) Ectognatha

Archaeognatha

(Insecta)

Thysanura Paleoptera Dicondylia

Odonata Ephemeroptera Exopterygota Orthopteroid (9 orders)

Pterygota Neoptera Hemipteroid (6 orders)

Endopterygota Neuropteroid (5 orders) Mecopteroid (5 orders) Hymenopteroid (1 order)

PHYLOGENY OF INSECT ORDERS Order Entognatha

(Parainsecta) (Hexapoda)

Common Name

1. 2. 3.

Protura Collembola Diplura

Proturans Springtails Diplurans

4.

Archaeognatha

Jumping bristletales

5.

Thysanura

Silverfish

6. 7.

Ephemeroptera Odonata

Mayflies Dragonflies & damselfli

Ectognatha (Insecta) Dicondylia Pterygota

Paleoptera

Neoptera

Exopterygota – “Orthopteroidea” ca. 25,000 species, 9 orders 8. Plecoptera Stoneflies (1,500) 9. Embioptera Webspinners (150) 10. Blattodea Cockroaches 11. Mantodea Mantids 12. Grylloblattodea Rock crawlers 13. Dermaptera Earwigs 14. Orthoptera Grasshoppers & Cricke 15. Isoptera Termites 16. Phasmatodea Walking Sticks

Exopterygota – “Hemipteroidea” ca. 90,000 species, 5 orders 17. Zoraptera Zorapterans 18. Psocoptera Booklice and barklice 19. Phthiraptera Chewing & sucking lice 20. Hemiptera Bugs, aphids, leafhoppers Suborders: Heteroptera & Homoptera 21. Thysanoptera Thrips Endopterygota (Holometabola) - ca. 700,000 species) Neuropteroidea (5 orders) 22. Megaloptera Alderflies & Dobsonflies 23. Raphidioptera Snakeflies 24. Neuroptera Lacewings 25. Coleoptera Beetles 26. Strepsiptera Twisted-winged flies Hymenopteroidea (1 order) 27. Hymenoptera Wasps, bees & ants Mecopteroidea ( 5 orders) 28. Mecoptera Scorpionflies 29. Siphonaptera Fleas 30. Diptera Flies 31. Trichoptera Caddisflies 32. Lepidoptera Butterflies & moths