an introduction to insects · digestive tract defensive glands communication glands insect...

1

Master Gardener TrainingMichael E. Merchant, PhD, BCE

[email protected]

Copyright Texas AgriLife Extension

An Introduction to Insects

Texas Cooperative Extension

What are insects and mites?

Phylum Arthropodabilaterally symmetricalhard outer exoskeletonsegmented bodiesjointed legs

Arthropod Examples

Lobsters, crabs, shrimp (Crustacea) Spiders, mites, scorpions (Arachnida)Centipedes, millipedes (Chilopoda) Insects (Hexapoda)

the most diverse form of life on the planet

Recent estimates of species diversity• 1.2 million species

described• Total estimated species

count: 8.7 million (Eukaryotes)• 2.2 million marine

• 86% of existing species undescribed (96% of marine species)

(Mora et al. 2011)

Three main body regions

• Six legged• Antennae• Metamorphosis

Insect Characteristics

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Head: Center for sensory perception

Photo ® Van Waters & Rogers /

Eyes Palpi

Antennae

Thorax: Center for movement


LegsWings

Abdomen:


Reproductive organs

Digestive tract

Defensive glands

Communication glands

Insect exoskeleton


Made of chitinous proteins strong resilient ideal for small organisms

Covered with wax layers for waterproofing

Pesticides designed to affect insect skeletal systems:

Diatomaceous earthAbrades insect cuticles

Silica aerogelsAbsorbs waxes from

exoskeleton

Note: Dessicants only really effective in dry environments.

Insect respiratory system

Simple series of tubes and openingsSpiracles Tracheae

Respiratory system


Spiracle

Trachea

Horticultural oil Vegetable oils

Mineral oils

armored scales

mosquito larva

Oil: An insecticide for all spiracles How insects grow and develop Molting occurs during immature stages Stages between molts called “instars”

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Cicada nymph final molt

Courtesy USDA ARS image gallery

Metamorphosis: (<Greek) a change in form

No metamorphosis in two groups: springtails and silverfish

Gradual * metamorphosis: grasshoppers, termites, thrips, dragonflies

Complete metamorphosis: beetles, butterflies and moths, flies, bees and wasps, ants, fleas

Gradual metamorphosis


Three life stages: egg, nymph, adult

Immatures called “nymphs” share a resemblance to the adult

Wing-pads develop externally

Gradual metamorphosis

Photos ® Van Waters & Rogers /

Egg

Nymph

Adult

Complete metamorphosis

Most advanced form of development

Four life stages: egg, larva, pupa, adult

Immature form called “larva”

Wings develop internally in larvae

Complete metamorphosis

Photos ® Van Waters & Rogers /

Eggs

Larvae

Adult

Pupa

Types of mouthparts

Chewingcrickets, termites, beetles,

caterpillars Piercing/suckingplant bugs, fleas, lice, mites,

hoppers Spongingsome flies

Siphoningmoths and butterflies

Chewing mouthparts

Side to side movementUpper lip: labrumJaws: mandibles,

maxillaeTongue: hypopharnyxLower lip: labium

Chewing, boring, mining damage possible

Piercing/sucking mouthparts

Microscopic food channel for liquids

Plant wilting, honeydew, disease transmission possible

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Usually folded under body, between legs

Milkweed bug, Oncopeltus fasciatus

Piercing sucking mouthparts Sponging mouthparts

Sponge-like labella on certain flies

Capable of feeding only on exposed liquids such as nectar or sap

Capable of transmitting pathogens in the house fly & blow fly

Siphoning mouthparts

Flexible maxillae form soda-straw like mouthparts

Incapable of piercing skin or plant surfaces.

How insects are classified and named

Carl Linnaeus (Carolus Linnaeus) 1707-1778

Father of taxonomy, born in Sweden

Professor, Uppsala University developed today’s system of

scientific names Species Plantarum (1753), Genera

Plantarum (1754) and SystemaNaturae (1758) standard reference for naming plants and animals

Linnaeus’ created a taxonomy

*added later by Latrielle

(> Greek: taxa=to arrange, classify or place)Memory aide

King Philip Came Over From Gloria Spain

Kingdom, Phylum, Class, Order, Family, Genus, Species

A word about scientific names..Blatella germanica (Linnaeaus)Genus species Author

Common names:croton bug (NY)German cockroach (U.S.)steamfly (U.S.)waterbug (U.S.)cucaracha (Spanish)küchenschabe (German)*&#@$!!* (universal)

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Wild and crazy namesTropical canopy-inhabiting beetles by Terry

IrwinAgra vationAgra cadabraAgra katewinslettae (ESA Newsl. 9/2005)

Hemipteran genera described by G. W. Kirkaldy in 1904Ochisme (sounds like O kiss me)PolychismePeggichismeDolichisme, etc. (Berenbaum 1993)

Wild and crazy names Tiphiid wasp described by V.S.L. Pate in 1947 Lalapa lusa (op. cit.)

Liparid fly named by B. Neumoegen in honor of colleague H.G. Dyar in 1893 dyaria (op. cit.)

Three species of slime mold beetles named by Q. Wheeler and K. Miller in 2005 Agathidium bushi Agathidium cheneyi Agathidium rumsfeldi (ESA Newsl. May 2005, Bull. Am. Mus.

Nat. Hist. 291 (1), 1-167)

Lots more at: http://home.earthlink.net/~misaak/taxonomy/taxPuns.html

How to classify?

Insect Orders 30 total, 5 “Big Orders” Archaeognatha (bristletails) Thysanura (silverfish) Ephemeroptera (mayflies) Odonata (dragonflies) Plecoptera (stoneflies) Isoptera (termites) Blattodea (cockroaches) Mantodea (mantids) Grylloblattodea (ice crawlers) Mantophasmatodea Orthoptera (grasshoppers) Phasmatodea (walking sticks) Embiidina (webspinners) Dermaptera (earwigs) Zoraptera

• Psocoptera (booklice)• Phthiraptera (lice)• Thysanoptera (thrips)• Hemiptera (bugs, aphids, etc)

Holometabolous orders• Megaloptera, Raphidioptera,

Neuroptera• Coleoptera (beetles)• Strepsiptera• Mecoptera (scorpionflies)• Siphonaptera (fleas)• Diptera (true flies)• Hymenoptera (bees, wasps, ants)• Tricoptera (caddisflies)• Lepidoptera (moths, butterflies)

Ptera = Latin for wings

Order Hemiptera Name: Hemi- half,

ptera=wing

Metamorphosis: gradual

Mouthparts: piercing/sucking

Two large suborders

Suborder Homoptera: Cicadas and their relatives

Name: homo = same, ptera = winged

Food: plant feeders

Notes:Wings uniformly membranous, held roof-like over the body. Aphids, whiteflies, leafhoppers, scales

Homoptera: mealybugs,aphids, leafhoppers, scales

Suborder Heteroptera: true bugs

Name: heteros Gr.= different, ptera = winged

Metamorphosis: gradual

Mouthparts:piercing/sucking

Food: plant feeders, predators

Heteroptera: True bugs

Only outer half of wings membranous, held flat over the body. Stink bugs, plant bugs, assassin bugs, leaf-footed bugs, etc.

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Coleoptera: Beetles

Name: Coleo = sheath, ptera = winged

Metamorphosis: completeMouthparts: chewingNotes: Only 2nd pair of wings used in

flight. Most diverse insect order. Many important pests of outdoor plants, stored grains and wood.

Beetle takingflight

First pair of wings is the elytra

Diptera: Flies

Name: di = two, ptera = winged

Metamorphosis: complete

Mouthparts: sponging, piercing/sucking

Notes: Excellent fliers. Larvae are legless and generally found in water or around wet environments. Many important indoor and outdoor pests.

Diptera: Flies

Diptera larvae

Legless and generally found in water or around wet environments.

Lepidoptera: moths and butterflies

Name: lepido = scale, ptera = winged

Metamorphosis: completeMouthparts: siphoningNotes: Scaly wings, often colorful. Some

important pests of fabric, stored products.Texas Cooperative Extension

Lepidoptera

Immature form: caterpillar

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Hymenoptera: Bees, wasps and ants

Name: humen = membrane, pteron = wing

Metamorphosis: complete

Mouthparts: usually chewing

Notes: Abdomen and thorax joined by narrow waist. Many social.


bees

parasitic wasps

ants

aculeate wasps Texas Cooperative Extension

Other notable Orders…

Collembola: springtails

Odonata: dragonflies

Orthoptera: Grasshoppers

Mantodea: mantids

Isoptera: termites

Isoptera: fleas

Every July, the fleas would test their endurance in the grueling Tour de Frank.

1

Master Gardener TrainingMichael E. Merchant, PhD, BCE

[email protected]

©2004 Texas Cooperative Extension

Problems with insecticides

Heavy use resulted in resistance

Toxic to non-target organisms

Secondary pest problems

Integrated Pest management

IPM - a strategy that focuses on long-term suppression of

pests uses a combination of control tactics minimizes pesticides’ negative impact

on people and the environment strives to be economical

The IPM pyramidPesticides

Biological controls

Physical / Mechanical

controls

Cultural / Sanitation Practices

Non-chemical controls for pests

cultural

mechanical

biological

Pesticides What are pesticides? Any substance or mixture of

substances used for controlling, preventing, destroying, repelling, or mitigating pests. insecticides, herbicides, fungicides,

bactericides, repellents, attractants

Pesticide modes of action

Nervous system poisons Metabolic inhibitors Hormone mimics Physical poisons Repellents Attractants

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Not all pesticides are equally hazardous!

How safe is this pesticide?Everyone wants to know

The dose makes the poison

Paracelsus (1493-1541) “All substances are poisons; there is none

which is not a poison. The right dose differentiates a poison and a remedy.”

Dose-Response Curve Dose-Response Curve

Some terms

LD50 (Lethal Dose 50) - The amount of material needed to kill half of a test population

Mg/Kg – The amount of toxin (in milligrams) per Kilogram of body weight of the test subject (equals parts per million)

EPA Pesticide Toxicity Classes

Pesticide Safety

Acute toxicityRapidly produced toxicity, usually resulting from a single exposure

Chronic toxicityToxicity due to slow-action or long-term exposure to a poison

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Pesticide Safety

Possible chronic effects:Carcinogenicity-cancer

Mutagenicity-genetic mutation

Teratogenicity-birth defect

Oncogenicity-tumors

Reproductive effects

Delayed neurological effects

Tests required to register a pesticide

Acute oral toxicity Acute dermal toxicity Acute inhalation Acute intraperitoneal Eye irritation Dermal irritation Dermal photosensitization Acute delayed neurotoxicity 90-day rat feeding study 12-month dog feeding study

21 & 90-day dermal Lifetime rat feeding study Lifetime mouse feeding

study Teratology (rat) Teratology (rabbit) Reproduction Excretion/metabolism &

accumulation Antidote Mutagenicity

It is impossible to provide experimental evidence that

anything is ABSOLUTELY safe!

Toxicity x Exposure = Hazard

Pesticide labeling Pesticide labeling

Most important source of information The label is the Law Read the label

before you buy/sell the product before you use the product before you dispose of the product

Common vs. trade names Trade name is a

proprietary name used by a company (e.g., Sevin®)

Common name is the generic name for the pesticide (e.g., carbaryl)

Extension publications use common names

The public looks for trade names : (

Pesticide formulations

Granules Baits Dusts Liquid concentrates Aerosols Suspensions RTU (ready to use)

Insecticide chemical classes

Organo-phosphates Carbamates Botanicals Pyrethroids Neo-nicotinoids Others

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Organophosphates

Many common pesticides chlorpyrifos (Dursban) diazinon acephate (Orthene) malathion

Disappearing from market

Botanicals

Pesticides derived from plants pyrethrins neem extracts & oils rotenone Mint oils citrus oils clove oil other essential oils

Pyrethrins

From ground-up flowerheads of pyrethrum daisies

A natural combination of six compounds: pyrethrins I and II, jasmolin I and II, and cinerinI and II

More uses approved than any other insecticide Usually includes a “synergist” to keep insects

from detoxifying it

Chrysanthemum cinerariifoliumC. coccineum

Spring cankerworm

Pyrethroids Synthetic chemicals based

on study of pyrethrinschemistry

Broad spectrum replacements for Dursban®, diazinon

Residual and stomach poisons

Low in toxicity to birdsand mammals, but hazardous to fish

University of Florida

Pyrethroids

Recognize by suffixes: -thrin or –ate

Examples: Esfenvalerate Permethrin Bifenthrin Cyfluthrin Allethrin Sumithrin Others

Neonicotinoids

New class of systemic pesticides imidacloprid (Bayer) dinotefuran (Spectracide?)

Effective against Homoptera Coleoptera (chewing, boring) Thysanoptera

Relatively low in mammalian, bird toxicity

Organic vs. synthetic

“organic” pesticides include products derived from natural sources

Synthetic pesticides are human-produced

Poison ivy

Are organic products inherently safe?

Giant hogweed

Plants also have carcinogens!

Tobacco (leaf) - 7 carcinogens Strawberry (fruit) - 7 carcinogens Onion (bulb) - 6 carcinogens Tea (leaf) - 6 carcinogens Carrot (root) - 6 chemicals Cauliflower (leaf) - 5 chemicals Grapefruit (fruit) - 5 chemicals

Source: Phytochemical Database, USDA - ARS - NGRL http://www.ars-grin.gov/duke/activity.html

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Low impact pesticides

Pesticides with minimal impact on people and on beneficial organisms, including beneficial insects


Insecticidal soaps & oils Kill small and soft-bodied

insects and mites. Contact insecticide with short residue.

Examples: Safer’s soap, Sunspray Ultrafine Spray Oil, vegetable and neem oils


Microbe-derived Consisting of, or derived from microbes. The

best are low in toxicity to humans and non-pathogenic to non-target organisms.

– Examples: Bacillus thuringiensisproducts, spinosad

Low impact pesticides Baits

Mixture of an insecticide with some sort of food attractive to pest. Generally low percentage active ingredients make these relatively safe.

Examples: fire ant baits, containerized cockroach baits, granular ant, cockroach and cricket baits

Low impact pesticides Botanicals

Derived from plants. Although some active ingredients are toxic, generally formulated as a low percentage a.i. and degrade quickly in the environment.

Examples: pyrethrum, rotenone, neem extract, mint oils, capsacin, others...

Low impact pesticides Insect growth regulators

Based on insect hormones unique to arthropods

Disrupts reproduction, molting, other growth processes

Excellent safety record Products for fire ants,

white grubs, fleas, others

Low impact pesticides Other low toxicity

pesticides Kill through physical or

stomach poison action. Generally non-toxic on skin. Examples: silica aerogel,

diatomaceous earth, boric acid and borate compounds, sulfur

Parts of a Label

Trade name Chemical name Common name Formulation type Allowed sites

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Parts of a Label

Precautionary statement

First aid Environmental

statement EPA Registration

number Directions for use Disposal instructions

Leeway with labels?

Very little Can use on pests not

listed only if the site of application is listed

In most cases you can use LOWER rate than on the label

Pesticide signal words

Caution LD50 greater than

500 mg/Kg Warning

LD50 50-500 mg/Kg Danger - Poison

LD50 less than 50 mg/Kg

1

Master Gardener Entomology TrainingMichael E. Merchant, PhD, BCE

[email protected]

Copyright Texas AgriLife Extension

Common Texas pests

Different types of insect damage Chewing

Mining Skeletonizing leaf feeding root feeding Boring

Sucking Meristem feeding Phloem feeding Mesophyll feeding

Gall making

Chewing insects

Tobacco budworm on petunia

Root feeding by Pyllophaga

Leaf skeletonizing by oak sawfly

Chewing pests Caterpillars

sawflies

beetles

grasshoppers

snails and slugs

Fall webworm/tent caterpillar

East

ern

tent

cat

erpi

llar

Fall

web

wor

m

Fall webworm Physical removal of webs,

larvae on smaller trees

Insecticides

Adult fall webworm

Chemical caterpillar control


soaps and oils

Bacillus thuringiensis

Spinosad Fertilome® Borer, Bagworm,

Leafminer & Tent Caterpillar Spray

Greenlight® Spinosad

pyrethroids

20/40 Rule for defoliators 20% spring

defoliation

40% summer defoliation before tree health is affected

Bagworm

Life spent in silken cocoon

Females wingless

One generation/year

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Bagworm

hand removal

Bt, spinosad

Pyrethroidinsecticides work well

Bagworm damaged tree

Photo courtesy Neil Sperry

What would you do?

Fall caterpillars

Damage usually not important to tree health

Spray tree with low impact pesticide for aesthetic purposes Treat tree with hose-end

sprayer or hire arborist for large trees

Walnut caterpillar on pecan

Leaf rollers and tiers Caterpillars specializing on various plants

Leaf roller on redbud

Leaf rollers and tiers Difficult to control

with insecticides

Early treatment best

Systemic insecticidesOrthene

Lesser canna leafroller

Fate of 3 types of insecticides

Contacts kill only through direct contact (you get what you hit!), otherwise they evaporate Soap, oils

Residuals remain on plant surfaces for varying times malathion, carbaryl (Sevin), diazinon, cyfluthrin (Bayer

Advanced Garden), permethrin (Spectracide Pro)…

Systemics absorbed by, and work from inside plant acephate (Orthene), imidacloprid (Merit), dinotefuran

(Safari)

Sawflies

Caterpillar-like Not susceptible to Bt,

spinosad Identification Single eyeFive or more pairs of

prolegs on abdomen

Loblolly pine sawfly

Snails and slugs Sanitation

Traps

Barriers

Baits metaldehyde iron phosphate

Grasshoppers Periodic outbreaks in rural

and urban fringe areas

Row covers

Insecticides permethrin (Conquest,

Spectracide) cyfluthrin (Bayer) bifenthrin (Ortho) esfenvalerate

Beetles


Residual insecticides work well

Flea beetles on crape myrtleCucumber beetle

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White grubs Immature form of the June

beetle

Underground root feeder 5-10 grubs per ft2

One generation per year Adult emergence in June,

July Ideal treatment time around

4th of July (July-early August)

White grub controls for homeowners

Granular insecticides imidacloprid + cyfluthrin (Bayer Advanced

Lawn® Complete Insect Killer) halofenozide (Scott’s GrubEx - old) Trichlorfon (Dylox®, Bayer Advanced Lawn

24-Hour Grub Killer Plus) chlorantraniliprole (Scott’s GrubEx)

Water-in with at least 1/2 inch water after application.

Sap-feeding insects

Brown soft scale

Aphid

Phloem feeders

Feed on the phloem (sap) of plantsAphidsWhiteflies Plant bugs ScalesMealybugs

Aphids

Pear-shaped

Long legs

Tiny tails (cornicles)

Found in colonies

Diagnosing aphids

Pear-shaped insects on leaves, stems (with or without wings) Cast skins Honeydew deposits

Honeydew

Crepe myrtle aphid and black sooty mold

Scale-caused black sooty mold

Aphids High reproductive rate Parthenogenesis (able to

reproduce without mating)

Damage plants via feeding, honeydew, disease transmission

Subject to many natural enemies

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Aphid natural enemies

Syrphid fly

Lady beetle

Green Lacewing

Aphid natural enemies-immature forms

Lacewing larva

Lady beetle larva

Syrphid fly larva lady beetle pupae

Bev Wigney, magickcanoe.com

New Mexico State University, http://www.nmsu.edu/biocontrol/bugs/

Healthy aphids

Parasitized aphid An aphid’s worst nightmare: parasitoidsEmerging parasitoid

Aphid mummies

Parasitoid stinging aphid

Aphid control

protect natural controls

water streams

soaps and oils

pyrethrins

systemics

organo-phosphates

USDA

Whiteflies Nymphs are sap

feeders on leaf undersides

Adults small, whitish flying insects

High reproductive rate

Often difficult to control

Adult whitefly

Whitefly control Soaps and oils

good coverage essential

Pyrethrins/neem Systemic insecticides

acephate (Orthene) imidacloprid

Multiple treatments may be needed on 7-10 day cycle

May be a secondary pest

Scale insects Euonymous scale

Brown soft scale

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Scale insect control

Soaps and oils dormant vs. summer oils

systemic insecticides

sprays timed to kill crawler stage

Scale crawlers

Crape myrtle bark scale

New pest on crape myrtle

dark trunks, leaves (black sooty mold)

dinotefuran, imidacloprid

Thrips Very tiny most commonly eaten

insect

Feed on meristemtissue

Damage: delay in growth darkening of flowers puckering and stunting

Thrips damage on chrysanthemum, U of Kentucky

Thrips control Systemic

insecticides acephate (Orthene)Disulfoton

Spinosad Treat before damage

becomes severeGreenhouse thrips

Mesophyll feeders Spider mites Lace bugs

Leafhoppers

Other plant bugs

Spider mites Fast reproductive rate

Live on leaf undersides

Favored under hot, dry conditions

Can be worsened by some insecticides permethrin imidacloprid

From w

ww.plantlilies.com

Spider mite control

Water streams Soaps and oils

pyrethrins

sulfur

bifenthrin

Lace bugs

lantana lace bug

http://ww

w.cedarcreek.um

n.eduD

r. John Haarstad

Corythuca

arcuata

Borers Enter as larvae through

weak spots in bark Adult forms emerge from

holes chewed in bark One generation per year,

usually

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Borer damage

Adult borers

University of Colorado

Borers Good horticultural

practices can prevent many kinds

Avoid wounding, damage to bark

Residual insecticides: permethrin cyfluthrin

Galls Plant response to a

stimulus or injury

Galls formed when tissue is growing

Most plants are not hurt by galls

No effective sprays for galls that have formed

Galls caused by wasps

Fire ants, Solenopsis invicta Exotic pests from South

America

Range from 40 to 400 mounds per acre

In addition to nuisance, can be economically, medically important

Fire ant mounds

Step 1: Let them eat bait

Broadcast a fire ant bait over the entire yard

Use a seed spreader to ensure uniform coverage

Secrets to success with baits

Apply only fresh baitscheck date of

manufacture test some first

Apply when rain is not expected

Apply when ants are active

Check date of manufacture or test first

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When are fire ants active? When soil surface

temperatures are between 70° and 95° FMay - September in

most areasEvenings during hot

weather

Fire ant bait products Amdro AmdroYard

Treatment Amdro Ant Block Conserve Once and Done Extinguish Extinguish Plus Distance Maxforce

How often should baits be applied? Every 8 weeks, or as

needed hydramethylnon (Amdro ®) spinosad (Eliminator ®)

Once or twice a year methoprene (Extinguish ®) pyriproxifen (Spectracide ®,

Distance ®) hydramethylnon+methopren

e (Amdro® Firestrike Fire Ant Bait)

Step 2: Treat the mounds

Treat problemmounds with an individual mound treatment

Not all mounds need to be treated

Individual mound treatments

Liquid concentrates and Ready-to-use liquids

Granular insecticides

Dusts

Aerosols

“Organic formulations”

Secrets to success with mound treatments

Use 1 to 2 gallons of water per mound when using liquids, granules and some dusts

Don’t disturb the mound unnecessarily

Insects in the City

Insect F@ctSheets

http://citybugs.tamu.eduUseful Internet Sites Http://insects.tamu.edu

AgriLife Extension Bookstore http://agrilifebookstore.org

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http://bugguide.netThe End

an introduction to insects · digestive tract defensive glands communication glands insect...

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