master gardener entomology module 2010

Entomology Crash Course for

Master Gardener Interns

Dr. Ayanava MajumdarExt. Entomologist, State SARE Coordinator

Gulf Coast Research & Ext. Center8300 State Hwy 104, Fairhope AL 36532

Tel: (251) 331-8416bugdoctor@auburn.edu

Entomology Crash Course Objective: opportunity to closely examine insects and understand ecological functions

Course lay-out:

• Insect form & function

• Insect classification

• Types of insect injuries

• Integrated pest management

• Insect monitoring using traps

• IPM in tomatoes

• Citrus psyllid - a new invasive insect

LET’S TAKE THE PRE-TEST FIRST!

Insect Form & Function

This sign indicates study of real insect specimen using a digital microscope (Dino-Lite Pro)

Fun Facts about insects

• Insects have been around for at least 350 million years

• Over 900,000 described species (75% of all animal species)– U.S. has about 91,000 described species – Less than 1% of these are considered pests

• Four largest insect orders: beetles (Coleoptera), flies (Diptera), ants (Hymenoptera), moths (Lepidoptera)

• Small size, cryptic in nature• Small food requirement• Rapid and prolific reproduction

– Parthenogenesis• Grows by molting (control over

growth rate)• Life stages feed on different

substrate

Why are INSECTS so successful?

– Segmented bodies and jointed appendages– Exoskeleton shed periodically

• Characteristics Insects:– Three body regions (head, thorax and abdomen)– Six legs or less or zero (NEVER more!)

Characteristics of arthropods

Grasshopper specimen

• Insects have a cuticle, cuticle has chitin

Insect Exoskeleton

Chitin molecules interlink to provide strength!

Exocuticle

Endocuticle

Epicuticle (topmost)

Hard cuticle of a cockroach

• Insects need to shed (molt) old skin to grow in size.

• The period between molts is called an instar.

• Most insects have 4–8 instars before becoming adult.

Insect Growth

Cicada nymph molts into an adult

• Metamorphosis: drastic change in shape and form for growth and development.

• Two types: complete and incomplete.

• The stage of development of an insect will affect insecticide efficacy:

Insect Growth

Complete metamorphosis

EGG

LARVA (mobile stage)

PUPA

ADULT

WHAT COULD BE THE ADVANTAGES OF THE LIFE STAGES?

Incomplete metamorphosis

WHAT COULD BE THE ADVANTAGES OF THE LIFE STAGES?

Insect mouthpartsInsects can be classified according to mouthparts

TYPE 1. Chewing Mouthparts:

• Examples – grasshoppers, beetles, weevils, cockroaches

• 4 basic parts; Mandibles used for chewing!

• Cannot feed on liquid materials

Grasshopper mouthpartsBeetle mouthparts

Insect mouthpartsTYPE 2: Chewing-lapping Mouthparts

• Examples – honey bees (picture below), wasps

• Complex modifications of MP

• Mandibles used for chewing, proboscis for drinking (lapping) and exchanging fluid

• Mouthparts allow molding wax, feeding on pollen, nectar

Honey bee mouthparts

Insect mouthpartsTYPE 3: Siphoning (coiled) Mouthparts

• Examples – butterflies, moths

• Severe reduction of mouthparts – only a proboscis or coiled tube is present

• Short lived as adult, feed intermittently

Hawk moth mouthparts

Insect mouthpartsTYPE 4: Sponging Mouthparts

• Examples – flies

• Reduced mouthparts suitable for soaking up liquids

• No ability to eat solid food

• Some flies can “bite” but is actually scratching to feed on blood

Fly mouthparts

Insect mouthpartsTYPE 5: Piercing and Sucking MP

• Examples – mosquitoes (6 needles), plant bugs (4 needles)

• All mouthparts shaped like needles that form feeding tubes

• Only female mosquitoes bite

• All sexes of plant bugs can feed on plant juices

Leaf-footed bug mouthparts

Mosquito

Plant bugs

Assassin bug mouthparts

Insect Orders

Key insect orders• Coleoptera• Diptera• Hemiptera• Lepidoptera• Orthoptera• Thysanoptera

Coleoptera (beetles,weevils)

Mexican bean beetle

Some insect have defense markings

(click beetle)

Wireworms

Vegetable weevil

Facts about beetles (Coleoptera)

• Characteristics: forewings are hard, hindwings are membranous, poor fliers

• Have four life stages – egg, larva (grub), pupa, adult

• Grubs have strong mouthparts & are root feeders

• Beetles (adult) are foliage/flower feeders and may transmit diseases

• Often overwinter as adult or larva

Beetle wings

Diptera (flies)

Vegetable leafminerSeedcorn maggots

Mouth hooks of maggots

Facts about flies (Diptera)• Characteristics: good flier (one

pair of wings), larva (maggots) with reduced head

• Have four life stages – egg, larva, pupa, adult

• Larva have mouth hooks to scrape root surface

• Adult flies feed on nectar or solids (sponging mouth type)

• Often overwinter in larval stages

Fly wings

Hemiptera (true bugs)

Piercing-sucking mouthparts (beak)

Stink bug

Leaf-footed bug

Aphids

Facts about true bugs (Hemiptera)• Characteristics: wings are partially

hardened, antennae short

• Some are beneficial species

• Have three life stages – egg, larva (nymph), adult

• Overwinter in adult stage – immatures are vulnerable to predation.

• Piercing-sucking mouthparts

Stink bug wingsPredatory stink bug

Lepidoptera (moths, butterflies)Fa

ll ar

myw

orm

Granulate cutworm

Tomato hornworm

Imported cabbageworm

Identifying larvae by appendages

Thoracic legs

Abdominal prolegs

Normal number of prolegs = 4 (cutworms, armyworms)

< Number of prolegs = 3 (green cloverworm)

Number of prolegs = 2 (cabbage looper) >>

Anal prolegs

• Complete lifecycle – egg, larva, pupa, adult

• Larvae are damaging stages…

• Some members have become insecticide tolerant (diamondback moth, corn earworm)

• Try controlling these pests in early stages (small larva)

Facts about moths & butterflies

Head of butterfly showing siphoning mouthparts (coiled

beak)

Orthoptera (grasshoppers)

• Short-horned grasshopper (Acrididae)• Crickets (Gryllidae)• Mole crickets (Gryllotalpidae)

• Life stages: egg, nymph, adult

• Damage is caused by overlapping generations

• Damage intense in dry years

• Eggs laid in clusters in soil, food for many natural enemies

• Extremely migratory and have unique behavior patterns (e.g., infections)

Facts about grasshoppers

Grasshopper ovipositor

Thysanoptera (thrips)

Flower thrips

Actual size = 5 mm

Tobacco thrips

• Actual size = 5 mm, commonly seen on flowers

• Life stages: egg, larva, prepupa, pupa, adult

• Damage is caused by the rasping MP

• Damage intense in dry years

• Transmit diseases between plants

Facts about thrips

Types of Insect InjuryPresentation + Simulated training

First know the definitions…INJURY

DAMAGE

Damage = injury + economic loss

Plant injury by INSECTS• Direct injury caused by feeding:

chewing mouthparts VS. sucking mouth parts

• Direct injury caused during oviposition: dimpling on tomato by thrips egg-laying

Image: UFL IFAS Ext.

Image: UFL IFAS Ext.

Plant injury by INSECTS

• Indirect injury from insect products: honeydew causes sooty mold (aphids, whiteflies)

Image: TopTurf.netImage: Iowa State

Plant injury by INSECTS

• Injury from disease transmission: aphids, thrips

Transmit cucumber mosaic virus (CMV), potato virus Y (PVY)

Transmit tomato spotted wilt virus (TSWV)

Images: U Wisconsin & Queensland Govt., Australia

Plant injury by INSECTS

Is it really an INSECT injury?

Image: Missouri Bot. Garden

General steps to diagnosis:• Define the problem

• Look for patterns: abiotic problems have patterns!

• Used a scouting technique

• How fast are symptoms spreading?

• Process of elimination to arrive at a diagnosis

VS.

Simulated Insect Injury10-minute Group Exercise:

• Divide into 5 groups – each group designate a leader

• Take a sheet of paper and write names of team members

• Take any one sample from the table

• Describe of the problem, leader take notes (normal vs. abnormal)

• What insect could have caused the injury? Direct/Indirect?

• Team leader will present – 1 minutes

• Diagnosis will be discussed (5 minutes)

Intelligent Plant Management

• Ecological approach to plant production• Common sense approach to solving plant health problems

Integrated Pest ManagementBasic concept, status of IPM in AL,

implementation

What is IPM?• “Integrated pest management (IPM) is a threshold

based decision management system which leads to judicious use of multiple pest control tactics.”

• IPM is currently insecticide-intensive…• 70% area under IPM yest major losses occur due to:

• Lack of early detection of insects• Insecticide resistance by misuse• Loss of natural control with insecticides

Need for IPM• Loss of tomatoes in the absence of insecticides: 95% (AL)*• Nationally, average gain from IPM is $19 for every dollar

spent (field crops)*

• There is increasing demand for organic crops…

• Insecticide use in AL is reducing, 1992-2002:

• Asparagus (-30%)

• Green peas (-73%)

• Green beans (-36%)

• Tomatoes (-20%)

*L. Gianessi, 2009. Crop Protection Research Institute.

IPM in home & garden• Remove abiotic stresses• Conserve natural enemies (habitat)• Correctly identify insect pest• Biological control agents (microbials)• Cultural tactics – variety, rotation, trap crop• Chemical insecticides• Correct insecticide delivery system: correct

application rate, timing, coverage

NE Conservation System

• Grass shelters natural enemies

• Many night-feeding insects hide in grass during day…treat the edges!

• Sample in grass and keep it under control

Grassy buffers

Grassy buffer zone in

temporary agroecosystem

Grassy buffer zone in

permanent ecosystems

Trap cropping arrangements

• Trap crop = early planted squash, apply insecticide on borders

• Squash lured away 66% cucumber beetles and 90% squash bugs (USDA res.)

Perimeter Trap Cropping

Main crop (watermelon, cantaloupe, cucumber)

Trap crop (squash)

Trap cropping arrangements

Plant trap crop (alfalfa) in rows within the main crop (strawberry) & a using vacuum!

Row Trap Cropping (contd.)

Alfalfa

Strawberry(34 rows)

Strawberry(34 rows)

Strawberry production in California

Western tarnished plant bug damage

Recommendations for trap cropping• Try it on a small scale to gain confidence• Integrate with biological/chemical i-cides,

pheromone trapping, etc.• Trap cropping can manage 1-2 insect species• Works great against sucking pests (plant bugs)

and slow fliers (beetles)• Spray only the trap crop…reduce cost

Alternative Insecticides for Gardeners

• Use them in rotation:

– Thuricide, Dipel (Bt)

– M-pede (soap)

– Safer pyrethrin

– Oils (with caution!)

• Contact a nursery for supplies & purchase early

• Do not use unlabeled insecticides (e.g., RTU home pesticides)

• Always read the label!

Toxicity of Some Insecticides (General Use Pesticides)

Ref.: “General use insecticides for home gardening” by Dr. Ric Bessin (UK)

Rule 1: Higher the LD50 safer will be the product!

Rule 2: Products containing highly toxic AI have very low % chemical.

Active ingredient (AI)

% AI in product

Use MOA Oral LD50 (mg/kg)

Dermal LD50 (mg/kg)

Toxicity to bees

Pyrethrin 0.02 Insecticide Contact 2600 370 Toxic

Cyfluthrin 0.75 Insecticide Contact 869-1271 >5000

Bifenthrin 0.01 Insecticide Contact 54 Toxic

Imidacloprid 1.47 Insecticide Systemic 450 >5000 Highly toxic

Acephate 9.4 Insecticide Systemic + Contact

866 Moderately toxic

Bacillus thuringiensis

0.80 Insecticide Stomach - Mild eye irritant

Practically non-toxic

Decision making in IPM…• Insect detection & monitoring• Insect identification• Population pressure• Economic threshold• Make treatment decision• Choosing right insecticide

Monitoring insects with TRAPPING DEVICES

What are insect pheromones?• Pheromones are chemicals

released into environment in small amounts by insects.

• Pheromones are species specific, stimulates opposite gender.

• Male moths detect pheromones with antennae.

• Synthetic sex pheromones are manufactured & used as lures.

Types of Insect Traps• Passive traps: do not use a lure of any kind,

e.g., pit-fall traps, ground sticky traps, water traps, flight interception trap (beat sheet)

Pit-fall trap with a metal sheet as hood

Interception trap (can be used with or without light)

Types of Insect Traps• Active traps:

– use a lure of some kind, e.g., food, color, shape, light…PHEROMONES

Dome Fly Trap with liquid bait for mass trapping fruit fliesLight trap

Types of Insect Traps• Active traps (contd.): use a lure of some kind

Active/passive trap: yellow water pan trap

Yellow/white Sticky Trap with grid

Use many traps for accuracy

Ball trap for dipteran flies

• Know what to scout for & when to scout INTENSIVELY

• Automatic identification of closely related species• Prediction models will be avail.

Why use pheromone traps?

Wing trap Pherocon trap Bucket trap

Stink bug trap

Parts of a Pheromone Trap

Top section (fixed)

Bottom section (replaceable sticky card with grid)

Metal support

Lure with lure holder

Wing Pheromone Trap

Types of Pheromone TrapsWing Traps

Simple wing trap with grid on sticky bottom

Wing trap with baffles (large trap surface)

Popular due to easy assemblage, large trap area, & low cost

Suitable for larger moths: armyworm, cutworm, fruitworms

Problem: weather & animals could ruin trap

Types of Pheromone TrapsDelta Traps

Delta traps with sticky insert having a printed grid. Sides fold to hold the sticky insert in place.

>>

Advantages: easy assemblage, low maintenance, less interferenceSuitable for small moths – diamondback moth, warehouse pestsProblem: small trapping surface

Types of Pheromone TrapsMass trapping kits

Advantages:Relatively inexpensiveConvenient cleaningLure lasts longer

Disadvantages:Needs a killing agent(“No Pest Strip”)

Trap & Lure SuppliersTRAPS:• Great Lakes IPM (MI)• Arbico Organics (AZ)• Gemplers

LURES:• Great Lakes IPM – Scentry Biologicals

(MT) & Trece, Inc.• APTIV, Inc. (OR)

AL Insect Monitoring Project(new in 2009)

• Use traps for early detection of pests

• What does trap catch tell you?

Catch = pop. density x activity

• Trap network (operated by REAs):

N-S: vegetable fields

E-W: peanut fields

• Commercial traps/lures used

• Trapping period: June-October

• Trapping interval (2009): 14 days

What is it?HINT: Several outbreaks of these insects occurred in AL, 2009

Beet armyworm, Spodoptera exigua Fall armyworm, Spodoptera frugiperda

Fall armyworm

20

19

15

32

48

27

36

29

17

1216

13

Monthly average activity (statewide)

Insect density (overall) per site

Year 2009

What are these?Tomato fruitworm, Helicoverpa zea

Tobacco budworm, Heliothis virescens

Corn earworm6

10

25

12

16

5

3

11

8

3

8

17

7

Monthly average activity (statewide)

Insect density (overall) per site

Year 2009

Impact of Weather on Trap CatchesSign. Correlation of TEMPERATURE :County BAW FAW CEW TBW LCB CRW

Cullman NS NS NS 0.9655 (-) NA NS

Chilton 0.9989 (-) 0.9028 (-) 0.6599 (-) 0.9913 (-) NA NS

Baldwin NS NS 0.5863 (-) NS NS NS

Escambia NS 0.8603 (-) NS 0.6295 (+) NS NS

Henry NS NS NS NS NS NS

Numbers indicate significant correlations at P = 0.10. +/- indicates direction of relationship (preliminary findings). Rain days indicate number of days rainfall exceeded 0.1 inch.

County BAW FAW CEW TBW LCB CRW

Cullman NS 0.9905 (+) NS NS NA 0.5988 (+)

Chilton NS NS NS NS NA NS

Baldwin 0.9154 (+) 0.9838 (+) NS NS 0.8347 (+) 0.5882 (-)

Escambia 0.6661 (+) NS 0.7080 (+) NS NS NS

Henry NS 0.9851 (+) NS NS 0.7368 (+) 0.8819 (-)

Sign. Correlation of RAIN DAYS :

Year 2009

Biological Control Agents

Asian citrus psyllid: has many natural enemies

General predators

Lacewings:Chrysoperla rufilabris

Ash-gray lady beetle, Olla v-nigrum

General predators

Multi-colored Asian lady beetle, Harmonia axyridis

Spotless lady beetle, Cycloneda sp.

Predacious stink bugs • Typically have short beak

• Abundant in orchards, weedy borders

• Voracious feeders of caterpillars

• Watch numbers: a sudden increase may indicated pest presence

Euthyrhynchus floridanus Podisus maculiventris Alcaeorrhynchus grandis

SB feeding on armyworm

Introduced parasitoid (Eulophidae)

Tamarixia radiata, in FL from Taiwan• Female wasp lays eggs under ACP nymph

• Parasite develops inside the body (arrow in picture)

• Adult wasp emerges from an exit hole

IPM in Vegetables:Tomato

(Applied Entomology: insect biology meets insect control)

What is it?Potato aphid, Macrosiphum euphorbiae

Green peach aphid, Myzus persicae

Monitoring/scouting techniques:Sample ten plants in several locationsYellow sticky traps at edge of fieldLike cool, dry weatherWatch for ants and lady beetlesET = 50% leaves with aphids

What is it?Western flower thrips, Frankliniella occidentalis

Tobacco thrips, Frankliniella fusca

Monitoring/scouting techniques:Use sticky cards (yellow, blue)Bag and shake techniqueNo action thresholdUse resistant varieties (BHN 444, 589, 640, Bella Rosa)

Tomato spotted wilt destroys plants

What is it?Monitoring/scouting techniques:

Monitor level of defoliation

Sample small plants with sweep net during morning hours

Observe activity of parasitoids, predators (sweep net)

ET = 5-10% defoliation early season, 25-30% defoliation mid-season

Flea beetles (many species)

What is it?Monitoring/scouting techniques:

Start looking on border rows

Scout intensely short crop (<6 inch)

ET = 5 beetles per 10 seedling or 10% defoliation in short crop

Colorado potato beetle, Leptinotarsa decemlineata

Larva of lady beetle (beneficial insect!)

What is it?Monitoring/scouting techniques:

Examine green fruit, stem terminals

Scout for egg masses or larvae

Use pheromone traps to detect first flight; ET = 5-10 moths per night when temp. is <85F

ET is ½ if temp. is >85F

Tomato fruitworm, Helicoverpa zea

Tobacco budworm, Heliothis virescens

What is it?Monitoring/scouting techniques:

Use a sweep net

Use pheromone trap (expensive? cumbersome?)

Intensify scouting at fruit setting

ET = 0.25 bugs per 10 plants (green fruit stage)

Southern green stink bug, Nezara viridula

Brown stink bug, Euschistus servus

Lygus bug, Lygus lineolaris

What is it?Monitoring/scouting techniques:

Minor foliar pests (ET = 5 larvae per 10 plants)

Easy to collect & identify – shake and collect

Watch for sun scald on fruits, esp. 20% defoliation

Look for fecal pellets on leaves

Cabbage looper, Trichoplusia ni

Soybean looper, Pseudoplusia includens

Asian Citrus Psyllid(Diaphorina citri, Hemiptera: Psyllidae)

First Reports of ACPACP was first detected in 1998 in backyard plantings of Murraya paniculata

At present, 33 counties in FL have ACP

ACP has been found in many states, but Citrus Greening Disease (CGD) is present in LO & FL

ACP in Baldwin County (2008)

No detection of ACP or CGD in 2009

www.SaveOurCitrus.org 

• Eggs are almond shaped

• Eggs pale when fresh, turn yellow or opaque

• Eggs laid on tips of growing shoot or tender leaves in clusters

ACP Life cycleHost plants: all citrus plants, 2 species of Murraya (all Rutaceae)

ACP EGGS

• Nymphs: 5 instars, red eyes, large wing pads

• Development fails below 50oF

• Live in feeding pits created by adults

Life Cycle & Identification

53F*51F

50F51F

52F

NYMPHS

*Liu & Tsai 2000

• Adult is 3 mm long, forewings broad apically• Tip of antennae black• Brown band on wings around the border• Wings with reduced venation, prominent veins

ADULT PSYLLID

Life Cycle & IdentificationACP specimen

• Active insect that rests with body at an angle• Adult psyllids readily jump on approach• Dispersion: good fliers, moved by wind

Auburn Team at a Baldwin County location

Behavior of ACP

Defense mechanism:Masses of waxy filaments produced by nymphs to keep honey dew away!

Life Cycle & Identification

• ACP has piercing-sucking mouthparts

• Loss of plant sap from foliage

Citrus Injury due to ACP

High reproductive capacity & survival of eggs/nymphs can cause rapid infestation (check new terminals)

CITRUS GREENING DISEASE (CGD) or Huanglongbing:

• Worst disease of citrus transmitted by ACP

• Bacterium Liberibacter

• Short feeding inoculates ACP

Citrus Injury due to ACP (contd.)

Citrus Injury due to ACP (contd.)SYMPTOMS OF CGD:Slowly kills the tree (vascular)Deformed yellow leavesBlotchy mottling, asymmetricalTwig dieback

Citrus Injury due to ACP (contd.)SYMPTOMS OF CGD:Lopsided fruitPartially greenDistasteful fruitAborted black seeds

Remember: other disorders may cause diagnostic problems

What can confuse you?Citrus thrips

(Scirtothrips citri)Long bristles on

wings

Citrus mealybug (Planococcus citri)

No wing-pads!

Brown citrus aphid (Toxoptera citricida)

Have tail-pipes!

Trash bug (trash-carrying

lacewing)

SOURCES OF INFORMATION on ACP

• Has insect ID section

• Has a Citrus Greening Tracker

• Has a list of high risk activities

• “What to do if you sight ACP?”

www.SaveOurCitrus.org

• Select a state• Directs you to

local contact

USDA Animal & Plant Health Inspection Service (USDA-APHIS)

YouTube videos

Internet Resources

eXtension.org

Image repositories:Flickr.comBugGuide.netBugwood.org

NEW ONLINE RESOURCES

Subscribe to Blogs/email alertsFollow on SlideShare

IPM COmmunication REsources (IPM-CORE) Project

Project archive: www.aces.edu/go/85 or www.aces.edu/go/88 “AU Pest Alert” (direct email): May-October Web outreach: Blogs, YouTube, AlabamaCrops.com,

AGFAX.COM IPM Hotline (messages): 1-800-446-0375 Make sure you see the AL IPM EXHIBIT Timely revisions to Extension bulletins

Goal: Synchronized rapid IPM information delivery to growers

Acknowledgements to AL IPM Team

• IPM Trapping Coordinators: – A. Majumdar– H. Fadamiro– K. Flanders

• IPM Team Members:– Lloyd Chapman– Neil Kelly– Michael Reeves– Gary Gray– James Miles– William East, Jr.– Brandon Dillard– Leonard Kuykendall– Chris Becker– Timothy Reed

Thank you very much.

Please take the POST-TEST