Identification and Management of Vegetable Garden …...Garden Insect Pests Kevin Burls, Ph.D....

Identification and Management of Vegetable

Garden Insect Pests

Kevin Burls, Ph.D.Integrated Pest Management EducatorUniversity of Nevada, Reno Extension

Grow Your Own, Nevada 2020Grant funding provided by

Photo: Cynthia Scholl

Outline• Basics of Integrated Pest Management (IPM)

• Insect pest identification

• IPM techniques and examples

• A few examples of integrated pest programs for common pests

What is a pest?

• Too many in one place• Takes resources from/

cause injury to production plants

• Appears where you don’t want it

• UnsightlyGreen peach aphid (Myzus persicae) giving live

birth to a nymph. Photo Credit: Jim Baker, North Carolina State University, Bugwood.org

How do things become pests?

• Unhealthy plants or soil• Stressful environment• Seasonality• Annual cycles• Lack of predators or

competition

Macrosiphum rosae, rose aphid. Photo by Anne W. Gideon, Bugwood.org

Integrated Pest Management (IPM)

• Integrated Pest Management• Management designed to reduce

pests below economic thresholds in ways that minimize non-target effects

• Some quick keys to pest management

• Identify the pest first• Monitor regularly• An ounce of prevention for a pound of

cure• Measure responses to treatment

Why think about IPM?

• Reduce chemical pesticide use

• React to changing conditions

• Reduce nontarget environmental effects

• Cost and time savings

• Protect native or vulnerable species

Why use IPM as a pest management framework?• Provides an algorithm for control tactics

• Facilitates the measuring of success or failure

• Control or prevention of multiple pests at once

• Best Practices for responsible pesticide use

IPM Basics

• Identification

• Monitoring & action thresholds• Economic

• Aesthetic

• Health and Safety

• A hierarchy of techniques

• Documenting and revising

Pitfalls of misidentification

Photo: Whitney Cranshaw, Colorado State University, Bugwood.org

Pitfalls of misidentification

By Judy Gallagher - https://www.flickr.com/photos/52450054@N04/8061 CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=55253277

Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org

Major groups of garden invertebrate pests

• True bugs• Aphids, stink bugs, and relatives

• Moths & butterflies• Caterpillars

• Earwigs• Grasshoppers, crickets and katydids• Beetles

• Elm beetles, longhorn beetles, weevils, and relatives

• Flies• Fungus gnats

• Thrips• Spider mites


A few things we won’t be covering

• Wasps

• Ants

• Spiders

• Most flies

My favorite arthropod identification books

General gardening and pollinators• Attracting Native Pollinators, Xerces Society, 2011• Farming with Native Beneficial Insects, Xerces Society, 2014

General insect identification• Kaufman Field Guide to Insects of North America, Eric Eaton & Ken Kaufman, 2007• National Wildlife Federation Field Guide to Insects and Spiders of North America,

Arthur V. Evans, 2008• www.bugguide.net or www.whatsthatbug.com

Bee identification• Bee Basics: An Introduction to Our Native Bees, Beatriz Moisset & Stephen

Buchmann, available for download at: http://www.pollinator.org/PDFs/BeeBasicsBook.pdf

• California Natural History Field Guide to the Common Bees of California, Gretchen Lebuhn, 2013

• The Bees in Your Backyard, Joseph Wilson and Olivia Messinger Carril, 2015

Insect AnatomyHead Thorax Abdomen

3 pairs of legs

Wings on thorax

Important areas to study to identify common insect orders

Head Thorax Abdomen

3 pairs of legs

Insect identification

Taxonomy: The field of naming and classifying organisms into groups

Example: Monarch butterfly

Kingdom= AnimaliaPhylum= Arthropoda

Class= InsectaOrder=Lepidoptera

Family= NymphalidaeGenus= Danaus

Species= plexippus

Common pitfalls to insect identification

• Missing the type of bug: mistaking a fly for a bee, a true bug for a beetle

• Believing a quick Google search: Many times your search terms will bring up the most common invasive instead of the native

• Trying too hard: Insects are very diverse, and becoming good at identifying anything takes time!

This level distinguishes many major groupings- beetles, flies, dragonflies and damselflies, etc.

Mimicry(Or: These bugs all look the same!)

Mimicry is the semblance to two or more different species to each other in a way that confers an evolutionary advantage (e.g. predator protection) for at least one of the species

Müllerian mimicry: Two species that are both well protected look like each other

Batesian mimicry: One or more unprotected species looks like an honestly well-defended species

bumblebee fly- bee mimic

By Judy Gallagher - https://www.flickr.com/photos/52450054@N04/8061651776/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=55253277

By Photo by Greg Hume (Greg5030) - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curid=4701104

Large milkweed bugs Boxelder bug

True bugs (Hemiptera)• Defined by a poking and sucking mouthpart that tucks back into a sheath• Aphids, planthoppers, squash bugs, boxelder bugs, whiteflies, scale insects, bed bugs• Assassin bugs, cicadas, water striders• Aphids: identified by pear shaped bodies, long legs and antennae• Adults often identified by V-shape made by closed wings (not present on immatures, or

nymphs)• Many species have a somewhat restricted diet so host plant will aid identification


By Jesse Keith Huffman - Author, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=63069106

Pentatomid bug

Aphids

Whiteflies

Whitney Cranshaw, Colorado State University, Bugwood.org

True bug eggs

By Bdm25 - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=35045808

Aphid eggs on rose Squash bug eggs


Moths & butterflies (Lepidoptera)• Adults have scale-covered wings and a flexible straw-like mouthpart• Approximately 10x as many moths as butterflies• Complete metamorphosis: larval life stage is a caterpillar- 6 ‘true legs’

up front, prolegs in back, chewing mouthparts• Moths are sometimes generalists with a broader diet, butterflies are

often specialists

Photos: Whitney Cranshaw, Colorado State University, Bugwood.org

Tomato hornworm, Manduca quinquemaculata,

one of 121 species of Sphingidae in NevadaCabbage white caterpillar, Pieris rapae

Fruit tree pests

Public Domain, https://commons.wikimedia.org/w/index.php?curid=657502

Apple codling moth, Cydia pomonellaWestern tent caterpillar,

Malacosoma californicum

By Franco Folini - originally posted to Flickr as Western Tent Caterpillars (Malacosoma californicum), CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=4095034

Geometrid moths

• Roughly 1,500 U.S. species; 35,000 species worldwide

Digrammia cinereola on Juniper, photo by Nick Pardikes, bugguide.net

Earwigs (Dermaptera)

• Rear pincers are a good diagnostic

• Often most detrimental to young seedlings

• Most common species are nonnative

• Hated by all who know them

Photo: Neil Bertrando

European earwigForficula auricularia

Grasshoppers, crickets,and katydids (Orthoptera)

• Long, jumping back legs and chewing mouthparts

• Often plant generalists• Crickets and katydids have long

antennae, grasshoppers have shorter antennae

• Locusts of yore no longer a problem• Today we have Mormon crickets


By C. V. Riley (1877) - The locust plague in the United States: being more particularly a treatise on the Rocky Mountain locust or so-called grasshopper, as it occurs east of the Rocky Mountains, with practical recommendations for its destruction., Public Domain, https://commons.wikimedia.org/w/index.php?curid=86723490

By Jacoby's Art Gallery - http://www.mnopedia.org/multimedia/minnesota-locusts-1870s, Public Domain, https://commons.wikimedia.org/w/index.php?curid=18570553

Rocky Mountain locust historic range

Katydids


Joseph Berger, Bugwood.org

Broad winged katydid eggs, Microcentrum rhombifolium

Broad winged katydid, Microcentrum rhombifolium

Beetles (Coleoptera)

• Distinguished by hard wing covers as adults• Larval forms have six true legs but no prolegs• Enormous variety in lifestyle and feeding

Ward Upham, Kansas State University, Bugwood.orgWhitney Cranshaw,

Colorado State University, Bugwood.org

Elm leaf beetle, Xanthogaleruca luteola (Chrysomelidae)

Jerry A. Payne, USDA Agricultural Research Service, Bugwood.org By Kaldari - Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=69838829

Prionus beetle (Prionus sp.) larva (left) and adult (right); each is 4 – 5 in. long

USDA Forest Service – Region 2– Rocky Mountain Region, USDA Forest Service, Bugwood.org

Leah Bauer, USDA Forest Service Northern Research Station, Bugwood.org

Flies (Diptera)• Distinguished by having only one pair of wings, large

eyes, short antennae• Large variety of mouthparts and feeding methods• Complete metamorphosis with soil dwelling larvae• Pest status of most flies is related to local

environmental conditions- they do not destroy the plants themselves

Photos: Whitney Cranshaw, Colorado State University, Bugwood.org

Fungus gnat larvae and adults

Thrips (Thysanoptera)• Adults are tiny, slender flying insects with fringed

wings (no wings on nymphs)• Cut open leaves and digest contents• Biological control requires correct ID• Herbivore and predator lifestyles

Diane Alston, Utah State University, Bugwood.orgAlton N. Sparks, Jr., University of Georgia, Bugwood.org

Spider mites (Arachnida: Acari)

• Arachnids, not insects- 8 legs, sucking mouthparts

• Spin silk around colonies for protection

• Severe damage results in yellow stippling

• Herbivore and predator lifestyles

• Often made more abundant with insecticides


I found something tiny on my plant!• Consider a hand lens or magnifying glass

• Ask the following:• Does it have a visible head, legs, and/or wings? General coloration?• Are there tiny projections on the back of the abdomen?• Are they mostly active or sedentary?• Do things fly away in large numbers when disturbed?• Is there webbing on the plants?• Is there honeydew on the plants/do they feel sticky?• What does the plant damage look like? Yellowing, stippling, or wilting?

IPM insect strategies for the garden

Macrosiphumrosae, rose aphid. Photo by Anne W. Gideon, Bugwood.org

Don’t feel bad about having pests!The insects have been at this much longer than you

Many traits that make plants tasty for us make plants tasty for them

Plague of Locusts(detail, Golden Haggadah codex, 14th c.)

British Library Additional 27210 f. 13

Integrated Pest Management

• Integrated Pest Management• Management designed to reduce pests

below economic thresholds in ways that minimize non-target effects

• Some quick keys to pest management• Identify the pest first• Monitor regularly• Focus on healthy plants• An ounce of prevention for a pound of

cure

IPM Basics

• Identification

• Monitoring & action thresholds• Economic

• Aesthetic

• Health and Safety

• A hierarchy of techniques

• Documenting and revising

Monitoring: The cornerstone of any IPM program

• You can’t catch what you can’t see

• Traps are available for some species

• One bug does not an infestation make

• You can still kill them• Some plants can withstand large

seasonal infestations• Some pests are often present but

rarely abundant• Only monitoring can effectively tell

you what action to take


Monitoring as an all-season effort

Time

Energy

Money

Specificity

IPM techniques overview

Preventative technique: plant health

Plant pests seek out unhealthy plants

• Mulch, water, fertilize your plants (but not too much)

• Understand the context your plants are in

• Ensure new plants are healthy and pest-free

Preventative techniques: Windbreaks

• Good for plant and animal pests• Multi-function: Wind & snow abatement, erosion

control, pollinator/beneficial insect habitat

USDA

Preventative techniques: Covers

• Lightweight, tight row cover can be effective for:• True bugs• Caterpillars• Beetles• Others

Cultural techniques

• Changes to your normal actions that can reduce pest reproduction, dispersal or survival

• Examples• Crop rotation• Plant species selection• Grazing intensity• Vegetation and groundcover management• Irrigation schedules• Fertilization schedules• Sanitation

Cultural techniques: plant selection

• Boxelder trees• Elm trees



Cultural techniques: plant selection


Squash bug, Anasa tristis

VulnerableYellow squashPumpkinsGourdsMelons

ResistantAcorn squashButternut squashEarly summer crookneckImproved green hubbardSpaghettizuchinni

Cultural techniques: crop rotation


Squash bug, Anasa tristis

Physical Treatments• Treatments that directly kill or remove

pests• Think hand pulling or torching weeds

• Squishing is effective for small infestations of:

• Squash bugs/shield bugs• Caterpillars

• Water jets effective for small numbers of:

• Aphids & other sedentary insects

• Traps used to collect adult insects for disposal

• Chickens can be good physical control

By Swtpc6800 en:User:Swtpc6800 Michael Holley - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=4192223

Biological control

• Use of natural enemies to control pest populations

• May mean some pests remain throughout treatment

• Often hindered by chemical pesticide use

• Classical Biological Control• Augmentative Biological Control• Conservation Biological Control

Classical Biological Control


Red Storm Photo

Conservation Biological Control• Focused on increasing abundance

and diversity of naturally occurring predators and parasitoids

• Most are nectar feeders as adults and predators as larvae

• More commonly applied to animal pests, but can be extended to plant pests

• Some are predatory at all life stages

Preventative Cultural Physical Biological

Insectary strips

Plant selectionHedgerows

Grazing modificationsBurning modifications

Timing changeCover crops

Bee housesBeetle banksBrush piles

Banker plantsAlternative hosts

Predators• Spiders

Banded garden spiderArgiope trifasciata

By Alvesgaspar - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?c

urid=20594342

Neil Bertrando

Parasitoids• Organism that uses another animal as a host for part of its life cycle, typically killing

the host in the process of development

• Typically flies and wasps, along with a few other groups

Tomato hornworm

Manducaquinquemaculata

Tobacco hornworm

Manducasexta

Hyposoter exiguae Cotesia congregata Trichogramma

Above photos from University of California IPM

Tachinid flyGymnosoma sp.

More Nevada parasitoids

Chemical control• Includes biopesticides and synthetic pesticides• Use of synthetic chemicals

• Focus is on selectivity and effectiveness

• You are required to read and understand pesticide labels

• You assume legal responsibility for using pesticides• It is unlawful to use a pesticide in a way other than

specified on the label

General pesticide application Best Management Practices

• In general, avoid the following:

• spraying during daytime/blooming periods

• Drift conditions• Non-target locations (water,

pollen, nectar, nesting materials, etc.)

• Minimize use and plan timing for using:

• Neonicotinoids• Pyrethroids• Organophosphates• N-methyl carbonates

http://ucanr.edu

A few examples of an IPM schemeSquash bugs

• Monitoring• Monitor daily- flip over leaves, inspect stems for egg masses• take action at ~1 egg mass per plant

• Preventative• Windbreak• Row cover (remove for pollination)

• Cultural• Crop Rotation• Variety selection

• Physical• Hand removal/vacuum egg masses and adults• Remove heavily infested plants

• Biological• Insectary strip

• Chemical• Insecticidal soaps and oils are most effective on nymphs

• Cool temps only• Nonorganic nonselective pesticides are available

Gerald Holmes, Strawberry Center,

Cal Poly San Luis Obispo,

Bugwood.org

Earwigs

• Monitoring• Monitor weekly using newspapers/bags/bucket/boards

near crops• Preventative

• Windbreak• Row cover (remove for pollination)

• Cultural• Remove debris and weeds

• Physical• Tanglefoot• Diatomaceous earth• Hand removal• Traps

• Biological• Insectary strip

• Chemical• Spinosad can be applied but may not be effective• Nonselective insecticides are available

Photo: Neil Bertrando

Aphids (exact guidelines vary by plant species)

• Monitoring• Monitor 2x/week in young veggie plants• Check for both live and mummified (parasitized) aphids

• Preventative• Windbreak• Row cover (remove for pollination)

• Cultural• Remove related “reservoir” plants- thistles, mustards• Prune infested areas of plants• Use slow-release fertilizers• Reflective (plastic) mulch

• Physical• Hand removal• Water jet

• Biological• Insectary strip• Parasitoid wasps• Augmented release

• Chemical• Insecticidal soaps and oils are most effective on nymphs

• Cool temps only• Dormant oils are a good option here

• Nonselective insecticides are available, including neonicotinoids


Take-home messages

• Insect pests are a part of garden life

• Only a small segment of insects are responsible for the vast majority of pest problems

• Preventing pest infestations is the best investment

• Many techniques used in pest control can have multiple functions


Thank you!

Kevin Burls, Ph.D.Integrated Pest Management [email protected]

Master Gardener Cell: 775-399-8522This work is supported by the Nevada Extension Implementation Program (Grant 2017-70006-27198) from the USDA

National Institute of Food and Agriculture

Identification and Management of Vegetable Garden …...Garden Insect Pests Kevin Burls, Ph.D....

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