identification and management of vegetable garden …...garden insect pests kevin burls, ph.d....
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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
Photo: Cynthia Scholl
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 Judy Gallagher - https://www.flickr.com/photos/52450054@N04/8061651776/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=55253277
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
Photo: Whitney Cranshaw, Colorado State University, Bugwood.org
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
Photo: Cynthia Scholl
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
Whitney Cranshaw, Colorado State University, Bugwood.org
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
Photo: Whitney Cranshaw, Colorado State University, Bugwood.org
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
Photo: Whitney Cranshaw, Colorado State University, Bugwood.org
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
By Judy Gallagher - https://www.flickr.com/photos/52450054@N04/8061651776/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=55253277
Whitney Cranshaw, Colorado State University, Bugwood.org
Cultural techniques: plant selection
Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org
Squash bug, Anasa tristis
VulnerableYellow squashPumpkinsGourdsMelons
ResistantAcorn squashButternut squashEarly summer crookneckImproved green hubbardSpaghettizuchinni
Cultural techniques: crop rotation
Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org
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
Macrosiphum rosae, rose aphid. Photo by Anne W. Gideon, Bugwood.org
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
Macrosiphum rosae, rose aphid. Photo by Anne W. Gideon, Bugwood.org
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
Photo: Cynthia Scholl
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