Identification and Management of Vegetable Garden Insect Pests
Kevin Burls, Ph.D. Integrated Pest Management Educator University of Nevada, Reno Extension
Grant funding Grow Your Own, Nevada 2020 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 • Unsightly Green 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 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
Photo: Whitney Cranshaw, Colorado State University, Bugwood.org 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 Anatomy Head Thorax Abdomen Wings on thorax
3 pairs of legs Important areas to study to identify common insect orders
Head Thorax Abdomen
3 pairs of legs Insect identification
Taxonomy: The field of naming and Common pitfalls to classifying organisms into groups insect identification Example: Monarch butterfly • Missing the type of bug: mistaking a fly for a bee, a true bug for a beetle Kingdom= Animalia Phylum= Arthropoda • Believing a quick Google search: Class= Insecta Many times your search terms will Order=Lepidoptera bring up the most common invasive Family= Nymphalidae instead of the native Genus= Danaus • Trying too hard: Insects are very Species= plexippus 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
Large milkweed bugs Boxelder bug
bumblebee fly- bee mimic
By Photo by Greg Hume (Greg5030) - Own work, CC BY 3.0, https://commons.wikimedia.org/w/index.php?curi d=4701104 By Judy Gallagher - https://www.flickr.com/photos/52450054@N04/8061651776/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=55253277 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
Pentatomid bug
By Jesse Keith Huffman - Author, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=63069106 By Judy Gallagher - https://www.flickr.com/photos/52450054@N04/8061651776/, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=55253277 Aphids Whiteflies
Whitney Cranshaw, Colorado State University, Bugwood.org True bug eggs
Aphid eggs on rose Squash bug eggs
Photo: Whitney Cranshaw, Colorado State University, Bugwood.org By Bdm25 - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=35045808 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 Tomato hornworm, Manduca quinquemaculata, Cabbage white caterpillar, Pieris rapae one of 121 species of Sphingidae in Nevada
Photos: Whitney Cranshaw, Colorado State University, Bugwood.org Fruit tree pests
Western tent caterpillar, Apple codling moth, Cydia pomonella Malacosoma californicum
By Franco Folini - originally posted to Flickr as Western Tent Caterpillars (Malacosoma Public Domain, https://commons.wikimedia.org/w/index.php?curid=657502 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) European earwig Forficula auricularia
• 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 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 Rocky Mountain locust historic range
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 By Jacoby's Art Gallery - http://www.mnopedia.org/multimedia/minnesota- recommendations for its destruction., Public Domain, locusts-1870s, Public Domain, https://commons.wikimedia.org/w/index.php?curid=86723490 https://commons.wikimedia.org/w/index.php?curid=18570553 Katydids
Broad winged katydid eggs, Broad winged katydid, Microcentrum rhombifolium Microcentrum rhombifolium
Joseph Berger, Whitney Cranshaw, Bugwood.org Colorado State University, Bugwood.org Beetles (Coleoptera)
• Distinguished by hard wing covers as adults • Larval forms have six true legs but no prolegs • Enormous variety in lifestyle and feeding
Elm leaf beetle, Xanthogaleruca luteola (Chrysomelidae)
Whitney Cranshaw, Ward Upham, Kansas State University, Bugwood.org Colorado State University, Bugwood.org Prionus beetle (Prionus sp.) larva (left) and adult (right); each is 4 – 5 in. long
Jerry A. Payne, USDA Agricultural Research Service, Bugwood.org By Kaldari - Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=69838829 USDA Forest Service – Region 2– Rocky Mountain Region, USDA Forest Service, Leah Bauer, USDA Forest Service Northern Research Station, Bugwood.org 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 Fungus gnat larvae and adults
Photos: Whitney Cranshaw, Colorado State University, Bugwood.org 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
Alton N. Sparks, Jr., University of Georgia, Bugwood.org Diane Alston, Utah State University, 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 Photo: Whitney Cranshaw, Colorado State University, Bugwood.org 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
Macrosiphum rosae, 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 Photo: Whitney Cranshaw, Colorado State University, Bugwood.org rarely abundant • Only monitoring can effectively tell you what action to take Monitoring as an all-season effort
IPM techniques overview
Time
Energy
Money
Specificity 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/, Whitney Cranshaw, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=55253277 Colorado State University, Bugwood.org Cultural techniques: plant selection
Squash bug, Anasa tristis
Vulnerable Yellow squash Pumpkins Gourds Melons
Resistant Acorn squash Butternut squash Early summer crookneck Improved green hubbard Spaghetti zuchinni
Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org Cultural techniques: crop rotation
Squash bug, Anasa tristis
Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org 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
By Swtpc6800 en:User:Swtpc6800 Michael Holley - Own work, Public Domain, • Water jets effective for small numbers https://commons.wikimedia.org/w/index.php?curid=4192223 of: • Aphids & other sedentary insects
• Traps used to collect adult insects for disposal
• Chickens can be good physical control 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 Red Storm Photo W. Gideon, Bugwood.org Conservation Biological Control • Focused on increasing abundance • More commonly applied to animal and diversity of naturally occurring pests, but can be extended to plant predators and parasitoids pests
• Most are nectar feeders as adults • Some are predatory at all life stages and predators as larvae
Preventative Cultural Physical Biological
Plant selection Grazing modifications Bee houses Banker plants Hedgerows Burning modifications Beetle banks Alternative hosts Insectary strips Timing change Brush piles Cover crops Predators • Spiders
Neil Bertrando
Banded garden spider Argiope trifasciata By Alvesgaspar - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?c urid=20594342 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 Tobacco hornworm hornworm
Manduca Manduca quinquemaculata sexta
Hyposoter exiguae Cotesia congregata Trichogramma
Above photos from University of California IPM More Nevada parasitoids
Tachinid fly Gymnosoma sp. 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 http://ucanr.edu for using: • Neonicotinoids • Pyrethroids • Organophosphates • N-methyl carbonates A few examples of an IPM scheme Squash 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 Gerald Holmes, Strawberry Center, • Insectary strip Cal Poly San Luis Obispo, • Chemical Bugwood.org • Insecticidal soaps and oils are most effective on nymphs • Cool temps only • Nonorganic nonselective pesticides are available 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 Photo: Neil Bertrando • Nonselective insecticides are available 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 Macrosiphum rosae, rose aphid. Photo by • Chemical Anne W. Gideon, Bugwood.org • 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
Photo: Cynthia Scholl Thank you!
Kevin Burls, Ph.D. Integrated Pest Management Educator [email protected]
Master Gardener Cell: 775-399-8522
This work is supported by the Nevada Extension Implementation Program (Grant 2017-70006-27198) from the USDA National Institute of Food and Agriculture