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Arthropod Pest Management Diego J. Nieto Janet A. Bryer University of California, Santa Cruz Insects’ Taxonomic Position Kingdom: Animalia Phylum: Arthropoda Class: Insecta Order: Hemiptera (true bugs) Family: Miridae Genus: Lygus Species: hesperus Common name = lygus bug Arizona State University Undiscovered Life Current species diversity Vertebrates Insects Crustaceans Mollusks Roundworms Plants Fungi Protozoans 0 400 800 1,200 1,600 Number of species (x 1,000) Red = Known species Gold = Estimated number of species not yet discovered Beetle Diversity • The number of taxonomically described beetles (only one of 31 orders of insects) is more than 250,000 species – 1/5 of all described animals Insect Anatomy Head: sensory Thorax: movement, locomotion Abdomen: respiration, digestion, reproduction Diagram: Berkeley Natural History Museum Hemimetabolous Development Diagram: V. Boucher, UCD Holometabolous Development Diagram: Bugwood Wiki parasites and parasitoids teritary consumers (predators) secondary consumers (predators) primary consumers (herbivores) producers decomposers and detritvores teritary consumers (predators) decomposers and detritvores producers Functional Categories PNAS.org bugguide.net tamu.edu urbangardencasual.com ORTHOPTERA grasshoppers, crickets and katydids ORTHOPTERA grasshoppers, crickets and katydids Carlos Porto Orthopterans in CA • Melanoplus spp. occasionally a pest in wheat and small grains, particularly when adjacent to foothills (UC IPM) • Katydids in peaches HOMOPTERA planthoppers, leafhoppers, aphids, scale, cicadas and mealybugs HOMOPTERA planthoppers, leafhoppers, aphids, scale, cicadas and mealybugs HOMOPTERA planthoppers, leafhoppers, aphids, scale, cicadas and mealybugs Homopterans in CA • • • • • • Aphids in vegetables Scale in citrus Leafhoppers in grapes Whiteflies in cucurbits Mealy bugs in floriculture Pysllids in tomatoes Homopterans as Vectors USDA Asian Citrus Psyllid Yellow dragon disease or HLB Quest.org Potato Psyllid growing produce.com Zebra chip Asian Citrus Psyllid The Disease: Huanglongbing caused by three bacteria in the genus Candidatus Liberibacter The bacteria infect the phloem, the circulatory system that transports sugars from the tree canopy to the roots, resulting in blockages. Phloem Xylem The blockages starve the roots, which stop properly absorbing nutrients from the soil to send back up to the tree canopy, a circulatory system known as the xylem. Scientific American 2013 Hemiptera true bugs Hemiptera true bugs Hemiptera true bugs Andreas Kay Hemipterans in CA • • • • • Lygus bugs in strawberries, cotton Stink bugs in tomatoes, almonds False chinch bugs in grapes, walnuts Bed bugs…everywhere! Predators: minute pirate bug, bigeyed bug, damsel bug, assassin bug, stink bug lygus bug Colin Brown damsel bug Lepidoptera butterflies and moths Lepidoptera butterflies and moths Lepidoptera butterflies and moths Lepidopterans in CA • • • • • • • • Diamondback moth in cole crops Artichoke plume moth Codling moth in apples Navel orange worm in almonds Citrus cutworm Western grapeleaf skeletonizer Tomato hornworm Corn earworm Jack Kelly Clark agf.gov.bc Diptera true flies Diptera true flies csiro.au Dipterans in CA • • • • • • • Olive fruit fly Spotted-wing drosophila in raspberries Cabbage maggot in cole crops Walnut husk fly Seedcorn maggot in cucurbits Syrphid fly (predacious maggots) Tachinid fly (parasitic maggots) cisr.ucr.edu Syrphidae hover flies Coleoptera beetles Coleoptera beetles Coleoptera beetles J. Oldham Coleopterans in CA • • • • • • • Cucumber beetle in cucurbits Flea beetle in cole crops Palestriped flea beetle in carrots Grape bud beetle Pepper weevil Tenlined June beetle in almonds Predators: lady bird beetles, collops beetles, soldier beetles, rove beetles, etc. bugguide.net bugguide.net cucumber beetle pepper weevil Wikipedia.org flea beetle palestriped flea beetle uky.edu lady bird beetle collops beetle Mick Talbot Halverson Photography leather-winged soldier beetle rove beetle Hymenoptera bees, wasps, ants bugguide.net Hymenoptera bees, wasps, ants Janet Good Hymenoptera bees, wasps, ants RPF gsquaredbugs.com Trichogrammatidae Alex Wild Braconidae Lord V wikimedia.org Eulophidae Ichneumonidae Arachnida: Araneae wolf spiders dwarf spiders jumping spiders Arachnida: Acari ua.edu two-spotted spider mite arbico-organics.com uky.edu persimilis predatory mite Insecticide Use In 2010, there were over 173 million lbs of pesticide (AI) reportedly used in California (CDPR 2011) Pesticide Resistance • Pesticides kill insects… • Some insects survive and reproduce • If this “resistance” has a heritable basis, it will becomes more common with each generation Chromosome with allele conferring resistance to pesticide Additional applications will be less effective, and the frequency of resistant insects in the population will grow Pesticide application Survivors Why are herbivorous insect pests so adept at developing resistance? Hint: think co-evolution PBS.org Insecticide Resistance In "Managing Resistance to Agrochemicals" (M. D. Green, H. M. Le Baron, and W. K. Moberg, eds.), pp. 18-14. ACS Symposium Series 421. Insecticide Resistance • Pesticide resistance costs US $1.5 billion/yr (Pimentel 2009) • In the last 50 years, U.S. crop losses have risen from 7% to 13%, despite a 10-fold increase in insecticide use (Pimentel 2009) Organic Management of Insect Pests • No single solutions • Many inter-related components • Prevention vs. Suppression colourbox.com Pest Status • Key pests: herbivores that are reliably present every growing season, and if not properly managed, will likely exceed economic thresholds • Secondary pests: herbivores that are often present but rarely exceed economic thresholds due to naturally-present predation and parasitism • Occasional pests: may cause problems once every few years; only occurs when environmental conditions favor their development Pest Identification? nathistoc.bio.uci.edu inaturalist.org Direct Damage • Marketable portion of the crop is negatively affected by feeding CA red scale Lygus bug Codling moth Cab aphid photo cabbage aphid Indirect Damage • Portions of the crop that are not marketed are fed upon: roots, leaves, stems, etc. CA red scale cabbage maggot fly Asian citrus psyllid Economic Damage • Damage is the monetary value lost to the commodity as a result of injury by the pest (e.g., spoilage, reduction in yield, loss of quality, etc.) • At some point, a pest population reaches a point where it begins to cause enough damage to justify the time and expense of control measures Taken from JR Meyer, NCSU Economic Injury Level • EIL: A = B A.) How much financial loss is the pest causing? B.) How much will it cost to control the pest? • EIL exceeded when A > B; action warranted Adapted from JR Meyer, NCSU UC IPM Economic Thresholds Beneficial Species • Predators are more diverse (greater spp. richness) and more abundant (greater spp. evenness) in organic crops, relative to their conventionallymanaged counterparts • Species richness and evenness contribute to better pest control (Crowder et al. 2010) Adjusted Thresholds • Conventional CA strawberries: – 1 lygus bug nymph/10 suctions • Organic CA strawberries: – 1 lygus bug nymph/25 suctions* *approximate and unofficial Colin Brown General Rule of Scouting • Any time you find a lot of one type of pest insect (more then 5 on 2–3 plants in a row with no predators found in that same area) the pest/beneficial ratio is out of balance and some outside control will be necessary (W.H. Settle) Timing is Everything • When are pests present? • What temporal requirements do natural enemies have? • When do pests cause economic damage? uci.edu Syrphid Fly Life Cycle Larvae can consume up to 500 aphids from egg-hatch to pupation (Hopper et al. 2011) Theoretical Organic Broccoli Field insect abundance syrphid larvae aphids $$$ 50 aphids: egg-laying threshold time Theoretical Organic Broccoli Field insect abundance syrphid larvae aphids Insecticide application 50 aphids: egg-laying threshold $ time Late aphid establishment, due either to late arrival or an early insecticide application Integrated Pest Management • UC IPM: Integrated pest management (IPM) is an ecosystembased strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties. Pesticides are used only after monitoring indicates they are needed according to established guidelines, and treatments are made with the goal of removing only the target organism. Pest control materials are selected and applied in a manner that minimizes risks to human health, beneficial and nontarget organisms, and the environment. Prevention • • • • • • Site selection Planting date Crop rotation Host resistance Field sanitation Landscape diversity • • • • • • Alternate host management Fertilization/Irrigation Row covers Cultivation Cover cropping Farmscaping Pest Avoidance (Temporal) oisat.org umn.edu Pest Avoidance (Spatial) • Crop rotation prevents pest population build up during consecutive growing seasons • Especially relevant for soil-dwelling or largely sessile insects eatlikenoone.com ucanr.edu ucanr.edu Pest Avoidance (Physical) A physical barrier to pest infestation Row covers Flea beetles Field Sanitation • Remove pest habitat and reduce reproductive opportunities gardenandplants.co.uk Fertilization Excess nitrogen on broccoli tends to increase cabbage aphid Pest Suppression • • • • • • Pheromones Habitat Management Biological Control Mechanical Control Soil Solarization Insecticides Pheromones • Emitted chemical that elicits a response from other members of a population – Sex pheromones most often used in agriculture Most sex pheromones are produced by the female and used by the male for mate location. wind Taken from Andrew Lawson, CSUF 75 Mating Disruption: codling moth in apples gardenofeden.blogspot.com usu.edu Mating Disruption Using Pheromone Twist-Ties Habitat Modification Pest problems happen when conditions required for survival by the pests are favorable. Habitat modification intentionally limits or alters one or more of these requirements alfalfa trap crop sweet alyssum beneficial insectary Biological Diversity • Functional diversity is most valuable to a grower Biological Control There are three approaches or types of biological control: Classical Augmentation Conservation Classical BC • Introduced species constitute 98% of the U.S. food system (Pimentel et al. 2005) • Creates trophic imbalances in agroecosystems • Classical BC is a chemical-free approach to restoring top-down control of pests using only the most selective organisms Classical BC for Asian Citrus Psyllid (ACP) • CA oranges worth $716 million annually • ACP first detected in Los Angeles in 2008 • CDFA started spraying pesticides in LA to eradicate ACP and prevent them from spreading • CDFA sprayed 46,941 properties at a cost of $4.7 million • As 40% of houses in LA have at least one citrus tree (i.e. 1.2 million properties), many more homes would need to be sprayed • Once the state suspended its pesticide campaign in LA, more sustainable and cost effective strategies (i.e. biological control) were utilized Scientific American 2013 Tamarixia radiata (Hymenoptera: Eulophidae) Scientific American 2013 Classical BC for Asian Citrus Psyllid (ACP) ACP nymphs Scientific American 2013 parasitized ACP nymphs Augmentative BC Mechanical Control Mechanical controls include practices that mechanically destroy pests or present a physical barrier to their infestation sanluisobispo.com Tractor-mounted vacuum Tanglefoot band to exclude ants Organic Insecticides • • • • Not cheap! Not always effective Not always selective Not always on the OMRI (Organic Materials Review Institute) list • Similar to conventional crops, should be used as a last resort Organic Insecticides • Botanicals: derived from plants – Pyrethrum (from Chrysanthemum) or Azadirachtins (from the neem tree) • Soaps: K fatty acids used for soft-bodied insects – M-pede® • Microbials: bacteria harmful to certain insects – Bt or Entrust® (from Saccharopolyspora spinosa) Are there any questions? References Cited • California Department of Pesticide Regulation (CDPR). 2011. Pesticide Use in California Increases after Four-Year Decline. http://www.cdpr.ca.gov/docs/pressrls/2011/111228.htm Accessed 27 May 2013. • Crowder DW, Northfield TD, Strand MR & WE Snyder. 2010. Organic agriculture promotes evenness and natural pest control. Nature 466: 109113. • Kuchment A. 2013. The end of orange juice. Scientific American. March, 2013. • Pimentel D, Zuniga R & D Morrison. 2005. Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecological Economics 52: 273–288. • Pimentel D. 2009. Environmental and Economic Costs of the Application of Pesticides Primarily in the United States. In: Integrated Pest Management: Innovation-Development Process, pp 89-111.