BIOLOGICAL CONTROL ofof LeafyLeafy SpurgeSpurge comprehensive, easy-to-read manual on how Ato use biological control as an effective leafy spurge management tool. A product of the USDA-ARS TEAM Leafy Spurge Area-Wide IPM Program beetles, like what they are and how they work. We’ll then move on to topics that, if used, will greatly enhance your chances of successfully incorporating biological control into your leafy spurge management plan: How to select a release site, where to obtain insects, how to release insects, how to monitor and manage Leafy Spurge advantage of a weed or insect pest through the established populations, how to collect and If you’ve had any experience with leafy spurge, use of natural enemies such as parasites, preda- redistribute biocontrol agents, and how to inte- you already know it’s a pretty tough customer. tors or pathogens. grate biological control with other leafy spurge A native of Europe and Asia, leafy spurge Introduced weed species are prime candidates management tools. emerges early in the spring and gets a head for biological control. The concept is simple: Find The key is STARTING. Biological control is start on other vegetation in a race for space, sun- natural enemies of the target weed in the weed’s not a cure-all or overnight solution, and it light, nutrients and water. Prolific seed production homeland. Such enemies are selective, or host won’t work every time in every situation. It is, and an extensive root system give the plant a specific, and well-adapted to establishing long- however, a long-term, sustainable and inex- huge competitive advantage and make consis- term relationships with the target weed that result pensive approach that should ALWAYS be The Problem tent, long-term control difficult. Deep tap roots – in reduced weed densities. In fact, the absence considered when formulating a leafy spurge An extensive root system, capable of storing which can exceed 20 feetintroduction in depth – store of natural enemies are why weeds like leafy management plan. nutrient reserves and producing numerous reserves of nutrients to see the plant through spurge flourish and spread so quickly when intro- But it won’t work unless you give it a try, shoots, makes leafy spurge extremely versatile hard times, while lateral roots form a network duced into a new environment. It’s interesting to and the sooner you try, the sooner it can start and persistent. Biological control, quite literally, that enable it to rapidly reproduce and spread. note that many weeds like leafy spurge are not working for you. gets to the root of the problem. And, perhaps worst of all, leafy spurge is highly considered a problem in their homelands, where Good luck! adaptable and can thrive in a variety of condi- natural enemies are abundant and control infes- tions and situations. tations. In short, this exotic invader is extremely com- The use of biological control is nothing new. petitive and quite The Chinese used capable of com- predatory ants to pletely displacing control insect desirable plants. pests in stored The economic foods and citrus and environmental groves more than Introduction, pages 2-3 For • Can They Be Field Days, pages 17-18 impacts of leafy 2,000 years ago, • Leafy Spurge • Biological Harvested? • A Tip • A Great Tool – Do It! • Plan spurge are signifi- and numerous Control • The Goal Ahead! • Date & Time • Either, cant. It invades a efforts followed. A Harvesting & Redistributing, Or • Who? • Communications variety of land lot has been Flea Beetles, pages 4-5 pages 11, 14-15 • Supplies • Safety types, reduces learned since • Meet the Flea Beetle • Flea • Harvesting • First Of All… range productivity then, but the rea- Beetle Biology • Damage to • Look Early, Look Often Frequently Asked Questions and species diver- sons why people Leafy Spurge • When to Harvest • How to (FAQs), pages 19-20 sity, threatens The Enemy were interested Harvest • Sorting & Counting sensitive species, Introduced to the way back then Implementing Biological •Packagingcontents • Storing & The Payoff, page 21 degrades wildlife Great Plains a century remain true today: habitat and ago, leafy spurge has Biocontrol is easy Control, pages 6-7 Transportation Some examples of what reduces land val- proven to be a formi- to use, inexpen- • The Objective • Where to happens when flea beetle ues. Infestations dable opponent. No sive, self-sustain- Get Insects • Site Selection • Before & After Pictures, populations explode, and of in Wyoming, type of land is immune ing, target specific Habitat Preferences • pages 12-13 unmanaged leafy spurge Montana and the from infestation, and and well-suited to Releasing Insects • Mark Your Examples of what biocontrol infestations Dakotas alone are rangelands are partic- incorporate with Sites!!! can potentially do for you estimated to cost ularly susceptible. other manage- TEAM Leafy Spurge, page 22 agricultural pro- ment tools. Release Site Information Evaluating Biocontrol, page 15 • The “TEAM” • Partnerships ducers and tax- Form, pages 8-9 • Is It Working? • Will It Work? • The Approach • The Bottom payers more than $144 million a year in produc- The Goal A field-ready form to help you • And If Not… Line tion losses, control expenses and other impacts The goal of this manual is simple: Providing to the economy. you, the rancher, landowner or land manager, record release site information with the information you need to effectively use Integration, page 16-17 For More Information, page 23 Biological Control biological control – specifically, leafy spurge flea Monitoring Release Sites, • IPM, IPM & more IPM Contact names & numbers Biological control, or biocontrol, can be defined beetles. page 10-11 • Why It Works • Herbicides as a reduction in the abundance or competitive We’ll start with basic information about flea • Monitoring • What to Look •Grazing • Burning • Cutting Acknowledgements, back cover - 2 - - 3 - ally move to larger roots and buds or shoots as grasses and other desirable plants a chance to they develop, and progress through three larval reestablish and thrive. stages (called instars). As cool weather Flea beetles typically take several years to approaches, the larvae – now in the third and impact leafy spurge infestations, but the payoff final larval stage – move into deeper soil, where can be well worth the wait. Researchers have they spend the winter. documented leafy spurge canopy cover reduc- tions of up to 95 percent and stem density reduc- Meet the Flea Beetle cyparissiae, A. czwalinae and A. flava – have not Damage to Leafy Spurge tions of 250-plus stems per square meter to Researchers have been working with leafy been as successful at establishing populations or Adult flea beetles feed on leafy spurge leaves fewer than five stems per square meter. spurge biocontrol since 1964, when the Hyles reducing leafy spurge infestations. and bracts in the summer, but the most signifi- It is important to understand that flea beetles hawk moth – a colorful but generally ineffective cant damage is caused by root-feeding larvae. do not eliminate leafy spurge. When flea beetles agent – was released. The most exciting develop- Flea Beetle Biology Feeding by the adults (see page 10 for a photo) work, they establish a natural balance with the ment in leafy spurge biocontrol, however, didn’t Flea beetles over-winter as larvae in soil near and larvae (photo below) stress the host plant, weed, reducing it to a non-impact plant and toler- occur until 1985, when the first of six Aphthona spurge roots. As soil temperatures warm up, gen- and create wounds that allow naturally occurring able member of the plant community. flea beetles was approved and used. erally in April or May, the larvae “wakes up” and soil-borne plant pathogens to invade the plant Later, in a separate section of this manual, Aphthona flea beetles, as the name implies, begins feeding on spurge roots. The larvae and cause additional damage. we’ll discuss another critically important aspect are small, flea-like beetles that feed exclusively pupates during a one- to two-week period, gen- The stress and damage caused by the adults, of biological control: The stress and damage on leafy spurge. Ranging in sizeflea from 2 to 3.5 erally inbeetles late May to mid-June, then emerges larvae and pathogens results in delayed emer- caused by biocontrol agents makes the weed far mm, flea beetles are gregarious and tend to con- from the soil as an adult. Adults live 45-65 days, gence, thinner stands, shorter and weaker more susceptible to other leafy spurge manage- gregate for feeding and during which time they feed plants, delayed maturity and flowering, and ment tools, like grazing and herbicides (see page mating. Flea beetles can on spurge leaves and stems decreased seed production. In short, the weed’s 16).That’s why biocontrol works so well when competitive advantage is reduced, giving native integrated with other management tools. and do fly, but most often lthough some variation can be and reproduce. move about by using strong Females lay eggs in the expected depending on geogra- hind legs to hop like fleas. soil near the base of leafy In well established popula- A phy, climate & seasonal condi- spurge stems. Females lay tions, adults are clearly visi- tions, elevation and other factors, the 50-500 eggs, with some ble when feeding on spurge chart below gives a good general idea variation according to in the summer. of the flea beetle life cycle. species. Eggs hatch in 14- Of the six Aphthona flea 19 days, and the newly beetle species approved emerged larvae seek out and released for leafy spurge biocontrol, two spurge roots and begin feeding. This is an have been particularly successful. A. nigriscutis, extremely sensitive life stage for the flea beetle, first released in 1989, and A.