Urban Landscape Entomology

David Held

• Publisher: Academic Press
• Year: 2019
• Print ISBN: 9780128130711
• eBook ISBN: 9780128130728
• Topic: Biological Sciences
• Subtopic: Entomology
• Index: Biological Sciences

Urban Landscape Entomology provides readers with the background needed to adequately understand and manage many of the complexities of urban landscape pest management. For those who need training in landscape entomology, this work serves as a practical guidebook and resource. Its chapters include quality color images of pests, along with pest management tactics, such as tree injection procedures. This topical arrangement facilitates easy extraction of information relevant to a particular situation (e.g., management of borers) and uses practical terms without oversimplifying the subject matter.This work is an invaluable resource for practitioners of landscape entomology, including technicians and operations that service local landscape management needs, such as horticultural and turfgrass management. In addition, it is also a useful reference for advanced courses in landscape entomology.- Includes diagnostic information on both turfgrass and ornamental pest management- Concludes each chapter with a list of key papers for further reading and research- Provides information on open-source online resources for insect identification and insecticide classification- Includes details of the author's international work in such urban landscapes as China, Costa Rica and Cuba, also including additional global perspectives

Chapter 1

Introduction

Abstract

Urbanization creates effects on the land, plants, and pests unlike other agroecosystems. Urbanization is the process where people move toward cities for various reasons but often for better social or economic opportunities. The United States generally lags behind most of Asia and Africa in present and future urbanization, but the United States has several megacities (e.g., New York, Los Angeles). This lag is likely due to our relatively new colonization compared to Europe and Asia, but several United States megacities (e.g., New York, Los Angeles) are rapidly catching up with international megacities. Many sources have estimated the rapid pace of urbanization in the United States with the UN data being the most cited. In the 40-year period from 2010 to 2050, urban populations are supposed to increase 10%. The United States is already 82% urban and, by 2050, should grow to 90% of the population in urban\suburban areas. Globally, the same trends are happening. Megacities are growing and 68% of the global population is expected to be urban within the next 30 years.

Keywords

Biodiversity; Primary consumer; Primary producer; Secondary consumer; Urban ecology; Urbanization

Urbanization: trends and relevance

Urbanization creates effects on the land, plants, and pests in ways unlike other plant systems (agriculture or forestry). Urbanization is the shifting of people into or nearby cities, but often for better social or economic opportunities. The United States generally lags behind most of Asia and Africa in present and future urbanization (1). This lag is likely due to our relatively new colonization compared to Europe and Asia, but several United States megacities (e.g., New York, Los Angeles) are rapidly catching up with international megacities. Many sources have estimated the rapid pace of urbanization in the United States with the UN data being the most cited. In the 40-year period from 2010 to 2050, urban populations are predicted to increase 10%. The United States is already 82% urban and, by 2050, should grow to 90% of the population in urban\suburban areas. The same trend is occurring globally. Megacities are growing and 68% of the global population is expected to be urban within the next 30 years (2).

If you have witnessed urbanization firsthand in the United States, it was likely agricultural or tree crop (forestry or tree fruit) production lands converted to various urban developments. I call this the crops to cul-de-sacs effect. Losses of land to urban development are considered permanent as it is uncommon but not impossible (3) to convert urban spaces back to natural or agricultural lands. The lower 48 states have a finite land mass of 768.9 million ha (1.9 billion acres). From 1982 to 2012, urban development in the United States increased by 17 million ha (42.2 million acres) (Fig. 1.1). In 2012, urban areas accounted for 5.86% (46,174,631 ha or 114.1 million acres) of the entire United States land cover (4). These statistics are also cited as the basis for claims that urbanization is a threat to agricultural productivity and global biodiversity (5). As we replace arable lands with houses, golf courses, or shopping malls, a greater burden of food and fiber productivity is shifted to less land. The average farmer in 2012 was feeding about 100 people in the United States (3.2 million farmers feeding a population of >300 million people) (6,7). The ratio of people in the United States to farmers increases with every Census of Agriculture and is driving agricultural intensification, or more productivity from less land.

Figure 1.1 The continental United States has 1.9 billion acres of land cover. Of this, an increasing portion is becoming urban mainly at the expense of cropland (4).

Box 1.1

Plant communities shape insect communities.

Plants are the primary food source in these communities. As we will see later, these effects are well documented for plant-feeding insects as well as insect natural enemies and pollinators. These effects in research papers are called “bottom-up” effects or forces (for more information, see Ref. (8)).

Landscape structure, both living and hardscape components, are drivers of ecological change in urban landscapes (Box 1.1). As plant species and abundance change, insect populations change. The addition of hardscape (buildings) or impervious surfaces (roads, sidewalks) covers soil or removes topsoil, changes temperatures, and the biological components of landscapes are impacted by these changes (9). Understanding these interactions and their influences on plants, insects (pests and beneficials), and people (socioeconomics) are common themes in the broader field of landscape ecology.

Have you heard someone suggest that they see fewer fireflies (9), dragonflies, or other insects today relative to their childhood or even 10 years ago? Or maybe you have read a story on the windshield effect (10), where people perceive fewer insects by the number of splats on their windshield? Some popular press writers have even dubbed these documented losses of insect biodiversity as an “insect apocalypse” (11). Habitat destruction through urbanization is often implicated in these effects on insects (5). To document these effects, scientists commonly compare urban to nonurban locations to discern the effects of urbanization. If there are significant differences between the two locations, then an urbanization effect is affirmed and the causes can be further investigated. A few studies, however, have carefully documented changes in insect communities at one location over time. Using historic records or insect collections in museums, it is possible to estimate local extinctions of a group or species of insects over time. Annual data collection is the basis for two well-publicized North American projects, Monarchwatch.org and lostladybug.org. Europe, however, has more years of urban development and data collection. Rome, one of the oldest cities in the Western world, is an excellent case study. As Rome urbanized, species of darkling beetles (Tenebrionidae) became less dense and isolated and some became locally extinct. Darkling beetles are not pests of landscape plants, but a common family that provides biological services like decomposition, scavenging, and biological control (12,13).

Urban landscapes: interactions of people, plants, and insects

How can urbanization cause such effects? Let us begin by imagining a fictitious expanse of land, fully or partially forested, located somewhere in eastern North America. If we go back in time before European colonization, plants would be exclusively native trees, shrubs, and groundcovers (grasses or other herbaceous plants) adapted for this location, with biological associations among insects, birds, and mammals. Large trees like mature oaks, maples, beech, or evergreens may represent the overstory, which is the highest canopy layer in a forest. The understory, the tree layer below the overstory, includes the younger saplings of overstory trees, and understory trees like dogwoods or redbuds. The shrub layer could contain oakleaf hydrangeas, bayberry, rhododendrons, or hollies. The ground layer would be a mixture of herbaceous perennials, annuals, vines, and decomposing leaves.

Now, overlay onto this plant background some ecological processes and relationships (Fig. 1.2). The plants represent the food-making component called primary producers. Plants harvest the sun's energy and carbon dioxide to generate biomass (leaves, stems, flowers, fruit, roots). Primary consumers get their energy, and the ability to grow and develop, from the primary producers. The insects tend to dominate the primary consumers consuming mainly leaves but also other plant parts like pollen. A third level called decomposers would recycle the unused plant biomass and animal waste. Among insects, plant feeders (herbivores) can either be specialists, using a few plants as hosts, or generalists, using a wide range of hosts. Azalea lace bugs (Stephanitis pyrioides) are examples of specialists, and Japanese beetles (Popillia japonica) are examples of generalist herbivores. The n...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Preface
• Acknowledgments
• Chapter 1. Introduction
• Chapter 2. Landscape structure and complexity
• Chapter 3. Plants as active participants in urban landscapes
• Chapter 4. Abiotic factors and interactions with urban pests
• Chapter 5. Sampling insects and decision-making
• Chapter 6. Insects and mites in turfgrass
• Chapter 7. Insects and mites attacking woody and herbaceous plants
• Chapter 8. Nonchemical approaches to pest management
• Chapter 9. Insecticides: A balance of plant protection and environmental stewardship
• Index