J.C. van Lenteren

Bio: J.C. van Lenteren is an academic researcher from Wageningen University and Research Centre. The author has contributed to research in topics: Encarsia formosa & Trialeurodes. The author has an hindex of 56, co-authored 320 publications receiving 12297 citations. Previous affiliations of J.C. van Lenteren include Leiden University & Beijing Normal University.

Biological and Integrated Pest control in Greenhouses

Abstract: The total world area covered by greenhouses is very small (approximately 150,000 ha; Table 1), yet developments in biological pest control in this cropping system have been significant and are of particular interest for several reasons. Few specialists in biological control anticipated that it would be possible to employ natural enemies in greenhouses because growing vegeta­ bles and ornamentals in this protected situation is expensive and pest damage is not tolerated. Successful greenhouse growers cannot afford to risk any damage from insects for idealistic reasons, e .g. a belief that biological control may cause fewer negative side effects than chemical control. If chemical control is more effective, growers will certainly use it. In tomatoes, for example, pest control represents only 1-2% of the total overall cost of production (52); thus, the cost of pest control is not a limiting factor. Yet although chemical control is easy and inexpensive, the development and application of biological control has been remarkably fast. Biological control in greenhouses is also worthy of attention because (a) a new system of introducing natural enemies is used; (b) research on pests in greenhouses has resulted in extensive theoretical developments in understanding how biologi­ cal control works; and (c) a close relationship among researchers, develop­ ment and extension workers, and growers has resulted in a rapid transfer and use of information on biological control in greenhouses. To date, most of the

A total system approach to sustainable pest management

Abstract: A fundamental shift to a total system approach for crop protection is urgently needed to resolve escalating economic and environmental consequences of combating agricultural pests. Pest management strategies have long been dominated by quests for “silver bullet” products to control pest outbreaks. However, managing undesired variables in ecosystems is similar to that for other systems, including the human body and social orders. Experience in these fields substantiates the fact that therapeutic interventions into any system are effective only for short term relief because these externalities are soon “neutralized” by countermoves within the system. Long term resolutions can be achieved only by restructuring and managing these systems in ways that maximize the array of “built-in” preventive strengths, with therapeutic tactics serving strictly as backups to these natural regulators. To date, we have failed to incorporate this basic principle into the mainstream of pest management science and continue to regress into a foot race with nature. In this report, we establish why a total system approach is essential as the guiding premise of pest management and provide arguments as to how earlier attempts for change and current mainstream initiatives generally fail to follow this principle. We then draw on emerging knowledge about multitrophic level interactions and other specific findings about management of ecosystems to propose a pivotal redirection of pest management strategies that would honor this principle and, thus, be sustainable. Finally, we discuss the potential immense benefits of such a central shift in pest management philosophy.

Biological control and sustainable food production

Abstract: The use of biological control for the management of pest insects pre-dates the modern pesticide era. The first major successes in biological control occurred with exotic pests controlled by natural enemy species collected from the country or area of origin of the pest (classical control). Augmentative control has been successfully applied against a range of open-field and greenhouse pests, and conservation biological control schemes have been developed with indigenous predators and parasitoids. The cost–benefit ratio for classical biological control is highly favourable (1 : 250) and for augmentative control is similar to that of insecticides (1 : 2–1 : 5), with much lower development costs. Over the past 120 years, more than 5000 introductions of approximately 2000 non-native control agents have been made against arthropod pests in 196 countries or islands with remarkably few environmental problems. Biological control is a key component of a ‘systems approach’ to integrated pest management, to counteract insecticide-resistant pests, withdrawal of chemicals and minimize the usage of pesticides. Current studies indicate that genetically modified insect-resistant Bt crops may have no adverse effects on the activity or function of predators or parasitoids used in biological control. The introduction of rational approaches for the environmental risk assessment of non-native control agents is an essential step in the wider application of biological control, but future success is strongly dependent on a greater level of investment in research and development by governments and related organizations that are committed to a reduced reliance on chemical control.

Assessing risks of releasing exotic biological control agents of arthropod pests

Abstract: More than 5000 introductions of about 2000 species of exotic arthropod agents for control of arthropod pests in 196 countries or islands during the past 120 years rarely have resulted in negative environmental effects. Yet, risks of environmental effects caused by releases of exotics are of growing concern. Twenty countries have implemented regulations for release of biological control agents. Soon, the International Standard for Phytosanitary Measures (ISPM3) will become the standard for all biological control introductions worldwide, but this standard does not provide methods by which to assess environmental risks. This review summarizes documented nontarget effects and discusses the development and application of comprehensive and quick-scan environmental risk assessment methods.

Integrated pest and disease management in greenhouse crops.

Abstract: Viruses cause many important plant diseases and are responsible for yield and quality losses in crops in all parts of the world. No curative methods are available for infected plants and the main control strategies are cultural practices including prophylactic measures to prevent virus arrival, installation and spread into the crop or use genetic resistance to limit disease damage. Factors driving viral emergence include genetic variability of plant viruses, changes in agricultural practices, exchanges of plant material and new introduction or increase in the population of insect vectors in the environnent of the crops. In this review, we briefly describe the most important viruses emerging in economically important vegetable greenhouse crops including pepper, tomato and cucurbit species.

The Theory of Island Biogeography

Abstract: Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Host Defense of Drosophila melanogaster

Abstract: To combat infection, the fruit fly Drosophila melanogaster relies on multiple innate defense reactions, many of which are shared with higher organisms. These reactions include the use of physical barriers together with local and systemic immune responses. First, epithelia, such as those beneath the cuticle, in the alimentary tract, and in tracheae, act both as a physical barrier and local defense against pathogens by producing antimicrobial peptides and reactive oxygen species. Second, specialized hemocytes participate in phagocytosis and encapsulation of foreign intruders in the hemolymph. Finally, the fat body, a functional equivalent of the mammalian liver, produces humoral response molecules including antimicrobial peptides. Here we review our current knowledge of the molecular mechanisms underlying Drosophila defense reactions together with strategies evolved by pathogens to evade them.

Citation classic - optimal foraging - a selective review of theory and tests

Abstract: Beginning with Emlen (1966) and MacArthur and Pianka (1966) and extending through the last ten years, several authors have sought to predict the foraging behavior of animals by means of mathematical models. These models are very similar,in that they all assume that the fitness of a foraging animal is a function of the efficiency of foraging measured in terms of some "currency" (Schoener, 1971) -usually energy- and that natural selection has resulted in animals that forage so as to maximize this fitness. As a result of these similarities, the models have become known as "optimal foraging models"; and the theory that embodies them, "optimal foraging theory." The situations to which optimal foraging theory has been applied, with the exception of a few recent studies, can be divided into the following four categories: (1) choice by an animal of which food types to eat (i.e., optimal diet); (2) choice of which patch type to feed in (i.e., optimal patch choice); (3) optimal allocation of time to different patches; and (4) optimal patterns and speed of movements. In this review we discuss each of these categories separately, dealing with both the theoretical developments and the data that permit tests of the predictions. The review is selective in the sense that we emphasize studies that either develop testable predictions or that attempt to test predictions in a precise quantitative manner. We also discuss what we see to be some of the future developments in the area of optimal foraging theory and how this theory can be related to other areas of biology. Our general conclusion is that the simple models so far formulated are supported are supported reasonably well by available data and that we are optimistic about the value both now and in the future of optimal foraging theory. We argue, however, that these simple models will requre much modification, espicially to deal with situations that either cannot easily be put into one or another of the above four categories or entail currencies more complicated that just energy.

Microbial interactions and biocontrol in the rhizosphere

Abstract: The loss of organic material from the roots provides the energy for the development of active microbial populations in the rhizosphere around the root. Generally, saproptrophs or biotrophs such as mycorrhizal fungi grow in the rhizosphere in response to this carbon loss, but plant pathogens may also develop and infect a susceptible host, resulting in disease. This review examines the microbial interactions that can take place in the rhizosphere and that are involved in biological disease control. The interactions of bacteria used as biocontrol agents of bacterial and fungal plant pathogens, and fungi used as biocontrol agents of protozoan, bacterial and fungal plant pathogens are considered. Whenever possible, modes of action involved in each type of interaction are assessed with particular emphasis on antibiosis, competition, parasitism, and induced resistance. The significance of plant growth promotion and rhizosphere competence in biocontrol is also considered. Multiple microbial interactions involving bacteria and fungi in the rhizosphere are shown to provide enhanced biocontrol in many cases in comparison with biocontrol agents used singly. The extreme complexity of interactions that can occur in the rhizosphere is highlighted and some potential areas for future research in this area are discussed briefly.

Ecology of infochemical use by natural enemies in a tritrophic context.

Abstract: Parasitoids and predators of herbivores have evolved and function within a multitrophic context. Consequently, their physiology and behavior are in­ fluenced by elements from other trophic levels such as their herbivore victim (second trophic level) and its plant food (first trophic level) (126) . Natural enemies base their foraging decisions on information from these different trophic levels, and chemical information plays an important role. This review is restricted to the ecology of chemical information from the first and second trophic levels. The importance of so-called infochemicals, a subcategory of semiochemicals, in foraging by parasitoids and predators has been well documented (e.g. reviewed in 31, 78, Il l , 183, 185) , and we do not intend to repeat the details. But because of a lack of testable hypotheses, all this research is conducted rather haphazardly: the total puzzle of infochemical use has not been solved for any natural enemy species. Here we approach the use of infochemicals by natural enemies from an evolutionary and ecological standpoint. Our basic concept is that information from the first and second trophic levels differs in availability and in reliability, a difference that shapes the way infochemicals are used by a species. We generate hypotheses on (a)