Biological Control of Plant Pests Asst. Prof. Dr. Samaporn Saengyot Biological Control Technology Learning Center, Faculty of Agricultural Production, Mae JO University, San Sai, Chiang Mai
Introduction to Pests and Pest Control
What are pests? • Pests are undesirable or unwanted organisms by man. • Pests include insects, mites, invertebrates, vertebrates, weeds, plant diseases, animal diseases etc. • Pests of agricultural importance. • Pests of medical and public health importance.
Pest Control • Any action, natural or man-made, to reduce or mitigate pest problems. • Pest control can be: - Natural Control (Environmental factors) - Applied Control (Man-made)
Natural Pest Control • Natural Control: (Environmental factors) - Abiotic (physical, density-independent) - Biotic (biological, density-dependent)
Applied Pest Control • Applied Control: (Man-made) - Cultural control - Mechanical control - Microbial control - Genetic control - Integrated control
- Physical control - Biological control - Chemical control - Regulatory control
Pest Control in IPM System
Pest Management • PM = The intelligent selection and use of pest control actions that will ensure favorable economic, ecological and socioecological consequences (Dale Bottrell, 1979).
Integrated Pest Management - IPM • IPM = The selection, integration, and implementation of pest control actions based on predicted economic, ecological and sociological consequences of the actions (Dale Botttrell, 1979).
Integrated Pest Management - IPM • IPM is a decision support system for the selection and use of pest control tactics, singly or harmoniously coordinated into a management strategy, based on cost/benefit analyses that take into account the interests of and impacts on producers, society, and the environment (Marcos Kogan, 1998).
Natural Control and IPM • If the natural enemies are doing an effective control under the natural control system, the IPM decision could be “doing nothing.” • At times, “no action” is the best action. • If natural control is ineffective, applied control such as biological, chemical and other control must be adopted.
Biological Control and IPM • Biological control is one of the applied pest control tactics and should be considered as the key or major pest control tactic in any IPM system. • Other control tactics should be aligned and harmonized with natural and biological control as much as possible.
Introduction to Natural and Biological Control
Definition of Natural Control • NC = The maintenance of a more or less fluctuating population density of a pest within certain upper and lower limits over a period of time by the actions of abiotic and/or biotic environmental factors.
Natural Control • Abiotic Factors: Temperature, humidity, climatic factors, geographical barriers, topography, etc. • Biotic Factors: Living organisms such as parasites or parasitoids, predators, pathogens, other competitors, etc.
Prof. Harry Scott Smith (1893-1957) University of California at Berkeley Coined the term “Biological Control� in 1919
What is Biological Control? • Biological control is “The study and utilization of parasites, predators, and pathogens for the regulation of host population densities” (Paul DeBach, 1964). • Fields of biological control are: - Basic study - Importation of natural enemies - Augmentation of natural enemies - Conservation of natural enemies
Paul DeBach (1914-1992) University of California at Riverside Coined the “Definition of Biological Control� in 1964
Biological Control Methods • Biological control methods may be: - Naturally-occurring biological control, or Natural biological control - Classical biological control - Augmentative biological control - Conservation biological control
Naturally-occurring Biological Control • It is an on-going natural phenomenon in the regulation of insect populations brought about by both abiotic and biotic factors. • Abiotic factors are physical factors such as temperature, moisture and unfavorable climatic condition, etc. • Biotic factors are mainly the predators, parasitoids and pathogens (3Ps) and other biological competitors, etc.
Classical Biological Control • It is mainly used for controlling invasive alien species (IAS) or exotic pest species. • It is carried out by exploration and searching for effective natural enemies in the native habitat of the pests in foreign countries and introducing or importing them to control the IAS and/or exotic pests in the country where they become serious pests.
Classical Biological Control • Most parasitoids used in classical biological control involving importation or introduction are in the order Hymenoptera and, to a lesser degree, Diptera. • The most frequently used groups are: Braconidae, Ichneumonidae, Eulophidae, Pteromalidae, Encyrtidae and Aphelinidae in the Hymenoptera; and Tachinidae in the Diptera.
Classical Biological Control • Up to 2000, > 390 species in 194 genera of parasitoids have been used in classical biological control projects of > 2,740 species of insect pests in > 860 occasions worldwide resulting in > 215 effective control cases. • This is in addition to the use of predatory insects.
Augmentative Biological Control • It is the utilization of resident or native natural enemies to control the insect pest species. • It is undertaken by rearing natural enemies in large quantity and releasing them in the fields where there is no such natural enemies or where their populations are low and not adequate to control the pests. • Field releases can be inoculative or inundative depending on the number of natural enemies reared and available in the laboratories.
Conservation Biological Control • It is the manipulation of the environment to minimize any adverse environmental effects to suit certain needs of the natural enemies. • It is carried out in order to render them more suitable and conducive for the survival and persistence of the natural enemies. • Avoidance of using agrochemicals in the area is a good example.
Other Biological Control Methods • There are several other pest control methods claimed, misunderstood, and mistaken to be biological control methods because they are “non-chemical” and as such they claim to be “biocontrol” or “biological control” method. • They are all “pseudo-biological control” and are not be classified as “true” biological control, but rather be classified as: - Para-biological control - “Me-too” biological control
Para-biological Control • Para-biological control is “biological control” involving other methods which are non-chemical but are biologically-based such as: - Sterile insect technique (SIT) - Insect growth regulators (AGR) - Semiochemicals such as pheromone - Botanical insecticides such as pyrethrum - Resistant plant varieties - Genetically modified (GM) crops resistant to insects such as Bt cotton, Bt soybean and Bt corn
Modern Biological Control • With the advent of r-DNA technology, or genetic engineering which is also termed as modern biotechnology, BC has also been defined as: “The use of natural or modified organisms, genes, or gene products to reduce the effects of undesirable organisms (pests), and to favor desirable organisms such as crops, trees, animals, and beneficial insects and microorganisms” (U.S. National Academy of Science, 1988).
Categories of Biological Control • • • • • • •
Natural biological control Augmentative biological control Conservative biological control Classical biological control Para-biological control Modern biological control Pseudo-biological control
Fields of Biological Control • • • • •
Basic and applied study Importation (Introduction) Augmentation Conservation Evaluation
Targets/Areas of Biological Control • Insect pests and weeds of importance in agriculture, forestry and fisheries. • Insect pests and insect vectors of medical and public health importance. • Other pest organisms such as plant diseases, vertebrate pests, etc.
Biological Control Questions • Biological control is for exotic pests only? • Pests of foreign origin (exotic pests) vs. Pests of domestic origin (endemic pests). • The most easily found or most common natural enemy is not necessarily the best. • It might often be said that: “A good natural enemy is a scarce natural enemy!”
Evaluation of Biological Control Success • BC evaluation is relatively difficult and ambiguous, time-bound or endless. • Once achieved and completely successful, the end result is invisible! • Qualitative as: Total failure (TF), Partial control (PC), Substantial control (SC) and Complete control (CC).
Natural Enemies of Insect Pests • Predators, Parasitoids and Pathogens are collectively known as “Natural enemies” of noxious insects and are colloquially called “3Ps”. • Under natural conditions they are responsible for “Natural control” of insect populations under the phenomenon of “Naturally-occurring biological control” or “Natural biological control”.
Natural Enemies
Parasite or Parasitoid
Coccinellid Predator
Pathogen (Fungus)
Diversity of Insects on Earth • Species composition of living organisms (after Strong, Lawton and Southwood, 1982. Insects on plants: Community patterns and mechanisms) - Green plants - Phytophagous insects - Saprophagous, predaceous & parasitic insects Total insects - Other invertebrates - Invertebrates - Protozoa Total
308,000 361,000 431,000 792,000 213,000 54,000 30,000 1,097,000
Diversity of Insects on Earth • Of about 1 million insect species known, most are general and beneficial insects, predators and parasitoids, and few are pest species. • No more than 0.5 % or 5,000 insect species are known to be noxious insect pests. • Commonwealth Agricultural Bureau Intl (CABI) in UK began compiling Distribution Maps of Plant Pests since 1951 to 2010 totaling 60 years, there are only 738 plant pest species from all over the world which are of economic importance. • The remaining is kept unharmed by natural enemies.
Orders and Families of Insect Predators
14 Orders and 167 Families
(Sweetman, 1936) • Order Coleoptera Family Coccinelidae and
Carabidae (ground beetle and tiger beetle) •Order Odonata including Dragonfly and Damselfly
• Order Neuroptera (27 Families) such as Family Myrmeleontidae (antlion) and Chrysopidae (lacewing)
Insect Predators
Insect Predators
Insect Predators
Insect Predators
Insect Predators
Insect Predators (Green lacewing larva)
Insect Predators
Insect Predators (Syrphus spp.)
Insect Predators
Insect Predators
Insect Predators
Insect Predators (Apefly, Spalgis epius (Westwood) ,Lepidoptera: Lycaenidae)
Predatory mite: Phytoseiulus persimilis :
Insect Orders with Parasitoids Most parasitoids are in Hymenoptera (all parasitic wasps). • Diptera contains some parasitoids (pipunculids or big-headed flies, tachinid flies). • All species of Strepsiptera are parasitoids (stylops or stylopids or twisted-wings insects). • Few parasitoids are found in Coleoptera (blister beetles, rhipiphorids) and Lepidoptera (epipyropids or planthopper parasite moths). •
Parasitoids
Parasitoids
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Microplitis plutellae
Apanteles sp.
Cotesia plutellae
Parasitoids
Parasitoids
Coccobius fulvus
Cephaleta brunniventris
Parasitoids Encarsia formosa,
Parasitoids (Azalea lace bug egg parasite)
Parasitoids
Parasitoids
Parasitoids Order Strepsiptera (twisted-winged parasites)
Microbial Control
A brief history (Bombyx mori L.) / CordycepsIsaria
Agostino Bassi (father of insect pathology)
• White muscardine, Beauveria bassiana
Metarrhizium anisopliae / wheat cockchafer, Anisoplia austriaca) / Metarhizium anisopliae
E. Berliner / Bacillus thuringiensis (Bt.) /(Mediterranean flour moth, Anagasta kuehniella)
1938 •Sporéine
Edward Arthur Steinhaus (1914-1969)
(Mode of action of entomopathogenic microorganisms)
1. Contact type
2. Ingestion type
Mode of action of entomopathogenic microorganisms
(Entomopathogenic microorganisms) • Viruses: • Baculoviruses - Nuclear polyhedrosis viruses (NPVs): caterpillar, sawfly larvae - Granulosis viruses (GVs): caterpillars - Non-occluded (Oryctes virus): scarab larvae
Entomopathogenic microorganisms
• Viruses: • Cytoplasmic polyhedrosis viruses (CPVs): caterpillars • Entomopoxviruses: grasshoppers, scarab larvae • Iridoviruses: mosquito larvae
(Entomopathogenic microorganisms) • Viruses:
Entomopathogenic microorganisms
• Bacteria: - Bacillus popillae: scarab larvae - B. thuringiensis: caterpillars, beetle larvae - B. t. israelensis (Bti): mosquito and black fly larvae - B. sphaericus: mosquito larvae (Culex sp., Anopheles sp.) - Serratia entomophila: scarab larvae
Entomopathogenic microorganisms
• Bacteria:
Entomopathogenic microorganisms • Fungi: • Mastigomycotina (aquatic fungi) - Coelomomyces species: mosquito larvae - Culicinomyces clavosporus: mosquito larvae - Lagenidium giganteum: mosquito larvae - Tolypocladium cylindrosporum: mosquito larvae
Entomopathogenic microorganisms
• Fungi: • Zygomycotina - Entomophthoraceous fungi: aphids, caterpillars, beetles, grasshoppers - Conidiolobus: aphids - Entomophaga: grasshoppers, caterpillars - Entomohaga grylli: locusts, grashopper - Entomophthora: aphids - Erynia neoaphidis: aphids - Zoophthora: aphids, caterpillars, beetles
Entomopathogenic microorganisms
• Fungi: • Deuteromycotina (Imperfect fungi) - Beauveria bassiana: beetle larvae, caterpillars, grasshoppers - Hirsutella thomsonii: mites - Metarrhizium anisopliae: beetle larvae, leafhoppers, spittle bugs, cockroaches
Entomopathogenic microorganisms
• Fungi: • Deuteromycotina (Imperfect fungi) - Nomurea rileyi: noctuid caterpillars - Paecilomyces fumoso-rosea: whiteflies - Verticillium lecanii: aphids, whiteflies
Entomopathogenic microorganisms • Fungi:
Entomopathogenic microorganisms • Fungi:
Entomopathogenic microorganisms • Fungi:
Entomopathogenic microorganisms • Microsporidia (Protozoa): - Nosema species: grasshoppers, mosquito larvae, beetles - Nosema locustae: locusts and grasshoppers - Nosema pyrausta: corn borers - Vairimorpha necatrix: caterpillars
Entomopathogenic microorganisms
• Microsporidia (Protozoa):
Entomopathogenic microorganisms
• Nematodes: - Mermithids: grasshoppers, mosquito larvae - Agamermis species: grasshoppers, mosquitoes - Mermis species species: grasshoppers, mosquitoes
- Romanomermis culicivorax: mosquito larvae - R. iyengari: mosquito larvae - Steinernematids, Heterorhabditis: caterpillars, beetle larvae, mole crickets - Steinernema carpocapsae: > 250 caterpillar spp.
Entomopathogenic microorganisms
• Nematodes:
Microbial Insecticides
Economic Importance of Parasitoids
Economic Overview of Hymenoptera • The Hymenoptera, with more than 115,000 described species, includes as much as 10% of the species diversity of the planet. • Economically and ecologically, they are one of the most important groups of organisms.
Economic Overview of Hymenoptera • Various Hymenoptera are either: • Severe economic pests threatening both the forest industry and agriculture (sawflies). • Medical and noxious pests of urban landscapes (stinging wasps and ants). • Pollinators (bees and others).
Economic Overview of Hymenoptera • Defenders of our agricultural crops through their ability to parasitize and control pest insects (parasitic Apocrita).
Economic Role of Parasitoids • Parasitoids, together with predators and pathogens, under natural condition are important “natural enemies” of insect pest of agriculture and forestry and insect vectors of medical and public health importance. • They are of high economic value but are not known nor recognized by man. • Their roles are not visible and their economic value is thus overlooked.
Economic Role of Parasitoids • Both parasitoids and predators have been used in biological control. • While pathogens (bacteria, fungi, viruses, protozoa and nematodes) have been used in microbial control.