Introduction Lecturer: Ayodele O. P House Rule Attendance is key Schedule Adherence All phones on Silence Decent Dressing Participatory
Crop protection
Crop protection Course Outline Definition of pests. The major pests, insect, fungi, bacteria, viruses and nematodes, weeds and other diseases of tropical crops and stored products. Study of insect pests of major local crops, their significance and principles of control. Study of the effects of diseases caused by Virus, bacteria, fungi and nematodes. Control of these diseases. Effect of weeds on crops and livestock and the principles and methods of control of weeds. Brief outline, shortcomings and advantages of different pest assessment and pest control methods. Strategies of integrated pest control and pest management. Agy 303
Definitions: Pest Pest can be defined as any organism which injuries man, his property or his environment, or which annoys him. Pest is any organism that interferes negatively with human activities. A pest can be described as any organism capable of causing damage to crop plants. According to Edward & Heath (1964), the pest status is reached when there is 5% loss in yield of a particular crop. The pest concept is anthropocentric and circumstantial. It is anthropocentric the sense that man is the central focus and circumstantial in the sense that an organism may be a pest under one condition and be beneficial in another situation. Agy 303
Examples of Pest Insects Fungi Nematodes Birds Rodents Weeds Bacteria Concepts for Appraising Pest Situation Economic Damage Economy Injury Level Economic Threshold Agy 303
Definitions of Pest Concepts Economic Damage This amount of damage done to the crop that will justify the cost of artificial control measure. It is damage done to crop by pest that is statistically significant at 5% level of probability. Economic Injury Level (EIL) This is the lowest pest population density that can cause economic damage. EIL is the number of pest that will cause a damage that is equal to the cost of controlling the pest Economic Threshold The pest population density at which control measure should be started or introduced to prevent the ever increasing pest population from reaching Economic Injury Level. Agy 303
Economic Threshold ET = C. PDK Where, ET = Economic Threshold C = Cost of implementing control measure P = Price of crop per tone D = Loss in yield (t ha -1 ) associated with the number of pest K = Reduction in pest by use of control measure
Economic Threshold The idea of economic threshold is based on the fact that organism in relatively stable environment will reach a state of equilibrium in the environment over a time There is an average population density which is stable over a long period of time. The Economic Threshold and Economic Injury Level are normally above the average population.
THORITICAL PEST POPULATION IN REACTION TO ECONOMIC THRESHOLD & ECONOMIC INJURY LEVEL The Non-economic / Potential Pests: These are pests whose population level never reaches the Economic Threshold or Economic Injury Level Occasional Pests: These are pests whose population occasionally reaches Economic Threshold or Economic Injury Level. The variegatus grasshopper (Zonocerus variegatus) in West Africa and host of Lepidopterous larva (butterfly) attacking deciduous forest trees, arable as well as plantain crops are examples. Population
THORITICAL PEST POPULATION IN REACTION TO ECONOMIC THRESHOLD & ECONOMIC INJURY LEVEL Key or Major Pests: They are pests whose population frequently reaches the Economic Threshold or Economic Injury Level. They perennially inflict damage on crops and their population level hardly fall below Economic Threshold level. Examples is the case of Maruca testulalis on cowpea, Dysdesus spp and red boll worms on cotton.
THORITICAL PEST POPULATION IN REACTION TO ECONOMIC THRESHOLD & ECONOMIC INJURY LEVEL Perennial Pests: These are pests whose population is always above the Economic Injury Level and Economic Threshold. Control measures should be introduced immediately such pest is seen.
Conditions that Promote Pests Favourable climatic conditions Biological change Change in cultural practices Change in the character of the food supply Introduction to new environments Change in host/natural enemy relationships Loss of competing species Economic change
INSECT PEST Entomology is a branch of biology that focuses on the study of insects Pterygota (winged) Kingdom Phylum Class Apterygota (wingless) Animalia Arthropoda Insecta Insects could be further classified based on Family, Order, Genus and Species The class INSECTA could be divided into winged and wingless insects called Pterygota and Apterygota respectively. The class INSECTA possesses 28 Orders. Each order is divided into families.
INSECT PEST The housefly could be classified as thus Kingdom Phylum Class Family Order Genus Species Animalia Arthropoda Insecta Muscidae Diptera Musca domestica Common and Scientific names of some insects are: Larger Grain Borer Prostephanus truncatus Lesser Grain Borer Rhizopertha dominica Bean Weevil Callosobruchus maculatus Maize Stalk Borer Busseola fusca Elegant Grass Hopper Zonocerus variegatus Honey Bee Apis mellifera
INSECT PEST Characteristics of Insect Pest Possession of one pair of antennae Possession of one pair of eyes Possession of three pairs of legs Possession of breathing tube or trachea Possession of one or two pairs of wings Possession of maxillae and mandible Body divided into head, thorax and abdomen Post-embryonic development is usually by metamorphosis Abdomen is devoid of ambulatory appendages Possession of chitinous exoskeleton Possession of segmented that bears paired limbs
Insect Morphology: External Anatomy Grasshopper Body Parts Agy 303
Insect Morphology: External Anatomy THE HEAD: The head bears the antennae, the mouth part and the eyes. The compound eyes are located on either side of the head and composed of hexagonal facets called corneal lenses. Compound eyes are complex and diverse. ANTENNAE MOUTH PARTS These are paired appendage that articulate with head capsule and are located on the anterior part near the compound eye. This varies with feeding habits. The mouth part of a chewing insect such as the grasshopper has upper lip called the labrum; and a lower lip called the labium. These two serve to hold the food The upper jaws or mandibles are for crushing; and the lower pair, the maxillae manipulate (breaks it into smaller particles) the food Agy 303
THE THORAX: The head is attached to the thorax by means of a membranous region, the neck or cervix. The insect thorax is divided into three segments namely; Prothorax, Mesothorax and Metathorax. On the each of the segment is a pair of legs in winged insects. The thorax also bears one or two pairs of wings. Spiracles which are the external openings of the respiratory system are located on each side of the pleura LEGS: The generalized insect legs consist of six segments as follows: (i) a basal coax (ii) Trochanter (iii) Fermur (iv) Tibia (v) Tarsus (vi) Pretarsus Agy 303
Leg types Cursorial Fussorial walking and running forelegs highly modified bearing heavily sclerotised digging claws Raptorial with forelegs modified for grabbing and holding preys Salfatorial with enlarged hind legs that accommodate muscles used in jumping Natational with leg modified for swimming Agy 303
WING: The wings are borne on either or both the mesothorax and metathorax segments. The wings arise as outgrowth of the integuments between the tergal and pleural sclerites. There are considerable variations in the wings of insects with respect to size and veination. Functions: The most obvious function of the wings is for flying; however, wings have been modified for; (i) Protection: - e.g. hard forewings of the beetles. (ii) Production of sound e.g. the Homoptera (iii) Stability of flight: - Trueflies with balancers ABDOMEN: The abdomen typically has 11 segments; though no more than 10 are visible. It contains a large part of the digestive system. The terminal segment may bear a pair of appendage called CERCI. Agy 303
Economic Classification of Insects Insects are a very important group of animals because of their beneficial and adverse effects on the life of man. Injurious Insects Household and Disease Carrying Insect Beneficial Insects Helpful Insects Agy 303
Economic Importance of Insect Pests This refers to the merits and demerits of insect pests. Demerits Reduces values or quality of food Reduce yield or quantity of output. Vector of Diseases Injuries to Man and Animals Effects of Recreation. Effects on Stored Products, Household and Structural Materials Merits Agent of Pollination Subject of Scientific or Biological Studies Source of Drugs Predators and Parasites. Aeration of Soil Food for Man and Animals.
General Classification of Insects Subclass Apterygota- primitively wingless insects 1 Protura - Proturans 2 Collembola - Springtails 3 Diplura - Diplurans 4 Thysanura - Bristletails 5 Microcoryphia - Jumping bristletails
General Classification of Insects Subclass Pterygota: Winged and secondarily wingless insects. 6. Ephemeroptera - Mayflies 7. Odonata - Dragonflies and damselflies 8. Orthoptera - Grasshoppers, crickets, cockroaches, mantis and walkingsticks 9. Dermaptera - Earwigs 10. Isoptera - Termites 11. Embioptera - Web spinners 12. Plecoptera - Stoneflies 13. Zoraptera - Zorapterans 14. Psocoptera - Psocids 15. Mallophaga - Chewing lice 16. Anoplura - Sucking lice 17. Thysanoptera - Thrips 18. Hemiptera - Bugs 19. Homoptera - Aphids, scale insects, hoppers, cicadas, psyllids and whiteflies.
General Classification of Insects Division Endopterygota - Complex body change during growth 20. Neuroptera - Alderflies, anthions, dobsonflies, fishflies, lacewings, snakeflies and owlflies 21. Coleoptera - Beetles 22. Strepsitera - Twisted-winged parasites 23. Mecoptera - Scorpionflies 24. Trichoptera - Caddisflies 25. Lepidoptera - Butterflies and moths 26. Diptera - Flies and mosquitoes 27. Siphonaptera - Fleas 28. Hymenoptera - Ants, bees, wasps and sawflies
General Classification of Insects Focus Isoptera Coleoptera Diptera Hymenoptera - Termites - Beetles - Flies and mosquitoes - Ants, bees, wasps and sawflies
Order Isoptera - The Termites Example is Macrotermes nigeriense (Edible termites). Insects in this order are termites, soft bodied insects that live together in large communities. Primitive species tunnel into wood, others build large ant hills (termitaria) made up of faeces, saliva and mud. Termites have biting mouth parts. The two pairs of elongated wings are very similar, hence the name Isoptera meaning equal wings. Some lower termites feed on wood, digested through the help of symbiotic protozoa e.g. Trichonympha in the gut while the higher termites feed on fungi, humus and soil organisms and maintain a garden of fungi to feed the young ones and the queen.
Order Isoptera - The Termites They are polymorphic i.e. exist in different forms or castes. They appear in three basic forms: Reproductive forms The winged-reproductive forms usually swarm after heavy rains especially in the mornings and night, they cast off their wings after flying for some time The soldiers (sterile males and females) The soldiers have highly sclerotised head with well-developed mandibles. The workers (Sterile males and females). The workers enclose the queen and king in a royal chamber. There are numerous workers in the colony, who are responsible for building nests, fetching food, nursing the young and cleaning the nest with their mouth parts.
Order Isoptera - The Termites
Order Coleoptera (The Beetles) This order is the largest order in the animal kingdom. Coleopterans are essentially terrestrial insects, found in soil or decaying matters on soil. Some are aquatic e.g. Dytiscus (water beetle). Most beetles in this order are of economic importance because they destroy farm crops, timber and stored products. Fore wings are modified into hard protective elytra which meet in a line down the back. Hind wings are membranous and folded beneath the elytra (forewings) and sometimes the hind wings may be absent. Mouth parts are biting type.
Order Coleoptera (The Beetles) Beetles undergo complete metamorphosis from egg - larva - pupa. Hence three types of larva appear in different members of this order. Compodeiform: Active predatory larva with well-developed antenna, legs, and sensory organs. Eruciform (Scarabeiform): These are C Shaped with large sclerotised head. Thoracic legs are well developed and abdomen is inflated, soft and whitish in colour. Apodous: (Legs absent): Are crescent shaped and eyeless found in groups living in groups in food e.g. weevils.
Order Coleoptera (The Beetles)
Order Diptera (The True-Flies) They are commonly known as true flies, members of this order include mosquitoes, houseflies, midges, and sandflies. A representative feature of this order is presence of a single pair of membranous wings which are borne on the enlarged mesothorax. The hind wings are modified to a pair of halters or balancers. Mouth parts for sucking alone or for piercing and sucking. Many feeds on nectar of flowers or decaying organic matters, examples include mosquitoes, midges; tsetse flies that notably sucks blood. Members in this order undergo complete metamorphosis
Order Diptera (The True-Flies) House fly Mosquito Economic importance of flies Either as adults or as larvae, the blood sucking flies transmit pathogenic organisms causing various diseases, such as malaria, sleeping sickness elephantiasis, yellow fever and filariasis. Housefly act as mechanical carriers of germs on their legs, hairy body and contaminate food. Their larva cause injuries to crops and their activities result in great financial losses
Order Hymenoptera This order constitutes sawflies, bees, ants, wasps. Members are large and about 100,000 species. They exhibit interesting social habit, instinctive behaviour, polymorphism, parasitism and communication. Wings are membranous and have biting mouth type modified for licking and sucking. The larva may be polypodous (with many legs) or Apodous (without legs) like a caterpillar
Economic importance of Hymenoptera Honey bees yield honey and wax Bees are important pollinators of flower Parasitic hymenoptera are helpful in the biological control of injurious insects Family Vespoidea wasps are carnivorous, they paralyse caterpillars with their sting and store them in the nests for young ones to feed on. Family Apoidea bees hind legs are highly modified for pollen collection stored in their nest for their larva, while workers function as nurses, ventilators, cleaners foragers depending on their age.
Concepts of Plant Disease What is Phytopathology? Greek = Phyton (plant) Pathos (suffering) Logos (study) It is the study of the suffering plant Plant pathology is that branch of agricultural, botanical or biological sciences which deals with the study of: Cause of the disease Resulting losses and Control of plant diseases
Objectives of Plant Pathology Study of origin, causes or reasons. Study of living, non-living and other causes of disease or disorder in plants- Etiology: Study of mechanism of disease development i.e. processes of infection and colonization of the host by the pathogen. This phase involves complex hostpathogen interactions- Pathogenesis Study the interaction between the causal agent and the diseased plants in relation to environmental conditions. Generally at the population level- Epidemiology Development of management systems of the diseases land reduction of losses caused by them- Control / Management.
What is health? The ability to carry out normal physiological functions at a acceptable level consistent to genetic potential. Normal physiological functions include: Normal cell division, differentiation and development; Absorption of water and minerals from the soil and translocation; Photosynthesis and translocation of photosynthates; Utilization and storage of photosynthates; Metabolism of metabolites and synthates; Reproduction; Storage of reserves for overwintering or reproduction Plant pathology is both science of learning and understanding the nature of disease and art of diagnosing and controlling the disease
Disease The process in which a pathogen interferes with one or more essential plant cell functions Marshall Ward (1901): Disease represents a condition in which functions of the plant are not properly discharged. Disease is a harmful deviation from normal functioning of physiological processes. (British Mycological Society, 1950) Horsfall & Diamond (1957): Disease can be defined as a physiological disorder or structural abnormality that is deleterious or harmful to the plant or its part or product that reduces its economic value. Disease can be defined as the result of interaction between host, pathogen and environment
Disease There are many ways in which plant disease pathogens can affect plants By utilizing host cell contents By killing host or by interfering with its metabolic processes through their enzymes, toxins etc. By weakening the host due to continuous loss of the nutrients. By interfering with the translocation of the food, minerals land water. They can suppress the chlorophyll content. They can reduce the leaf area. They can curb the movement of solutes and water through the stems. They sometimes reduce the water-absorbing capacity of the roots. They suppress the translocation of photosynthates away from the leaves. They sometimes promote wasteful use of the products of photosynthesis as in the formation of galls.
Disease Triangle Environment TIME Pathogen Disease Host Conditions for disease Host should be susceptible Pathogen should be virulent Environment should be favourable for the disease
Based on type of symptoms Based on type of crop Blights Rusts Smuts Rots Wilt Cereal diseases Vegetable diseases Based on type of organ affected Fruit diseases Root diseases Based on cause Infectious diseases Non-infectious disease
Plant Disease Agents Living Organisms Fungi Bacteria Virus Nematodes Non-living Organisms Unbalanced soil fertility Toxic chemical Air pollution Frost Drought Sunburn Wind
Infectious Plant Diseases Causes Fungi Bacteria Virus Nematodes Viroids Virusoids Protozoa Algae Parasitic Plants Disorder Non-infectious diseases Environmental stress / excess Temperature e.g. high or low Moisture e.g. excess- rotting or Stress wilt /drying Air Light e.g. etiolation Nutrition Imbalanced Excess Deficiency e.g. N deficiency, Zn deficiency An abnormal physiological change due to non-parasitic agent or non-parasitic physiological malfunctioning due to either excess or deficiency in environmental factors or nutrients
Terminology Parasite Pathogen Pathogenicity Pathogenesis Symptom Sign Syndrome Hypersensitivity Host Alternate host Collateral host Resistance Susceptibility Tolerance
Terminology Parasite : An organism that lives on or in another organism and obtains food from the second organism. Pathogenicity is the ability of a pathogen to cause the disease by interfering with one or more of the essential plant cell function. Pathogen: Any entity that can cause disease in a host e.g. fungus, bacteria, virus, phytoplasma, viroids, RLO s, parasitic plants, nematodes. Symptom are the expression of the disease caused by the manifestation of the physiological reaction of the plant due to harmful activity of the pathogen Sign - physical evidence of the presence of disease agent (e.g., mold or fungal spores, bacterial ooze)
Terminology Syndrome : Defined as sequential appearance of disease symptoms on a plant during the development of the disease or sum total of symptoms exhibited by a disease For instance, necrotic spot - blight -fungal growth -death of organ or plant Biotroph: A plant-pathogenic fungi which establishes a long- term relationship with the living cells of host without killing it as part of the infection process.. e.g. Rusts, powdery mildew Necrotrophs: kill their host before feeding on the cells or the cell s contents and live on dead tissue. e.g Rhizoctonia Host: Any organism that harbours another organism is called host. Alternate host: is the host that help in the completion of the life cycle of the pathogen and its survival, belong to different family.
Terminology Collateral host: host of the same family and help in the survival of the pathogen Infection: Establishment of organic relationship between host and pathogen Pathogenesis: Chain of events that takes place during the development of disease (inoculation to survival of the pathogen) Susceptibility: Inability of the host to resist the attack of the pathogen Resistance: Ability of the host to resist the attack of the pathogen Horizontal resistance Vertical resistance Hypersensitivity: is the quick death of the host tissue in the vicinity of the pathogen
Terminology Disease escape: it is ability of the susceptible host to avoid the damaging disease stress e.g. unfavourable environment / growth habit Virulence: It is defined as the degree of pathogenicity of a particular isolate or race of the pathogen. Aggressiveness: it is the capacity of the pathogen to invade and colonize the host and to reproduce on or in it. Predisposition: it is the set of conditions that makes the plant vulnerable to the attack of the pathogen.
Thank you Lecture slide Created by Ayodele O. P olatunde.ayodele@aaua.edu.ng