eChapters

Objective synonym: An absolute or nomenclatural synonym resulting from the proposal either of a replacement name for a supposedly preoccupied name or of names based on the same specimen, illustration, or taxonomic entity (cf. Synonym, Subjective synonym).

Obligate parasite: A parasite that requires a living host to survive and reproduce and which cannot exist in any other way.

Obligatory: Compulsory, or exclusive; e.g. obligatory diapause is a resting stage that occurs in every individual of each individual of each generation of a univoltine insect.

Oblique sternals: Lateral abdominal muscles in other than longitudinal or dorsal-ventral orientation

Pacemaker: A region from which waves of contraction in the heartbeat cycle are propagated.

Paedogenesis: Reproduction by the juvenile form; the production of eggs or young by an immature or larval stage of an animal; reproduction by larviform individuals.

Paeudotrachea: A ridged groove on the ventral surface of the labellum of some higher Diptera, used to take up liquid food.

Page precedence: The principle that when two or more conflicting homonyms or synonyms are published in the same work (or portion of a work) and, as a consequence, are of the same date, the names shall have priority according to the sequence in which they first appear in the work (or portion) concerned.

Paint gun: Type of small, hand-carried, air-blast machine.

Pair-wise coevolution: see Specific coevolution.

Quadrangle: A cell immediately beyond the arculus (Odonata, Zygoptera).

Quadrat: A four-sided defined area from which a sample is collected, used in population determination.

Quadrivoltine: Four life cycles per year.

Qualitative defenses of plants: Toxins and small-molecular-weight compounds (such as alkaloids) that are active against the physiological systems of phytophagous insects; complex, digestibility-reducing substances (such as tannins) that reduce the ability of insects to feed on plants.

Quantitative specificity: In serology, the principle that a given kind of antibody will react more strongly, under comparable conditions, with the particular kind of antigen used in its formation than with any other substance (cf. Antibody, Antigen, and Precipitin reaction).

Race: A subspecific category that is based on particular attributes, such as behavioral or physiological (other than morphological) differences; similar to a subspecies; often used in describing plant pathogens.

Race: Subspecies (q.v.).

Race: A naturally occurring group within a species usually visually indistinguishable but with some physiological difference from other members of the species, e.g., with a different plant host range. cf. strain.

Radial cell: A cell bordered anteriorly by a branch of the radius; the marginal cell (Hymenoptera).

Radial cross vein: A cross vein connecting R₁ and the branch of the radius immediately behind it.

Radial sector: The posterior of the two main branches of the radius.

Radiation: See Adaptive radiation.

Sabadilla: A botanical insecticide extracted from seeds of Schoenocaulon officinale

Safener: A chemical additive that reduces the phytotoxic properties of a pesticide.

Salivarium or salivary reservoir: The cavity into which the salivary gland opens, between the hypopharynx and the labium.

Salivary gland: The exocrine gland that produces saliva and typically associated with the labial segment; highly variable in size, structure, and function.

Saltation: Discontinuous variation produced at a single step by mutation (cf. Mutation).

Ultra low volume spraying (ULV): The application of pesticides in extremely concentrated or undiluted form using 10 liters or less per hectare (1 gal per acre); highly concentrated pesticide applied without dilution at a rate of 0.5 gallons per acre or less.

Umbilical cord: The cord containing blood vessels supported by connective tissue that unites the embryo or fetus of a mammal with the mother during development in the uterus. (L. umbilicus = navel).

Ungulate: Having hoofs, as a deer or (L. ungula = hoof).

Unguligrade: Walking or adopted for walking on hoofs. (L. ungula = hoof + gradior = to step).

Ungue: Pretarsal claw.

Unguiculate: Having claws, as a cat. (L. unguis = claw).

Vagina: A pouch-like or tubular genital chamber of the female genitalia; external opening of the female reproductive system; or the terminus of the female reproductive tract that opens to the outside; or the terminal portion of the female reproductive tract which receives the copulatory organ of a male in mating (L. sheath).

Valid name: The name of a taxonomic category which is available nomenclaturally and also is recognized as valid on Zoological grounds (cf. Available name).

Valvar lamina: The posterior margin (usually prolonged posteriorly) of the eighth abdominal sternite (female Odonata).

Valve: In animals, any structure that limits or closes an opening; the thin folds in veins, lymph vessels, or hearts or the circular muscles about a tubular exit; also, either external shell of bivalve mollusk, brachiopod, or some crustaceans.

Valvifer (s): A basal sclerite of a valve of the ovipositor, articulating with the tergum; or proximal structures of the ovipositor that bear the valvulae; in female insect genitalia, derivations of gonocoxites 8 and 9, supporting the valves of the ovipositor.

Valvulae: Distal structures of the ovipositor borne on the valvifers; the three pairs of processes forming the sheath and piercing structures of the ovipositor.

Wettable powder (WP): An insecticide formulation consisting of finely ground solid particles of active ingredient plus inert carrier; forms a suspension when added to water.

Waggle dance: A communication dance of honey bees. A form of recruitment in the honey bee in which direction and distance to a food source are indicated.

Waiting period: See time interval.

Waiting period: The prescribed period between last application of a pesticide to crop and harvest.

Warble: The swelling on the host body caused by the larva of a warble fly.

Warm-blooded (Homoiothermous): Animals in which body temperature normally does not change with changes in atmospheric temperature e.g.birds and mammals.

Warning: Signal word used to designate a moderately toxic pesticide; oral LD₅₀ = 50 to 500 mg/kg body formulated.

Xerophyte: Plant adapted for survival in desert or physiologically dry soil.

Xylem: The water-conducting woody tissue in vascular plants.

Xylomycetophagy: Cultivation and feeding upon symbiotic fungi growing in woody tree tissues; for example, some Scolytidae.

Xylophage (adj. xylophagous): An eater of wood.

Xylophagy: Feeding on xylem tissues.

Yellow fever: An infectious, mosquito-transmitted viral disease.

1.1 Introduction

The human population is growing rapidly at an alarming rate, disproportionately to the production of food supplies, which will necessitate production of more food in the near future. The human population has already crossed the 7 billion mark and is expected to rise over 8-10 billion by 21st century. More than 800 million people are reported to suffer from malnutrition (Matson et al., 1997).  Thereby necessitating the need for more food production. Presently, agriculture faces the double challenge of feeding a fast growing population and at the same time prevents the degradation of the agricultural resource base. There appear to be two options for developing countries; either to improve agriculture through modernization, by emphasizing pesticides, fertilizers, machinery and modern varieties of crops; or use sustainable agriculture, promoting improved traditional, small-scale techniques (Pretty, 1999).

2.1    Introduction

The hot and usually wet conditions in tropics adversely affect the performance of insecticides as well as biology of the pests. Pesticide usuage is declining throughout the world, but in tropics it is likely to increase threatening basic biological components of pest management, environment and safety of people.  Pest management in tropical agriculture is basically influenced by high diversity of organisms, diversity of physical features and ecosystems, moderate seasonal weather changes, and the human factor. The high biological diversity of the tropics includes a wide range of interacting organisms from which have been identified pests that affect health crops and livestock as well as cultural practices for pest management.  Physical features of the tropics are also diverse, and include high-altitude temperate zones, rain forests, savannah woodlands, grasslands, and desert zones. Each zone has its own biological diversity either existing in isolation or overlapping with others. Moderate seasonal weather changes in the tropics affect populations indirectly, through modification of interactions between organisms.

Introduction

The tropics extends on  vast region of the earth surface ranging from 23½^°C North to the Tropic of Cancer and 23½^°C South to the Tropic of Capricorn. Several countries of Asia, Africa and Latin America include tropical areas. The tropical regions are the warmest area on the earth with average temperatures ranging between 20^°C and 35^°C. More than 80 % of the area in tropics supports forests and savannah and only 15% is under deserts, shrubs and grasses. About 5% of the area is under mid or high altitude with moderate climatic conditions. Evidently, the tropics support great diversity of physical and climatic conditions in different ecologies and different ecosystems. Temperature and daylight length is much higher throughout the year which induces more number of insect pests, their generations causing more damage in tropics. The increased menace of insect pests requires frequent and repeated use of chemical pesticide to mitigate the insect pest damage.

4.1 Introduction

Insecticides, biocontrol agents and resistant varieties are the three important pest management tactics in vogue across the globe. Though several biocontrol agents have been recorded on major pests of economically important crops, mass multiplication techniques for most of them are yet to be perfected, and in several instances, the inundative releases of natural enemies are costlier than chemical insecticides. Moreover, unlike perennial crop ecosystems, the annual crop ecosystems like rice, cotton, sugarcane, pulses, etc. are frequently disturbed and hence, inoculative releases of biocontrol agents are often impractical. Above all, in spite of sustained effort from dedicated plant breeders across the globe, the resistant varieties with outstanding yield potential are very limited in numbers. Genetic engineering of crop plants though paved the way for introducing insecticidal genes more precisely and efficiently, the poorly understood ecological and sociological implications of genetically engineered crops in their target environment resist their strong footing in the pest management programmes in most of the crops especially of food crops. In this backdrop, insecticidal interference is inevitable to manage the insect pests, and they are the only weapon whenever the pest population crosses the economic threshold level.

5.1 Introduction

Rainfed agriculture accounts for about 60-95% of farmed land in major areas of the world covering Saharan Africa, Latin America, North Africa and East Asia and South Asia. Agriculture in about 60 percent of 142 m ha of net cultivated area in India is rainfed without access to any source of irrigation. Rainfed agriculture is mostly practiced in arid, semi-arid and sub-humid regions where the rainfall is low in quantity, erratic in distribution and is also characterized by high inter-year variability. Together with poor and degraded soils, this limits the length of growing season as well as the choice of crops that can be grown sustainably. Coarse cereals, pulses, oilseeds and cotton dominate the cropping pattern in the regions where rainfed agriculture is concentrated. More importantly, these rainfed regions provide a livelihood to a majority of the rural poor, and as a result they are often described as concentrations of mass poverty and hotspots for civic strife. The productivity of crops grown in rainfed areas is considerably lower than its potential and much lower than that of irrigated crops. Enhancing the productivity of rainfed crops is therefore important from the viewpoints of growth, equity and sustainability.

6.1 Introduction

The sensitivities of plants and of crop yield to a changing climate, is a major challenge for the agricultural research community to relate these findings to the broader societal concern with food security. This chapter reviews the direct effects of climate on both crop growth and yield and on plant pests and pathogens and the interactions that may occur between crops, pests, and pathogens under changed climate. The better understanding of the roles of pests and pathogens in crop production systems that might   make to enhanced food security is discussed. Evidence for the measured climate change on crops and their associated pests and pathogens is starting to be documented. Globally atmospheric CO₂ has increased, and in northern latitudes mean temperature at many locations has increased by about 1.0–1.4 ^°C with accompanying changes in pest and pathogen incidence and to farming practices. Many pests and pathogens exhibit considerable capacity for generating, recombining, and selecting fit combinations of variants in key pathogenicity, fitness, and aggressiveness traits that there is little doubt that any new opportunities resulting from climate change will be exploited by them.

7.1 Introduction

Sustainable agricultural systems must be adopted to increase the food production keeping in view of increase in human population. In tropical countries, insect pests are major challenges to increase food production by causing significant damage in the crop fields and stored grains and their products. Interventions by implementing timely integrated pest management strategies are necessary to reduce the yield losses. Efforts to control insect pests have predominantly relied on the use of broad-spectrum insecticides.  However, indiscriminate and irrational applications of insecticides have created the problems such as insecticide resistance, resurgence, secondary pest outbreak and the presence of residues in food and environment (Ansari et al., 2013). Globally, to reduce the pesticide dependence, various technologies have been developed using different approaches to monitor and maage insect pests which are discussed in this chapter.

8.1 Introduction

Vegetables are cultivated over an area of about 19 million ha globally, with an annual production of 268 million tonnes; Asia and Africa account for more than 90% of the hectarage and production (FAO, 2011). Vegetable crops contribute to human and environmental health. Most vegetables can supply plant proteins, vitamins (especially vitamins A and C), folic acid, minerals such as iron and calcium, and dietary fiber to the human diet (Fowler, 2011). Vegetable legumes also fix atmospheric nitrogen in the soil, thus improving soil fertility. Their haulms can be used as high quality livestock fodder. Most vegetables are high-value, repeat-cycle crops that can help lift small-scale farmers out of poverty in developing tropical countries (Genova et al., 2010). However, vegetable production is often constrained by several severe biotic- and abiotic factors that reduce yields and profits.

9.1 Introduction

Cereal crops are of global importance and the lifeline of the human civilization. The four most important cereals grown for human food in the tropics are rice, maize, sorghum and pearl millet. There are other minor cereals of tropical origin which are of local importance in the tropics. These include finger millet (Eleusine coracana), a staple food in parts of East and Central Africa; barnyard millet (Echinochloa frumentacea), cultivated in India and Southeast Asia; foxtail millet (Setaria italica), grown in parts of India; and teff (Eragrostis tef), which is confined to the Ethiopian highlands. The winter cereals wheat and barley are also grown to a limited extent in the tropics, largely at high altitudes: for example, wheat in Kenya and barley in Ethiopia. Wheat and barley are important crops in the Indian subcontinent, and are grown there in the cool season at low altitudes, but the bulk of the crop area lies outside the tropics.

10.1 Introduction

Grain legumes such as chickpea, pigeonpea, cowpea, field pea , lentil, ,  and Phaseolus beans are the principal source of dietary protein among vegetarians, and are an integral part of daily diet in several forms worldwide. They are an important component of cropping systems to maintain soil fertility because of their ability to fix atmospheric nitrogen, extract water and nutrients from the deeper layers of the soil as compared to cereals, and add organic matter into the soil through leaf drop. However, grain legumes are mainly grown under rainfed conditions and the productivity levels are quite low mainly because of severe losses due to insect pests and diseases.  Average grain yield of pulses (0.86 t/ha) is only about one-fourth the average yields of cereals (3.54 t/ha).  Production and productivity of grain legumes is constrained by several biotic and abiotic factors, and suffer an average of 31.9 to 69.6% loss in crop productivity due to insects, diseases, drought, weeds,  and soil fertility. Pod borers (Helicoverpa and Maruca), Fusarium wilts, viral diseases, Ascochyta blight and Botrytis gray mold (Chen et al., 2011).

11.1 Introduction

Tropical Root and Tuber Crops serve as primary or secondary staple to meet the calorie needs of one fifth of world’s population. These crops have myriad and complex roles to play in the food security and reduction of hunger and elimination of poverty. The starch content, pharmaceutical and nutraceutical value endow these crops with an extra ordinary range of potential and uses. Root and tuber crops are also greater sources of industrial raw materials for biodiesel and starch derived materials.