eChapters

Mutations are sudden heritable changes in characteristic of the organism, that is other than due to recombination (Swaminathan, 1983). Mutations occur naturally as spontaneous mutations and induced as spontaneous mutations and induced artificially by treating the biological materials with physical and chemical agents (mutagens). Experimental mutagenesis is effective method to enlarge genetically controlled variation, considerably within a short time.

Darwin’s theory of evolution explains that “variation is the mainspring of evolution”. The extent of genetic variability available in the breeding population and the selection techniques determine the efficiency of any breeding programme. In classical plant breeding programme, variation is generated by hybridization and selections are made from the resulting segregating generations. Induced mutagenesis can supplement hybridization or replace as a source of variability. Thus, mutation provides the raw material for crop evolution (Mahadeva and Randerson, 1982) and it provides the fundamental variability required for crop improvement by breeding (Konzak, 1984).

A mutagen is a physical or chemical agent that changes the genetic material (DNA) of an organism and thus increases the frequency of mutations above the natural incidence. Errors during DNA replication, repair and recombination also causes spontaneous mutations naturally. Mutagens may be of chemical, physical or biological origin. The properties of each mutagen vary by causing damage to the DNA, and most often result in replication error.

Biological materials

Seeds from self fertilized plants will be obtained from the concerned breeder. Hand picked, uniform sized seeds will be chosen for mutagenic treatments.

Gamma irradiation

Gamma irradiation will be performed in gamma chamber, exposing the seeds to gamma rays from ⁶⁰Co source: well filled and hand picked uniform sized seeds with a moisture content of 8.5 per cent will be chosen for irradiation. A sample of say 120 seeds per treatment will be packed in butter paper cover and placed in 100 curie ⁶⁰Co gamma cell. The treatments will be given for various duration depending on the doses required with the dose rate of say 54.05 rads/sec.

Chemical mutagenesis

The seeds will be soaked in water for say 6 hours before the chemical treatment. The duration of pre-treatment with water will be determined on preliminary blank experiment. In cowpea genotype Co. Vu. 623, there was about 5-10 per cent radical emergence about 12 hours after soaking in water. There was no radicle emergence before 12 hours water soaking. An initial pre-soaking period of 6 hours was therefore adopted for later treatment with mutagens. The total treatment period will be about 12 hours (6 hours with water and 6 hours with chemical mutagen). The duration of treatment with chemical mutagens will also be based on the half-life period of the mutagen solution.

Experimental mutagenesis is an important unconventional source to produce mutations in high frequencies in cultivated plants. It makes possible the achievement of desired breeding objectives or atleast decisive progress in this direction through selection of mutants. By establishing extensive collection of mutants based on productive varieties excellent sources of valuable material for theoretical studies and for breeding work can be provided. The induced mutagenesis helps in diversifying varieties and in internal rectification. The simultaneous realization of different breeding objectives may be possible through induced mutagenesis especially in leguminous crops.

Stubbe (1959) stated that mutation breeding as a modern method of plant breeding has proved its justification. It mutation breeding, basic information is a prerequisite on the type of spectrum of induced mutations and relative effectiveness and efficiency of different mutagens.

Mutation in M₂

The output of mutations in M₂ and subsequent generations solely depends upon the complex interaction between many factors in the treated organism together with the specific modes of action of particular mutagen. These results are expressed quantitatively by the mutation rate and qualitatively by the mutation spectrum. The proportion of mutated plants to normal ones which is the mutation rate can be computed on the number of mutations per 100 M₁ plants (Gustafsson, 1940), number of mutations per 100 M₁ spikes (Stadler, 1928), and number of mutants per 100 M₂ plants (Gaul, 1960). After comparing the three indices, Gaul (1960) has concluded that mutants per 100 M₂ plants provided the best index, as it is proportional to the initial mutation rate and is independent of variations in progeny size and size of mutated sector. In Pisum, Blixt (1966) has confirmed this. Mohan Rao (1972) has reported that in barley, the M₂ seedling method determined the total induced mutation frequency. This method is also superior since it accounted for the components of induced mutation frequency viz., the frequency of mutated initials in each spike primordium and the frequency of spike primordia mutated.

The qualitative output of mutation in M₂ and later generations is expressed as the mutation spectrum which reflects the different frequencies of different mutations. Westergard (1960) found that the alkylating chemicals induced a higher proportion of less drastic mutations such as Viridis compared to extreme mutations such as Albina than those induced by radiations because of their apparent slight effect on chromosomes. Sidorova (1966) found a positive correlation between the spectrum of chlorophyll and the spectrum of morphological mutations.

Macromutations were observed in the present set of experiments, under all the treatments (Table 12-14).

As the dosage of gamma rays increased, there was a decrease in their frequency. EB showed less mutation frequency than gamma rays and EMS. But in combination with gamma rays it produced more frequency of macromutations. As the dose increased the frequency also increased. EMS as single treatment produced macromutations like that of gamma rays, but in combination with gamma rays it produced more frequency than gamma rays as individual treatment. However, as the dosage increased the mutation frequency was also reduced. Medium dose combination produced more mutations than higher and lower dose combinations of gamma rays + EMS.

On M₂ plant basis, gamma rays in combination with EB produced the maximum viable mutation rate (4.04), whereas gamma rays individually induced a maximum rate of 2.23 and EB as a sole mutagen generated a maximum rate of 0.79. But EMS as a single treatment showed 1.69 as viable mutation rate, in combination with gamma rays it generated as much as 2.49. Combination treatment showed a less than synergistic effect.

The induction of mutations in polygenes controlling quantitative characters can be detected by the estimation of mean and variance of progenies from normal looking mutagen treated populations. Induction of micromutations in different crop plants have been reviewed by various investigators like Gregory (1955, 1968) in peanut, Rawlings et al. (1958) in soybean, Oka et al. (1985) in rice, Brock and Latter (1961) in Trifolium, Borojevic (1966) and Scossiroli (1966) in wheat, Gaul (1961a, 1966), Astveit (1966) in barley and Brock (1967) in Arabidopsis.

Though more reliable results can be obtained from the study of quantitative variation in the advanced generations than in M₂ (Aastveit, 1968, and Scossiroli, 1977), an estimation of the extent of induced genetic variability in quantitative traits in M₂ itself will be valuable in providing information for future selection programme. It was therefore considered worthwhile to study the shift of mean values and to gather information on induced genotypic variance heritability and genetic advance for different quantitative traits from families of M₁ from different mutagenic treatments.

A detailed treatment on the concepts of mutagenic effectiveness and efficiency was given by Konzak et al. (1965). They proposed the term “effectiveness” as a measure of gene mutations in relation to the dose and “efficiency” as an estimate of the mutation rate in relation to other biological effects induced, such as lethality, injury or sterility. To obtain high efficiency, the mutagenic effect must greatly surpass other effects in the cell, such as chromosomal aberrations, and toxic effects which generally lead to damage

Germination between M₁ and M₂ had a non-significant relationship in germination between M₁ and its corresponding M₁ progenies in M₂ (Table 27). Probably the reduction in the germination in M₁ might be very highly and significantly influenced by the conditions prevailing in germination and physiological disturbances that would be strictly associated in M₁ alone. Whereas the survival of the seedlings between M₁ and M₂ showed a strong positive relationship. The differential behaviour of the mutagens affecting germination and survival was also evident as discussed elsewhere.

However, seedling height on 10^th day sorted a differential relationship between M₁ and M₂. It was negative and non-significant. A non-significant relationship was exhibited for seedling height on 30^th day between M₁ and M₂ in all the doses. It may be interpreted that extent of physiological disturbances that occurred in the early stages and the extend of recovery mechanism that operated subsequently may be the major cause for this; not withstanding the haplontic and diplontic selection that operated in the biological system. Further the type of physiological disturbances happened, whether the enzyme systems affected or a substantial amount of toxic substances produced besides the genetical causes have not been studied in the present investigation. Moreover if the reduced growth was due to mitotic arrest in the meristamatic regions of the roots of M₁ plants, the disorder may not be completely inherited to its offspring’s (M₂ plants), in that sense selection at the cell level damages might occur in the M₁ itself and the selection for a cell with normal mitosis and extent of chromosomal damages that will be tolerated alone might be selected and hence the effect in M₁ need not be always related with M₂; it also depends upon the potency of the cell to recover from the mutagen induced damages. The ability of the cell in general, should be more in M₁ than in M₂ recover the disorder after several cell generations.

Knowledge on genetic variability of the available population is very essential for any crop improvement programme, as it will positively enhance the efficiency of selection. The variability in quantitative characters increase considerably by treating the biological materials with different mutagenic agents. It is possible to identify mutants for different characteristics which can be useful in further programme. Variability is measured by different statistics viz., phenotypic coefficient of variation (PCV) and genotypic co-efficient of variation (GCV). GCV would be more useful for the assessment of inherent variability as it exhibits the heritable portion only.

Polygenic characters exhibit a wide range of expression but the action of genes may be either additive or non-additive. According to Fisher et al. (1932), Smith (1936) Lush (1945), Panse (1946) and Mather (1949) the genetic advance can be achieved through selection of the heritable variation in only due to additive. So, selection for a particular character based on phenotypic variability without estimating the heritable part of it will not be successful. Heritability estimates along with genetic advance are normally more helpful in predicting the gain under selection than heritability estimates alone (Singh, 1997). Therefore, the heritability enters into every formula connected with breeding methods and many practical decisions are taken considering the heritability value.

The frequency distribution of the populations of M₂ and M₃ generation for each genotype was extracted according to Panse and Sukhatme (1961). Skewness and Kurtosis for all the characters were calculated as per the standard method. Skewness refers to the symmetry of the frequency distribution. A measure of skewness is obtained as making use of the second and their moments about the mean. It is defined as,

Ethylene is a primary plant hormone involved in the senescence of plant tissues including flowers and leaves. In carnation, inhibition of the synthesis or action of ethylene delays the onset of senescence symptoms and lengthens the vase life of flowers. Leaves of cut chrysanthemum of some cultivars frequently become yellow, sometimes prior to onset of flower senescence, in response to exogenous ethylene. Generation of transgenic plants with suppressed production or action of ethylene is an excellent way to lengthen the longevity of these ornamental plants. This paper reviews our studies on generation and characterization of carnations with reduced ethylene production and chrysanthemum with reduced sensitivity to ethylene.

Ethylene is a primary plant hormone involved in the senescence of cut flowers of many ornamentals such as carnation, sweetpea and delphinium. It is produced on a large amount at a later stage of flower senescence. The increased ethylene production accelerates withering and dropping of petals. Inhibition of synthesis or action of ethylene delays the onset of senescence symptoms and extends the vase life of flowers.

Delineating species boundaries correctly and also identifying species are crucial to the discovery of life’s diversity because it determines whether different individual organisms are members of the same entity or not (Dayrat, 2005). The identification of species depends on the knowledge held by taxonomists whose work cannot cover all taxon identification requested by non-specialists. To deal with these difficulties, the ‘DNA Barcode of Life’ project aims to develop a standardized, rapid and inexpensive species identification method accessible to non-taxonomists.

DNA barcoding is a technique in which species identification is performed by determining and comparing the sequences of several hundred base pairs of nucleotides from a small fragment of an identified gene, with the aim of contributing to a wide range of ecological and conservation studies in which traditional taxonomic identification is not practical (Krishnamurthy and Francis, 2012). The two main ambitions of DNA barcoding are to assign unknown specimens to species and to enhance the discovery of new species and facilitate identification, particularly in cryptic, microscopic and other organisms with complex or inaccessible morphology (Hebert et al., 2003a). Apart from these, identification of species previously defined by other criteria to also is an objective of barcoding. Another major objective could be the definition of operational units for ecological studies. This may also be used for forensic purposes by linking the specimens with already identified databases.

In this era of molecular markers in genetic studies, genome analysis encompasses several stages of increasing resolution and sophistication, leading to the generation of high resolution chromosome maps. Since the entire plant kingdom cannot be covered under sequencing projects, molecular markers and their correlation to phenotypes provide us with requisite landmarks for elucidation of genetic variation.

A molecular marker is a site of heterozygosity for some type of DNA variation. Such a DNA marker in mapping analysis is analogous to a conventional heterozygous allelic pair. When they are used for mapping the genome, the identity of this DNA fragment is not important, but is simply used as a reference point to arrange and order the genetic information along the length of a chromosome. The molecular markers provide landmarks along the length of chromosome that facilitate the manipulation of chromosome segments in breeding and chromosome engineering programs.

Climate Change: Understanding our Earth and Atmosphere

Our Mother Earth is the fifth largest planet in the solar system and the third from the sun. It is also the sole planet whose name comes from old English language only, and not from names of any other celestial bodies, whose names originated mostly from Greek/Roman mythology. Earth has a diameter of 6378 km, of which the earth crust (uppermost skin) is only 24 km. Earth is the only planet where water exists as liquid and 71% of its surface is covered by water. The earth’s atmosphere is made up mostly of nitrogen (77%) and oxygen (21%) gases. CO₂ consists of a very small (trace) fraction (0.03%) of atmosphere, but is most vital for the life cycle. When earth was created, it has got much higher CO₂ than today, and all of them have been sequestered in rocks as carbonates and dissolved in oceans and a negligible amount is distributed in plant communities. This extremely small quantity of CO₂ is keeping life on earth, by maintaining earth’s temperature at a comfortable 14°C (without CO₂, earth’s temperature would have been -21°C). This effect is called the ‘greenhouse effect’, revolving which all issues of climate change exist. It is also to be noted that water vapour is also an important greenhouse gas (GHG). It is to also to be noted that in spite of substantial increase in solar constant, earth’s average temperature has remained stable for billions of years. It is understood that this was possible through variation in CO₂, and it is the biological processes (Earth biosphere) that controlled the environment over years (Gaia hypothesis).

Understanding biology and genetics at molecular level has become very important for better understanding and manipulation of genome architecture and this creates new opportunities to streamline plant breeding. Breeding is simply defined as the selective mating of individuals of a population to isolate or combine desired morphological, physiological or genetic traits such as appearance, yield, and disease resistance. This is performed with the assistance of identifiable traits.

Molecular markers have contributed significantly in this respect and have been widely used in plant science in a number of ways, including genetic fingerprinting, diagnostics, identification of duplicates and selecting core collections, determination of genetic distances, genome analysis, identification of markers associated with desirable breeding traits which are useful in marker assisted breeding, genomics and development of transgenics. Use of these markers also significantly reduces breeding time and cycles required for crop improvement. This is reflected in the fact that complete molecular and genetic maps have now been constructed for at least 20 major crop species and many more have been characterized at less defined level and the genomes of a few model plant species were completely sequenced.

The harmony between human beings and plants is one of the evergreen reasons that maintains and supports life on earth. This fact clearly explains why any hazard to the life of plants prominently affects man. One important feature distinguishing plants from other complex multicellular organisms is that plants are sessile and thus have to endure environmental challenges (Zhu, 2001).

Crop productivity is limited by stress factors. The stresses which pose major threats to survival of plants belong to two categories- abiotic and biotic stress. Drought, salinity, high or low temperatures, light, deficient or excess nutrients, heavy metals, pollutants etc., either individually or in combination causes abiotic stresses. Biotic stress refers to any stress provided by living organisms, be it unicellular or multicellular. Plants facing a variety of biotic and abiotic stresses are able to protect themselves by means of tolerance mechanisms which result from changes at the molecular level. They are often confronted by a multitude of stresses in their natural environment. To overcome this, plants have evolved various defence strategies, which involve comprehensive reprogramming of the cellular metabolism.

Sustainability refers to productive performance of a system over time. It implies use of natural resources to meet the present needs without jeopardizing the future potential. The Technical Advisory Committee of the Consultative Group of International Agricultural Research has defined sustainability as “Successful management of resources for agriculture to satisfy changing human needs while maintaining or enhancing the quality of the environment and conserving natural resources” (TAC, 1989). A sustainable system must be sustainable both ecologically and economically.

During the past several decades, production of horticultural crops has undergone a tremendous change in both developed and developing countries due to the development and use of fertilizers, pesticides, mechanization, soil fumigation, container production in soil-less media, breeding, micropropagation, pathogen elimination and a number of other innovations for attaining its future stability and sustainability. Recently, in modern horticulture, enhanced productivity depends heavily on inputs of fertilizers and pesticides to maintain an economic level of productivity. On the other hand, social and economic pressures are demanding that agricultural/horticultural practices, that have a damaging impact on the environment and pose risk to health of mankind, be curtailed. Thus throughout the world, agriculture including horticulture is at crossroads in terms of its future stability and sustainability. The solution for the above lies in developing new technology with reduced use of fertilizer and pesticides besides maintaining a sustainable level of productivity. The increased concern about the sustainability and undesirable side-effects of chemistry-based agriculture is prompting many researchers to more seriously evaluate alternative approaches. One such effort was put forth in the management of microbes that live in the rhizosphere soil around the roots of nearly all terrestrial plants. It has been believed that the main orchestrators of microbial activity in the rhizosphere are mycorrhizal fungi.

Consumption of fruit and vegetables has dramatically increased globally during the past a few decades. These are living perishable biological entities which perform a number of metabolic functions and have a short life span. Once the fruit is harvested, respiration and transpiration continue, but only for as long as the fruit can draw on its own food reserves and moisture. It is this limited ability to continue vital metabolic functions which define fruit as perishable. It is also estimated that about 20% of all fruits and vegetables produced are lost each year due to spoilage. The process of the fruit spoilage is just the decomposition of the fruit itself. Once harvested, this begins to deteriorate until eventually it becomes unfit for consumption. This deterioration is known as decay and that leads to spoilage. Latter may be defined as “any sensory change (physical, visual, olfactory or flavour) which the consumer considers to be unacceptable. The gradual changes which cause deterioration and decay in fruits are due to certain organisms and chemicals present in the food and outside the food. Carbohydrates play a major role in the fruit spoilage process (Prasanna et al., 2007) by way of depolymerization leading to decreased molecular size with concomitant increase in the levels of ripening inducing specific enzymes, whose target differ from fruit to fruit. The major classes of cell wall polysaccharides that undergo modifications during ripening are pectins, cellulose, starch, and hemicelluloses (Hallet et al., 2005). The focus of this chapter is to provide information about carbohydrate metabolism during fruit spoilage.

The potato (Solanum tuberosum L.) is one of the four most important food crops of the world, the other three being rice, wheat and maize. It is a high yielding and nutritive crop and produces highest dry matter, carbohydrates, edible protein, minerals and vitamin C and B per unit of area and time. In view of the shrinking cultivable land area and increasing population of India, the potato has a high potential to solve the problems of hunger and malnutrition in our country. But, potato is a perishable commodity and its harvest time (February/March) in Indo-Gangetic plains (which account for nearly 87% of the country’s potato production) coincides with steep rise in ambient temperatures. From April onwards, temperatures start shooting up and the produce has either to be consumed within a short period of time or is required to be preserved in the cold stores. Due to inadequate, expensive and unevenly distributed refrigerated storage facilities in the country, there have been frequent gluts in the market causing substantial economic losses to farmers and wastage of precious food. Such gluts occur every 3 to 5 years. The glut years are followed by a reduction in potato area and production leading to high potato prices in alternate years which again encourage farmers to increase potato area in subsequent years resulting again in a glut situation and price crashes. This boom and bust cycle has thus continued for long (Pandey et al., 2009).

Pomegranate is one of the oldest known edible fruits and is associated with ancient civilizations of the Middle East. From its origin in the area now occupied by Iran and Afghanistan, the pomegranate spread east to India and China and west to Mediterranean countries (Turkey, Egypt, Tunisia, Morocco, and Spain). Spanish missionaries brought the pomegranate to the Americas in the 1500s (Hodgson, 1917; LaRue, 1980). The primary commercial pomegranate growing regions of the world are the Near East, India and surrounding countries, and southern Europe. The fruit is consumed fresh or processed into juice, syrup, jams, or wine (Fig. 1) (LaRue, 1980; Adsule and Patil, 1995; Kumar, 1990; Patil and Karale, 2001; Roy and Wasker, 1997).

Recent awareness of consumers towards innovative probiotic fermented food products containing friendly bacteria and healthier foods has coined the term functional foods. Food development in the world is taking place mainly in three strategic directions as functional foods, organic foods and national foods. Every year the global demand is increasing at the rate of 15–20 %.

Fermentation by newer technologies involves specific strain of lactic acid bacteria. This brings specific fermentation under controlled conditions resulting in a specific fermented product with enhanced organoleptic, nutritional and therapeutic qualities.

Recently people are moving towards newer trends in food diversification for value addition. The beneficial effects could be either maintenance, promotion or well being of health or reduction of the risk of a pathogenic process or a disease. Genetically modified (GM) crops / foods, algae, mushrooms and probiotics are among the important functional foods which apart from improving health also protect against infections and/or stimulate immune systems. The interactive research between physiology, microbiology, food technology and molecular biology may produce many healthful, diversified value based food products for human consumption. The concept of value addition in food is changing significantly. Earlier the emphasis was on survival through hunger satisfaction but today it is aiming towards food safety and food sciences at developing foods which promote good health and reduce the risk of major diseases. With these efforts, these products have come into the market and are identified as functional foods. These include foods containing phytochemicals, dietary fibre, structural lipids, bioactive peptides, polyunsaturated fatty acids.

Spices are defined as a strongly flavored or aromatic substance of vegetable origin, obtained from tropical plants, commonly used as a condiment. India is known as ‘land of spices’. Chilli (Capsicum annuum L.) also known as hot peppers and Capsicums also referred as bell peppers or sweet peppers belong to the genus Capsicum which is a member of the Solanaceae family. The native home of chilli is considered to New Mexico with secondary origin at Guatemala. They are known from pre-historic remains of Peru. Chilli was introduced into India by Portuguese in 16th century. Chilli is considered as one of the major commercial crops of the world. Both green and dried chillies are the important components of our routine diet. Chilli also contains vitamin A, C and E. It will give the required pungency, colour, taste and flavour to our dishes. The presence of capsaicin in chilli is responsible for its pungency and it has medicinal value. The extracted capsaicin is used in pain balms, cosmetics and medicines related to heart diseases. Capsanthin, a pigment in chilli is used for natural colouration to Jams, Jellies and squashes, since it is a natural pigment and no harmful or side effects on human health. Oleoresin is used in pain balms, vapours, etc. Hence, there is lot of demand for chilli oleoresin in the world market. The largest producer of chillies in the world is India contributing 52 per cent of world production, accounting for 11.67 lakh tonnes of production from an area of 7.5 lakh ha with 1550 kg/ha of productivity followed by Nigeria (17%), China (16%), Peru and Bangladesh (6%). India exported 1.8 million tonnes of chilli during 2009 (Reddy, 2010).

Ash gourd (syn:wax gourd, winter melon, white gourd, white pumpkin, ash pumpkin, Chinese preserving melon and hairy melon) is a vegetable belonging to family Cucurbitaceae and genus Benincasa with only one cultivated species, Benincasa hispida (Thunb.) Cogn. (2n=2x=24). Ash gourd is an important vegetable especially in the Indo-China region, which is also the major producer of ash gourd (Rubatzky and Yamaguchi, 1997), but it is also a potential crop of tropical Africa and America (Sirohiet al., 2005).

Borer pests cause significant yield losses and are one of the most serious production constraints in tropical vegetable production. For instance, eggplant fruit and shoot borer (EFSB), Leucinodes orbonalis Guenée (Lepidoptera: Pyralidae) reduces yield as much as 70% (Dhandapani et al., 2003). Tomato fruit borer, Helicoverpa armigera Hubner (Lepidoptera: Noctuidae) causes about 5 to 55% loss in almost all the tomato producing areas in the world (Kashyap and Batra, 1987). Up to 80% yield losses have been reported in various vegetable and grain legumes due to legume pod borer (LPB), Maruca vitrata F. (Lepidoptera: Pyralidae) damage (Singh et al., 1990; Sharma, 1998; Gressel et al., 2004; Hammig et al., 2008; Zahid et al., 2008). Due to higher yield losses, growers tend to apply extremely high quantities of chemical pesticides to control borer pests on vegetable crops. Because the borer larvae are exposed on external plant parts only for a brief time after hatching, the window for effective pesticide application is very brief; vegetable farmers spray throughout the growing season, but without satisfactory results. A survey of pesticide use in Bangladesh indicated that farmers spray up to 180 times with chemical insecticides during a year to protect their eggplant crop against EFSB (SUSVEGAsia, 2007). Pesticide application often exceeded 50 sprays per tomato crop season in south India (Nagaraju et al., 2002). In Bangladesh, country bean (Lablab purpureus) is being sprayed at weekly or biweekly intervals—sometimes every day—to control LPB (Hoque et al., 2001). On average, farmers used 10-24 kg/ha of pesticides in cabbage and cauliflower in India to manage the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae) and other pests (Weinberger and Srinivasan, 2009).

Horticulture includes fruits, vegetables, floriculture, spices, tubers, plantation crops, medicinal and aromatic plants and mushrooms. The sector has established its importance in improving land use, promoting crop diversification, generating employment and above all providing nutritional security to the people. Even though India is the second largest producer of horticulture produces in the world, our per capita consumption of fruits and vegetables are very low.

“Age and Area”: The hypothesis (by Willis) that the older a species is, the wider will be its geographical distribution.

A-Without; lacking.

A.I.: See active ingredient.

A.O.U. Code: A code of nomenclature published in 1885 (revised 1908) by the American Ornithologists’ Union for the standardization of bird nomenclature.

Ab-Away from; off.

Bacillus thuringiensis (Bt): Soil-inhabiting bacterium that produces an insecticide effective against larval stages of many species of Lepidoptera, although some strains are effective against various beetle, mosquito, and blackfly larvae.

Backcross: A cross between a hybrid and one of its parents; a cross between a heterozygote and a homozygote (cf. Hybridization, Heterozygous, Homozygous).

Bacterial insecticide: Bacteria pathogenic to insects (e.g., Bt or B. popilliae). Applied using application techniques also used for chemical pesticides.

Bacterium (pl. bacteria): Microscopic, prokaryotic, single-celled organisms having cell walls but lacking membrane-bound organelles. Important in decomposition, nitrogen fixation and other symbiosis, and as pathogens. A significant component of soil food webs.

Bait (B): A pesticide formulation that combines an edible or attractive substance with a small amount of toxic active ingredient (usually about 5%). Baits containing poisonous chemical and food stuffs are primarily offered to pests as food for control of animal pests like mollusks, cutworms, and rodents.

Caecae: Saclike or tubular structures open at only one end (blind), often opening from the mid-intestine (Fig. 41).

Caecum (pl. caeca): A blind-ending tube or sac or pouch sac of the alimentary canal (L. caecus= blind) e.g., haepatic caecae in the alimentary canal of insects (Fig. 41).

Calamistrum: One or two rows of curved spines on the metatarsus of the hind legs (spiders; fig. 608, clm).

Calibration: The adujustment of application equipment so that a defined quantity of chemical or other material is applied per unit time or area.

Calling: A vergin female moth releasing sex pheromones to attract males for the purpose of mating.

Calliphorin: A protein produced in the fat body and stored in the haemolymph of larval Calliphoridae (Diptera).

Dall code: A code of nomenclature prepared by W.H. Dall at the direction of the American Association for the Advancement of Science (1877).

Damage boundary: The level of injury where damage can be measured.

Damage threshold: Pest population above which crop loss occurs.

Damage: Measurable reduction in crop growth or yield; or a measurable loss of host utility, most often including yield quantity, quality, or aesthetic appeal.

Damping off: Infection of newly formed roots and stems of young seedlings by fungi or bacteria, typically at soil level, resulting in decay or seedling death.

Danger: A signal word used on pesticide labels to inform the user that the pesticide is highly toxic, as defined by FIFRA. The word poison and the skull and crossbones symbol always accompany the signal word danger.

Early postemergence: The application of herbicide after plant emergence and during the initial growth phases of crop or weed seedlings.

EC: See emulsifiable concertrate.

Ecdysial cleavage lines: Preformed lines of weakness along which the shed cuticle of the cranium splits during ecdysis; cuticle in the region of these lines lacks the exocuticle (Fig. 100).

F₁ generation: The first-generation offspring of a particular mating.

F₂ generation: Derived from a mating within the F₁ generation.

Face: The front of the head, below the frontal suture (Fig. 108).

Facet: The hexagonal external surface of an individual compound eye unit of ommatidium.

Facies: In taxonomy, the general aspect, appearance, or habits of a species or group.

Gain threshold: The beginning point of economic damage, expressed in amount of harvestable produce; when cost of suppressing insect injury equals money to be gained from avoiding the damage.

Galea: The lateral lobe of the maxillary stipes; tonguelike, distal lobe attached to the stipes of the maxilla; an apical lobe of the maxilla of an insect; the outer two-jointed lobe of the “pincers” present on the maxilla of insect mouthparts; in adult Lepidoptera the two are joined and enlarged to form the proboscis. (Fig. 63)

Gall: Swellings, deformities, or growths of plant tissue that result from the activities various types of pests, including bacteria, nematodes, mites and insects; an abnormal growth of plant tissues, caused by the stimulus of an animal or another plant (Fig. 128).

Gallicolous: Living in a plant gall either as the producer or inquiline.

Hard pesticide: One which persists for a long time in the environment; particularly applies to organochlorine insecticides.

Habit, Habitus: The general appearance of an organism; facies.

Habitat modification: Alteration of the environment where an organism occurs, e.g., cultivating land for agriculture.

Habitat: The environmental conditions and associated organisms that occur in a particular site; the place where plants and animals live, usually with a distinctive boundary (e.g. field, pond, sand-dune, rocky crevice); the natural or usual dwelling place of an individual or group of organisms. (L. habitus = condition).

Habituation: A form of associative learning in which a given stimulus no longer elicits a response; learning not to respond to a stimulus that provides no reward or punishment.

Habituation: Reduction in the response to a stimulus with repeated exposure, through modification of the central nervous system.

Haematophagous: Blood-sucking; blood –feeding.

Haemocoel (also hemocoel): The main body cavity of many invertebrates, including insects, formed from an expanded ‘blood’ system that is filled with blood (haemolymph) within which the internal organs lie.

Ichthyology: Science dealing with the study of fishes – a class of aquatic vertebrates most of whom depend for respiration exclusively on oxygen dissolved in water (Gr. ichtys = fish + logos = study).

Idiobiont: A parasitoid that prevents its host from developing any further, by paralysis or death; see also Konobiont.

IGR: See insect growth regulator

Ileum: The second section of the hindgut, preceding the colon differentiated region of the anterior intestine of the hindgut preceding the rectum in some insects (Fig. 120).

Imaginal buds: See imaginal disc.

Jet: Liquid emitted from a nozzle orifice (in USA = nozzle).

JH: An abbreviation of juvenile hormone.

Johnston’s organ: A sense organ similar to a chordotonal organ, located in the second antennal segment of most insects; functions in sound reception in some Diptera (Fig. 153); an organ in the pedicel of the antenna, consisting of a cluster of chordotonal sensilla.

Kairomone: A chemical produced by an individual of one species that has a beneficial effect on the recipient individual of another species; a chemical that is adaptively favourable to the receiving organism; an interspecific messenger substance that benefits the receiver but not the releaser (e.g., attractants, excitants); an interspecific chemical messenger that benefits the receiver but not the emitter; a communication chemical that benefits the receiver and is disadvantageous to the producer; see also Allomone; Synomone.

Karyological character: A character involving chromosome structure or number (cf. Taxonomic character).

Keeled: With an elevated ridge or carnia.

Keratin: The inert exoskeleton protein of vertebrate animals forming skin, hair, feathers, claws, nails, scales, etc.; similar in structure and function to the arthropod chitin.

Keratolytic: Pertaining to or promoting loosening or separation of the outer layer of the skin.

Label: Technical information about a registered pesticide in the form of printed material attached to, or printed on, the pesticide container. It is illegal to use the pesticide in ways inconsistent with the label.

Labella (sing. labellum): In certain flies, paired lobes at the apex of the proboscis, derived from labial palps; apical spongelike structure on the proboscis of nonbiting muscoid flies (Fig. 156).

Macro: Large.

Macro-and microconsumers: In an ecosystem the primary consumers, feed on plants while other consumers, e.g., secondary and tertiary consumers are called macroconsumers. The decomposers, like bacteria and fungi, are called microconsumers.

Macro-and micronutrients: Some salts or elements needed in relatively large amount are termed macronutrients while some others though essential for maintaining the life-system are required in minute amounts and are the micronutrients.

Macroclimate: General climate prevailing over a large area, considered as a unit. The opposite is microclimate.

Macroevolution: Major phylogenetic patterns that develop over wide spans of geological time.

Macrofauna: The larger members of a particular fauna. Open to different levels of interpretation for they may be larger vertebrates or alternatively the larger insects of a habitat. The opposite is microfauna.

Macrogamete: The female gametocyte of a malaria parasite, Plasmodium spp; see also Microgamete.

Macrophage: An eater of large particles; see also Microphage.

Naiad: The immature stage in insects with incomplete metamorphosis that feed and develop in water; an aquatic, gill-breathing, immature instar of hemimetabolous insect.

Narcotic: A chemical that causes reversible depression of the nervous system.

Narrow spectrum (as applied to insecticides): Having an effect on only a narrow range of insects.

Nasus: A nose, the snout of certain termite soldiers (nasutes).

Nasute (pl. nasuti): A type of soldier caste in certain termites; this form bears a median frontal rostrum or snout through which it ejects a defensive fluid; the jaws are small or vestigial.

Nasutus (pl., nasuti): An individual of a termite caste in which the head narrows anteriorly into a snoutlike projection.

Natality: Population ‘increase’ factor; birth rate; often measured as total number of eggs or eggs per female per unit of time.

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).

Tactile: Referring to the sense of touch.

Taenidium (pl. taenidia): The spiral thickening of the tracheal wall that prevents collapse; helical fold in the cuticular lining of tracheae and tracheoles (Fig. 230); cuticular ridges that support the walls of tracheae; a spiral or circular thickening of the inner surface of the tracheae.

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.