Independent Research Project

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Independent Research Project

Differential Transmission of Tomato Leaf Curl Viruses by Whiteflies Species

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Acknowledgements

The aid I received from my professors, mentors, and friends has been invaluable, and I want to express my gratitude to them all. Thanks to my professor (insert name), I was able to finish my project on time. I wouldn’t have been able to complete my project without the help of my professor.

Table of Contents

Abstract

Background

Known as “protective foods” because of the specific nutrients they contain as well as their broad availability, tomatoes are the world’s most popular vegetable crop. The tomato plant produces one of the most widely eaten vegetable crops in the world: its fruit. The tomato is one of the most important crops in the world both commercially and nutritionally. Known scientifically as Lycopersicon esculemtun, the tomato belongs to the Lycopersidae family of plants, which includes peppers and eggplant. Virus transmission and acquisition may be influenced by the interactions between whitefly proteins and Begomoviruses. When it comes to studies on whitefly-transmitted beg virus, researchers have mainly looked at how the virus is kept in check throughout the plant-insect-plant cycle. There has been minimal consideration paid to transovarial transmission.

Objective

An important goal of this research project is to properly test and investigate the current knowledge and information related to the transmission of Tomato leaf curl virus by whiteflies. This research investigation will be able to show a new piece of knowledge.

Method

The researcher has used the interpretivism philosophy, inductive research approach, explanatory research design, secondary qualitative data collection process and descriptive analysis method.

Findings

The virus may also harm squash plants, which makes the issue much more urgent. This might have disastrous consequences for the country’s harvest squash plants. Furthermore, since the disease’s symptoms cannot be detected before the fruit ripens, there is no way to stop its spread and rescue the crop. Even when the fruit is fully ripe, the symptoms aren’t fully visible, and this has a negative impact on the crop.

Chapter 1: Introduction

1.1 Background of the Research

As the greatest vegetable crop in the world, tomatoes are renowned as “protecting foods” for the particular nutrients they provide as well as their widespread availability. Fruits from the tomato plant, one of the world’s most significant vegetable crops, are consumed worldwide. Commercially and nutritionally, the tomato is one of the most important crops in the world. The tomato’s scientific name is Lycopersicon esculemtun and it is a member of the Lycopersidae family of plants. Tomatoes are a helpful dietary supplement. Economically, it is important, and as a result, the amount of land under cultivation for this crop is steadily expanding (Pan et al., 2018). Ketchup, sauce, chutney and soup are all examples of preserved tomato products. It has been determined that ten of the country’s most potential tomato-producing states have been selected for further investigation. In terms of tomato crop area, Bihar State is in first place, followed by Uttar Pradesh and Orissa.

Karnataka came in second, followed by Punjab and then Assam as the states with the highest output and productivity. “Maharashtra, on the other hand, had a 110% rise in the area planted in tomato crops between 1990 and 1996, while Bihar and the United Provinces of India saw a 72% and 44% growth, respectively”. For a given time period, Punjab may expect a production rise of roughly 114%. In terms of tomato output, UP experienced an 8.3 percent growth, followed by Assam (75 percent) and Karnataka (72 percent) (Fiallo-Olivé et al., 2020). “Between 1990-91 and 1990-92, Maharashtra had an area expansion of over 90%, with studding increasing proportionately in succeeding years, followed by Bihar (48%), and Karnataka (33 percent). There were just two states that had a 15% or more growth between 91-92 and 92-93, UP and Punjab, whereas West Bengal, Karnataka, and Punjab saw a 15% or more increase in the following period”.

Tomato output in Maharashtra, Punjab, and Assam, on the other hand, increased proportionately by 72 percent, 46 percent, and 31 percent from 1990-91 to 1990-92. From 1991-1992 to 1992-1993, production in Uttar Pradesh, Bihar, and Karnataka increased. Only Maharashtra State continues to grow at a steady rate for the rest of the time. The creation of high-yielding tomato varieties/hybrids, breeding for biotic and abiotic stressors, resistance, and heterosis breeding have all contributed to this remarkable success in tomato output. Begomoviruses have emerged as major insect-borne plant viruses of agricultural importance in the last several decades. For many crops in the tropical and subtropical regions, Begomovirus is the biggest genus of plant viruses, and various viruses of this genus have become severe restrictions to the production of many crops, particularly in tropical and subtropical areas. Plant DNA viruses known as Begomoviruses have icosahedral genomes of roughly 2700 nucleotides that are encased in two linked incomplete icosahedra (Guo et al., 2019).

Yellow leaf curl disease in tomatoes is caused by the begomovirus TYLCV, which is spread by whiteflies and is a leading cause of tomato yellow leaf curl disease. More than 35 cryptic species of whitefly Bemisia tabaci are thought to exist in the hemispheric whitefly family Aleyrodidae. Plants are harmed by whiteflies of this species group because they feed on and transmit plant viruses. MEAM1 and MED, formerly known as the B and Q “biotypes,” are two species in the complex that have wreaked havoc on agriculture all over the world owing to their quick and extensive spread over the last three decades (Gautam et al., 2022).  “B. tabaci species have been identified in China based on mitochondrial cytochrome oxidase I (mtCOI), 17 indigenous species and two invading species, MEAM1 and MED, respectively. Southern, south-eastern, and southwest Asia are home to the native B. tabaci fauna of China. Many biotic and abiotic variables influence Begomovirus transmission”.

A variety of Begomoviruses may be transmitted by various B. tabaci complex species, and each whitefly species may be able to transmit just a limited number of viruses. Certain whitefly main salivary gland cells regulate Begomovirus retention and transmission based on the Begomovirus’ ability to pass the midgut of a certain species’ whitefly compared to that of another species’ whitefly. “Begomoviruses may be transmitted through endosymbionts in whiteflies or the GroEL protein they make, according to new research (Pan et al., 2018). The connections between whitefly proteins and those of Begomoviruses may influence how the viruses are acquired and transmitted. Whitefly-transmitted Begomovirus research, on the other hand, has mostly focused on the maintenance and dissemination of Begomovirus during the plant-insect-plant cycle”. Transovarial transmission has received just a little amount of attention.

1.2 Problem Statement for the Research

A circulative propagative plant virus, transovarial transmission has been documented to be a characteristic of TYLCV replication in its vector. For the first time, real-time RT-PCR has shown that the vector contains both viral and complimentary strands of DNA that can replicate. For the first few days following viral acquisition, the virus level in whiteflies might also grow (Chi et al., 2020). Even after virus acquisition had halted, the DNA of both strains of TYLCV in whiteflies was still stable, even if the viral levels had decreased.

1.3 Research Objectives and Aims

1.3.1 Research Aims

This study aims to effectively experiment and examine the knowledge and information regarding differential transmission of Tomato leaf curl viruses by whiteflies species. Through this, a unique information will be demonstrated through this research study.

1.3.2 Research Objectives

To identify the transmission efficiency of Tomato Leaf Curl Virus by the whitefly Bemisia tabaci.

To measure the impact of different Whiteflies species on tomato production throughout the world.

To identify the undertaken initiatives for reducing the issues caused by different whiteflies species.

1.4 Research Questions

What is the transmission efficiency of tomato leaf curl virus by the whitefly Bemisia tabaci?

How different whiteflies species impact on tomato production throughout the world?

What kinds of initiatives have been taken to reduce the issues cause by different whiteflies species?

How the undertaken initiatives impact the product of tomatoes in the market?

1.5 Research Rationale

During the consideration of the entire study, it becomes evaluated that the study will proficiently identify and evaluate the knowledge and information regarding there are around 12 genetic groupings within the B. tabaci species complex, each of which is distinct in terms of its capacity to disperse, reproduce and cause harm to crops. Most prevalent biotypes are B and Q biotypes, which vary greatly in terms of many fitness parameters: B is characterised by high fecundity, while Q is known to develop resistance to pesticides (Gottlieb et al., 2010). Symbiotic bacteria also differ across the two biotypes, which is interesting. A reason for future students and researchers of this specific study subject may be found herein.

1.6 Research Structure

Chapter One introduces the reader to the study’s goal and scope, as well as the general structure of the investigation. An overview of the study context is provided in this chapter, as well as a reason for the choice of research topic. In addition, the first chapter defines the purpose and goals of the study, as well as the research framework. A survey of the existing literature is presented in Chapter Two, which also includes an examination of previously developed conceptual models and theoretical frameworks. This chapter covers the search technique for secondary data and provides definitions of key terminology. Other writers’ perspectives on the study topic and the research challenge in particular are provided logically in this chapter. Methodology is the focus of Chapter Three. In this chapter, the research method is explained, as well as the philosophical difficulties surrounding research.

In addition, the methodology chapter explains the study concept and the techniques of data collecting that were selected and implemented. This chapter also covers the study’s sampling methods and ethical implications. in-depth data from surveys, interviews, focus groups, and other research methods are presented in Chapter 4. The presentation of primary data results has been made easier by the use of bar and pie charts. Each chart has been explained with a brief explanation. Discussions and analyses are the focus of Chapter Five. This chapter is crucial to the success of the research goals and objectives. Literature review data has been compared to primary data in this chapter. In addition, each research goal has been discussed in detail in the accompanying text. Chapter Six finishes the study and summarises its progress toward its stated goals. The chapter acknowledges the study’s shortcomings while also pointing up the need for more research in the same field.

Chapter 2: Literature Review

2.1 About the Crop

2.1.1 Agronomy of Tomato

Name of the Crop

Tomato

Botanical Name

Solanum Lycopersicum

Cultivation

Warm Season

Method of Planting

Deeply Digging

Spacing

Sowing should be done thinly in lines spaced at 10-15 cm distance

Depth of Sowing

2-3 cm

Climate

21-24°C

Seed Rate

400-500g/ha

Type of Soil

Well-drained, sandy or red loam soils

Crop Duration

140-145 days

Verities

Cherry tomatoes, Grape tomatoes, Roma tomatoes, Beefsteak tomatoes, Heirloom tomatoes, tomatoes on the Vine, Green tomatoes

Fertilisers

Dr. Earth Home Grown Fertiliser

Jobe’s Tomato Fertilizer Spikes

Burpee Organic Tomato and Vegetable Plant Food

Greenway Biotech Tomato Fertiliser 4-18-38

Yield

20-25 Tonnes/ha

Harvesting

By twisting motion of hand to separate fruits from the stem

Cropping

Tomato can be grown on a wide range of soils from sandy to heavy clay.

2.1.2 Taxonomy of Tomato

Kingdom

Plant

Division

Magnoliophyte

Class

Magnoliopsida

Order

Solanales

Family

Solanaceae

Subfamily

Asteridae

Genus

Solanum

Species

s. lycopersicum

2.2 Tomato

2.2.1 Uses

When the side branches of a determinate plant are removed, a flower cluster and a bush-like structure form, as stated by Ochilo et al. (2019), an indeterminate plant develops a single stem. Once the flowers are set, plants with a strong sense of purpose grow faster because they focus all of their energy on producing a consistent output. They are more often used in locations where the seasons are shorter and just one crop is cultivated. Short, bushy stems make them ideal for harvesting processed goods and cultivating fresh tomatoes in the garden. Indeterminate plants’ flowers keep blooming, according to Mulugeta et al. (2020). Crops like this might benefit from a longer growth season if they are properly cared for. They’ll be able to grow to 32 feet tall in only 9 to 10 months, making them ideal for greenhouse production.

Staking may be expensive for both indeterminate and determinate crops, but it’s well worth the investment in the long run. There is little doubt that tomatoes are a warm-season crop that may be badly harmed by frost at any stage of their growth, according to Villaseor-Aguilar et al. (2019). Crops that are exposed to temperatures below 500 degrees Fahrenheit have poor early development. The ripening of fruit may be delayed by low temperatures. When temperatures rise beyond 95 degrees Fahrenheit, fruit set is slowed and the colour of the red flesh is reduced. A plant may produce soft fruit when it is under water stress and experiencing high temperatures simultaneously.

Figure 1: Seeds, Leaves and Flower of Tomato

(Source: Conesa et al., 2020)

Tomatoes like temperatures of 640F to 810F for optimum growth. Over 81 degrees Fahrenheit, floral growth is negatively affected. The bulk of outdoor crops are thus grown in temperate zones, “between the 30th and 40th parallels in both the northern and southern hemispheres” in both directions. Tomatoes, on the other hand, are becoming more common in tropical regions owing to the creation of new cultivars, according to Conesa et al. (2020). Humidity levels between 60 and 80 percent are ideal for glasshouse crops. In hydroponics, 75 and 85 percent relative humidity are typical during night and day.

2.2.2 Origin

Carillo et al. (2019) stated that the Andean area of “South America”, which now includes “Peru”, “Bolivia”, “Chile” and “Ecuador”, is where wild tomato plants first appeared. Tomatoes may have been initially cultivated by the Aztecs and Incas as far back as 700 A.D. The tomatoes that were cultivated back then were much different from the ones we have now in terms of size and flavour. It is not known how or when tomato seeds were carried to Europe, although allusions to tomatoes started to emerge in the 16th century. In the 18th and 19th centuries, Europe saw an increase in domestication. According to the viewpoint of Testen and Miller (2018), it is unclear when or from whence the tomato was brought to North America, although it is thought to have arrived in the 16th or 17th century at the earliest. Tomatoes were grown in the United States by the middle of the 18th century, but they were not generally eaten.

Tomatoes were thought to be harmful since they were members of the nightshade family. In the early 1800s, an American reportedly ate tomatoes in public to prove that they were safe for consumption. Despite the fact that tomatoes have been shown to be safe, many individuals still find them too acidic for their liking. As per the viewpoint of Opatić et al. (2018), the Solanaceae family includes the tomato, pepper, potato, and eggplant. Nightshades are a kind of plant in this family. More than 3000 kinds of night-shade plants exist, many of which are commercially valuable.

S. Lycopersicon is the only tomato species that can be grown commercially, despite the fact that there are over 7000 variants. The Galapagos taxa are more diverse than previously thought, as part of a wider study on the taxonomy and phylogeny of the wild tomatoes and their near relatives and broader investigations of evolutionary genetics of the imported and native tomatoes in the Galapagos Islands (SD). Based on the viewpoint of Darwin, Knapp and Peralta (2003), examined herbarium specimens, and conducted morphometric analysis on greenhouse-grown tomato accessions from all Galapagos tomato species to produce this report.

2.3 Tomato Leaf Curl Virus

2.3.1 Estimation of Losses for Different Virus Species

As viewed by Sevik and Arli-Sokmen (2012), many nations rely heavily on the tomato, which is a key crop. There are almost 0.3 million hectares of tomato farmland in Turkey, which ranks it as the third-largest tomato-producing nation in the world after the United States and China. More than 40 viral infections may affect tomato plants and fruits. It is one of the most devastating viruses for tomatoes, causing losses of up to 100 percent in certain cases. Tospovirus is a Bunyaviridae genus that includes TSWV. In addition to tomato, TSWV has been found in more than 1,090 plant species belonging to 84 families. Narladkar (2018) viewed that many commercially significant crops suffer major yield losses as a result of the virus. There are at least nine kinds of thrips that are the only ones capable of transmitting it. TSWV-infected tomatoes display a broad range of symptoms.

According to the opinion of Sheridan et al. (2020), the appearance and severity of the disease depends on the genotype, the plant growth stage at the time of infection, the viral isolate, and the environmental circumstances. There is typical bronzing or purpling on tomato leaves, as well as downward curling and leaf deformation; brown or reddish concentric rings; irregular white or necrotic leaf patches and flecks; and full yellowing and stunting of the plant as a result of infection with this virus. As per the opinion of (Caini et al. 2018), pre-infected tomato fruits seem normal, however fruit that develops after the infection may show more obvious signs of illness. It is common for green tomato fruit to acquire spots and blotches of light green, white, or yellow, or even lumps, on the surface. Fruit from severely afflicted plants may not develop at all, or it may be of such a tiny size that it is unfit for human consumption.

2.3.2 Disease Caused

While previously known plant viruses have been found in Spain and Mexico, two new species have developed in the last decade that seem to be related but unique. It was shown that both viruses generated necrotic or burn-like disease signs in tomato crops. As recently as 2001, tomato plants in the Murcia region of Spain’s southeast were showing significant necrotic leaf signs. Based on the opinion of Hanssen, Lapidot and Thomma (2010), the illness was dubbed “torrado” (roasted) sickness in the area because of the charred look of the damaged leaves. There are necrotic areas at the base of leaflets, and a light green or yellow region surrounds them.

As opined by Sharma and Prasad (2020), leaves and fruit show severe necrosis later on, and plants as a whole develop slower, causing significant economic harm. Infected plants had PepMV, however the symptoms were not typical of PepMV, necessitating more investigation into the disease. electron microscopy revealed the presence of isometric viral particles in addition to the rod-like PepMV particles. When PepMV was inoculated on the two indicator plants that were not sensitive to the virus, it was discovered that the virus had a bipartite positive-stranded RNA genome with three “Open Reading Frames (ORF)”. Li et al. (2021) opined that “the virus has nucleotide sequence and virion features in common with viruses from the genera ‘Sequivirus’, ‘Waikavirus’, ‘Sadwavirus’ and ‘Cheravirus’; however, phylogenetic analysis on two distinct genome sections indicated a different taxonomic position”. ToTV was suggested as a new genus, and the species was renamed.

2.4 The Whitefly, Bemisia Tabaci

2.4.1 Different Species of the Whiteflies

According to the argument of Naga et al. (2021), as a result of its sucking of the phloem sap and transferring a variety of plant viruses, the whitefly “Bemisia tabaci (Gennadius)” is responsible for severe output losses in numerous crops, including potatoes. It is usual to refer to B. tabaci’s genetic groupings as cryptic species. Genetic groupings of B. tabaci vary physiologically in terms of host plant selection, insecticide resistance, reproductive capability and the ability to transmit begomoviruses. Therefore, identifying genetic diversity across populations is critical for generating crop-specific distribution profiles and management. As per the argument of Pan et al. (2020), using B. tabaci samples obtained in important potato-growing regions of India, researchers sequenced the mitochondrial cytochrome oxidase I (mtCOI) gene. A BLAST search of the Gene Bank sequences against the 24 mtCOI sequences found four distinct B. tabaci genetic subgroups. “Asia II 1, Asia II 5, Asia 1, and MEAM1 B. tabaci genetic groupings were found by mtCOI analysis”.

“The Indo-Gangetic Plains now have a new genetic group, Asia II 5, according to this research. ToLCNDV-Asia II 5 B virus-vector connection investigation is ongoing”. Tabaci found that females are more effective at transmitting the virus than males. This female behaviour may be explained by the fact that females are able to acquire higher viral titers than men. Based on the argument of Naveen et al. (2017), this research will contribute to a better knowledge of viral infections caused by whitefly genetic groups. “A variety of insecticides were found to have varying levels of susceptibility, with Asia-Ii-7 being the most susceptible, while Asia-I and Asia-II-1 populations showed significant resistance to these insecticides”.

“The variability of the LC50 values was seven times among Asia-I, five times among Asia-II, three times among Asia-II-1, and three times among Asia-II-7 populations”. “Compared to the most vulnerable PUSA population (Asia II-7), a significant rise in resistance ratios was seen in both the Asia I and Asia II-1 populations. As argued by Khamis et al. (2021), the Sri Lankan cassava mosaic virus (family Geminiviridae, genus Begomovirus) is a causal agent of CMD”. “A report of ICMV on Jatropha curcas in Singapore is the only known case in Asia of CMGs outside of South Asia”.

2.5 Transmission of Tomato Viruses by Whiteflies

When viruses infect plants, their insect vectors undergo behavioural and performance changes that enhance the spread of the virus. The second time around, this was found in Asia II. In that case, (Marchant et al., 2020), stated that, even while whiteflies still carry a large amount of virus, they eventually lose their capacity to infect tomato plants, presumably because older insects are less active. The virus’s DNA and structure may develop changes over time that reduce its infectiousness.

Whitefly virus ingestion and accumulation vary in speed and quantity, but the time-course pattern is similar. The insect’s biotype, age, and gender, as well as the viral load in infected source plants, all affect its virulence and the virus’s ability to spread to other plants and cause sickness. As per the statement of Zhao et al., (2019), Plant defence against whitefly infection seems to be dependent on the generation of terpenes, which may be inhibited by a viral illness. MEAM1 may more easily infect crops that have been contaminated with the begomovirus Tomato yellow leaf curl China virus (TYLCCNV). Volatile substances beta-myrcene, thymene, beta-phellandrene, caryophyllene, 4-carene, and alpha-humulene concentrations dropped considerably in tomato plants afflicted with the Tomato Yellow Leaf Curl Virus (TYLCV).

As per the opinion of Chi et al., (2020), Although MEAM1 and MED were unable to transmit the Tomato leaf curl Multan virus, B. tabaci Asia II 7 was successful in doing so. Extensive study in the field of agriculture has demonstrated that one particular species of whitefly is responsible for the reduction in the nutritional value and PH level of tomatoes. Adult Asia-I-Coimbatore mosquitoes became more attracted to healthy plants with higher concentrations of certain terpenes after being infected with the ToSRV infection. In other words, after becoming viruliferous, begomoviruses may cause whiteflies to change their preference for non-infected plants, altering their olfactory response and increasing the pace at which the virus spreads. While the odours of ToSRV-infected plants may influence whiteflies’ ability to pick up virus particles, it seems that this impact is minimal.

Asia II 1 has been identified as the major species of whitefly in areas of Pakistan and western India that have a high incidence of cotton leaf curl disease (CLCuD). These areas are characterised by a high frequency of illness. Two recent studies in China retrieved information on the transmitting efficacy of viral proteins via MEAM1, Asia II 1, and two other species (Ghosh and Ghanim, 2021). These studies revealed that, among such species, Asia II 1 is the most efficacious at trying to spread Tomato leaf curl Multan virus (CLCuMuV) and Tobacco curly shoot virus. MEAM1 was found to be the least effective at spreading these two viruses (TbCSV). In addition to differences in the effectiveness of viral transmission, these whitefly species differ in their resilience to pesticides and their preferences for host plants stated by Pan et al., (2021). When feeding on plant infections caused by TYLCV, for example, the B. tabaci MED species reaps the benefits of virus-vector interactions. This is most likely because the viral infection alters the nutritional content of the plant host and impedes the manufacturing of herbivore-induced defensive system enzymes.

The domestication of tomato and pepper resulted in a reduction of their genetic variation, which made the plants more sensitive to biotic and abiotic stresses, such as attacks by insects (Ghosh and Ghanim, 2021). Although there has been no research on the feeding habits of whiteflies that colonise cassava, it is common knowledge that the eating habits of sap-sucking insects, such as whiteflies, are significantly connected with the compatibility of the host and the effectiveness of viral transmission.

2.6 Literature Gap

Throughout the consideration of the entire study, it is identified that the researcher has extracted the knowledge about overall worldwide aspect. This provides some general information about differential transmission of tomato leaf curl viruses by whiteflies species. Therefore, the researcher has decided to conduct further research in order to demonstrate some specific information for highlighting any country perspectives to provide specific and authentic information and knowledge regarding the study topic.

3. Methodology

3.1 Research Philosophy

Research philosophy is often ranked as one of the most significant aspects of research practice. It gives the researcher a set of guiding principles to successfully carry out the planned research strategy, which relates the researcher’s standards to the proper execution of the strategy (Holden and Lynch, 2004). As the investigation proceeds, the researcher chooses the philosophy to adhere to while continuing to use more conventional research methodologies. Interpretivism will be used as the guiding research philosophy for this present study so that the results may be interpreted appropriately. The premise that the researcher has a unique role to play in the process of monitoring the social environment is the cornerstone of the interpretative research philosophy.

According to this research philosophy, the research is founded on the interests of the researcher, and it heavily draws on those interests. Research that adheres to the interpretivist paradigm says that one’s perception of social reality may be subjective. Gaining a deeper understanding of how people communicate and engage with one another in social settings is the primary objective of this research (Tuffour, 2017). It has analysed these meaning-making techniques and shown how they yield observable effects following the objectives of the research.

3.2 Research Approach

Both a strategy and a plan, the research methodology can be thought of in either of these terms. It takes into account everything, from broad generalisations to the methodical gathering (Kothari, 2004), analysis, and interpretation of data. Because of this, it is dependent on the character of the study issue that is now being examined as a result of this through the inductive research approach. The setting in which research is carried out may affect how the findings are understood, and how the research is carried out is wholly dependent not just on the researcher but also on the topic that is the focus of the investigation (Thomas et al., 2022).

Both an approach of inductive and deductive research methodology can be thought of in either of these terms. It takes into account everything, from broad generalisations to the methodical gathering, analysis, and interpretation of data. Because of this, it is dependent on the character of the study issue that is now being examined as a result of this. The setting in which research is carried out may affect how the findings are understood, and how the research is carried out is wholly dependent not just on the researcher but also on the topic that is the focus of the investigation.

3.3 Research Design

One of the most important components of the evaluation process is how the research was designed. The researcher can execute the analysis with more precision and get the results that were expected thanks to the study design, which is a comprehensive collection of methodologies. During the stage of doing research, there is a need for a variety of activities and methods (Firdaus, Zulfadilla and Caniago, 2021). Planning, explanation, and the physical organisation of the data make up the three most important aspects of the study. A researcher’s ability to get reliable findings is directly correlated to the quality of the design they use.

The examination will be carried out using a research design known as descriptive research. A group, circumstance, or phenomenon is attempted to be defined as precisely and uniformly as possible via the use of descriptive research. It will respond to questions about what, where, when, and how, but not those concerning why. To analyse one or more elements, a descriptive research design could make use of a wide number of research methods. Another advantage of descriptive research is that it allows the researcher to determine the behaviour of individuals in their natural environment.

3.4 Research Sampling

The sampling methods used in the research are simply known as the “research sampling”. The total sampling of the research is the flies in the world and as the research is based on the effects of white flies on the tomato leaves. The sampling is done on the white flies in different countries and the effects of these on the taken topic. Thus the white flies are the sample frame of the research. The sample has been taken randomly and these are helpful to complete the research. The important factors of the research are described in the research sampling. The size of the sample is large and the research is done on white flies on different countries and species. The research is done taking the effects of white flies into focus and serves as the best outcome of the information gathered from the samples that are chosen.

3.5 Data Collection Process

The research aim and objectives are taken briefly and these are the base of the whole research. The important factors of research are fulfilled by the finding data from the research questions and these are sampled briefly. The “data collection process” is the important factor of a research project where the researcher collects the important information regarding his/her knowledge and this also helps to make a better research project. The important data must be collected briefly and thoroughly and these are deducted as the theories are made. In short, the important research papers are made based on the collected data and thus the data must be brief, authentic and perfect to analyse.

The important data collected by different means and these all are helpful to make a better research project. The important factors of the research project are found by the collected data and the data is suggested to be true. This is very important to make a better data collection to complete the research and thus the tried and tested techniques must be used. The research is being completed following the secondary research method and the data are collected from the previous research result, journals and other articles.

3.6 Data Analysis Process

The data analysis process is an important step in the research project where the researcher follows a proper method to analyse the collected data. This step describes the important factors of the collected data and crucially discusses the important factors related to the research topic. The important factors of data analysis are served as the most important result of the whole research and this makes a clear assumption of the research project. This step can be taken as the base of the whole research process and helps to make a better assumption of the chosen topic. This step serves the desired result for the data analysis process and serves a better idea about the important factors of the topic.

The data analysis is done taken the collected data into account and this serves a better idea about the sections of the research. Some important data analysis methods are there and these are helpful to make a better idea about the collected data. The researcher must choose a perfect data analysis method that helps to make a better and authentic result for the research project. The data analysis method chosen for this research project is authentic and fruitful to make a better assumption of the chosen research topic.

3.7 Ethical Consideration

This is very important to maintain a perfect ethical behaviour throughout the research conduction process and keep a respectful approach to every step. The essential steps must be taken as the important factors of the research project and ethical consideration must be followed during the project. Some important factors must be followed during the conduction of the research project to maintain a proper ethical behaviour. This helps the researcher to maintain a good and cultured atmosphere during the process and serve an emotional approach to the process. The important factors are followed respectfully to maintain the ethical practice.

The first and foremost consideration that the researcher must follow is a proper consent during the data collection process and all the interviewee must know about the research. This is also important to respect the confidentiality of the interviewees and use the information collected from them briefly. The interviewees must be taken anonymous and they must not be harmed during the whole process. All these considerations are followed during the process of research conduction and the ethical manner was followed to conduct this research project.

Chapter 4: Research Findings

4.1 Secondary Qualitative Data

Whiteflies are responsible for the transmission and spread of viruses that are harmful to the food supply across the globe. Insects known as whiteflies have emerged as one of the most significant threats to crop security in the tropics and subtropics.  It is anticipated that the amount needed to repair the damage would be in the millions of dollars. Whiteflies belonging to the genus Bemisia are responsible for transmitting geminiviruses. This includes the virus that causes tomato yellow leaf curl, which was only recently found in the valleys of Imperial and Coachella (Guo et al., 2015).

The spread of this virus throughout the state presents a substantial threat to the number of tomatoes that may be harvested. It is important to refrain from importing transplants from other states or moving transplants or other Bemisia-infested hosts from an area where the disease is known to be prevalent to an area where it is not present to prevent the spread of the Tomato yellow leaf curl virus to other parts of the state of California. Only tomato seedlings that have been verified free of viruses by the CDFA and the agricultural commissioner of the county should be grown and transported from the Imperial Valley.

This pest causes damage to plants by reducing plant production either directly by sapping phloem sap or indirectly by expelling honeydew on leaves, which promotes the production of sooty moulds that restrict leaf photosynthesis, and by transferring viruses such as the tomato chlorosis crinivirus. It does this directly by draining the sap from the hyphae of the plant, and it does this indirectly by secreting honeydew onto the leaves of the plant (Chen et al., 2022). It is possible to ingest the phloem of a plant without immediately causing any damage to the plant; but, doing so would drastically reduce the plant’s overall health. Honeydew, which is produced by whiteflies, supports the growth of sooty mould, which in turn impedes the process of photosynthesis. Whiteflies are responsible for the production of honeydew. On the other hand, whiteflies are often regarded as the most pernicious pests due to the severity of the diseases that they transmit to plants.

It has been shown that a select group of whiteflies, namely multiple species of the Bemisia tabaci complex and Trialeurodes vaporariorum, are capable of transmitting plant viruses. Begomoviruses, criniviruses, carlaviruses, ipomoviruses, and torradoviruses are all transmitted by the B. tabaci whitefly, which is the most prevalent species of whitefly in terms of viral transmission. Begomovirus, crinivirus, carlavirus, and ipomovirus are some of the viruses that may be carried by B. tabaci, which is often found in tropical and subtropical regions (Guo et al., 2019).

Even though the impacts of the bug may be observed on the leaves of squash plants, it has been shown that the whitefly only causes damage to the fruit of tomato plants. This is in contrast to the fact that the insect causes damage to squash plants. Toxins are produced when whiteflies feed on tomato plants; these toxins cause the fruit to ripen in an irregular pattern (Czosnek et al., 2017). Because symptoms don’t develop until the fruit has reached its complete maturity, it would seem that mature green fruits are perfectly healthy. On the surface of the tomato, one of the most typical signs is the appearance of yellow or green regions that fail to grow in a longitudinal pattern. The portion of the fruit that has not yet reached its full maturity may be found relatively deep inside the pulp of the fruit. Tomatoes that have been damaged may give the appearance that they are ripening with time, but the inside of the fruit will continue to stay green throughout the process.

Middle East Asia Minor 1 (MEAM1) is thought to have begun in the Middle East and has since expanded around the world. Whiteflies of the Middle East-Asia Minor 1 (MEAM1), formerly known as “biotype B,” are of global relevance because of their invasiveness and broad host range (Czosnek et al., 2017). This species was originally found in the Middle East but has now been found in a variety of locations throughout the world, including Pakistan’s southern Sindh province. Pakistan is home to two whitefly species, with Asia II 1 being the most common in the country’s central region.

A variety of whitefly species recorded in Pakistan have been shown to differ in several aspects, including viral transmission, pesticide resistance, and host range. Tomato yellow leaf curl virus is more easily disseminated by MEAM1 than Asia II 1. Tomato leaf curl Hainan virus (ToLCHnV) is transmitted more efficiently by Asia II 1 than by TYLCV, according to a study done in Vietnam, where Asia II 1 is native [28]. Asia II 1 is the most common whitefly species in Pakistan and western India where cotton leaf curl disease (CLCuD) is prevalent (Firdaus, 2012).

Significant research indicates that the majority of newly discovered plant viruses are really old viruses that have moved to new geographical locations and obtained the potential to infect new hosts. Emerging viral species that have just been found are very uncommon (Firdaus, 2012). New plant viruses can spread through a variety of mechanisms, including mutation, recombination, or reassortment of genetic material; changes in populations of plant-transmitting vectors; and international transport of infected plant material.

Whiteflies have a long history of wreaking havoc on agricultural systems across the globe, including the transmission of illness and the ruination of crops. The agriculture sector suffers losses up to hundreds of millions of dollars as a direct result of their effect (Milenovic et al., 2019). It is believed that an increase in the whitefly population in South Africa was the cause of the appearance of the Tomato Torrado virus (ToTV), an increase in the prevalence of the Tomato chlorosis virus (ToCV), and an increase in the frequency of the Tomato curly stunt virus (ToCS). All of these viruses cause tomatoes to become wilted and stunted (ToCSV). Researchers carried conducted a countrywide analysis to get a better understanding of the prevalence and distribution of viruses that are transmitted by whiteflies in South Africa’s tomato industry.

Whitefly numbers may be effectively controlled by the use of integrated pest management, which is the most effective technique. Its goal is the rational and effective control of diseases and pests, with the result being a reduction in the number of residues found in harvested commodities. It is very necessary to combine cultural measures, biological control, and phytosanitary treatments; nevertheless, it is preferable to use natural treatments rather than chemical ones. When compared to other natural pesticides for whiteflies on tomato plants (Milenovic et al., 2019), the Nakar product stands out as having a higher performance in tests and a high degree of specialisation.

This is because it was developed specifically for use against whiteflies. It is a biopesticide that offers effective protection against soft-shelled insects during all stages of plant development, especially whitefly in tomatoes. Because of its cutting-edge makeup, it can penetrate insect cell membranes and destroy the lipoprotein matrix that they contain. The disruption of the insect’s membrane, which results in the discharge of the insect’s cellular contents, is ultimately what causes the insect to become dehydrated and pass away.

This pesticide is an excellent candidate for integrated pest management (IPM), a method that combines the effectiveness of an insecticide with biological management. Its natural origin and suitability with the action of the whitefly’s natural predators and parasitoids make it an ideal candidate for this method (Naveen et al., 2017). In a similar vein, Pirecris, an insecticide that is based on natural pyrethrins, is created utilising co-formulants of botanical origin, which are fully natural, and as a result, it does not use Piperonil Peroxide (PBO) as a synergist. Pirecris was developed by Syngenta. The method currently holds a valid patent.

In the context of this situation, attempts are being made to construct environmentally friendly integrated pest control systems with the ultimate objective of minimising the number of pesticides that are used. One of the purposes of these initiatives is to reestablish the natural equilibrium that formerly existed between the many systems of microbial control, including parasitism (Naveen et al., 2017), parasites, and predators. Whiteflies are notoriously difficult to remove completely due to the ease with which they develop resistance to chemical insecticides. “an integrated approach that focuses on preventive and utilises on cultural and biological control measures wherever feasible,” is what the United States Department of Agriculture (USDA) suggests as the best course of action.

According to the findings of one piece of research, TYLCV is transmitted via the eggs of stick insects for at least two generations. There was evidence of TYLCV DNA in the progeny of insects that had the virus transmitted to them via the egg. Both the adult children of the viruliferous insects and the adult offspring of the viruliferous insects’ progeny were capable of infecting tomato test plants with indications of whitefly illness (Milenovic et al., 2019). The following are the possible outcomes given this situation: Tomato yellow leaf curl causes the new development of crops to have fewer internodes, which results in the appearance of the plant being stunted and its height is reduced. The immature leaves are similarly considerably smaller in size and crumpled, with yellowed veins and upward-curling edges, giving it the impression of being in the shape of a cup.

Another thing to consider is that the Bt-insecticidal toxin-based crop protection measures, which are particularly effective against insect pests, have been developed as a result of the development of genetic approaches and knowledge of bacterial insecticidal toxins. In this case, this is an important consideration (Firdaus, 2012). To prevent the spread of the tomato whitefly, research has been conducted on the development of transgenes that have been shown to have an insecticidal impact on microorganisms. Whiteflies and the viral epidemics that often accompany them provide a significant problem for farmers in the state of Florida. It is very necessary to begin protecting crops against viruses as soon as feasible. Because young, rapidly developing plants need continuous protection against whiteflies, soil-applied systemic insecticides need to be transported into growing tissues and continue to remain there. It is common to practice to treat seedlings grown in greenhouses with systemic insecticides one week before planting, and then to treat them once again with the same herbicide immediately after transplanting them into the field.

Chapter 5: Discussion

5.1 Discussion

The findings of the research project serve a better idea about the results of the whole project. The result of the research can be found through this discussion and this can make a better result for the project. The research is conducted through the secondary qualitative method and thus serves an analytical and assumed outcome. The data collected for the research project were authentic and true and the whole project serves as a better idea about the result. The samples collected for the research helped to make a better assumption of the result and thus serves a better idea.

The research findings have suggested that the Gemini viruses are spread throughout the tropical and subtropical areas in the world. As these viruses are found at the coasts of Imperial and Coachella, this can be said that the white flies are active at these areas and these are the reasons that the Gemini virus is spreading at these areas. This is also can be depicted that this is important to arrange a better crop security matter for the tomato farms at this area as this virus can affect the farming. In short, the spread of the Gemini virus is because of the white flies from the “genus Bemisia” group and this can cause a good threat to the crops at this area.

The finding also suggested that the most important factors of prevention of the disease that can make the most effective precaution. As the findings suggested, refraining of the transportation from the affected area or to the affected area from any safe place can help to prevent the spreading of the diseases. As it is discussed that the spreading of the disease can be done throughout of the harvested areas and this can cause a challenge for the country. This makes the job of the agricultural commissioner and the “California Department of Food and Agriculture” hiked as they need to test and research on every tomato seed and omit the effected seeds from the seeds that are free from the disease. This can help to prevent the disease to spread in the other parts of California.

The dangerous effects of the pest can affect the plant in two different ways, either by sapping the phloem or by preventing photosynthesis of the plants. Thus, two of the essential parts can be affected by this either the steam or the leaves of the plant. Another very important factor of the virus that can affect the plants is that the pest can spread another virus known as the “tomato chlorosis crinivirus”. Thus, the plants can be affected by the pest directly or indirectly which can cause a dangerous effect on the harvested tomato plants.

The findings have suggested that the treatment for the pest can be harmful for the plants. Ingestion of the phloem tissue of the plant can save the plant from the virus; however, this can affect the overall health of the plant. Immediate actions are required to secure the harvest and this takes good research for the CDFA. Another technique can be used by lowering the production of honeydew by the pest but there still not any process found to do so. Thus, the threat is remains and the scientists are still researching on the process.

The findings also served a proper idea about the spreading of the disease as this can caused by some specific species of the pest, namely “Bemisia tabaci complex” and “Trialeurodes vaporariorum”. The B tabaci complex variety is the most prevalent carrier of the viruses and this can spread some of the different varieties of the virus. Different viruses like criniviruses, carlaviruses, ipomoviruses, and torradoviruses can be transmitted by this insect which can affect the harvest in no time. This is very important to make proper research on the factors of spreading the virus and this can help to find out a way to prevent the disease.

Studies also say that the viruses can affect the squash plants and this makes the problem more crucial. The harvest squash plants are also can be affected by this and the scenario can be devastating for the country. More importantly, as the symptoms of this disease cannot be seen before the fruits become mature, no way is there to prevent the spread of the virus and save the harvest. Even after the maturity of the fruit, the symptoms are not completely shown and this makes a dangerous effect on the harvest. The most prominent symptom of the disease can be shown at the final stage of the disease and this is too late to prevent the disease. In short, the prevention of the disease is very crucial and continuous research, monitoring and observation is needed to make sure that the plants are free from the disease and completely healthy.

5.2 Summary

The toxic effects of the white flies are crucial for the harvest in California and this must be treated as a dangerous factor. The agricultural commissioner and the “California Department of Food and Agriculture” are working continuously to find out the solution of the spreading of the disease and they have found the important species of the fly that causes spreading of the disease. They have also found the evil virus that causes the disease and they are working on the prevention of it. The researchers found that the disease only can be prevented by shorting the affected seeds of the plants out and only harvesting the seeds that are free from the disease. The researchers also found out the important species that are most crucial of spreading the disease and this serves an idea to prevent the disease. The important results of the research also found that the virus also affects the squash plants and this can be dangerous for both the agriculture and the economy of the country.

The dangerous effect of the same can be taken as the crucial and pathetic scenario for the country and this must be prevented as soon as possible. The researchers also found out the areas that can be affected by the virus and this is crucial to make plans to prevent that. An important factor of the disease that the researchers have found out that the disease can be prevented by ingesting the affected areas of the plant and this can be served as a preventive factor by the plants. However, the researchers also found that these criteria can affect the whole system of the plant and can affect the overall health of the harvest. However, this cannot be used to make the plant free from the disease and the spreading is continuing.

Another factor that the researchers have found out that the virus can affect the squash plants as well as the tomato plants. The symptoms cannot be found effectively and the disease can be spread silently in the plants. The symptoms of the disease only can be seen after the maturity of the fruit and this makes the prevention more difficult.

Chapter 6: Conclusions

6.1 Conclusion

Through considering the entire study, it is concluded that The begomovirus TYLCV, which is carried by whiteflies and is the primary cause of tomato yellow leaf curl disease, is the primary cause of yellow leaf curl disease. Bemisia tabaci, a whitefly of the Aleyrodidae family, is one of more than 35 cryptic species estimated to exist in the hemisphere whitefly family. Whiteflies of this genus prey on and spread plant viruses, which causes damage to plants. Because of their rapid spread over the past three decades, MEAM1 and MED, previously known as the B and Q “biotypes,” are two species in the complex that have caused havoc on agriculture throughout the globe. “In China, 17 indigenous B. tabaci species and two invading species, MEAM1 and MED, have been identified using mitochondrial cytochrome oxidase I (mtCOI). The native Chinese B. tabaci fauna may be found in Asia’s southern, southern-eastern, and southwestern regions.

Biological and abiotic factors have a role in the spread of Begomovirus “Nonetheless”. Moreover, the literature study also highlighted the most effective and prominent knowledge about the uses and origin of Tomato and estimation of the losses for different virus species. In addition to this, what kinds of disease caused for different species of whiteflies like tomato leaf curl virus have been significantly and reliably demonstrated within this study. Furthermore, in order to collect and gather and analyse the most prominent and evident information and knowledge from the sources, the researcher has utilised the most appropriate and resilient method like secondary qualitative data that has been significantly collected for this study. In this way, the researcher has demonstrated that the country’s future is in jeopardy and must be avoided as soon as feasible. The researchers also discovered the places where the virus may spread, which is critical to preventing the spread of the infection.

Researchers have discovered a way to avoid the illness by consuming parts of the plant that have been infected, and this may be used by the plants themselves as a preventative measure. These parameters, however, may have a significant impact on the general health of the plant and the crop as a whole. However, this is unable to rid the plant of the illness, and as a result, it continues to spread throughout the plant. Researchers have also shown that the virus may harm both squash and tomato plants. The illness may spread undetected in plants because the symptoms are difficult to detect. The disease’s symptoms are only visible after the fruit is fully ripe, making it more difficult to avoid. White flies pose a serious threat to the harvest in California, and this must be taken into consideration as a serious issue.

The agricultural commissioner and the “California Department of Food and Agriculture” (CDFA) are constantly striving to find a solution to the spread of the illness, and they have identified the most significant species of fly that causes the sickness to spread. They’ve also discovered the disease-causing virus, and are now attempting to thwart it. To avoid the spread of the illness, experts observed that it is only possible to shorten the infected seeds of the plants and only collect the disease-free seeds. As a result of their findings, scientists now have a better concept of how to stop the illness from spreading. The virus also damages squash plants, which might pose a serious threat to the country’s agricultural and economy, according to the findings of the study.

6.2 Recommendations

When all of the research is taken into account, it’s determined that tomato farmers have previously adopted Bt-Insecticidal Toxin-Based Crop Protection methods. In addition, the Integrated Pest Management technique was applied in tomato cultivation as well. To use this pesticide in an integrated pest management (IPM) strategy, people must combine an insecticide with biological control. Whitefly’s natural enemies and parasitoids make it a good choice for this strategy because of its natural nature. Toxin-based Bt crop protection methods, which are especially efficient against insect pests, were created as a consequence of the development of genetic techniques and understanding of bacterial insecticidal toxins. This should be taken into account as well. This is a crucial aspect in this scenario (Firdaus, 2012). Nevertheless, various whitefly species continue to pose a variety of dangers to tomato growers. As a result, tomato growers throughout the globe will need to adopt and use a more effective and robust approach for eradicating various types of whiteflies.

6.3 Future Research Scope

In this aspect, the researcher has only utilised and implemented the secondary qualitative data for this research study. Through this, the researcher has been able to collect and analyse the most evident and crucial information and knowledge regarding the study. However, the authenticity of this information and knowledge has been disrupted. Therefore, the researcher has decided to conduct further research in the market in order to collect the most authentic and reliable information through conducting the survey and interview among the farmers to collect the primary quantitative and primary qualitative data from the sources.

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