**1. Introduction**

The genus *Capsicum* belonging to the family *Solanaceae* consists of approximately 31 species, of which only five have been domesticated: *C. annuum*, *C. chinense*, *C. frutescens*, *C. baccatum* and *C. pubescens* [1]. *Capsicum* is known by various names including pepper, chile, chili, chilli, aji, and paprika. Throughout the world, *Capsicum annuum L.* is the most commercially important and widely grown species within this genus. The abundant varieties of *C. annuum*, including sweet peppers and chilli peppers, are important horticultural crops produced worldwide, especially in countries such as Spain and Mexico. Their fruits have remarkable sensory attributes in terms of colour, acidity and aroma, as well as an ample diversity of antioxidants, such as phenolic compounds and flavonoids [2]. Moreover, some types present high levels of capsaicin (8-methyl-*n*-vanillyl-6-nonenamide), which provide them with their spicy flavour in addition to therapeutic applications due to their anti-cancer properties [3].

The growth and development of *Capsicum* can be limited by various abiotic and biotic factors that negatively affect its fruit production and quality. It is estimated that losses caused by biotic factors such as invertebrates, pathogens and weeds can vary from 27 to 42%, which would increase to between 48 and 83% if the crops

were not protected [4]. Among these, pests and plant diseases seriously affect *Capsicum* crops, in addition to the fact that their production is carried out under limited environmental conditions, which translates into a decrease in yield and quality [5]. For the control of these biotic agents, chemically synthesised pesticides have been traditionally used, which have generated several controversies due to their toxicity in humans and animals, and their damaging effects to the environment. Additionally, they can generate resistance in pathogenic microorganisms [6] and insects [7].

Regarding phytosanitary problems, the high temperatures and high levels of humidity generated in intensive production systems promote the development of fungal diseases that can progress rapidly [8]. Among the diseases that affect *Capsicum*, soil-borne diseases caused by pathogens of the genus *Phytophthora*, *Fusarium*, *Pythium* and *Rhizoctonia* are especially significant. At the fruit level, this crop is affected by pathogens such as *Botrytis cinerea* and *Anthracnose*, the latter caused by a complex of *Colletotrichum* species that is considered a serious problem with heavy losses in fruit yield, exceeding 80% [9]. Another important problem in the cultivation of *Capsicum* is viruses, since there are approximately 70 types that can affect this crop [10], especially the cucumber mosaic virus, pepper mild mottle virus and potato virus Y, among others [11–13]. In general, viruses can interfere with the chlorophyll synthesis of the plant, causing chlorosis and mottling of the foliage (mosaic).

On the other hand, several insect pests affect this crop during the entire growth and production cycle, causing significant yield losses ranging from 50 to 90% [14]. This has resulted in an intensive use of insecticides, mainly chemical. Among the plagues that affect *Capsicum* are: whiteflies, like *Trialeurodes vaporariorum* Westwood (Hemiptera: *Aleyrodidae*) and *Bemisia tabaci* Gennadius (Hemiptera: *Aleyrodidae*); flower thrips, *Frankliniella occidentalis* Pergande (Thysanoptera: *Thripidae*); aphids *Myzus persicae* Sulzer (Hemiptera: *Aphididae*) and *Aphis gossypii* Glover (Hemiptera: *Aphididae*); worms *Helicoverpa armigera* Hübner (*Lepidoptera: Noctuidae*), *Spodoptera litura* Fabricius and *S. exigua* Hübner (Lepidoptera: *Noctuidae*); and mites *Polyphagotarsonemus latus* Banks (Acari: *Tarsonemidae*), *Tetranychus urticae* Koch, *T. ludeni* Zacher and *T. evansi* Baker and Pritchard (Acari: *Tetranychidae*) [15–17]. Within this group, whiteflies, aphids and thrips are considered pests of economic importance worldwide [18]. They have a wide range of hosts, from agricultural species to ornamental plants and are difficult to control due to their high reproductive rate, short life cycle and cryptic behaviour [19–21].

Finally, phytoparasitic nematodes are also organisms present in the cultivation of *Capsicum* and can cause serious problems affecting its performance [22]. Among the nematodes that affect *Capsicum*, those of the genus *Meloidogyne* are especially significant, such as *M. incognita* (Kofoid and White) Chitwood, *M. arenaria* (Neal) Chitwood, *M. enterolobii* (Yang and Eisenback) and *M. javanica* (Treub) Chitwood, which are responsible for root-knot disease [23–25]. These nematodes are found throughout the world, especially in warm areas and in greenhouses. Other nematodes that also cause economic damage in *Capsicum* include the false root-knot nematode *Nacobbus aberrans* Thorne and Allen [26]. Nematode control strategies are based on the use of chemicals; however, their high cost and principally their toxic effects have led to a search for more sustainable alternatives.

With a growing world population, currently, the main challenge for agriculture is to achieve food security; thus, food production has increased in recent years. However, pests and plant diseases, where *Capsicum* is no exception, have also increased as a result of changing climatic conditions, intensification of production systems and the opening of borders for the free transit of food, including fresh produce. In a conventional way, the high populations of insect pests and plant diseases

**55**

*Biological Control in* Capsicum *with Microbial Agents DOI: http://dx.doi.org/10.5772/intechopen.93509*

country where they are used.

**2. Microbial biological agents**

**2.1 Biological pest control with microorganisms**

processes, not phytotoxic and not harmful to humans [30].

in *Capsicum.*

cause diseases).

have been controlled through the use of chemical pesticides. Biological control through the use of antagonistic microorganisms, such as bacteria, fungi and viruses, is presented as an alternative to the use of chemicals. It has received more attention in recent years and arises in response to the search for ways to control pathogens, insects and nematodes in a sustainable manner. However, this type of control must meet some requirements such as being effective against the target organism, not causing problems to the health of people and animals, reaching adequate control levels in the field, the feasibility of being incorporated into integrated management practices and meeting with phytosanitary measures according to the enforced regulations in each

Considering the above, the objective of this chapter is to review the importance of microbial agents in the biological control of pests, plant diseases and nematodes

In recent years, world markets have expressed increasing concern about the use of agrochemicals. Biological control, which is defined as the reduction of pest populations by natural enemies and usually involves human intervention, is presented as an alternative to the use of chemical pesticides [27]. Biological control agents are classified into predators, parasitoids and pathogens (microorganisms that

After being identified, isolated and reproduced, biocontrol microorganisms are applied in a directed way in dilutions or released on the insect pests and diseases of the crops so that they can carry out their colonising action, produce antagonism, and specific diseases in the agents that require control, with the purpose of reducing the incidence to inoffensive levels [28]. Many microorganisms have been used as biopesticides because they offer a number of additional benefits beyond their target function [29]. An antagonist microorganism used for biological control must meet certain requirements, such as being genetically stable, effective at low concentrations, undemanding in nutrients, adapted to different environmental conditions, effective for a wide range of pathogenic microorganisms, easily grown, easily manipulated, resistant to chemical pesticides, compatible with commercial

Among the microorganisms that have been most studied and reported as antagonists of insect pests and plant pathogens of *Capsicum* are bacteria such as *Bacillus* spp. and *Pseudomonas* spp., and the fungi *Beauveria* spp., *Metarhizium* spp., *Paecilomyces* spp., *Trichoderma* spp. and *Clonostachys* spp., while the viruses of the Baculovirus group have proven to be effective insect controllers. The genus *Bacillus* is made up of species that have been widely used to control insect pests and plant diseases due to the morphological and physiological characteristics that allow them to be ubiquitous in nature. It is especially important to note that species of this genus produce metabolites with antimicrobial properties used for the control of plant pathogens. In addition, the species *B. thuringiensis* Berliner has important qualities for the control of nematodes and protozoa [31, 32]. Another important group used in the control of insect pests in *Capsicum* is the entomopathogenic fungi, which have been widely studied. For more than a century, Pasteur predicted the advantages of entomopathogenic fungi because of their role as bioregulators of pests, acting as parasites to insects that are harmful to plants. Currently, more than 700 species of fungi are known to affect insects of various orders and their use as

#### *Biological Control in* Capsicum *with Microbial Agents DOI: http://dx.doi.org/10.5772/intechopen.93509*

Capsicum

and insects [7].

foliage (mosaic).

were not protected [4]. Among these, pests and plant diseases seriously affect *Capsicum* crops, in addition to the fact that their production is carried out under limited environmental conditions, which translates into a decrease in yield and quality [5]. For the control of these biotic agents, chemically synthesised pesticides have been traditionally used, which have generated several controversies due to their toxicity in humans and animals, and their damaging effects to the environment. Additionally, they can generate resistance in pathogenic microorganisms [6]

Regarding phytosanitary problems, the high temperatures and high levels of humidity generated in intensive production systems promote the development of fungal diseases that can progress rapidly [8]. Among the diseases that affect *Capsicum*, soil-borne diseases caused by pathogens of the genus *Phytophthora*, *Fusarium*, *Pythium* and *Rhizoctonia* are especially significant. At the fruit level, this crop is affected by pathogens such as *Botrytis cinerea* and *Anthracnose*, the latter caused by a complex of *Colletotrichum* species that is considered a serious problem with heavy losses in fruit yield, exceeding 80% [9]. Another important problem in the cultivation of *Capsicum* is viruses, since there are approximately 70 types that can affect this crop [10], especially the cucumber mosaic virus, pepper mild mottle virus and potato virus Y, among others [11–13]. In general, viruses can interfere with the chlorophyll synthesis of the plant, causing chlorosis and mottling of the

On the other hand, several insect pests affect this crop during the entire growth

Finally, phytoparasitic nematodes are also organisms present in the cultivation of *Capsicum* and can cause serious problems affecting its performance [22]. Among the nematodes that affect *Capsicum*, those of the genus *Meloidogyne* are especially significant, such as *M. incognita* (Kofoid and White) Chitwood, *M. arenaria* (Neal) Chitwood, *M. enterolobii* (Yang and Eisenback) and *M. javanica* (Treub) Chitwood, which are responsible for root-knot disease [23–25]. These nematodes are found throughout the world, especially in warm areas and in greenhouses. Other nematodes that also cause economic damage in *Capsicum* include the false root-knot nematode *Nacobbus aberrans* Thorne and Allen [26]. Nematode control strategies are based on the use of chemicals; however, their high cost and principally their

With a growing world population, currently, the main challenge for agriculture is to achieve food security; thus, food production has increased in recent years. However, pests and plant diseases, where *Capsicum* is no exception, have also increased as a result of changing climatic conditions, intensification of production systems and the opening of borders for the free transit of food, including fresh

produce. In a conventional way, the high populations of insect pests and plant diseases

and production cycle, causing significant yield losses ranging from 50 to 90% [14]. This has resulted in an intensive use of insecticides, mainly chemical. Among the plagues that affect *Capsicum* are: whiteflies, like *Trialeurodes vaporariorum* Westwood (Hemiptera: *Aleyrodidae*) and *Bemisia tabaci* Gennadius (Hemiptera: *Aleyrodidae*); flower thrips, *Frankliniella occidentalis* Pergande (Thysanoptera: *Thripidae*); aphids *Myzus persicae* Sulzer (Hemiptera: *Aphididae*) and *Aphis gossypii* Glover (Hemiptera: *Aphididae*); worms *Helicoverpa armigera* Hübner (*Lepidoptera:* 

*Noctuidae*), *Spodoptera litura* Fabricius and *S. exigua* Hübner (Lepidoptera: *Noctuidae*); and mites *Polyphagotarsonemus latus* Banks (Acari: *Tarsonemidae*), *Tetranychus urticae* Koch, *T. ludeni* Zacher and *T. evansi* Baker and Pritchard (Acari: *Tetranychidae*) [15–17]. Within this group, whiteflies, aphids and thrips are considered pests of economic importance worldwide [18]. They have a wide range of hosts, from agricultural species to ornamental plants and are difficult to control due to their high reproductive rate, short life cycle and cryptic behaviour [19–21].

toxic effects have led to a search for more sustainable alternatives.

**54**

have been controlled through the use of chemical pesticides. Biological control through the use of antagonistic microorganisms, such as bacteria, fungi and viruses, is presented as an alternative to the use of chemicals. It has received more attention in recent years and arises in response to the search for ways to control pathogens, insects and nematodes in a sustainable manner. However, this type of control must meet some requirements such as being effective against the target organism, not causing problems to the health of people and animals, reaching adequate control levels in the field, the feasibility of being incorporated into integrated management practices and meeting with phytosanitary measures according to the enforced regulations in each country where they are used.

Considering the above, the objective of this chapter is to review the importance of microbial agents in the biological control of pests, plant diseases and nematodes in *Capsicum.*
