Influence of Biochar on Soil Insect Dynamics and Infestation

Abstract

Biochar, a carbonaceous material produced through pyrolysis of organic matter, has garnered attention for its potential to enhance soil fertility, structure, and overall health. However, its effects on soil-dwelling insects remain a subject of considerable interest and debate. This chapter critically examines the current state of knowledge regarding the interactions between biochar applications and soil-dwelling insects, encompassing diverse aspects such as alterations in insect community composition, population dynamics, behavioral changes, and potential mitigation of infestations. Through an exploration of empirical studies and theoretical frameworks, it aims to elucidate the intricate relationships between biochar amendments and soil insect ecology.

1. Introduction

Soil health stands as the bedrock of terrestrial ecosystems, serving as a vital foundation for agricultural productivity, ecological stability, and the sustenance of diverse life forms [1]. Within this intricate web of soil dynamics, the role of soil-dwelling insects emerges as an integral component, orchestrating a delicate balance in the ecosystem [2, 3, 4]. In recent years, the integration of biochar as a soil amendment has garnered considerable attention for its potential to revolutionize soil health and agricultural sustainability [5, 6]. Biochar, derived from the pyrolysis of organic materials under controlled conditions, manifests as a stable carbonaceous product [7]. Its application as a soil amendment dates back centuries, with historical practices like terra preta showcasing its enduring benefits in enhancing soil fertility and structure [8, 9, 10]. The porous nature of biochar contributes to its exceptional capacity for water retention, nutrient adsorption, and microbial habitat provision [11]. Its introduction to soil systems holds promise not only for improving agricultural yields but also for mitigating environmental degradation by sequestering carbon [12]. Soil health constitutes a complex interplay of physical, chemical, and biological attributes that sustain life below ground [13, 14]. Soil-dwelling insects, encompassing a diverse array of species, play pivotal roles in nutrient cycling, decomposition, soil aeration, and pest regulation [15]. Their interactions within the soil ecosystem contribute significantly to the overall health and functionality of terrestrial environments [16]. However, disturbances in soil health, induced by factors such as land-use changes, pollution, and climate variations, can disrupt the delicate equilibrium of soil-dwelling insect populations, potentially leading to ecological imbalances and decreased agricultural productivity [17, 18, 19, 20, 21, 22]. This chapter aims to delve into the intricate nexus between biochar applications, soil health, and soil-dwelling insects. It seeks to comprehensively explore the influence of biochar on soil insect dynamics, community structure, and infestation patterns within soil ecosystems. Through a synthesis of empirical studies, theoretical frameworks, and practical insights, this chapter endeavors to unravel the multifaceted effects of biochar as a soil amendment on the intricate relationships between soil health and the myriad inhabitants dwelling beneath the soil surface (Figure 1).

Figure 1.

Depicting biochar in plant-biotic interactions like soil insect pest management where the biomass waste by pyrolysis gets converted to biochar-clay organo complex in the soil resulting in controlling soil pests.

2. Soil insect pests

Insect pests are almost a year-round problem in the whole universe. Pests can be above ground or below ground [23]. While it is somewhat easier to observe foliar insects, it is a daunting task to really know what is inside the soil before it is too late. Various soil insects such as wireworms, cutworms and white grubs among many others are regular occurrence in various fields [24]. It is always very important to take a shovel sample of soil in raised beds or open fields to retrieve sample of insect pests that may be infesting the soil. Soil provides a structure for a plant to anchor its roots and is a source of nutrition and water necessary for plant growth. Soil-inhabiting insects also utilize this substrate for part of or for their entire life. Although many insects are dependent on soil for food and shelter, only a few soil-borne insects such as weevils, ants, and termites are detrimental to the citrus tree.

3. Types of soil insect pests

Wireworms: These are the immature stage (larva) of the click beetle. Wireworms are cylindrical, about 1–1/2 inches long, brownish to yellow, and are rather hard-bodied. These insects eat seeds, cut into small shoots, and often bore into stems, roots, and tubers. They attack many vegetables including potatoes, onion, corn, carrots, peas, beans, and melons.

White grubs: These are cream-colored, C-shaped larvae with brown heads. They include the immature stage of European chafer, Japanese beetle, and May/June beetles. They stay in the soil and feed on the roots of corn, beans, peas, and other vegetables. They are most likely to damage plants in or near ground that was recently sod covered.

Cutworms (Agrotis ipsilon): These are the larval, or immature, stage of certain moths. They can often destroy a stand of plants in a garden. Cutworms are night feeders and are seldom seen during the day. These insects cut off small plants at or near the ground level and feed on the tender stem. Some types climb up the stem and feed on foliage. Many plants are attacked by cutworms, but they are especially damaging to corn, beans, tomatoes and peppers.

Seed corn maggots (Delia platura): These are the larvae of small flies. They develop in the soil and feed on seed and seedlings of corn, beans, peas, potatoes, cabbage, melons, and other crops. Cool wet springs and soil with a high concentration of organic matter favor the development of this pest [25].

Termites: Termites, often referred to as “silent destroyers,” wield their devastating impact beneath the surface, wreaking havoc on soil health and structures. Their presence manifests through several damaging symptoms within the soil. One prominent sign of termite infestation is the formation of intricate tunnels and galleries snaking through the earth. These subterranean passages, constructed by termites as they forage for food and establish their colonies, weaken the soil structure, compromising its stability. Additionally, the accumulation of termite excrement, commonly known as “termite mounds,” alters the soil composition, leading to nutrient imbalances and decreased fertility. As termites consume organic matter within the soil, they accelerate its degradation, impacting the natural processes that sustain its vitality. The cumulative effect of their activity disrupts the delicate balance of the ecosystem beneath the surface, posing a considerable threat to agricultural productivity and ecosystem health.

4. Definition and composition of biochar

Biochar, a carbon-rich, porous material derived from the thermochemical conversion of biomass under controlled conditions of low oxygen, holds immense promise as a versatile soil amendment. Its composition, production methods, and diverse applications across agricultural and ecological landscapes underline its potential in revolutionizing soil health and sustainability [26]. Biochar is characterized by its stable carbon structure, resulting from the pyrolysis or thermal decomposition of organic materials such as wood chips, agricultural residues, or other biomass. This process occurs in the absence or limited presence of oxygen, preventing complete combustion and yielding a carbonaceous residue. The resulting biochar typically contains varying percentages of carbon (ranging from 60% to 95%), along with hydrogen, oxygen, and small quantities of nitrogen and other minerals. Its high surface area, porosity, and stable carbon content distinguish biochar from other organic amendments, rendering it resistant to degradation and offering long-term benefits to soil systems.

5. Production methods and variations

Biochar production methods encompass a spectrum of techniques, each influencing the characteristics and properties of the final product. Traditional methods include pyrolysis in kilns, retorts, or pits, where organic materials undergo thermal decomposition at temperatures typically ranging from 300°C to 1000°C. Variations in pyrolysis conditions, such as heating rates, residence time, and temperature, significantly impact the physical and chemical properties of biochar [27]. Modern approaches, like gasification and hydrothermal carbonization, offer more controlled processes, allowing for the customization of biochar properties by adjusting operating parameters. Different feedstocks and production techniques yield biochars with diverse pore structures, surface areas, elemental compositions, and functionalities. For instance, pyrolyzing feedstocks like woody materials tend to produce biochars with higher carbon content and greater stability, while agricultural residues might result in biochars with varying nutrient contents and properties. These variations underscore the importance of tailoring biochar production to specific applications and desired soil outcomes [28].

6. Application techniques and considerations in agricultural and ecological settings

Biochar’s versatility in application spans agricultural and ecological domains, offering a spectrum of benefits. In agricultural settings, incorporating biochar into soil enhances its physical structure, water retention capacity, and nutrient-holding capabilities [29]. Various application methods exist, including surface application, incorporation into soil via tilling or mixing, or integration into composts or organic fertilizers. The choice of application method depends on factors such as soil type, crop type, climate, and desired outcomes. For instance, mixing biochar into soils during land preparation facilitates its distribution and integration, while surface application suits established crops or erosion-prone areas. Ecologically, biochar finds use in habitat restoration, carbon sequestration, and remediation of contaminated soils [30]. Its porous structure serves as a refuge and substrate for beneficial microorganisms, promoting soil biodiversity and ecosystem resilience. Additionally, biochar’s ability to sequester carbon aids in mitigating climate change by locking away carbon dioxide in stable forms, contributing to carbon-negative strategies. Considerations in biochar application involve dosage, feedstock selection, soil interactions, and potential impacts on soil pH and nutrient availability. Determining optimal application rates, accounting for regional variations, and monitoring long-term effects are crucial for maximizing biochar’s benefits while minimizing any unintended consequences [31].

7. Soil insect dynamics and ecology

The complex world beneath our feet teems with an intricate tapestry of soil-dwelling insects, a diverse array of organisms that play pivotal roles in shaping soil ecosystems and influencing the health of terrestrial environments. These often-overlooked inhabitants encompass a broad spectrum of taxa, including beetles, ants, earthworms, mites, springtails, nematodes, and many others, each contributing distinctively to the intricate web of interactions within the soil matrix [32]. Their presence and activities are integral to the functioning of soil ecosystems, orchestrating a myriad of ecological roles that profoundly influence nutrient cycling, decomposition processes, soil structure, and the broader dynamics of terrestrial environments. The diversity of soil-dwelling insects within these ecosystems is staggering, with an estimated one-quarter of all described animal species inhabiting soil habitats. This diverse assemblage fulfills an array of ecological roles, contributing significantly to nutrient cycling through their roles as decomposers, predators, herbivores, and symbiotic partners [33]. For instance, earthworms, among the most recognizable soil inhabitants, aid in organic matter breakdown and soil aeration, enhancing nutrient availability and soil structure. Ants and termites are key ecosystem engineers, influencing soil architecture and nutrient distribution through their burrowing and foraging activities. Meanwhile, predatory insects like ground beetles and rove beetles help regulate pest populations by preying upon other soil-dwelling organisms, thus exerting top-down control within these ecosystems. A multitude of factors influences the population dynamics and distribution patterns of soil insects. Abiotic factors such as soil moisture, temperature, pH, and texture, alongside biotic factors including plant root exudates, microbial communities, and interspecific interactions, collectively shape the abundance and diversity of soil-dwelling insects [34]. Soil physicochemical properties profoundly impact insect survival, reproduction, and movement, creating microhabitats that favor certain species over others. Additionally, the intricate relationships between soil-dwelling insects and aboveground organisms, such as plants and predators, contribute significantly to their population dynamics [35]. For instance, plant root exudates not only provide a food source for soil insects but also influence the composition and activity of soil microbial communities, indirectly affecting insect populations through complex trophic interactions. Interactions within soil ecosystems are characterized by intricate food webs and symbiotic relationships that govern energy flows and nutrient cycling [36]. Soil insects form intricate networks of interactions with microorganisms, plants, and other soil fauna, exerting cascading effects on ecosystem processes. For example, mycorrhizal associations between fungi and plant roots influence soil insect dynamics by altering resource availability and quality. Predatory interactions among soil insects regulate populations of other soil organisms, thereby influencing decomposition rates and nutrient cycling. Furthermore, soil insects play critical roles in the breakdown of organic matter, facilitating nutrient release and recycling within the ecosystem. Understanding the complexity of soil insect dynamics and their ecological roles is crucial for deciphering the intricate functioning of soil ecosystems [37]. These often inconspicuous organisms wield immense influence over soil health, nutrient cycling, and ecosystem stability. Thus, elucidating the factors shaping their populations and unraveling the web of interactions within soil ecosystems is pivotal for devising sustainable land management strategies, preserving biodiversity, and ensuring the resilience of terrestrial ecosystems in the face of global environmental changes.

8. Impact of biochar on soil insect community composition

8.1 Influence of biochar on soil insect populations

The impact of biochar on soil insect community composition represents a critical aspect of understanding how this soil amendment influences the intricate balance and dynamics within terrestrial ecosystems [38]. Soil-dwelling insects, comprising a diverse range of taxa, play integral roles in nutrient cycling, decomposition, and ecosystem functioning. Biochar application can alter soil properties and, consequently, affect the abundance, diversity, and interactions among these vital organisms [37].

8.2 Response of different taxa

Biochar application exhibits variable effects on different soil-dwelling insect taxa. Studies across diverse ecosystems have demonstrated contrasting responses among various insect groups post-biochar application [39]. For instance, while some investigations report increases in the abundance of certain decomposer organisms such as earthworms and springtails, others document shifts in the relative abundance of predatory insects like beetles or ants. These responses often vary depending on biochar type, application rates, soil characteristics, and specific insect taxa [40]. The varied responses among soil insect groups highlight the complexity of biochar-soil interactions and the nuanced effects on different trophic levels within soil ecosystems. The altered conditions resulting from biochar application can influence resource availability, microhabitat preferences, and interactions among soil-dwelling insects, contributing to the observed changes in their abundance and distribution.

8.3 Altered relative abundance

Observations post-biochar application often reveal changes in the relative abundance of soil insect species [41]. Some studies indicate shifts in the dominance or proportional representation of specific insect taxa within soil communities. For instance, while certain studies report an increase in the abundance of earthworms or springtails following biochar incorporation, others note decreases in the abundance of certain beetle species or mites. These alterations in the relative abundance of soil-dwelling insects can be attributed to biochar-induced modifications in soil properties, such as changes in pH, nutrient availability, or microbial activity [42]. Such shifts might impact the competitive advantage of certain insect groups, influencing their population sizes within the soil ecosystem.

8.4 Shifts in diversity

Biochar application can elicit changes in the diversity indices and species richness of soil insect communities. While some studies report an increase in species richness and diversity metrics, others indicate no significant changes or even reductions in diversity following biochar incorporation [43]. The observed shifts in diversity indices might result from alterations in soil conditions that selectively favor certain insect taxa or impact their interactions within the ecosystem. Increased diversity might stem from improved habitat conditions, such as enhanced soil structure or nutrient availability, fostering a more favorable environment for a wider range of soil insects. Conversely, reductions in diversity might arise due to changes in competitive interactions, resource availability, or alterations in microenvironmental conditions induced by biochar amendments. Understanding these shifts in species richness and diversity indices is crucial in deciphering the ecological implications of biochar application on soil insect communities [44]. It underscores the intricate nature of biochar-soil insect interactions and the need for comprehensive assessments considering various environmental factors influencing community composition.

8.5 Modulation of population dynamics

The modulation of population dynamics among soil-dwelling insects in response to biochar application represents a crucial aspect of understanding how this soil amendment shapes the functioning and interactions within terrestrial ecosystems. Biochar, with its diverse physicochemical properties, can exert influences on the behavior, activities, and population sizes of various insect groups, impacting key ecological roles such as nutrient cycling, decomposition, and soil engineering [45].

8.6 Activity levels and foraging behavior

Biochar application can elicit alterations in the activity levels, movement patterns, and foraging behavior of soil-dwelling insects. Studies have documented changes in the behavior of various insect taxa following biochar incorporation into soils. For instance, increased activity levels and alterations in movement patterns among decomposer organisms like earthworms or springtails have been observed [46]. These changes are often linked to biochar-induced modifications in soil properties, such as enhanced soil moisture retention, improved nutrient availability, or changes in microhabitat conditions. Moreover, alterations in foraging behavior, feeding patterns, and resource utilization by soil insects post-biochar application have been noted. Certain insect groups might exhibit preferences for biochar-amended zones within the soil, influencing their feeding habits or colonization patterns. Such changes in behavior can potentially impact nutrient distribution, organic matter decomposition rates, and soil structure, thereby influencing ecosystem functioning [47].

8.7 Decomposer dynamics

Biochar amendments have demonstrated effects on decomposer populations, influencing their abundance and activity within soil ecosystems. Decomposers, such as earthworms, springtails, and other microarthropods, play pivotal roles in organic matter breakdown, nutrient mineralization, and soil organic carbon dynamics [48]. Studies suggest that biochar can enhance the abundance and activity of certain decomposer organisms, potentially accelerating organic matter decomposition rates and nutrient cycling processes. Increased populations or activities of decomposer organisms following biochar application can contribute to enhanced nutrient availability in soils. Through their roles in fragmenting and processing organic materials, these decomposers facilitate the release of nutrients essential for plant growth and ecosystem functioning. Biochar-induced improvements in soil conditions, such as increased microbial activity or changes in substrate quality, might favor decomposer communities, subsequently influencing nutrient turnover rates and soil fertility [49].

8.8 Engineering species response

Soil engineers, including earthworms, ants, termites, and other burrowing organisms, can respond to biochar applications by altering their abundance and activities within soil ecosystems. These organisms significantly influence soil structure, aeration, water infiltration, and nutrient distribution. Studies have indicated changes in the abundance or behavior of soil engineers post-biochar incorporation, impacting soil physical properties and ecosystem processes [50]. For instance, increased earthworm activity following biochar application can contribute to improved soil structure and nutrient availability by enhancing soil aggregation and organic matter decomposition. Changes in the abundance of ants or termites might influence soil architecture through burrowing activities, affecting water infiltration and nutrient distribution patterns within the soil profile. Understanding the responses of soil engineers to biochar amendments is essential as their activities play critical roles in shaping soil properties and ecosystem functions. These changes in population dynamics and activities among soil engineers reflect the broader implications of biochar applications on soil structure, nutrient cycling, and ecosystem resilience [51].

8.9 Behavior modifications and trophic interactions

Behavior modifications and trophic interactions among soil-dwelling insects in response to biochar amendments represent critical aspects of understanding the nuanced influences on insect behavior, ecological interactions, and soil ecosystem functioning. Biochar-induced alterations in soil properties can intricately shape the foraging behavior, trophic relationships, and indirect effects on soil insects mediated through changes in soil microbial communities.

8.10 Foraging behavior changes

Biochar application can induce modifications in the foraging behavior and feeding patterns of soil-dwelling insects. Changes in soil properties resulting from biochar amendments, such as increased water retention, alterations in nutrient availability, or modifications in soil structure, can influence the resource utilization and feeding preferences of various insect taxa. Studies have documented shifts in the foraging behavior of soil insects, including alterations in their preferences for specific food sources or changes in feeding rates [52]. For instance, certain decomposer organisms might exhibit preferences for biochar-amended zones within the soil, potentially altering their feeding habits or substrate selection. Additionally, biochar-induced changes in nutrient availability or modifications in the quality of organic matter might influence the nutritional value of food resources for soil insects, thereby impacting their feeding behavior and resource utilization strategies [53].

8.11 Trophic interactions

Biochar amendments can influence predator-prey relationships and trophic interactions within soil ecosystems. Changes in the abundance, behavior, or distribution of predator and prey species in response to biochar application can significantly impact trophic dynamics and population regulation within soil insect communities. Studies suggest that biochar-induced alterations in soil conditions can affect the abundance or behavior of predatory insects or other predators within soil ecosystems. Changes in predator abundance or activity might influence the population sizes of prey species, potentially affecting community structure and trophic cascades. Additionally, alterations in prey populations due to biochar-induced modifications in their habitat or resources can influence the dynamics of predator-prey interactions, subsequently impacting the structure and stability of soil insect communities [54].

8.12 Microbial-driven effects

Biochar amendments can indirectly influence soil-dwelling insects through their effects on soil microbial communities. Biochar-induced modifications in soil properties, such as alterations in pH, nutrient availability, or microbial activity, can influence the composition and activity of soil microbial communities, subsequently impacting soil insects. Changes in microbial communities mediated by biochar can influence the availability of food resources, decomposition rates, or soil nutrient dynamics, indirectly affecting soil insect populations. For instance, alterations in microbial-driven processes, such as decomposition rates or organic matter breakdown, can influence the availability of substrates for soil insects, consequently shaping their abundance, behavior, or community composition [55].

9. Ecological interactions and feedback mechanisms

Ecological interactions and feedback mechanisms within soil ecosystems following biochar amendments represent a complex interplay between soil nutrient cycling, microbial dynamics, plant-insect interactions, and the broader soil food web. The application of biochar as a soil amendment exerts multifaceted influences on soil properties, subsequently impacting nutrient dynamics, microbial communities, and interactions among soil-dwelling organisms [56].

10. Biochar’s impact on soil nutrient dynamics

Biochar amendments can significantly influence soil nutrient cycling by altering several key processes. Firstly, the porous structure of biochar provides a habitat for soil microorganisms, fostering microbial activity and affecting nutrient transformations. Microbes colonizing biochar pores engage in nutrient cycling processes, potentially enhancing nutrient retention or immobilization. Secondly, biochar’s high cation exchange capacity can influence nutrient availability [57]. It can adsorb and release nutrients slowly over time, affecting their mobility and availability to plants and soil organisms. For instance, biochar can adsorb and retain cations such as potassium, calcium, and magnesium, preventing their leaching and improving their availability to plants and soil biota. Additionally, biochar can modify soil pH, albeit to varying degrees depending on feedstock and application rates. Changes in pH can influence nutrient availability, impacting the form and solubility of nutrients in soil. Alterations in soil pH resulting from biochar applications can indirectly affect nutrient uptake by plants and subsequently impact the quality and quantity of resources available to soil-dwelling insects [58].

11. Indirect effects of biochar on soil insects via nutrient cycling

The modifications in soil nutrient dynamics induced by biochar can have indirect effects on soil-dwelling insects. Soil insects, comprising a diverse range of taxa involved in decomposition, nutrient cycling, and predation, rely on soil resources for their survival and reproduction [43]. Changes in nutrient availability and cycling processes due to biochar amendments can influence the nutritional quality of food resources available to soil insects. For instance, alterations in nutrient availability can impact the quality and quantity of organic matter and microorganisms available as food sources for soil insects [59]. Changes in the nutritional content of these resources may affect the growth, reproduction, and survival of soil-dwelling insects, subsequently influencing their population dynamics within soil ecosystems. Moreover, shifts in nutrient availability and cycling processes can indirectly impact plant health and growth. Soil-dwelling insects often interact with plants, either as herbivores, pollinators, or in symbiotic relationships. Changes in plant health resulting from biochar-induced alterations in nutrient availability may influence plant-insect interactions, subsequently impacting the dynamics of soil insect populations.

11.1 Interactions between soil microbes and plants in biochar-amended soils

Interactions between soil microbes, plants, and insects within biochar-amended soils represent a complex web of ecological relationships crucial for understanding soil ecosystem functioning, nutrient cycling, and the dynamics of soil-dwelling organisms. Biochar amendments can intricately influence the interactions among these key components, shaping soil microbial communities, plant health, root exudation patterns, and subsequently impacting soil insect populations [60]. Biochar amendments can alter the structure, composition, and activities of soil microbial communities. The porous structure and high surface area of biochar provide habitats for microbial colonization and influence microbial diversity, abundance, and functional traits. Studies indicate that biochar incorporation into soils can promote the proliferation of certain microbial taxa, alter microbial community structures, and affect microbial metabolic activities. The presence of biochar in soil can create microenvironments that support microbial growth, modify soil moisture, aeration, and nutrient availability. Changes in soil physicochemical properties resulting from biochar amendments, such as alterations in pH, organic carbon content, or nutrient availability, can selectively favor certain microbial groups, influencing their activities and functions within soil ecosystems [61].

Biochar-induced alterations in soil microbial communities can impact plant health, growth, and root exudation patterns. The interactions between biochar, soil microbes, and plant roots can lead to modifications in the quality and quantity of root exudates. Changes in the rhizosphere resulting from biochar applications can influence soil microbial communities associated with plant roots, affecting nutrient cycling, disease suppression, and plant growth promotion. Additionally, biochar amendments can influence plant responses to herbivory and modify plant secondary metabolite profiles [62]. These alterations in plant defenses and responses to biotic stressors can be attributed to changes in root exudates and the rhizosphere environment, subsequently affecting plant-insect interactions within soil ecosystems. The relationships between soil microbes and soil-dwelling insects in biochar-amended soils are multifaceted. Soil insects interact with microbial communities through their feeding activities, altering microbial communities and nutrient cycling processes. The activity of soil insects can influence the decomposition rates of organic matter and the release of nutrients through fragmentation and consumption, consequently affecting microbial communities and their functions [63]. Moreover, changes in microbial-driven processes, such as decomposition rates or nutrient turnover, can indirectly influence soil insect populations by altering the availability of food resources or habitat conditions. Interactions between soil insects and microbial communities can influence the structure and functioning of soil ecosystems, with implications for nutrient cycling, organic matter decomposition, and ecosystem stability. Further research efforts should focus on unraveling the complexities of these interactions under varying environmental conditions, considering the context-dependent responses of soil microbes, plants, and insects to biochar amendments. Comprehensive assessments are crucial to elucidate the ecological implications of biochar applications and guide sustainable soil management practices for enhancing soil health and ecosystem functioning [64].

Biochar has shown promising potential as a tool for managing soil insect infestations, offering multifaceted mechanisms that contribute to mitigating infestation patterns within agricultural and natural ecosystems. Several theories and mechanisms underpin its ability to effectively control soil insect populations, thereby presenting practical implications for pest management strategies [65].

12. Biochar as a potential tool for managing soil insect infestations

The application of biochar has demonstrated notable effects in reducing soil insect populations and mitigating infestation patterns. Its properties, such as high surface area, porous structure, and physicochemical characteristics, play key roles in altering soil conditions and influencing insect populations. Biochar amendments have exhibited insecticidal properties, affecting insect behavior, development, and survival rates [66].

12.1 Mechanisms and theories behind biochar’s ability to mitigate infestations

Several mechanisms contribute to biochar’s efficacy in managing soil insect infestations. One mechanism involves the adsorption of compounds detrimental to insects, such as volatile organic compounds or toxic substances released during biochar production. These adsorptive properties may disrupt insect communication, impede feeding behavior, or deter oviposition, thereby reducing insect populations [67]. Furthermore, alterations in soil physicochemical properties induced by biochar, such as changes in pH, nutrient availability, and microbial activity, can influence insect survival and behavior. Shifts in soil pH can directly affect the survival of certain insect species, while changes in nutrient availability might impact insect nutrition, growth, and reproduction. Additionally, biochar’s effects on soil microbial communities can indirectly influence soil insect populations by modifying their food resources or altering microbial-driven processes essential for insect survival [68].

12.2 Practical implications and applications in pest management

The practical implications of biochar in pest management strategies are significant. Incorporating biochar into agricultural soils offers a sustainable and eco-friendly approach to controlling soil insect infestations. Its use aligns with integrated pest management practices, minimizing the reliance on chemical pesticides and reducing environmental risks associated with conventional pest control methods. Moreover, biochar applications present opportunities for long-term pest management by improving soil health and fostering a balanced soil ecosystem. Enhancements in soil structure, nutrient retention, and microbial activity due to biochar amendments can create conditions unfavorable for certain insect pests, thereby contributing to sustained pest suppression [69]. Implementing biochar in pest management strategies requires considerations of various factors, including biochar type, application rates, soil type, and specific pest species. Field trials and experimental studies tailored to specific agroecosystems are essential for elucidating the most effective biochar application methods and understanding the nuanced responses of different insect pests to biochar amendments [70].

13. Challenges in studying biochar-soil insect interaction

Studying the intricate interactions between biochar and soil-dwelling insects presents numerous challenges, highlighting limitations in current research while pointing toward essential future directions in understanding and applying biochar in pest management strategies [71].

One primary challenge lies in the complexity of soil ecosystems. Soil is a dynamic environment with intricate interactions between biotic and abiotic factors, making it challenging to isolate and understand the specific mechanisms through which biochar influences soil-dwelling insects [72]. The diverse responses exhibited by different insect taxa to biochar amendments add to this complexity, requiring comprehensive assessments and tailored approaches for various pest species. Moreover, the variability in biochar properties stemming from differences in feedstock, production methods, and pyrolysis conditions contributes to challenges in studying biochar-soil insect interactions. Understanding how these variations influence the effectiveness of biochar in mitigating pest infestations necessitates standardized protocols for biochar characterization and application across studies. Another challenge involves the timescale and persistence of biochar effects. Long-term studies are essential to discern the temporal dynamics of biochar-induced changes in soil properties and their sustained impacts on soil insect populations. Considering the slow release of nutrients and alterations in soil conditions due to biochar amendments, assessing its persistence and durability in affecting soil insect communities over time becomes crucial [73].

14. Limitations of current research and areas for improvement

Current research on biochar-soil insect interactions faces limitations in terms of the breadth and depth of investigations. Many studies focus on specific insect taxa or limited ecological contexts, providing a fragmented understanding of biochar’s effects on soil insect communities. Broader assessments encompassing diverse insect groups, ecosystems, and environmental conditions are necessary to elucidate generalizable patterns and mechanisms [74]. Furthermore, the majority of existing studies predominantly explore short-term effects, often overlooking the long-term implications of biochar applications on soil insect populations and ecosystem dynamics. Longitudinal studies examining the persistence of biochar-induced changes and their cascading effects on soil insect communities are critical to ascertain sustained pest management outcomes. The methodologies employed in studying biochar-soil insect interactions also warrant improvements. Integrating interdisciplinary approaches that combine ecological, biochemical, and molecular techniques could offer comprehensive insights into the underlying mechanisms driving biochar’s effects on soil insect populations. Additionally, employing advanced imaging technologies and molecular tools could enhance our understanding of the direct and indirect impacts of biochar on insect behavior, physiology, and community dynamics [75].

15. Future directions for research and practical applications

Future research endeavors should prioritize investigating context-specific responses of diverse soil insect taxa to biochar amendments. Understanding the differential responses among pest and beneficial insect species and their trophic interactions in various agricultural and ecological settings is crucial. This knowledge can guide the development of targeted biochar-based pest management strategies that minimize adverse impacts on beneficial insect populations. Long-term field trials across diverse ecosystems are imperative to assess the practical applicability and efficacy of biochar in managing soil insect infestations. Field studies spanning multiple growing seasons can offer valuable insights into the persistence of biochar effects on soil properties, insect populations, and crop performance, facilitating the development of sustainable pest management practices. Furthermore, translating research findings into practical applications necessitates collaborations between researchers, agricultural practitioners, and policymakers. Engaging stakeholders in knowledge dissemination, developing guidelines for biochar application, and integrating biochar-based pest management approaches into existing agricultural systems are essential steps toward fostering its adoption and implementation in real-world scenarios.