Interaction Scenario of Insects, Plants, and Mycorrhizal Fungi

V.K. Mishra, Usha, Umesh Pankaj, and M. Soniya

Introduction

Insects are programmed to recognize and rapidly respond to patterns of host cues. Particularly, specialist insect species have to find specific plant species on which they can feed and reproduce (host plants). Some plant species do not support feeding and/ or reproduction of insects (non-host plants). Thus, in an environment with a changing availability and quality of host plants, phytophagous insects are under selection pressure to find quality hosts. To maximize their fitness, they need to locate suitable plants and avoid unsuitable hosts. Thus, they have evolved a finely tuned sensory system for the detection of host cues, and a nervous system capable of integrating inputs from sensory neurons with a high level of spatio-temporal resolution time and space, which also influence plant responses to insects. The time dimensions are of major significance, since whether or not odors arrive simultaneously at the antenna can change the type of behavioral response elicited in the insect. The huge number of species of flowering plants on our planet (approximately 275,000) is thought to be the result of adaptive radiation driven by the coevolution between plants and their beneficial animal pollinators (Yuan et al. 2013). The fossil record shows that pollination originated 250 million years ago (Labandeira 2013). Some plants have evolved with their pollinators and produce olfactory messages which make them unique for their specific pollinators (Grajales-Conesa et al. 2011). For example, certain orchid flowers mimic aphid alarm pheromones to attract hoverflies for pollination (Stoekl et al. 2011). Furthermore, insect herbivores can drive real-time ecological and evolutionary change in plant populations. Recent studies provide evidence for the rapid evolution of plant traits that confer resistance to herbivores when herbivores are present but the evolution of traits confer increased competitive ability when herbivores are absent (Agrawal et al. 2012; Ziist et al. 2012). While phytophagous insects have been adapting to exploit their hosts, the plants have simultaneously been evolving defensive systems to counteract herbivore attack (Anderson and Mitchell-Olds 2011; Johnson 2011). The evolutionary development of the tremendous variety of insects that we are able to see today is from the fossil record. From this, we can speculate that the earliest insects were wingless, Thysanura-like forms that abounded in the Silurian and Devonian periods. The major advance made by their descendants was the evolution of wings, facilitating dispersal and, therefore, colonization of new habitats. During the Carboniferous and Permian periods, there was a massive adaptive radiation of winged forms, and it was at this time that most modern orders had their beginnings. Although members of many of these orders retained a life history similar to that of their wingless ancestors, in which the change from juvenile to adult form was gradual (hemimetabolous or exopterygote), in other orders a life history evolved in which the juvenile and adult phases were separated by a pupal stage (holometabolous or endopterygote). The great advantage of having a pupal stage is that the juvenile and adult stages can become very different from each other in their habits, thereby avoiding competition for the same resources. The insects and mycor- rhizal fungi interact with one another in complex ways that are beneficial to fungi, insects, and host plants (Gehring and Whitham 2002; Gange and Bower 1997; Gange 2007). There is a need to place insects, mycorrhizal fungi, and their host plants into a broader community context that includes other interactions; and potential for the mediation of interactions between insects and mycorrhizal fungi by fungus species or host plant.

Interaction between Plants and Insects

It is a well-known fact that plants and insects have coexisted together for about 4 million years. This has resulted in the development of certain offensive and defensive strategies by both plants and insects for their existence. In the natural ecosystem, the survival of plants through the evolutionary time is mainly due to their own defense mechanism which deters the feeding of herbivores. Moreover, plants also have the capacity to either tolerate or escape attack. On the other hand, with regards to insects, their selective ability, such as mechanical adaptations, detoxification, sequestration, host manipulation, association with microorganisms, and avoidance enables them to overcome these plant defense mechanisms and continue feeding.

In natural ecosystems, phytophagous insects have coexisted in a complex relationship with plant communities. Different species of plant-feeding insects had to seek out their host plants from the mixed wild vegetation. For this purpose, insects made use of various types of olfactory stimuli which work from long distances and taste stimuli which work in the vicinity of the host plants. In this search, they

Tri-trophic interaction between plant, herbivores, and natural enemies

FIGURE 12.1 Tri-trophic interaction between plant, herbivores, and natural enemies.

had to face the dangers of annihilation from various climatic and biotic agencies. Therefore, the damage caused by insects was probably quite limited. Pest problems originated with the origin of agriculture. As soon as the land was cleared of natural vegetation and replaced by a single species of food plant, humans came into conflict with phytophagous insects. These insects and other organisms feeding on the valuable crops which humans planted were called “pests”. Not only did the insect pests originate with agriculture, but the intensity of pests continued to increase with the intensification of agriculture.

The evolution of land plants (especially flowering plants) are a major force driving the diversity of insects. As the diversity of land plants has increased, the diversity of insects has also risen. Interaction between plants and insects is an example of coevolution (Figure 12.1). Co-evolution can occur between: a single plant and a single insect, or a single plant and a group of insects, or a group of insects, and a group of closely related plants. Interactions are often examined from the plant’s perspective. Insect-plant interaction can occur in one of two ways, depending on whether the interaction is beneficial to both parties (mutualism) or is beneficial to insects but harmful to plants (herbivory). Phytophagous insects have coexisted in a complex relationship with plant communities.

Interaction between Fungi, Insects, and Plants

The majority of mycorrhizal fungi, plants, and insect studies have focused on insect herbivores and observed many ways in which mycorrhizal fungi can influence the

Interaction among herbivores/pollinator, ecto-mycorrhiza, and arbuscular- mycorrhizal fungi on common host plant

FIGURE 12.2 Interaction among herbivores/pollinator, ecto-mycorrhiza, and arbuscular- mycorrhizal fungi on common host plant.

interaction between plants and their herbivores (Figure 12.2). Both ecto-mycorrhizal (EM) and arbuscular mycorrhizal (AM) fungi have been shown to increase plant size and alter plant quality through changes in nutrient content (Smith and Read 1997). Mycorrhizal fungi may also alter plant-herbivore interactions through changes in constitutive and inducible defenses as well as tolerance to herbivory (Bennett et al. 2006). There are a growing number of studies focused on the indirect effects of EM and AM fungi on plant herbivores with the following basic protocol: plants are grown with a single mycorrhizal fungal species (for AM fungal studies, species are most commonly from the genus Glomus) and subjected to herbivory (often by a single herbivore species), and various traits (herbivore survival or growth, plant chemical content, or plant tolerance to herbivory) are measured and compared with control plants not inoculated with mycorrhizal fungi. However, this narrow glimpse into the role of mycorrhizal fungi in plant-herbivore interactions has largely ignored the variation in the ecology of mycorrhizal fungal species (Hart and Reader 2002,2005; Klironomos 2003; Karst et al. 2008; Singh et al. 2018, 2017a, b, c; 2019; Tiwari et al. 2018, 2019a, b; Kour et al. 2019a). Species of mycorrhizal fungi can vary greatly (from parasitic to mutualistic) in the benefit they provide to hosts (Klironomos 2003; Karst et al. 2008), and in AM fungi, variation in host growth benefit is thought to derive from variation in colonization or competitive ability in host roots (Hart and Reader 2002).

Mutualistic Co-Evolution

• In mutualistic co-evolution, the two parties evolve in such a way to enhance the effectiveness of the interaction.

  • • This type of co-evolution is common in interactions between plants and their insect pollinators, as well as in some other specialized cases.
  • • The relationship between plant and their insect pollinators are mutualistic in which the plants provide sugar or amino acid-rich nectar and pollen to insects and insects, in turn assisting the plants by transmitting the male gametes to the female flowers (cross-pollination).
  • • If the co-evolution is “extreme” enough, the two partners may become completely dependent on each other (obligate mutualism like ants and Acacia). Many species of plants in the genus Acacia have mutualistic ants of the genus Pseudomyrmex associated with them. Ants prevent herbivores from feeding on plants by killing them or chasing them off. Ants also remove any other plants growing nearby or on “their” Acacia (which decreases competition). On the other hand, plants provide a safe home to ants (ants live in the trunk, and enter by chewing through the large hollow thorns). It also provides two food sources: (a) extra floral nectarines, and (b) Beltian bodies which are high in proteins (Magallon and Sanderson 2001).
  • Effects of obligate mutualism: Effects of ant removal on Acacia. When ants were removed and kept off Acacia plants, the growth rate of ants decreased dramatically due to the unavailability of food resources. The number of herbivorous insects increased dramatically; as a result, survival of the plant over the course of a year declined drastically.

A Detailed Study of Figure and Figure Wasp, Blastophaga Psenes (Agaonitae: Hymenoptera) Mutualism

Fig is pollinated by fig wasp only. There is no other mode of pollination. There are two types of fig, caprifig and Symrnafig. (i) Caprifig: (a) is a wild type of fig, i.e. not edible; (b) it has both male and female flowers; (c) pollen is produced in plenty; and (d) it is the natural host of the fig wasp, (ii) Symrnafig: (a) is the cultivated type of fig, i.e. edible; (b) it has only female flowers; (c) pollen is not produced; and (d) it is not the natural host of the fig wasp.

  • • Fig wasp: male - wingless, present in caprifig; and female - winged.
  • • Female wasp lays eggs in caprifig, larvae develop in galls in the base of the flowers.
  • • Male mates with female even when the female is inside the gall.
  • • Mated female wasp emerges out of flower (caprifig) with a lot of pollen dusted around its body.
  • • The female fig wasp enters Symrnafig with lot of pollen and deposits it on the stigma.
  • • It cannot oviposit in the ovary of Symrnafig which is deep-seated.
  • • It again moves to caprifig for egg-laying. In this process, Symrnafig is pollinated.
  • • Caprifig will be planted next to Symrnafig to aid in pollination.

Herbivores and Herbivory: A Negative Interaction

Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based food, principally autotrophs such as plants, algae, and photosynthesizing bacteria. Herbivory is the act of feeding by herbivores. Examples of herbivores are: mammals, birds (parakeet, parrot, scarlet, goose, etc.), reptiles like tortoise, invertebrates like insects (grass hoppers, butterflies, leaf hoppers, tree hoppers, aphids, caterpillars, etc.), or other invertebrates like garden snails, earthworms, etc. Herbivores form an important link in the food chain. Insect-eating plants are referred to as phytophagous species. Phytophagous insects may be monophagous, oligophagous or polyphagous.

Categories of Phytophagous Insects

  • • Leaf chewers (caterpillars, coleopterans, and orthopterans)
  • • Plant miners and plant borers (larvae of dipterans and lepidopterans)
  • • Sap suckers (hemipterans)
  • • Seed feeders (harvester ants, coleopterans, and dipterans)
  • • Nectar or pollen feeders (hymenopterans, lepidopterans, coleopterans, dipterans, and thysanopterans)
  • • Gall formers (hemipterans, dipterans, or hymenopterans)

Plant Defense against Herbivory

  • • Plant defense is a trait which increases survival and/or reproduction (fitness) of plants under pressure of consumption by herbivores.
  • • Defense can be divided into two main categories, i.e. tolerance and resistance.
  • • Tolerance is the ability of a plant to withstand damage without a reduction in fitness.
  • • Resistance is the ability of a plant to reduce the amount of damage caused by herbivores and can occur by avoiding space and time (Milchunas and Noy-Meir 2002).
  • • Defenses can either be constitutive, i.e. always present in the plant or induced i.e. produced or translocated by the plant following damage or stress (Edwards and Wratten 1985; Nishida 2002).
  • • Mechanisms of plant defenses are given below:
    • 1. Physical defenses (mechanical defenses) - These are the physical structures that act as barriers against herbivores. For example, thorns found on roses, acacia trees, spines on cactuses, small hair-like structure known as trichomes may cover leaves or stems and are especially effective against invertebrate herbivores.
    • 2. Chemical defenses - These are due to secondary metabolites produced by the plant that deter herbivores (Tilmon 2008).
  • - Plants normally maintain a baseline level of metabolites. Plants respond to insect damage by releasing a range of volatiles from the damaged site. These volatiles attract parasitoids and predators to the plant under attack. Parasitoids and predators pick up these biochemical cues with the help of specific receptors present in their antenna. Each host plant-insect pest pair is believed to release a range of different and combination specific volatiles (Rashid et al. 2012).
  • - The adaptation dance - The back and forth relationship of plant defense and herbivore offense can be seen as a sort of “adaptation dance” in which one partner makes a move and the other counters it (Karban and Agrawal 2002). This reciprocal change drives coevolution between many plants and herbivores, resulting in a “co- evolutionary arms race” (Mead et al. 1985).

Molecular Basis of Insect–Plant Interactions

  • • The ultimate goal of ecology is to understand how the traits of an individual contribute to its fitness in terms of reproductive success.
  • • This was investigated by comparing the performance of individuals or populations that differed in certain traits without (much) information on the underlying mechanisms and genes.
  • • Recent developments in molecular genetics have opened stimulating new avenues for ecologists through a molecular genetic approach.
  • • With the sequencing of plant genomes and the availability of well-characterized mutants and genetically modified traits that mediate interactions between plants and their biotic community members, ecologists can now address the ecological function of individual traits in very precise ways (Dicke 2004).

Conclusion

Thus it can be concluded that there exists an interaction between plants and insects. Insects play one of the most important roles in their ecosystems, which include many roles, such as soil turning and aeration, dung burial, pest control, pollination, and wildlife nutrition. This has resulted in the development of certain offensive and defensive strategies by both plants and insects for their existence. The evolution of land plants (especially flowering plants) is a major force driving the diversity of insects. With the increase in diversity of land plants, the diversity of insects has also increased. Interaction between plants and insects is an example of coevolution. Insect-plant interaction can occur in one of two ways, depending on whether the interaction is beneficial to both parties (mutualism) or is beneficial to insects but harmful to plants (herbivory). Insects play one of the most important roles in their ecosystems, which include many roles, such as soil turning and aeration, dung burial, pest control, pollination, and wildlife nutrition.

Interactions among insect-mycorrhizal fungus-plant have shown great community perspective in both above and below ground in a natural habitat with a complex community of organisms. However, research conducted under an isolated environment may not represent the whole story of these interactions (insects, plants, and mycorrhizal fungi). Further research is needed on the mechanisms of insect-plant- mycorrhizal fungal interactions, thereby enabling predictions as to their place in an evolutionary context.

References

Agrawal, A.A., Hastings, A.P., Johnson, M.T., Maron, J.L., Salminen, J.P. 2012. Insect herbivores drive real-time ecological and evolutionary change in plant populations. Science 338:113-116.

Anderson, J.T., Mitchell-Olds, T. 2011. Ecological genetics and genomics of plant defences: Evidence and approaches. Functional Ecology 25:312-324.

Bennett, A.E., Alers-Garcia, J., Bever, J.D. 2006. Three way interactions among mutualistic mycorrhizal fungi, plants, and plant enemies: Hypotheses and synthesis. The American Naturalist 167:141-152.

Dicke, A.E. 2004. Nutritional interactions in insect-microbial symbioses: Aphids and their symbiotic bacteria Buchnera. Annual Review of Entomology 43:17-37.

Edwards, P.J., Wratten, S.D. 1985. Induced plant defences against grazing: Fact or artefact? Oikos 44:70-74.

Gange, A.C. 2007. Insect-mycorrhizal interactions: Patterns, processes, and consequences. In: T. Ohgushi, T.P. Craig, P.W. Price (Eds.), Ecological Communities: Plant Mediation in Indirect Interaction Webs. London, United Kingdom: Cambridge University Press, pp. 124-143.

Gange, A.C., Bower, E. 1997. Interactions between insects and mycorrhizal fungi. In: A.C. Gange, V.K. Brown (Eds.), Multitrophic Interactions in Terrestrial Systems. Oxford, United Kingdom: Blackwell, pp. 115-132.

Gehring, C.A., Whitham, T.G. 2002. Mycorrhizae herbivore interactions: Population and community consequences. In: M.G. A. van der Heijden, I.R. Sanders (Eds.), Mycorrhizal Ecology. Berlin, Germany: Springer, pp. 295-320.

Grajales-Conesa, J.. Melendez-Ramirez, V.. Cruz-Lopez, L. 2011. Floral scents their interaction with insect pollinators. Revista Mexicana De Biodiversidad 82:1356-1367.

Hart, M.M., Reader, R.J. 2002. Taxonomic basis for variation in the colonization strategy of arbuscular mycorrhizal fungi. New Phytologist 153:335-344.

Hart, M.M., Reader, R.J. 2005. The role of the external mycelium in early colonization for three arbuscular mycorrhizal fungal species with different colonization strategies. Pedobiologia 49:269-279.

Johnson, M.T.J. 2011. Evolutionary ecology of plant defences against herbivores. Functional Ecology 25:305-311.

Karban, R., Agrawal, A.A. 2002. Herbivore offense. Annual Review of Ecology and Systematics 33:641-664.

Karst, J., Marczak, L., Jones, M.D., Turkington, R. 2008. The mutualism-parasitism continuum in ectomycorrhizas: A quantitative assessment using meta-analysis. Ecology 89:1032-1042.

Klironomos, J.N. 2003. Variation in plant response to native and exotic arbuscular mycorrhizal fungi. Ecology 84:2292-2301.

Kour, D.. Rana, K.L., Yadav, N.. Yadav, A.N., Rastegari, A.A., Singh. C.. Negi, R. Singh. K., Saxena, A.K. 2019a. Technologies for biofuel production: Current development, challenges, and future prospects. In: A. A. Rastegari et al. (Eds.), Prospects of Renewable Bioprocessing in Future Energy Systems, Biofuel and Biorefinery Technologies, Vol. 10. Berlin: Springer, pp. 1-50.

Labandeira, C.C. 2013. A paleobiologic perspective on plant-insect interactions. Current Opinion in Plant Biology 16:414-421.

Magallon, S., Sanderson, M.J. 2001. Absolute diversification rates in angiosperm clades. Evolution 55:1762-1780.

Mead, R.J., Oliver, A.J., King, D.R., Hubach, PH. 1985. The co-evolutionary role of fluoroac- etate in plant-animal interactions in Australia. Oikos 44:55-60.

Milchunas, D.G., Noy-Meir, I. 2002. Grazing refuge, external avoidance of herbivory and plant diversity. Oikos 99:113-130.

Nishida, R. 2002. Sequestration of defensive substances from plants by Lepidoptera. Annual Review of Entomology 47:57-92.

Rashid, A., Dicke, M., Van Poecke, RM.P. 2012. Mechanisms of plant defense against insect herbivores. Plant Signaling and Behavior 7:1306-1320.

Singh, C., Tiwari, S., Boudh, S., Singh, J.S. 2017a. Biochar application in management of paddy crop production and methane mitigation. In: J.S. Singh, G. Seneviratne (Eds.), Agro-Environmental Sustainability: Managing Environmental Pollution, 2nd ed. Switzerland: Springer, pp. 123-146.

Singh, C„ Tiwari, S.. Gupta. V.K.. Singh, J.S. 2018. The effect of rice husk biochar on soil nutrient status, microbial biomass and paddy productivity of nutrient poor agriculture soils. Catena 171:485-493.

Singh, C., Tiwari, S., Singh, J.S. 2017b. Impact of rice husk biochar on nitrogen mineralization and methanotrophs community dynamics in paddy soil. International Journal of Pure and Applied Bioscience 5:428-435.

Singh, C., Tiwari, S., Singh, J.S. 2017c. Application of biochar in soil fertility and environmental management: A review. Bulletin of Environment, Pharmacology and Life Sciences 6:07-14.

Singh, C., Tiwari, S., Singh, J.S. 2019. Biochar: A sustainable tool in soil 2 pollutant bioremediation. In: R.N. Bharagava, G. Saxena (Eds.), Bioremediation of Industrial Waste for Environmental Safety. Berlin: Springer, pp. 475-494.

Smith, S.E., Read, D.J. 1997. Mycorrhizal Symbiosis, 2nd ed. London, United Kingdom: Academic.

Stoekl, J., Brodmann, J., Dafni, A., Ayasse, M., Hansson, B.S. 2011. Smells like aphids: Orchid flowers mimic aphid alarm pheromones to attract hoverflies for pollination. Proceedings of the Royal Society B: Biological Sciences 278:1216-1222.

Tilmon, K.J. (Ed). 2008. Specialization, Speciation, and Radiation: The Evolutionary Biology of Herbivorous Insects. USA: Univ. California.

Tiwari, S„ Singh, C., Boudh, S.. Rai, P.K., Gupta. V.K.. Singh. J.S. 2019a. Land use change: A key ecological disturbance declines soil microbial biomass in dry tropical uplands. Journal of Environmental Management 242:1-10.

Tiwari, S., Singh, C., Singh, J.S. 2018. Land use changes: A key ecological driver regulating methanotrophs abundance in upland soils. Energy, Ecology, and the Environment 3(6):355—371.

Tiwari, S., Singh, C., Singh, J.S. 2019b. Wetlands: A major natural source responsible for methane emission. In: A.K. Upadhyay et al. (Eds.), Restoration of Wetland Ecosystem: A Trajectory Towards a Sustainable Environment. Berlin: Springer, pp. 59-74.

Yuan, Y.W., Byers, K.J.R.P.. Bradshaw. J.R.H.D. 2013. The genetic control of flower-pollinator specificity. Current Opinion in Plant Biology 16:422-428.

Ziist, T., Heichinger, C., Grossniklaus, U„ Harrington, R., Kliebenstein, D.J., Turnbull,

L.A. 2012. Natural enemies drive geographic variation in plant defenses. Science 338:116-119.

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