Ecological turmoil in evolutionary dynamics of plant–insect interactions: defense to offence

Abstract

Available history manifests contemporary diversity that exists in plant-insect interactions. A radical thinking is necessary for developing strategies that can co-opt natural insect-plant mutualism, ecology and environmental safety for crop protection since current agricultural practices can reduce species richness and evenness. The global environmental changes, such as increased temperature, CO₂ and ozone levels, biological invasions, land-use change and habitat fragmentation together play a significant role in re-shaping the plant-insect multi-trophic interactions. Diverse natural products need to be studied and explored for their biological functions as insect pest control agents. In order to assure the success of an integrated pest management strategy, human activities need to be harmonized to minimize the global climate changes. Plant-insect interaction is one of the most primitive and co-evolved associations, often influenced by surrounding changes. In this review, we account the persistence and evolution of plant-insect interactions, with particular focus on the effect of climate change and human interference on these interactions. Plants and insects have been maintaining their existence through a mutual service-resource relationship while defending themselves. We provide a comprehensive catalog of various defense strategies employed by the plants and/or insects. Furthermore, several important factors such as accelerated diversification, imbalance in the mutualism, and chemical arms race between plants and insects as indirect consequences of human practices are highlighted. Inappropriate implementation of several modern agricultural practices has resulted in (i) endangered mutualisms, (ii) pest status and resistance in insects and (iii) ecological instability. Moreover, altered environmental conditions eventually triggered the resetting of plant-insect interactions. Hence, multitrophic approaches that can harmonize human activities and minimize their interference in native plant-insect interactions are needed to maintain natural balance between the existence of plants and insects.

Tissue-specific transcription of proteases and nucleases across the accessory salivary gland, principal salivary gland and gut of Nezara viridula

“…Trypsins are known to play a significant role in the downstream activation and regulation of other proteases in insects (Barillas-Mury et al, 1995;Lehane et al, 1996). In addition to providing efficient protein degradation, the trypsin complex also contributes to an adaptive advantage for insects feeding on plants such as soybean that produce trypsin inhibitors in defense against herbivores (Bown et al, 1997;Mishra et al, 2015;Zhu-Salzman and Zeng, 2015). The impact of host plant on the digestive enzymes of N. viridula is a question that is now ripe for investigation.…”

Integrated Transcriptomic and Proteomic Analyses Suggest the Participation of Endogenous Protease Inhibitors in the Regulation of Protease Gene Expression in Helicoverpa armigera

“…Adaptations of insects to a variety of plant compounds are partly attributed to their ability to breakdown or eliminate different phytotoxins (1). Although plants produce various antifeedants and insecticidal molecules to deter insects from feeding on them, insects are known to overcome these using various specialized mechanisms (1,2). For instance, plant defensive protease inhibitors (PIs) 1 interfere with the insect protein digestion whereas insects counteract by producing battery of digestive proteases with wide specificity.…”

“…In general, three adaptive mechanisms, to counter ingestion of plant PIs have been prominently observed in insects. These include, (1) overproduction of proteases so that the concentration of PIs would be insufficient to inhibit proteolytic activity (5,6), (2) incorporation of change in the PI binding site of the protease to make it PI insensitive (4,6), and (3) expression of proteases that can recognize the cleavage site in the PIs and degrade them (3). Insects also overexpress protease from one class to compensate with the inhibition of another class (8).…”

Capsicum annuum proteinase inhibitor ingestion negatively impacts the growth of sorghum pest Chilo partellus and promotes differential protease expression

“…Use of PIs for crop protection through various methods has been demonstrated as a sustainable pest control strategy [18] , [19] , [20] , [21] , [22] . In particular, non-host plants PIs have been found to be effective against many insect pests including H. armigera [23] , [24] , [25] , [26] , [27] , [28] .…”