Molecular Entomology, 2025, Vol.16, No.1, 39-49 http://emtoscipublisher.com/index.php/me 42 The nutritional adaptation of herbivorous insects in morphology and behavior is also very obvious. For example, many borers (stem borers, weevils) have evolved hard jaws and specialized digestive tracts to destroy and digest harder tissues in the wood or seeds; pin-mouthed insects are adapted to piercing nutrition, and their saliva contains enzymes to help prevent sieve tube blockage and keep plant nutrients flowing (Dofuor et al., 2024). In addition, some insects co-evolve with symbiotic microorganisms to supplement nutritional adaptability. Symbiotic bacteria in the intestines of locusts and termites can help decompose cellulose; symbiotic bacteria in aphids synthesize essential amino acids to make up for the imbalance of plant sap nutrition (Horgan, 2024). On an evolutionary time scale, the evolution of the host range of herbivorous insects reflects the trade-offs of nutritional adaptation. Some lineages have chosen a specialized strategy, deeply adapted to the nutritional environment of a single crop, and are highly competitive on this host (e.g., the codling moth is almost exclusively inhabiting apples and related fruit trees); other lineages have adopted a broad-spectrum feeding strategy, acquiring the ability to process a variety of plant secondary metabolites through gene duplication and functional differentiation (Crossley et al., 2021). 3.2 Behavioral and sensory adaptations In order to find host plants and escape natural enemies and environmental stresses in complex agricultural environments, herbivorous insects have evolved a variety of behavioral and sensory adaptations. These adaptations ensure that pests can effectively complete feeding and reproduction, reflecting the evolutionary adjustment of insects to agricultural ecology from a behavioral ecology perspective. Herbivorous insects have sophisticated host location and selection behavioral adaptations. This relies on their highly sensitive sensory systems, such as smell, vision, and touch. Many insects have a large number of olfactory receptors distributed on their antennae, which can detect plant volatile organic compounds and identify suitable host species from a distance. Herbivorous insects have evolved a variety of feeding behavior adaptations to circumvent plant defenses and improve feeding efficiency. Some pests adopt a secret feeding method, such as leaf miners and braconid wasp larvae that sneak into the leaf tissue to obtain stable nutrition while avoiding natural enemies and adverse environments. Another example is nocturnal feeding behavior: many Lepidoptera larvae hide during the day and come out to feed at night to avoid predatory natural enemies during the day and high temperature and dry environment (Lawton et al., 2022). Adaptability is also reflected in reproductive and developmental behavior. Oviposition site selection is a key behavior of herbivorous insects to ensure that their offspring can obtain suitable nutrition. In addition, in some insects, clustering helps to enhance resistance to natural enemies or improve the microenvironment. For example, aphids secrete warning pheromones, and other aphids quickly escape when their companions are attacked by predators (Wyckhuys et al., 2024). 3.3 Adaptation and evolution of pesticide resistance The large-scale application of pesticides has exerted strong selection pressure on herbivorous insect populations, prompting them to develop resistance in a relatively short period of time. This is one of the most interesting areas in the study of evolutionary adaptation of herbivorous insects. Pesticide resistance adaptation and evolution are specifically manifested in the reduced sensitivity of pests to the toxicity of pesticides, so that they can still survive and reproduce at field concentrations (Gould et al., 2018). The evolutionary mechanisms of insect resistance are diverse, mainly including target site mutations, metabolic resistance, and behavioral and physiological resistance. Many chemical pesticides work by acting on key proteins in the insect nervous system or development process, such as organophosphates and carbamates inhibiting acetylcholinesterase, pyrethroids acting on voltage-gated sodium ion channels, and Bt toxins needing to bind to midgut receptors to exert toxicity. Metabolic resistance means that insects quickly detoxify and eliminate pesticides by enhancing the activity of metabolic enzymes in the body. This usually involves the upregulation or amplification of the expression of multiple genes, especially detoxification enzyme genes, such as P450 monooxygenase, carboxylesterase and glutathione-S-transferase (Guy et al., 2017; Schwander et al., 2019; Crossley et al., 2021; Lin et al., 2024). Behavioral resistance refers to the
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