Molecular Entomology, 2025, Vol.16, No.1, 39-49 http://emtoscipublisher.com/index.php/me 43 pests reducing their exposure to pesticides by changing their behavior, such as some noctuids moving their feeding parts downward or hiding to avoid the spraying site; or they produce a refusal to feed or inhabit the sprayed plants. Physiological resistance includes, for example, the thickening of the epidermis reduces the penetration of the pesticide and the excretion of toxins by osmotic pumps (Gould et al., 2018). 4 Species Dynamics and Population Ecology of Herbivorous Insects in Agricultural Ecosystems 4.1 Dynamic changes in herbivorous insect populations The population dynamics of herbivorous insects are the combined result of various density-independent factors (climate, host), density-dependent factors (natural enemies, competition) and human measures (pesticides, tillage) (Ziesche et al., 2024). Typical patterns include: pests increase in warm seasons and host-abundant periods, and decrease in cold or host-deficient periods; unreasonable farming can cause pests to rebound or remain at a high level after a short decline; good ecological regulation can maintain its low-level fluctuations. Understanding these patterns helps predict and warn of pest occurrences. For example, through long-term monitoring and accumulation of data, a statistical model of pest population dynamics and key climate, crop growth period and other factors can be established to predict the peak period and degree of damage of pests in the next season (Lawton et al., 2022). Adjusting agricultural management in accordance with the laws of population ecology, such as actively suppressing insect sources during the low period of pests and protecting natural enemies in the early stage of pest rise, can more effectively stabilize the insect state in farmland and provide a basis for integrated pest management. 4.2 Impact of climate change on the dynamics of herbivorous insect species Global climate change is increasingly affecting the geographical distribution, seasonal changes and population dynamics of herbivorous insects (Hamann et al., 2021). Among them, rising temperatures, changes in precipitation patterns and frequent extreme weather events are the main climatic factors affecting pest dynamics. Rising temperatures often accelerate the development rate and reproduction cycle of insects, which may lead to an increase in the number of generations of pests and an increase in annual reproduction. Studies predict that under the background of global warming, the annual number of generations of some major pests in temperate regions (such as armyworms and cotton bollworms) can increase from 2 to 3 generations to 3 to 4 generations, significantly increasing their cumulative population size (Deutsch et al., 2018). Changes in precipitation and humidity also have a significant effect on pest dynamics. Changes in precipitation patterns may affect the overwintering survival and reproduction of pests. For example, in areas with warm winters and heavy rains, pests are more likely to survive the winter, and the initial population density in the early spring of the following year is relatively high, causing early season damage (Lawton et al., 2022). The increase in extreme weather events (such as heat waves, droughts, heavy rains, and cold waves) also has complex effects on pest dynamics. Heat waves may cause large-scale deaths of pests and temporarily suppress the population, but if some individuals adapt to high temperatures and survive, the surviving population may have a stronger tolerance to high temperatures, that is, "selection screening" (Cusumano et al., 2019). In addition, climate change can also change local species dynamics by driving biological invasions. 4.3 Monitoring and prediction methods for the dynamics of herbivorous insect species Accurate monitoring and prediction of the population dynamics of herbivorous insects is the basis for effective pest early warning and control. Traditional field monitoring methods include: fixed-point surveys, light trapping, sex attractant trapping, yellow board trapping, field retrieval, etc. These methods are easy to operate and low-cost, and are still the main means of routine pest monitoring in the agricultural sector. In recent years, modern technology has been increasingly used in pest monitoring, improving monitoring efficiency and accuracy. Among them, remote sensing technology and Internet of Things monitoring are the most representative progress. Remote sensing monitoring uses high-altitude satellites, drones or aerial cameras to capture the growth and damage characteristics of crops over a large area, thereby inferring the occurrence of pests (Figure 2) (Mpisane et al., 2025).
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