Molecular Entomology, 2025, Vol.16, No.1, 11-18 http://emtoscipublisher.com/index.php/me 15 that of females is relatively smooth and lighter in color (Figure 2). This method is simple and intuitive, and can be used as an effective sex recognition tool before adult emergence (Chowdary et al., 2024). Figure 2 Male and female Spodoptera liturapupae In comparison, other characteristics such as weight, volume, and body color did not exhibit stable gender differentiation in this experiment, and further larger sample sizes and statistical validation are required. Related studies have also pointed out that the morphology of reproductive organs is one of the most accurate methods for distinguishing between male and female Spodoptera litura, particularly in the late larval or pupal stages (Chen et al., 2010). This technique has been widely applied in artificial breeding and mating experiments for other insects such as the cabbage white butterfly and cotton bollworm, improving experimental efficiency and data reliability (Sun et al., 2010). 3.3 larval feeding preference Observation shows that the newly hatched larvae are black in color and prefer to live in groups. They concentrate on feeding on leaf flesh near the egg mass and mainly stay on the back of soybean leaves, forming irregular transparent patches. As the insect age increases, feeding behavior tends to disperse. Middle and older larvae can fully feed on whole leaves and even invade pods and tender stems. From this, it can be seen that the Spodoptera litura has extremely strong feeding adaptability and plant destruction ability (Abbas et al., 2025). Spodoptera litura exhibits significant dietary advantages in leguminous, cruciferous, and solanaceous crops, with a particular preference for protein rich leaf tissues (Di et al., 2021). In high-density populations, its damage to the same plant can quickly spread to pods or even roots, causing serious impacts on yield. Yang et al. (2009) also suggested that "behavioral interference" could be introduced during the field stage by planting low-preference plants, which could slow down the damage rate, in combination with inducing plants or biopesticides for control. 3.4 Larval shyness and aggressive behavior The behavioral characteristics of Spodoptera litura larvae vary at different stages of their age (Li et al., 2021). After being startled, the first instar larvae often quickly scatter and run away or spin silk and fall, showing a "startle response". Older larvae shrink into a ball and pretend to be dead, falling to the ground while spitting out bodily fluids. This is a defensive behavior of pretending to be dead. However, under high-density rearing or food shortage conditions, frequent cannibalistic behaviors among larvae were observed, with even pupae being attacked. This behavior suggests that when space is limited and resources are scarce, the larvae become more aggressive and territorial, showing a strong territorial instinct (Wen et al., 2025). Such cannibalistic behavior leads to decreased survival and pupation rates. Wen et al. (2022) found that Spodoptera litura larvae became more aggressive under high-density rearing due to food scarcity and cramped space. To improve artificial rearing efficiency, Tu et al. (2010) recommended that after the third instar, larvae should be managed individually in separate containers and provided with enough food, which can reduce mortality and alleviate larval stress.
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