International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.2, 91-100 http://ecoevopublisher.com/index.php/ijmec 94 genus Diaporthe is the most common. The confirmed major pathogens include Diaporthe biconispora, Diaporthe sapindicola, Diaporthe eres and Diaporthe unshiuensis. They were identified as important pathogenic factors of leaf spot disease in China (Si et al., 2020; Si et al., 2021; Si et al., 2022. These fungi can form conidia, which are often identified by morphology combined with phylogenetic analysis and confirmed by pathogenicity assay (Si et al., 2021; Si et al., 2022. In addition to fungi, there are also insect hazards. The melon fly (Bactrocera cucurbitae) is one of the important pests and causes significant damage. Sapindus mukorossi seeds contain bioactive trypsin inhibitors, which can inhibit their growth and development and have potential control effects (Samiksha et al., 2019). Meanwhile, the extract of Sapindus mukorossi has molluscidal activity against Pomacea canaliculata, showing application prospects in pest management (Huang et al., 2003). 2.2 Symptoms and damage caused by pests and diseases inSapindus mukorossi Leaf spot disease often starts with the appearance of small yellow spots on the leaves. Subsequently, the spots gradually darken to a dark brown color, with clear or irregular edges. Such symptoms suggest that the plants have been infected by the Diaporthe pathogen, which not only affects the health of the plants but also damages their ornamental value (Figure 1) (Si et al., 2020; Si et al., 2021; Si et al., 2022. The related lesions not only have impaired appearance, but also have decreased medicinal value (Si et al., 2020). Figure 1 Symptoms on diseased leaves infected naturally (Adopted from Si et al., 2022) Image caption: A and B, Diseased leaves of Sapindus mukorossi infected naturally; C, pycnidia on the leaf lesion (Adopted from Si et al., 2022) In terms of pests, the larvae of the melon fly feed, causing tissue damage, making the fruit or tender parts vulnerable to damage. Studies have shown that trypsin inhibitors in Sapindus mukorossi seeds can down-regulate key digestive enzymes in pests, thereby reducing damage. In addition, saponins contained in plants can effectively control mollusks such as golden-threaded snails; otherwise, they may cause serious damage to crops (Huang et al., 2003; Samiksha et al., 2019. 2.3 The impact on yield and quality of Sapindus mukorossi Leaf spot disease caused by the genus Diaporthe significantly weakens photosynthetic efficiency, resulting in growth restriction, reduced yield, and thereby affecting commercial quality (Si et al., 2020; Si et al., 2021; Si et al., 2022. The ornamental value and medicinal value decreased simultaneously, thus the commercial feasibility was frustrated (Si et al., 2020). Pest infestation, especially the damage caused by fruit flies in pumpkins, will further amplify the yield reduction effect. The feeding of larvae reduces the vitality of the plant and damages the overall health of the plant. The utilization of bioactive components in Sapindus nutans, such as trypsin inhibitors and saponins, is expected to achieve effective control, thereby maintaining quality and alleviating yield loss (Huang et al., 2003; Samiksha et al., 2019.
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