Abstract:

【Objective】This study aimed to identify the species composition and population dynamics of major pests in the main cowpea-producing areas of Hainan, and to evaluate the effects of different planting patterns and cultivation managements on the pest community structure, thus providing a theoretical basis for developing precise control strategies. 【Method】Systematic investigations were conducted on the pest species and dominant pests on cowpeas during the winter-spring seasons from 2020 to 2025 in Hainan cowpea planting areas, using plant visual inspection and colored sticky trap methods. The population dynamics of pests were compared under different management practices (non-pesticide-treated and conventionally pesticide-treated) and different cultivation modes (open-field, semi-enclosed, and fully-enclosed). 【Result】(1) A total of 16 pest species infesting cowpea were identified in Hainan Province, which belonged to 6 orders, 9 families. In non-pesticide-treated cowpea fields, a higher diversity of pests was observed (6 orders, 9 families, 16 species), with the dominant species being Megalurothrips usitatus, Frankliniella intonsa, Liriomyza trifolii, Spodoptera exigua, and Aphis craccivora. In contrast, conventional pesticide-treated fields exhibited reduced pest diversity (4 orders, 5 families, 10 species), with thrips and leafminers remaining as the predominant pests. (2) Regardless of pesticide application, thrips and leafminers were present throughout the entire cowpea growth cycle. Thrips populations were significantly higher, showing low numbers at the seedling stage, a continuous increase during vine elongation, and multiple population peaks during the flowering stage coinciding with bloom. Leafminers were abundant from January to March in 2021, but caused only sporadic damage during 2024-2025. (3) Under both open-field and semi-enclosed planting modes, the pest species composition was similar, primarily consisting of thrips and leafminers, with M. usitatus as the dominant thrips species and L. trifolii as the dominant leafminer species. Thrips outbreaks generally occurred around January of the following year, while spider mite outbreaks were occasionally observed in semi-enclosed planting mode in certain years. Compared with open-field and semi-enclosed modes, the species of pests in the fully-enclosed planting mode were relatively few, and only thrips accounted for approximately 66% of the total pest population. During the later growth stages under higher temperatures (i.e., January to March of the following year), populations of Bemisia tabaci and Tetranychus urticae increased significantly. In conclusion, thrips caused the most severe damage throughout the cowpea growth cycle, significantly affecting both yield and quality. In some years, leafminers and T. urticae also inflicted considerable damage, while other pests were less detrimental. 【Conclusion】There are many kinds of pests in cowpea in Hainan, among which thrips are the most serious. The occurrence of pests in open-field planting mode is more serious, and the damage of pests in net-enclosed field is relatively light. The net-enclosed mode can effectively block some pests, but the fully-enclosed planting mode is affected by the micro-environment such as high temperature and high humidity, and the probability of outbreak of B. tabaci, T. urticae and other pests in the late growth stage of cowpea is large.

Key words: cowpea (Vigna unguiculata), pest species, dominant species, occurrence pattern, planting and management mode, Hainan Province