关键词: 豇豆, 豆大蓟马, 种群动态, 寄主植物, 海南三亚

Abstract:

【Objective】Megalurothrips usitatus is a persistent pest in major cowpea production areas in southern China such as Hainan. Its continuous infestation has led to a reduction in cowpea yields and quality, which has become a key biotic factor constraining the sustainable development of the industry. This study aims to provide theoretical support for cowpea thrips disaster early warning and control decision-making in tropical and subtropical cowpea-growing regions of China by systematically monitoring the annual pattern of M. usitatus in the main cowpea production area of Sanya, Hainan. 【Method】The population size of M. usitatus on host plants including Fabaceae, Cucurbitaceae, and Poaceae in Yazhou District, Sanya City, Hainan Province was investigated using the sticky trap method: August 2021 to July 2022 (the first year) and October 2023 to October 2024 (the second year). Based on the survey data, population dynamics of M. usitatus were analyzed through graphical visualization. Furthermore, by comparing population dynamic changes of M. usitatus across different years and seasons, the occurrence patterns and host transition behavior of M. usitatus on cowpea and other host plants were further analyzed. 【Result】(1) M. usitatus could cause damage on cowpeas throughout the year, and at all stages of growth. In the first year, the occurrence peaks of M. usitatus on cowpea and non-cowpea host plants occurred in winter and spring (December and January of the following year), which coincided with the peak planting period of cowpeas. In the second year, the occurrence peaks of M. usitatus on cowpeas occurred in summer and autumn (June and September), corresponding to the sporadic planting period of cowpeas. Its occurrence peaks on non-cowpea host plants occurred from early March to late April, coinciding with the large-scale crop termination period of cowpeas (pulling up seedlings after harvest). (2) M. usitatus exhibited a wide range of hosts, with significantly higher population densities on leguminous host plants (such as cowpeas, green beans, peanuts, and sesbania) than on non-leguminous host plants. (3) Studies on thrips host transfer patterns found that M. usitatus primarily infested cowpeas during the concentrated planting period of cowpea. Once cowpeas undergo large-scale crop termination (pulling up seedlings after harvest), it was likely to be transferred to the surrounding host plant plots such as eggplant, sesbania to conceal its infestation. 【Conclusion】In the Sanya region, the population density of M. usitatus on Fabaceae host plants was significantly higher than that on non-Fabaceae host plants. This pest can occur year-round in fields of cowpea, eggplant, and weeds, and exhibits the characteristic of shifting hosts to cause damage. The population dynamics of M. usitatus on cowpea and other plants show inter-annual and seasonal variations. Based on the annual population dynamic patterns of thrips in cowpea fields, it is recommended to conduct field sanitation before cowpea planting, including the removal of surrounding Fabaceae crops and weeds.

Key words: cowpea (Vigna unguiculata), Megalurothrips usitatus, population dynamics, host plant, Sanya, Hainan