关键词: 豇豆, 豆大蓟马, 摇花促脱, 吸花除虫, 物理防控, 防治效果

Abstract:

【Objective】Megalurothrips usitatus is a major biotic disaster for leguminous crops, particularly prone to damaging cowpeas. The study aims to clarify the relationship between field population dynamics of M. usitatus and cowpea flowers, and to develop new green control technologies. 【Method】The population dynamics of M. usitatus across different growth stages and plant organs of cowpeas were investigated, along with the influence of flower opening and shedding times on their activity patterns. The optimal timing for pesticide application was determined, and the abscission efficiency of five abscission methods (natural abscission, fan-induced abscission, lever-induced abscission, climbing net-induced abscission, and a combined method using both fan and lever) was compared. Additionally, the effectiveness of various flower-absorbing carriers (silver-gray plastic film, shading net, weed-proof fabric, hundred-knot net, and bare soil) was evaluated. Based on these findings, a novel integrated green control strategy, termed the “trinity, internal and external killing” approach, was developed and assessed for its efficacy in controlling M. usitatus, as well as its impact on cowpea quality and yield. 【Result】The population density of M. usitatus exhibited a trend of initial increase followed by a decline from the seedling stage to the end of flowering. The lowest population density was observed during the seedling stage, with a significant increase noted during the early flowering stage, peaking at full flowering stage. M. usitatus adults predominantly reside within flowers, while nymphs preferentially inhabit pods, followed by flowers and tender shoots. As flower buds open, the number of M. usitatus adults within flowers increases progressively. Flower closure typically occurs after 10: 00, encapsulating the insects within the floral structures. These closed flowers generally fall off gradually the following day; however, substantial numbers of M. usitatus remain concealed within the fallen flowers. Notably, flowers with receptacles harbor significantly higher numbers of M. usitatus compared to those without. A mass exodus of M. usitatus from the floral structures typically begins after 6: 00, at which point they migrate to new plant organs. For effective chemical control, application during the evening or early morning—when flowers are open—is most effective. Among the tested abscission methods, the combined use of a fan and lever demonstrated the highest efficiency in removing flowers. Additionally, the hundred-knot net significantly enhanced the effectiveness of flower collection. The implementation of the “trinity, internal and external killing” integrated green control strategy resulted in a 93.71% reduction in black head and black tail symptoms, a 96.87% reduction in wrapper tail, and a 91.55% reduction in overall malformation in cowpeas, accompanied by a 20.40% increase in yield. 【Conclusion】The “trinity, internal and external killing” technique not only challenges the conventional reliance on chemical pesticides, but also effectively suppresses M. usitatus populations, enhances cowpea quality and yield, and provides a valuable theoretical and practical framework for the development of green pest control strategies in other crops.

Key words: cowpea (Vigna unguiculata), Megalurothrips usitatus, flower-shaking for abscission promotion, flower-sucking for pest control, physical control, control efficacy