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| Population Dynamics Monitoring and Field Biological Control of Megalurothrips usitatus during Flowering Stage of Cowpea |
| LIU Motao1，2，CHEN Qi 1，2，XIAO Zhengkun1，2，WU Mingyue3，WANG Xing4，KONG Xiangyi3，XIE Wen5，6，HUANG Guohua1，2* |
| 1College of Plant Protection，Hunan Agricultural University，Changsha 410128，Hunan，China；2Hunan Provincial Key Laboratory for Biology and Control of Plant Diseases and Insect Pests，Hunan Agricultural University，Changsha 410128，Hunan，China；3Sanya Academy of Tropical Agricultural Sciences，Sanya 572000，Hainan，China；4Tropical Biodiversity and Bioresource Utilization Laboratory，Qiongtai Normal University，Haikou 571100，Hainan，China；5Institute of Vegetables and Flowers，Chinese Academy of Agricultural Sciences，Beijing 100081，China；6National Academy of Southern Propagation，Chinese Academy of Agricultural Sciences，Sanya 572024，Hainan，China |
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Abstract Megalurothrips usitatus，a tiny and discreet pest，is a major threat to cowpea（Vigna unguiculata）．It is the primary target of excessive chemical pesticide use among local cowpea growers．To accurately select safe，eff ective，and promising biocontrol agents，we investigated the population dynamics of M. usitatus in cowpea fields in Yazhou District，Sanya City．15 billion spores·g-1 of Beauveria bassiana WP，32 000 IU·mg-1 of Bacillus thuringiensis WP，8 000 IU·μL-1 of Bacillus thuringiensis SC，15 billion spores·mg-1 of Metarhizium anisopliae CQma421 OD，5 billion spores·mg-1 of Cordyceps javanica JS001 OD and 0.3% of martrine AS were used in fi eld trials of cowpea．Results showed that the population density of M. usitatus during the flowering stage of cowpea was time-dependent，with the highest count at 18：00，reaching 22.40 thrips per flower．Comparing the efficacy of different application times，the most eff ective treatment at 8：00 was 0.3% martrine AS，achieving a corrected effi cacy of 59.63% after 7 days．At 13：00，all treatments showed no significant efficacy．At 18：00，C. javanica JS001 OD exhibited the highest efficacy，reaching 62.37% after 7 days，whereas martrine AS peaked on day 3 and subsequently declined．Application of the aforementioned biopesticides signifi cantly reduced the occurrence of‘ black head and tail’ in cowpea．In conclusion，strategic application of martrine AS ，C. javanica JS001 OD，and M.anisopliae CQma421 OD enhances control efficacy against M. usitatus．These findings provide a basis for reducing pesticide use in cowpea cultivation.
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Received: 14 December 2023
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