关键词: 豆大蓟马, 驱虫网, 阻隔率, 防虫效果, 小气候环境

Abstract:

【Objective】The objective of this study is to evaluate the control effect of a new type of insect-repellent screen on Megalurothrips usitatus, and to clarify its effect on the microclimate environment in the field, so as to provide new technical support for the control of cowpea thrips. 【Method】The barrier effects of a new type of insect-repellent screen and conventional insect-proof screen on M. usitatus were investigated under laboratory and field conditions. Light intensity, ventilation, temperature, and humidity were measured using the illuminometer, anemometer, and thermo-hygrometer, respectively, under three treatments of insect-repellent screen, conventional insect-proof screen and open field. The effect of insect-repellent screen on the field microclimate was further analyzed based on the observed data. Gas chromatography-mass spectrometry (GS-MS) was employed to detect the types, contents of insect-repellent volatile compounds in the screen after two months of field application. 【Result】The laboratory results showed that the barrier rate of the new insect-repellent screen cage against M. usitatus adults generally exhibited a slowly declining trend within one month. The barrier rate of the insect-repellent screen was 52.81%-67.11%, significantly higher than that of the conventional insect-proof screen (46.32%-51.23%). Field results indicated that within one month of investigation during the flowering and pod-setting stage of cowpeas, the adult populations of M. usitatus in the insect-repellent screen, conventional insect-proof screen (both with a porosity of 69.40%), and open field were 4.3-7.4, 6.2-11.1 and 7.8-14.2 individuals/flower, respectively. The overall trend of population in the insect-repellent screen remained at a lower level, significantly lower than that in the conventional insect-proof screen and open-field cowpeas. No significant differences were observed among the three treatments (insect-repellent screen, conventional insect-proof screen, and open field) in terms of light intensity (11 900-73 800, 11 400-73 100, and 12 000- 73 900 lx, respectively), wind speed (0.16-1.38, 0.12-1.39, and 0.20-1.47 m·s^-1, respectively), daily mean temperature (18.73-25.75, 19.50-25.62, and 19.51-26.00 ℃, respectively), and daily mean relative humidity (65.00%-72.15%, 66.32%-73.78%, and 62.10%-69.66%, respectively). During a single day at the full blooming stage of cowpea, the temperature and relative humidity under all three treatments exhibited an inverted “U”-shaped and a positive “U”-shaped trend, respectively. Specifically, the temperature reached the highest value in the afternoon (13: 00-16: 00), while the relative humidity dropped to the lowest value in the afternoon (14: 00-15: 00). GC-MS analysis revealed that the volatile components of the insect-repellent screen contained compounds with high similarity to menthol and limonene, with similarity scores of 79.50% and 80.00%, and the volatilization rates after two months of application were 98.47% and 92.86%, respectively. 【Conclusion】The barrier effect of the new insect-repellent screen against M. usitatus is better than conventional insect-proof screen, showing dual effects of physical barrier and biological repellence, and has negligible impact on the field microclimate environment. The development and application of the new insect-repellent screen provides a novel approach for integrated control of cowpea thrips.

Key words: Megalurothrips usitatus, insect-repellent screen, barrier rate, insect-proof effect, microclimate environment