Parthenium hysterophorus is an invasive weed that poses significant threats to crop production, biodiversity, human and animal health. Few experiments have been carried out to test the effectiveness of biological control agents such as the beetle Zygogramma bicolorata against this invasive. We released Z. bicolorata beetles as bio-agent to control P. hysterophorus at the Tropical Pesticides Research Institute in Arusha, Tanzania, across two seasons, from February – July 2019 (wet) and August 2019 – January 2020 (dry). Feeding by Z. bicolorata reduced P. hysterophorus leaves, flowers, height as well as biomass, both in the dry and wet season. During the wet season, 100% of all P. hysterophorus leaves were eaten already 28 days after the onset of the experiment, particularly under the highest beetle population treatment (30 individuals). Parthenium hysterophorus flower numbers were greatly reduced under high beetle populations (30 individuals) compared to the control treatment (0 individuals) during both the wet and dry season. Parthenium hysterophorus height was reduced by 87% and 90% during the wet and dry season, respectively when 30 beetles were released. Similarly, biomass was reduced by 90% and 87% during the wet and dry season, respectively. Parthenium hysterophorus responses to beetle treatments did not differ significantly across seasons but the development of both the invasive and its control, Z. bicolorata, was slightly delayed in the dry season. We conclude that Z. bicolorata can be used as bio-agent to manage P. hysterophorus in Tanzania, particularly when released in large numbers.

Parthenium hysterophorus是一种入侵性杂草，对作物生产，生物多样性，人类和动物健康构成重大威胁。很少有实验来测试生物防治剂，例如甲虫Zygogramma bicolorata对这种侵害的有效性。我们在坦桑尼亚阿鲁沙的热带农药研究所发布了两个季节的Z. bicolorata甲虫作为生物制剂，以控制猪背线虫，这两个季节从2019年2月至7月（潮湿）和2019年8月至2020年1月（干燥）。在干燥和潮湿季节，双色Z.的摄食减少了P. hysterophorus的叶子，花朵，高度和生物量。在雨季，百分之一百实验开始后28天就已经食用了P. hysterophorus叶片，特别是在甲虫种群最高的处理下（30只）。在潮湿和干燥季节，高甲虫种群（30个体）下的单性hy花数目均大大低于对照处理（0个体）。当释放30只甲虫时，在潮湿和干燥季节，单性hen的高度分别降低了87％和90％。同样，在湿季和干季，生物量分别减少了90％和87％。甲s对甲虫治疗的反应在不同季节之间没有显着差异，但侵袭性及其控制的发展，Z. bicolorata在干旱季节略有延迟。我们得出的结论是，双色Z.可用作生物制剂来管理坦桑尼亚的斑节对虾，特别是大量释放时。