Cold winter temperatures significantly affect the biological control effort against water hyacinth, Pontederia ( = Eichhornia) crassipes Mart. (Pontederiaceae), in more temperate regions around the world. The population dynamics of the planthopper Megamelus scutellaris Berg. (Hemiptera: Delphacidae), a newly released biological control agent of water hyacinth, were recorded on the Kubusi River in the Eastern Cape Province (South Africa) over 15 months to determine the population recovery post-winter. Megamelus scutellaris incurred a severe population decline at the onset of winter when the water hyacinth plants became frost damaged. The combined effect of a population bottleneck and low minimum winter temperatures (6.12°C) below the agent's lower developmental threshold (11.46°C) caused a post-winter lag in agent density increase. Subsequently, the maximum agent population density was only reached at the end of the following summer growing season which allowed the water hyacinth population to recover in the absence of any significant biological control immediately post-winter. Supplementary releases of agents from mass-reared cultures at the beginning of the growing season (spring) is suggested as a potential method of reducing the lag-period in field populations in colder areas where natural population recovery of agents is slower.

中文翻译：

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注意差距：生物控制剂 Megamelus scutellaris Berg 种群的延迟恢复。（半翅目：鲟科）越冬后的水葫芦

寒冷的冬季温度显着影响了对水葫芦的生物防治工作，Pontederia (= Eichhornia) crassipes市场。（Pontederiaceae），分布于世界各地的温带地区。飞虱种群动态黄鳝伯格。（半翅目：水葫芦科）是一种新释放的水葫芦生物防治剂，在南非东开普省的库布西河上记录了 15 个月，以确定冬季后的种群恢复情况。黄鳝当水葫芦植物被霜冻破坏时，在冬季开始时导致人口严重下降。人口瓶颈和低于代理的较低发育阈值（11.46°C）的低冬季最低温度（6.12°C）的综合影响导致代理密度增加的冬季后滞后。随后，仅在下一个夏季生长季节结束时才达到最大药剂种群密度，这使得水葫芦种群在冬季后立即在没有任何显着生物控制的情况下恢复。建议在生长季节（春季）开始时从大规模养殖的培养物中补充释放药剂，作为减少药剂自然种群恢复较慢的较冷地区田间种群滞后期的潜在方法。