Abstract The fall armyworm Spodoptera frugiperda (J. E. Smith) invaded several West African countries in 2016 causing severe injury to maize plants and economic damage. This study assesses variations in the occurrence of this species in different Agro-Ecological Zones (AEZs) in Togo and Ghana during the 3 yr following its discovery. The surveys were conducted on 120 farms inTogo and 94 farms in Ghana by collecting larvae from 200 maize plants per hectare. Infestation levels were 68.46% in 2016, 55.82% in 2017, and 17.76% in 2018. The number of larvae recorded per hectare and infestation levels were higher in Togo than in Ghana. The lowest number of collected larvae and infestation levels of S. frugiperda were in 2018, compared to the other 2 yr. Larvae per hectare and the infestation level varied regionally inside the two countries. The southern part of Togo (AEZ five) contained higher numbers of larvae and higher infestation levels during the 2 yr following the invasion of the pest. We concluded that infestation levels of S. frugiperda are much lower in 2018 than the two previous years and it is therefore necessary to determine the factors that affect the population dynamics of S. frugiperda in the field, which is a perquisite for developing management interventions.

中文翻译：

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玉米侵染西非多哥和加纳农业生态区的秋粘虫（鳞翅目：夜蛾科）在其入侵后 3 年

摘要 秋粘虫草地贪夜蛾（Spodoptera frugiperda，JE Smith）于2016年入侵西非多个国家，对玉米植株造成严重伤害和经济损失。本研究评估了该物种在发现后 3 年内在多哥和加纳不同农业生态区 (AEZ) 中出现的变化。调查是在多哥的 120 个农场和加纳的 94 个农场进行的，收集了每公顷 200 株玉米植株的幼虫。2016 年的侵染水平为 68.46%，2017 年为 55.82%，2018 年为 17.76%。多哥每公顷记录的幼虫数量和侵染水平高于加纳。与其他 2 年相比，2018 年收集的幼虫数量和 S. frugiperda 的侵染水平最低。每公顷幼虫数量和侵染水平在两国内部因地区而异。在害虫入侵后的 2 年内，多哥南部（AEZ 5）包含更多数量的幼虫和更高的侵染水平。我们得出结论，2018 年草地贪夜蛾的侵染水平远低于前两年，因此有必要确定影响草地贪夜蛾种群动态的因素，这是制定管理干预措施的必要条件。