Abstract Invasive fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) is a pest of American origin that has recently invaded Asian countries, including India. After causing huge losses in the Africa and Asia, the FAW is now affecting large areas of India. Indigenous natural enemies of related pest species are the first defense against invasive pests and understanding their role in population suppression of invasive pests is a first step towards the development of a comprehensive management program. Therefore, we studied the natural enemy complex responsible for natural mortality of FAW in northeast India. Various locations were surveyed across five major districts of Meghalaya state, where more than 26 species of natural enemies were found attacking FAW. A total of 56.6% to 73.1% of larvae were found to be either parasitized or infected with naturally occurring entomopathogens. Species richness and diversity of predators were determined in maize fields at different locations. Values of Menhinick's species richness index (DMn) varied from 0.23 to 0.31 and Shannon-Wiener index (H) ranged from 2.16 to 2.6 across various locations. The Simpson Index (D) indicated high predator diversity in maize fields. The entomopathogenic fungus, Metarhizium rileyi (Farlow) Samson and the baculovirus, SpfrNPV were observed to be the dominant mortality factors throughout the season, responsible for >50% mortality of FAW larvae. This investigation demonstrated that indigenous natural enemies of related noctuid species can widen their host range and successfully adopt the invasive FAW as a novel host/prey in invaded regions. Therefore, conservation of such biocontrol agents could be vital for mitigating FAW damage in maize agroecosystems.

中文翻译：

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印度东北部玉米农业生态系统中入侵性秋粘虫 Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) 的自然死亡率

摘要 入侵秋粘虫（FAW）草地贪夜蛾（JE Smith）（鳞翅目：夜蛾科）是一种起源于美国的害虫，最近入侵了包括印度在内的亚洲国家。一汽在非洲和亚洲造成巨大损失后，现在正在影响印度大片地区。相关害虫物种的本土天敌是抵御入侵性害虫的第一道防线，了解它们在抑制入侵性害虫种群中的作用是制定综合管理计划的第一步。因此，我们研究了导致印度东北部秋粘虫自然死亡的天敌复合体。对梅加拉亚邦五个主要地区的不同地点进行了调查，发现有超过 26 种天敌攻击一汽。总计 56.6% 为 73。发现 1% 的幼虫被自然发生的昆虫病原体寄生或感染。在不同地点的玉米田中确定了捕食者的物种丰富度和多样性。Menhinick 物种丰富度指数 (DMn) 的值从 0.23 到 0.31 不等，香农-维纳指数 (H) 在不同地点的范围从 2.16 到 2.6。辛普森指数 (D) 表明玉米田中捕食者的多样性很高。昆虫病原真菌 rileyi (Farlow) Samson 和杆状病毒 SpfrNPV 被观察到是整个季节的主要死亡因素，导致一汽幼虫的死亡率超过 50%。这项调查表明，相关夜蛾物种的本土天敌可以扩大其寄主范围，并成功地将入侵的秋粘虫作为入侵地区的新宿主/猎物。所以，