120 International Journal of Entomology Research www.entomologyjournals.com ISSN: 2455-4758 Received: 20-05-2022, Accepted: 04-06-2022, Published: 21-06-2022 Volume 7, Issue 6, 2022, Page No. 120-128 Assessment of cohort laboratory rearing on performance and biology of the fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) Hend O Mohamed Department of Biological Control Research, Plant Protection Research Institute, Agricultural Research Center, Giza, Egypt Abstract Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is one of the main threats to food security and farmers' livelihoods worldwide. For developing an effective management against this pest, improving the rearing technique and basic information on its biology is required. Therefore, this study was designed to assess the cohort rearing on each developmental stage and reproductive behavior of FAW feeding on castor oil leaves under laboratory conditions. Results revealed that the larval development lasted (12-19 days) while suffered (13%) mortality in their early instars. The percentage of larvae succeeded to pupal stage was (68%). When larvae reared in cohorts, about (3%) cannibalism only were recorded. The period required for adult emergency was (7.70 days) with (68.04 %) survival. Moreover, the average male to female sex ratio was (1: 1.06) with non-significantly difference. The wing malformation in females (15.67%) was significantly higher than males (1.82%), while the longevity was insignificantly affected. Females emerged earlier and began to lay their eggs through (3.33 days) and the oviposition continued up to (4-7 days). Single fertile female laid about (1225 – 2363 eggs) throughout its lifespan. The incubation period of egg stage was (2.19 days) with (97.92 %) of hatchability. Eventually, the total life period lasted about (23-30 days). Therefore, Cohort-based method is recommended for rearing FAW in laboratory without mandatory effect on their larval cannibalism, survival and hence adult fecundity. Keywords: Spodoptera frugiperda, developmental duration, cannibalism, reproductive behavior, cohort- rearing Introduction Agriculture is the main key of economy in the developing countries. As a result of the transboundary movement of agricultural commodities and trade, traditional quarantine programs, human practices and climatic change; about 1300 invasive alien species (IAS) have been spread fast across 124 countries (Paini et al., 2016) [1] . These species caused extensive losses to the agricultural production, threatened food security, exposed farmer livelihood at risk, and ultimately leveled down national economy (Sharanabasappa et al., 2018) [2] . Among them, the fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is threatening more than 353 cultivated economical crops (Montezano et al., 2018; CABI, 2020) [3, 4] . Recently, FAW was recorded as "A 1 Quarantine pest" due to its high spread ability into new geographic areas, high fecundity rate, long- distance migratory behavior over 500 km (300 miles), polyphagous insect with continuous generations throughout the year, adaptable to climate conditions and strong flier moths up to 100 Km per night (Prasanna et al., 2018; FAO, 2019) [5, 6] . Since 2016, it invaded the African continent and spread widely to more than 28 countries (FAO, 2018) [7] . Afterwards, the first appearance of FAW in Egypt was in May 2019 in Aswan Governorate, Upper Egypt as reported by the Agricultural Pesticide Committee (APC), Ministry of Agriculture (Dahi et al., 2020) [8] . Within a short period of its invading, it has further spread almost all the Governorates of Egypt in 2021. The economic importance of this new pest led researchers worldwide to study its biology on different host plants or artificial diets in laboratories to manage it before destroying the crop fields or to use it as a factitious host of natural enemies. However, almost of these previous studies based on rearing FAW individually to avoid the cannibalistic behavior between their larvae (Chapman et al., 2000; Busato et al., 2006; Modolon et al., 2017; Montezano et al., 2019; Pinto et al., 2019; Gamil, 2020; Navasero and Navasero, 2020; Ashok et al., 2021; Kranthi et al., 2021; Navasero et al., 2021; Putra and Khotimah, 2021; Ramzan et al., 2021; Salem et al., 2021; Sari et al., 2021) [9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22] . In addition, it is difficult to maintain the FAW cultures on its natural host (maize) for a long period under laboratory condition. Therefore, improving the FAW rearing is required before the effective management. For this purpose, this study assessed the effect of cohort-based method on the performance and biology of FAW when reared on castor oil leaves under laboratory condition. Based on our knowledge, there is no detailed biology information of FAW related to cohort rearing.