Acta Scientific AGRICULTURE (ISSN: 2581-365X) Volume 6 Issue 11 November 2022 Biology and Demographic Parameters of Diaeretiella rapae (McIntosh) against Brevicoryne brassicae (L.) Tanvi Sharma, SC Verma, PL Sharma, RS Chandel, Tanuja Banshtu*, Shikha Katoch, Nidhi Sharma and Priyanka Sharma Department of Entomology, Dr. Yashwant Singh Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India *Corresponding Author: Tanuja Banshtu, Department of Entomology, Dr. Yash- want Singh Parmar University of Horticulture and Forestry, Nauni, Solan, Himachal Pradesh, India. Research Article Received: May 23, 2022 Published: October 04, 2022 © All rights are reserved by Tanuja Banshtu., et al. Abstract The cabbage aphid, Brevicoryne brassicae (Hemiptera: Aphididae), is a cosmopolitan insect pest that attacks cruciferous crops. It causes plant deformities, stunting, or killing of young plants thereby resulting in 35-75 per cent yield losses. The present investiga- tion was conducted during 2020-2021 at Dr. Y.S. Parmar University of Horticulture and Forestry, Nauni Solan, Himachal Pradesh. The study reveals that Diaeretiella rapae parasitized all nymphal instars of B. brassicae with a preference for the third instar (42%) fol- lowed by the fourth instar (30%), second instar (24%), and first instar (13%). The mean period of parasitoid from egg to host mum- mification and mummification to adult emergence was 9.04 and 3.5 days on the third instar and 10.55 and 5 days on the fourth instar, respectively. The total time period from egg to adult emergence was 12.45 and 15.55 days with the third and fourth nymphal instars of the host, B. brassicae, respectively. The fecundity, pre-oviposition, and oviposition period of the parasitoid were 53.2 eggs/female, 1.0 day and 7.1 days on the third instar, and 45.7 eggs/female, 1.0 days and 6.4 days on the fourth instar, respectively. The gross reproductive rate (GRR), net reproductive rate (R0), true intrinsic rate of increase (rm), finite rate of increase (λ), mean generation time (T) and doubling time (DT) of third instar was 42.47 female progeny/female, 26.60 female progeny/female, 0.1943 females/fe- male/day, 1.21 females/day, 16.89 days and 3.57 days, respectively and 28.65 female progeny/female, 22.85 female progeny/female, 0.1594 females/female/day, 1.17 females/day, 19.43 days and 4.30 days for the fourth instar, respectively. The age-stage survival rate (sxj), age-stage life expectancy (exj) and age-stage reproductive values (vxj) of D. rapae on the third instar of B. brassicae were 13- 15 d, 0.5 for males and 14 d, 0.51 for females, 19.75 days for eggs at age zero and 12.76 days for pupa at age seven, 31.59 d -1 on 13 d, respectively and 16- 20 d, 0.45 for male and 17-18 d, 0.5 for female, 22.65 days for eggs at age zero and 13.65 days for pupa at age nine, 31.49 d -1 on 16 d for the fourth instar, respectively. The present study revealed that the third instar nymphs of B. brassicae were most preferred by D. rapae for development. Therefore, the parasitoid, D. rapae can be utilized as one of the components in the integrated pest management programme of cabbage aphid (B. brassicae). Keywords: Biology; Cabbage Aphid; Demographic Parameters; Fertility; Parasitoid Abbreviations DT: Doubling Time; e xj : Age-Stage Life Expectancy; GRP: Gross Reproductive Rate; r m : True Intrinsic Rate of Increase; R o : Net Re- productive Rate; T: True Generation Time; v xj : Age-Stage Repro- ductive Value; λ: Finite Rate of Natural Increase Introduction The cabbage aphid, Brevicoryne brassicae (Hemiptera: Aphidi- dae), is a cosmopolitan insect pest that attacks cruciferous crops [1-5]. It causes plant deformities, stunting, or killing of young plants thereby resulting in 35-75 per cent yield losses [6-10]. Besides DOI: 10.31080/ASAG.2022.06.1194 Citation: Tanuja Banshtu., et al. “Biology and Demographic Parameters of Diaeretiella Rapae (McIntosh) against Brevicoryne Brassicae (L.)". Acta Scientific Agriculture 6.11 (2022): 03-14.