Quality control of the parasitoid wasp Trichogramma brassicae (Hymenoptera: Trichogrammatidae) over 45 generations of rearing on Sitotroga cerealella

Authors: GHAEMMAGHAMI, EHSAN - Tarbiat Modares University; FATHIPOUR, YAGHOUB - Tarbiat Modares University; BAGHERI, ABDOOLNABI - Tarbiat Modares University; TALEBI, ALI ASGHAR - Tarbiat Modares University; Reddy, Gadi V.P.

Submitted to: Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2020
Publication Date: 1/28/2020
Citation: Ghaemmaghami, E., Fathipour, Y., Bagheri, A., Talebi, A., Reddy, G.V. 2020. Quality control of the parasitoid wasp Trichogramma brassicae (Hymenoptera: Trichogrammatidae) over 45 generations of rearing on Sitotroga cerealella . Insect Science. 28(1):180-190. https://doi.org/10.1111/1744-7917.12757.
DOI: https://doi.org/10.1111/1744-7917.12757

Interpretive Summary: Trichogramma parasitoids are one of the most widely used biological control agents, and they have been applied extensively around the world for the control of many lepidopteran pests. We evaluated the quality and performance of T. brassicae over 45 laboratory reared generations using two-sex life table parameters and a parasitism assay. Although a significant difference in the female longevity was observed among sequential generations, no significant difference in the male longevity was found among tested generations. However, there was significant differences in the total life span among sequential generations of T.brassicae. On the other hand, population parameters showed significant differences over long-term rearing. These findings are useful and will deepen our knowledge about undesired changes that may occur during long-term mass rearing of T. brassicae.

Technical Abstract: In this study, we evaluated the quality and performance of a colony of T. brassicae that had been reared for over 45 generations (G) using two-sex life table parameters and parasitism capacity. We found that female adult longevity was significantly different among sequential generations, ranging from 5.58 ± 2.5 d (at G5) to 3.75 ± 1.42 d (at G45). However, no significant difference was found in male adult longevity among different generations. Although female wasps survived longer until the 15th generation, they allocated more days for egg laying at G5 and G10. The highest values of gross reproductive rate (GRR), net reproductive rate (R0), intrinsic rate of increase (r), finite rate of increase (') and mean generation time (T) were found in G5 and G10, which also showed significantly higher c0. No significant difference in the finite parasitism rate (') was found among generations up to G15. These results suggest that T. brassicae wasps held under continuous laboratory rearing can be used successfully in biological control programs until the 15th generation without any loss of quality or performance. However, laboratory mass rearing colonies declined in quality after 15 generations and we suggest that they should be rejuvenated regularly by adding field collected parasitoids periodically.