Abstract
BackgroundMaintaining the quality and efficacy of biological control agents during long-term mass rearing plays a crucial role in the success of a biological control program. In this study, the biological traits of a local population colony of Trichogramma embryophagum (Hartig) with rearing on Sitotroga cerealella (Olivier) eggs for over 40 generations (G) were assessed.ResultsFemale adult longevity was significantly different among generations, ranging from 7.98 d in G5 to 5.19 d in G40. The reared wasps showed highest fecundity (60.50 eggs/female) in G5 compared to the other generations. The female sex ratio varied from 63.16% in G5 to 49.31% in G40. Significant differences were observed in population growth parameters and the highest gross reproductive rate (GRR) (40.96 eggs/individual) and net reproductive rate (R0) (38.21 eggs/individual) were found in G5. However, a non-significant difference was found in the intrinsic rate of natural increase (r) until the 10th generation, but its values significantly declined with increasing the generation numbers. The finite parasitism rate (ω) ranged from 0.468 host/parasitoid/day in G5 to 0.274 host/parasitoid/day in G40.ConclusionsThe results showed that the quality of T. embryophagum reared under continuous laboratory conditions declined after 10 generations, and for use of them in biological control programs under field conditions, the reared population should be refreshed by adding wild individuals from time to time.
Highlights
Maintaining the quality and efficacy of biological control agents during long-term mass rearing plays a crucial role in the success of a biological control program
Sadat et al Egypt J Biol Pest Control (2021) 31:119 of the concerns in the mass rearing process is that they are produced under ambient conditions and in limited space may adapt to laboratory conditions and lose some characters during long-term maintenance and experience inbreeding depression, resulting in poor performance of the released wasp in the field (Badran et al 2020)
Reproductive parameters and survival the duration of the immature stages of T. embryophagum varied slightly over successive generations, it was non-significantly affected by the increase in generation numbers
Summary
Maintaining the quality and efficacy of biological control agents during long-term mass rearing plays a crucial role in the success of a biological control program. One. Sadat et al Egypt J Biol Pest Control (2021) 31:119 of the concerns in the mass rearing process is that they are produced under ambient conditions and in limited space may adapt to laboratory conditions and lose some characters during long-term maintenance and experience inbreeding depression, resulting in poor performance of the released wasp in the field (Badran et al 2020). Sadat et al Egypt J Biol Pest Control (2021) 31:119 of the concerns in the mass rearing process is that they are produced under ambient conditions and in limited space may adapt to laboratory conditions and lose some characters during long-term maintenance and experience inbreeding depression, resulting in poor performance of the released wasp in the field (Badran et al 2020) They may be unable to find and parasite their hosts under variable field conditions; it is very important to study the changes that may occur during mass rearing of natural enemies
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