Biological characters of Trichogramma dendrolimi (Hymenoptera: Trichogrammatidae) reared in vitro versus in vivo for thirty generations

Abstract

Trichogramma dendrolimi which is an economically important biological control agent were reared for 30 generations on a modified artificial medium and natural host. Biological characters were assessed and compared with parasitoids reared in vivo. Pupation rate and normal adults rate of in vitro–reared parasitoids were significantly higher compared with in vivo–reared parasitoids. The adult emergence rate, number of adults produced, and fecundity of T. dendrolimi reared in vitro were lower than those reared in vivo. The percentage of females and longevity did not vary between the two rearing methods. The overall fitness of the parasitoids reared artificially from the first to the 20th generation was higher than of those reared from the 21st generation onwards. No differences were observed in the fitness parameters of parasitoids reared in vivo across any of the 30 generations. The results suggest that the modified artificial medium used in this study is suitable for the continuous rearing of T. dendrolimi for at least 20 generations, and has the potential for the mass production of these parasitoids for use in biological control. Such a substrate could be examined for use in rearing other parasitoid species that are important in biological control.

Effects of cold storage on the quality ofTrichogramma dendrolimiMatsumura (Hymenoptera: Trichogrammatidae) reared on artificial medium

“…The method used for the in vitro rearing of T. dendrolimi was as previously published . Artificial egg cards were placed in a plastic tray (30 × 20 × 5 cm) and exposed to T. dendrolimi adults for 24 h. Parasitoids of both sexes were released into the trays using a parasitoid to artificial egg ratio of 6:1.…”

“…Recently, Lü et al . developed a modified artificial medium using an orthogonal array design that is suitable for the continuous rearing of T. dendrolimi Matsumura (Hymenoptera: Trichogrammatidae) for at least 20 generations and, thus, could have potential for the in vitro mass rearing of T. dendrolimi …”

“…Diapause was induced in T. dendrolimi reared on A . pernyi, and individuals were confirmed as diapaused prepupae when they remained in the prepupal stage after exposure to various low temperatures for differing periods, followed by exposure to 26 °C for 12 days . However, little research has focused on the storage of Trichogramma reared on artificial medium .…”

Effects of temperature and superparasitism on quality and characteristics of thelytokous Wolbachia-infected Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae) during mass rearing

“…Trichogramma dendrolimi Matsumura is widely used against multiple species of lepidopteran pests in fields across low latitude to high latitude regions 25,26 , making it likely to encounter a wide range of thermal conditions 11,27,28 . T. dendrolimi females usually deposit only one egg in a host egg of Corcyra cephalonica Stainton (Lepidoptera: Pyralidae) during a single oviposition event, but can also deposit more than one egg during multiple oviposition events, resulting in superparasitism 29,30 .…”

Untitled

“…Taken together, a potentially loose rearing condition of inbreeding can be expected in 280 terms of T. dendrolimi mass-reared in biofactories for biocontrol strategies. And the key fitness 281 costs involved in protocol of mass production should be the hosts of bad quality, superfluous 282 wasps to host eggs, confined and / or cluttered environment for parasitization, as stated by 283 previous researchers (Li and Zhang, 1980;Lü et al, 2017). Moreover, given the absence of 284 diploid males and inbreeding depression, selection and stabilization of beneficial biocontrol traits 285 such as big size, long lifespan, high fecundity and vagility (Boivin, 2010), through progressive 286 generations of inbreeding can be adopted (Bai et al,2005;Anbesse et al, 2013), to ameliorate 287 the efficiency and efficacy of T. dendrolimi in practical application.…”