Insect additives have been shown to improve the value of artificial media for Trichogramma species, but at the same time maintain dependence on parallel cultures of host insects. In the present study, Trichogramma dendrolimi Matsumura was reared in vitro from egg to adult on artificial media with different contents of pupal hemolymph of Chinese oak silkmoth Antheraea pernyi (Guérin-Méneville) and with supplements of distilled water, or of trehalose dissolved in water or in Grace's insect medium. The results indicated insect hemolymph was the key component of artificial medium. Developmental parameters, including rates of parasitism, pupation, adult emergence and normal adults, and numbers of produced adults, were increased on media supplemented with trehalose even when the proportion of pupal hemolymph was reduced. Two artificial media, the first containing 30% hemolymph and 10% trehalose in water with 98.9% parasitism rate, 77.7.0% pupation rate, 77.2% emergence rate, 80.0% normal adult rate and 333 produced adults, and the second containing 25% hemolymph and 15% trehalose in Grace's insect medium with 97.8% parasitism rate, 91.0% pupation rate, 85.2% emergence rate, 76.1% normal adult rate and 757 produced adults, were believed to hold potential to mass produce T. dendrolimi. The use of trehalose to partially replace pupal hemolymph in artificial medium of this and other Trichogramma species may contribute to a significant reduction in their production cost and may as such help to evade problems related to short supplies of lepidopteran eggs, which currently constitute the main factitious host for the mass rearing of the parasitoids.

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Successful complete development of Trichogramma species on artificial media is also related to the presence and proportions of ingredients other than host insect‐derived components. In this study, an orthogonal array with six factors at three levels was performed and parameters of parasitism, larval development, pupation, and adult emergence were monitored to reveal the most important components of an artificial medium and to improve the medium for in vitro mass rearing of Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae). Results indicated that biological parameters of T. dendrolimi were affected differently by six ingredients of the artificial medium: pupal hemolymph of Antheraea pernyi (Guérin‐Méneville) (Lepidoptera: Saturniidae), egg yolk, 10% malted milk solution, Neisenheimer's salt solution, trehalose, and sterile water. Statistical analysis indicated that trehalose and Neisenheimer's salt solution, 10% malted milk solution, and pupal hemolymph of A. pernyi were the main ingredients of the artificial medium based on rates of parasitism and pupation, the number of larvae developing in each artificial egg, adult emergence rate, and the number of normal adults produced. A follow‐up bioassay with a selection of optimized formulas confirmed the validity of the optimization as predicted by the orthogonal array analysis, indicating the usefulness of this method for selecting artificial diets for entomophagous insects. Adult emergence rate of the parasitoid and total number of normal adults produced per egg card (each containing 20 artificial eggs) averaged 88.8% and 956 females on the best performing optimized artificial medium, consisting of 3 ml pupal hemolymph of A. pernyi, 2.5 ml egg yolk, 1 ml 10% malted milk solution, 1 ml Neisenheimer's salt solution, 0.1 g trehalose, and 1.5 ml sterile water. The latter medium was superior to any formerly developed medium and may thus have potential for the in vitro mass rearing of T. dendrolimi.

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.

The diamondback moth was estimated to increase costs to the global agricultural economy as the global area increase of Brassica vegetable crops and oilseed rape. Sex pheromones traps are outstanding tools available in Integrated Pest Management for many years and provides an effective approach for DBM population monitoring and control. The ratio of two major sex pheromone compounds shows geographical variations. However, the limitation of our information in the DBM pheromone biosynthesis dampens our understanding of the ratio diversity of pheromone compounds. Here, we constructed a transcriptomic library from the DBM pheromone gland and identified genes putatively involved in the fatty acid biosynthesis, pheromones functional group transfer, and β-oxidation enzymes. In addition, odorant binding protein, chemosensory protein and pheromone binding protein genes encoded in the pheromone gland transcriptome, suggest that female DBM moths may receive odors or pheromone compounds via their pheromone gland and ovipositor system. Tissue expression profiles further revealed that two ALR, three DES and one FAR5 genes were pheromone gland tissue biased, while some chemoreception genes expressed extensively in PG, pupa, antenna and legs tissues. Finally, the candidate genes from large-scale transcriptome information may be useful for characterizing a presumed biosynthetic pathway of the DBM sex pheromone.