Establishment and characterization of the Bactrocera dorsalis (Diptera: Tephritidae) embryonic cell line QAU-Bd-E-2

Establishment of an embryonic cell line of Grapholita molesta (Lepidoptera: Tortricidae) and in vitro replication of Cydia pomonella granulovirus in it

The oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), is a major pest of fruit trees worldwide. In this study, an embryonic cell line QAU-Gm-E-L of the oriental fruit moth was successfully established. The cells grew adherently, round cells and spindle cells accounted for 43.0% and 42.2% of the total population, respectively, and rod-shaped cells accounted for 14.8%. The amplified mitochondrial cytochrome oxidase I subunit (CoI) gene fragment was 651 bp in length, and its similarity with the CoI gene of the oriental fruit moth was 100%. The chromosomes of QAU-Gm-E-L cells were granular or short rod-shaped. Its number varied from 66 to 444, indicating that aneuploidy occurred. The observations were consistent with the chromosome characteristics of lepidopteran insect cell lines. The population doubling time of QAU-Gm-E-L cells was 27.64 h. Real-time fluorescence quantitative polymerase chain reaction (qPCR) confirmed that the number of copies of Cydia pomonella granulovirus (CpGV) gradually increased in QAU-Gm-E-L cells with inoculation time. The electron microscopy observations results showed that occlusion bodies (OBs) of CpGV could be formed in the cells at 4 d post-infection; a large number of OBs were seen in the cells at 8 d post-infection. Hence, the QAU-Gm-E-L cells can support the in vitro replication and proliferation of CpGV, and it will provide an ideal material for the molecular biology research of oriental fruit moth and CpGV.

The roles of viruses in tephritid pest multitrophic interactions and an outlook for biological control

Tephritid fruit fly pests remain a considerable problem for agricultural fruit production around the world. New control methods that do not rely on synthetic insecticides are increasingly desirable to diversify tephritid pest management programs. Biological control through the release of parasitoid wasps has historically provided effective suppression of fruit fly pests, although molecular factors that influence the success of fruit fly parasitoids are understudied. Microbes have been demonstrated to facilitate myriad interactions between insects and their environment and have been the subject of recent investigation within tephritids. Specifically, the diversity and function of viruses found within fruit flies and associated parasitoids is an emerging field of research that has the potential to deepen our understanding of previously hidden factors that facilitate sustainable pest control. Most work to date has focused on identifying resident viral communities within fruit flies using metagenomic and metatranscriptomic sequencing approaches. Additionally, a growing body of evidence has revealed a multitude of functional dynamics that viruses have with fruit fly hosts, including vertically transmitted commensal viruses and parasitoid-vectored pathogens. Heritable viruses transmitted by fruit fly parasitoids, in particular, have been shown to play prominent roles in fruit fly multitrophic interactions, in which viral infection can shape the survival rate and host range of infected parasitoids. Furthermore, at least one parasitoid virus represents a lethal pathogen to a wide range of fruit fly pest species. Parasitoid viruses could therefore present novel opportunities to leverage natural antagonistic interactions for fruit fly pest control innovations.

A cell line derived from the black soldier fly, Hermetia illucens (Diptera: Stratiomyidae)

Insect cell lines are effective tools used in industry and academia. For example, they are used in screening potential insecticides, in making certain proteins for biomedical applications, and in basic research into insect biology. So far, there are no cell lines derived from the black soldier fly, Hermetia illucens (BSF). This may become an issue because BSFs are employed in a range of industrial and household processes. BSFs are used in producing biodiesel, in developing cosmetics and skin creams, and in the production of some medicines and animal feeds. BSF larvae process waste streams from a variety of sources into food for some animals and are also used in household composting. Our BSF cell line, designated BCIRL-HiE0122021-SGS, was developed from eggs using the medium CLG#2 (50% L-15 + 50% EX-CELL 420, with 9% FBS and antibiotics), with many other media being tested. This cell line consists of attached cells with a variety of morphologies and its identity was authenticated using CO1 barcoding. A growth curve was generated and the resulting doubling time was 118 h. We quantified the fatty acid methyl esters (FAMES) and recorded the expected range of saturated, monounsaturated, and polyunsaturated FAMEs, with only trace levels of lauric acid being noted. The BSF cell line is available free of charge by request.

A database of crop pest cell lines

We have developed an online database describing the known cell lines from Coleoptera, Diptera, Hemiptera, Hymenoptera, and Lepidoptera that were developed from agricultural pests. Cell line information has been primarily obtained from previous compilations of insect cell lines. We conducted in-depth Internet literature searches and drew on Internet sources such as the Cellosaurus database (https://web.expasy.org/cellosaurus/), and inventories from cell line depositories. Here, we report on a new database of insect cell lines, which covers 719 cell lines from 86 species. We have not included cell lines developed from Drosophila because they are already known from published databases, such as https://dgrc.bio.indiana.edu/cells/Catalog. We provide the designation, tissue and species of origin, cell line developer, unique characteristics, its use in various applications, publications, and patents, and, when known, insect virus susceptibility. This information has been assembled and organized into a searchable database available at the link https://entomology.ca.uky.edu/aginsectcellsdatabase which will be updated on an ongoing basis.