The exosomes are the most studied nanometer-sized extracellular vesicles (40-100 nm) in eukaryotic cell. Exosomeharbors various molecular components of their cell origin, including nucleic acids and proteins, and it is involved in intraand intercellular communication. These characteristics make exosomes to be a prospective biomarkers, therapeutic agents,or drug delivery vehicles. Edible insect industry is rapidly growing up in Korea. The insect exosomes were isolated fromthe larvae of Korean rhinoceros beetle, Allomyrina dichotoma, and White-spotted flower chafer, Protaetia brevitarsis, sothat they can be used for diagnosis of insect disease. The stable preservation of exosome is very important for diagnosisand research, especially for long term storage. Here, the stable recovery of exosome isolated from hemolymph of A. dichotomalarva was evaluated by analyzing exosomal protein and RNA after storage in -70°C for three months.

Insects are attracting the attention of alternative sources of protein. In order to produce high quality insects, studieson the development of safe and nutritious feed sources are needed. Given the cost of rearing insects, agricultural andindustrial by-products were good materials of insect feed. In the current study, Citrus unshiu peel (CP), soybean curdcake (SCC), soybean oil meal (SOM), and brewers dried grain (BDG) were investigated for their effects on larval growthand development of Protaetia brevitarsis. Interestingly, larvae fed on 10% SCC increased their weight by 3.5 times. Forthe larval period, they were significantly shorter than the control. Furthermore, minerals and amino acids were recordedto be high in them. The heavy metals were not detected in any of the investigated groups. These findings provided ascientific basis for the utilization of soybean curd cake as a nutritional feed source to promote larval growth and producequality insects.

Recently, Gryllus bimaculatus and the larva of Tenebrio molitor, Protaetia brevitarsis, and Allomyrina dichotoma were enlisted as general food ingredients by Ministry of Food and Drug Safety. As the interest in these insects is growing, the detailed investigation is needed for the standardization of suitable and safe rearing techniques. This survey was conducted via personal interviews about edible insect rearing farms in Korea. The basic feed is fermented oak sawdust for P. brevitarsis and A. dichotoma and wheat bran for T. molitor. The various feed additives are blended with each farm’s own recipes. It seems that larval weight was correlated with the rearing density and duration of the larval period. The heavy metal contents were analyzed after 48 hour starvation and they were very small amount or not detected. We believe that the present data will contribute to develop and standardize the safe rearing techniques of edible insects in Korea.

The frequency and time of the outbreak of insect diseases were investigated among the insect-rearing farms by regional groups. The purpose of this study was to predict the insect diseases and reduce the spread of diseases. From February to October 2016, 87 of diseased insects were collected in seven regions. It turned out that the pathogens for fungal diseases were identified as Metarhizium anisopliae. But in case of bacterial diseases, the pathogenicity of the bacteria isolated from the diseased insects were not confirmed. Bacterial diseases occurred mainly in June and August in Gyeonggi-do and Gangwon-do, while in Chungcheong-do, bacterial and viral disease raged. In Jeolla-do, both fungal and bacterial diseases occurred in June. Generally, bacterial diseases occurred mainly from June to October, while the frugal diseases occurred from January to March. It was concluded that the entomopathogenic fungi, Metarhizium anisopliae, tended to cause diseases during late-winter and early spring and bacteria, uncertain, was prone to cause diseases during summer. Therefore, it necessary to adequately control depending on the type of the entomopathogen.

The purpose of this study was to identify the new fungal disease of Scopendra subspinipes mutilans (Chilopoda: Scolopendridae) from Jeju island in Korea. Scopendra subspinipes mutilans are also known the Chinese red head and average 20cm in length. It is used for traditional medicine for skin-disease and tumor and S. s. mutilans is recently raised in Jeju island to use healing properties. We isolated fungi from surface of infected S. s. mutilans and incubated in SDBA at 24℃ for 14days, and then identified the morphology of the fungi by light and electron microscopy. For the specific diagnosis of Metarhizium spp. in S. s. mutilans, 18srRNA of fungi was amplified by primers ITS4_MF and LR3_MR and sequenced by using the BLAST server at the National Center for Biotechnology Information. The result of the 18srRNA sequencing alignment was Metarhizium anisopliae (99.9%). The entomopathogenic fungi, M. anisopliae would be fatal cause of higher mortality to S. s. mutilans, and it is needed in vivo assay to confirm the pathogenic activities of M. anisopliae to S. s. mutilans.

Many insects have gained increasing attention as an alternative protein for humans. Among those, the two-spotted cricket, Gryllus bimaculatus (Orthoptera: Gryllidae), was recently approved as a general food ingredient by the Korean Ministry of Food and Drug Safety. For industrial utilization of G. bimaculatus, mass rearing techniques and production system should be standardized first. In this study, we investigated the effects of five different feeds on the growth and development of G. bimaculatus. Feed is the one of the key factors that has considerable effects on rearing insects. With five different kinds of feed on 1st, 3rd, and 5th instar nymphs, the change of survival rate, body weight were monitored up to eight weeks after hatching. We concluded that 50% of soybean flour, 20% of corn powder, 10% of rice bran, 9% of milk serum, 10% of rice flour, 0.5% of microorganisms, and 0.5% of multivitamins and minerals (diet C) was the best mix for promoting growth and development of 3rd instar nymphs compared to the control diet.

In 2015, we reported a viral disease extremely fatal to Allomyrina dichotoma larvae spread in the majority of the larva-rearing farms in Korea. Currently, the virus-infected larva is diagnosed by PCR-based amplification but this requires laboratory equipment and agarose gel electrophoresis. Loop-mediated isothermal amplification (LAMP), a highly sensitive DNA amplification method, uses DNA polymerase isolated from Bacillus stearothemophilus and a set of six primers. It has great potential for field use because DNA is amplified under single temperature and the overall reaction completes in 30 min without laboratory equipments. Here, we report the development of on-site diagnosis method for Korean horn beetle larva infected by Allomyrina dichotoma Nudivirus.

The purpose of this stduy was to identify accurately and promptly the Microsporidia disease of bumble bees from Gangwon in Korea. Bumble bees are crucial pollinators of various crops and microsporidia are the critical infections of these hosts. Also, the various species of bumble bees have been used: Bombus terrestris, B. lucorum, B. occidentalis, B. ignites and B. impatiens etc. The symptoms of bumble bees infected microsporidia: their abdomens become distended, paralyzed and become sluggish and die early. We have identified the morphologies of the microsporidium by electron microscopy and found that the morphology of the microsporidium is rounded spore morph, with fairly small spores as described before in many other articles. For the specific and sensitive diagnosis of Nosema in bumble bees, we have developed the improved method of Polymerase Chain Reaction (PCR) conditions for expeditious diagnosis. Two pairs of primers were tested on N. bombi and the related microsporidia; Nosema apis and Nosema sp., both of which infect bumble bees and honey bees and further we have verified and analyzed DNA sequence data of N. bombi in bumble bees by using the BLAST server at the National Center for Biotechnology Information.

Since we reported a viral disease extremely fatal to A. dichotoma, had landed on Korea in 2015, we have investigated this disease nationwide and it was turned out the viral disease has spread in the majority of the larva-rearing farms all over the country. The transmission of this disease is most severe when the larvae are harvested and stored for overwintering. During this period, even a few virus-infected larvae can easily transmit the virus and about two hundreds of larvae stored in a container can be killed. In a peroral infection experiment, 80% of infected larvae were killed but survived larvae became adults fully functional physiologically. These survived beetles were confirmed as live virus carrier. Also, about 75% of larvae hatched from the eggs laid by the infected beetles were infected and killed by the virus. This vertical transmission is due to the feeding and secretion activity of the infected parents.

The white-spotted chafer, Protaetia brevitarsis (Coleoptera: Scarabaeidae) was recently listed as a temporal food ingredient by the Korean Ministry of Food and Drug Safety. Traditionally, this beetle has been regarded as a medicine for suppressing live cancer and preventing liver-related disease. Based on these facts, this beetle has been focused as a economically important insects in Korea. Therefore, this beetle is commercially reared and distributed in Korea. As the economic importance is growing, we have investigated to enhance insect rearing conditions for better commercial value. In this study, we compared two food supplements, clay and charcoal, on the larval weight gain for second instar larvae of P. brevitarsis. Clay and charcoal are generally known as a good adsorbent for heavy metals and bio-waste. However, clay and charcoal is not a conventional feed supplements, so its effects were not investigated for insect rearing. The second instar P. brevitarsis larvae were fed fermented sawdust with seven different combinations of cla and/or charcoal, and measured body weight for 17 weeks until pupated. Addition of clay at 2.5 % w/w of the fermented sawdust diet had no negative effect on larval weight gain, and thus may improve the quality of P. brevitarsis as a commercial food.

The current market size of insect industry in Korea is estimated at 300 million dollars and more than 500 local farms are related to many insect industry. One of the strong candidates for insect industry is Korean horn beetle, Allomyrina dichotoma. Early this year, we reported a viral disease extremely fatal to A. dichotoma larvae. While we were proceeding a nationwide investigation of this disease, several farmers answered that similar disease symptom has been occurred occasionally during past 10 years. The symptom can be easily confused with early stage of bacterial infection or physiological damage including temperature and moisture. A peroral infection with the purified virus to healthy larvae produced a result that only 21% of larvae survived and became pupae. Although some of the survived adult beetle were deformational, many of them had no abnormal appearance and even succeeded in mating. Later, these beetles were examined if they were carrying the virus, and all except one were confirmed as virus carrier. This implies that these beetle may fly out and spread the disease throughout the country. We found the evidence by collecting wild A. dichotoma larvae which were virus infected, near two local farms rearing the horn beetle. So far, transovarial transmission of this virus to the eggs, or horizontal transmission to other commercially reared insects are not known yet.

In Korea, the value of insect resources has been increased immensely and the insect industry is expected to increase up to 40 billion dollars by 2020. Among them, Korean horn beetle, Allomyrina dichotoma, is one of the strongest candidates for insect industry as medicinal purpose for various liver diseases and diabetes. In many local farms rearing larvae, a few bacterial and fungal pathogens causing disease of A. dichotoma larvae have been identified including Bacillus thuringiensis and Metarhizium anisopliae. For past few years, a disease seemingly due to viral infection has been reported for causing death of larvae en masse. The pathogen of this disease has not been identified so far. In Southeastern Asia, Oryctes rhinoceros nudivirus (OrNV) is known to cause severe disease in coconut palm rhinoceros beetle, Oryctes rhinoceros, and is used as a biological control agent to reduce the pest population. Here, we report for the first time that OrNV may have landed on Korea and may be the major pathogen for the diseased larvae of A. dichotoma. After peroral inoculation with the purified virus extracted from the hemolymph of diseased larvae, we confirmed that over 60% of infected larvae perished in six weeks. This viral disease spreads very fast in many farms nationwide throughout Korea. This threat not only makes economic loss of local farms rearing larvae, but also may disturb the ecosystem by transmitting to wild A. dichotoma.