The white-spotted flower chafer, Protaetia brevitarsis (Coleoptera: Scarabaeidae), is traditionally considered to be an important source of medicinal properties of suppression of cancer and prevention of liver-related diseases. Recently, it was listed as a temporal food ingredient by the Korean Ministry of Food and Drug Safety. To use this insect species without endangering wild populations and produce better quality insects, a mass rearing technique and the suitable rearing conditions are needed. The present study was carried out to determine whether different diets and temperatures can affect the larval weight of this beetle. The larval weight change of third instar larvae was tracked for 14 weeks with different combination of three rearing temperatures – 25, 27.5, and 30℃ - and two feed ingredients – soybean cake and rice bran. Among three temperatures, 27.5℃ was the best temperature condition for rearing this beetle. Among four combinations of two feed ingredients, the addition of soybean cake made significant weight increasement for third instar larvae. These results showed that adding soybean cake at 27.5℃ was the best rearing condition for larval weight gain. This rearing condition can be considered in terms of producing better insects and maximizing producers’ benefits.

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.

The purpose of this multiplex PCR assay is establishment and application for rapid and simultaneous detection of six pathogens related with insect diseases. Five pathogens were chosen based on the insect disease incidence rate in South Korea and specific primers of those pathogen were designed to detect insect diseases and test multiplex PCR for detecting Fungi; Beauveria bassiana(Bb), Metarhizium anisopliae(Ma), Bacteira; Bacillus thuringiensis(Bt), Pseudomonas aeruginosa(Pa), and Serratia marcescens(Sm). This research carried out the results detecting five kinds of insect pathogen of P. b. seulensis by multiplex PCR. Multiplex PCR is effective and save time to detect simultaneously these insect pathogens and multiple infections to prevent insect disease. In our study, using multiplex PCR, we demonstrated that P. b. seulensis was frequently infected with S. marcescens and co-infected with M. anisopliae in more than 80% of cases, indicating that such an analysis can be useful for pathogen identification, especially if different pathogens produce similar symptoms.

The white-spotted chafer, Protaetia brevitarsis (Coleoptera: Scarabaeidae), is the one of the mass-rearing insects in Korea. Traditionally, it has been considered as a medicine for preventing liver-related diseases and suppressing cancer. In addition, this beetle was recently enlisted as a temporal food ingredient by Korean Ministry of Food and Drug Safety. As the economic importance of this beetle is growing, the suitable rearing conditions are needed for more detailed investigation. In this study, we compared three different temperature conditions – 25, 27.5, and 30°C – and the four combinations of two ingredients – soybean cake, and rice bran. With these treatments, the weight change of third instar larvae was tracked for ten weeks. Among three temperatures, 27.5°C was identified as the best temperature condition for rearing this beetle. Among four combinations of different ingredients, the addition of soybean cake made significant weight incensement for third instar larvae. Based on these results, we concluded that adding soybean cake at 27.5°C is the best rearing condition among 12 combinations of temperatures and feed ingredients. In addition, we observed the body weight was reduced when the larvae were closed to the pupation period. Therefore, we recommend that ca. seven weeks after third instar is the best time to distribute it to the market.

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.