This study was performed to explore novel and valuable uses of insect resources, important subjects of the natural compound used in bio‐industries. The whole bodies of two crickets, Gryllus bimaculatus and Teleogryllus emma, selected from medicinal insect species, were carefully ground and treated with 80% EtOH. The insect extracts were solubilized and separated by hexane, butanol, and D.W according to their polarities. Three types of extracts, a D.W fraction (G1) and a boiling extract (G2) of an introduced cricket, G. bimaculatus, and a D.W fraction (T1) of a Korean local cricket, T. emma, were prepared to assay immune stimulating activity of cricket originated compounds. The all of three treated cricket extracts showed to increase IL‐4, IFN‐, and TNF‐α. Among those extract, extract G2, boiled extract from G. bimaculatus, was the best immune–enhancing fraction. The results of this study could be fundamental information for further works to use insects as natural resources having plenty of potentials and varieties.

The effect of cricket extract on high‐fat diet fed rat was observed. It was shown that cricket extract prevented the increment of body weight by high‐fat diet. The extract also decreased the value of AST in liver. The most significant effect of the extract was shown on lipid metabolism. The contents of total lipid and total cholesterol in liver and feces were reduced by the extract on dose‐dependent. These statistically significant results were clear in 3% extract treated group (HFD3) while were slight in 1% extract treated group (HFD1). The same result was also shown in body fat content.

Tissue‐ferritin was homogeneously purified from the hemolymph‐free whole body of Galleria mellonella larvae. Tissue‐ferritin was composed of four subunits, 26, 30, 32 and 34 kDa. The 34 kDa subunit among them was specifically found in tissue ferritin while its N‐terminal sequence of 19 amino acid residues was identical to that of 32 kDa hemolymph‐ferritin subunit. It was observed that the 32 and 34 kDa subunit of tissue‐ferritin were glycosylated like 32 kDa subunit of hemolymph‐ferritin. It suggests that the 34 kDa subunit is an isoform of 32kDa ferritin subunit according post‐transcriptional modification. By semi quantitative RT‐PCR, the distribution of 32 kDa ferritin subunit mRNA was observed in fat body, Malpighian tubules, integument, and muscle, but found in a very small amount in silk gland or not found in gut. On the other hand, 26 kDa subunit mRNA was found in all organs tested although it was in a small quantity found in gut and silk gland. By dietary Hg treatment, 34 kDa subunit of tissue‐ferritin was clearly up‐regulated.

The effect of Hg treatment on hemolymph and tissue ferritin in the wax moth Galleria mellonella was examined by western blotting. At 48 h after feeding HgCl2, the level of hemolymph ferritin increased approximately 1.8‐fold over that of control insects that were not fed HgCl2, while there was a small increase in tissue ferritin. Time series experiments showed that tissue ferritin had a typically saturated pattern, with a maximum level from 24 to 72 h, although it decreased 12 h following HgCl2 feeding, while hemolymph ferritin first decreased but subsequently increased. Tissue ferritin in the fat body, gut and Malpighian tubules, the main tissues of ferritin expression, was upregulated over time following treatment with Hg, and in particular, tissue ferritin in the gut increased by a large amount at 12–48 h. The results suggest that in G. mellonella, the ferritin‐inducible mechanisms following treatment with HgCl2 are different for hemolymph and tissue ferritin, as are their biochemical properties.

The effects of seven heavy metals on hemolymph and tissue ferritin in Galleria mellonella were examined by western blotting. Hemolymph ferritin was clearly upregulated by Hg, while tissue ferritin was dramatically upregulated by Cd, Cu, Mn, Zn and Ni. The level of hemolymph ferritin for Hg and Cd increased approximately 1.5‐fold over normal controls, while the level of tissue ferritin for Cd, Cu, Mn, Zn and Ni increased more than twofold, indicating that the regulation of hemolymph and tissue ferritin differ with the different heavy metals. Compared to normal control insects not fed CdCl2, ferritin subunit mRNA from the Malpighian tubules, muscle, the gut and the integument was clearly downregulated, as determined by semi‐quantitative reverse transcription–polymerase chain reaction, but ferritin subunit mRNA from the silk gland and the fat body did not show any change. These results suggest that in G. mellonella, tissue ferritin is responsible for Cd stress and is thus important for survival of the moth, and that tissue and hemolymph ferritin have different ferritin‐inducible mechanisms in response to dietary CdCl2.