Immune-Enhancing Activity Screening on Extracts from Two Crickets, Gryllus bimaculatus and Teleogryllus emma

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.     

Effect of mating status on the fecundity of a cricket,Teleogryllus emma

Abstract Fecundity in some insects is affected by mating status. The effect of mating status on the fecundity and total egg production of Teleogryllus emma (Ohmachi et Matsumura) (Orthoptera: Gryllidae) was examined in this study. The results showed that the pre‐oviposition period was shorter for amphigonic females than that for virgin females. However, no significant difference in pre‐oviposition was found between amphigonic females and those that had mated with a male with either the phallodeum or testes extirpated. There is no difference in adult longevity between the above four groups. The fecundity and total egg production were much higher in amphigonic females than in those controlled under the three non‐amphigonic treatments. The females of T. emma that mated with the testes‐extirpated males produced more eggs (up to two‐fold more) than both the virgin females and those that mated with the phallodeum‐extirpated males, but there was no difference between them. The fecundity‐enhancing substances transferred from male to female can stimulate the female to produce more eggs, but this stimulation has to occur in collaboration with sperm.     

Environmental adaptation and genetic variations in geographically isolated Emma field crickets Teleogryllus emma (Orthoptera: Gryllidae)

The Emma field cricket, Teleogryllus emma (Ohmachi & Matsuura), distributed between 43°N and 30°N in the Japanese archipelago, is univoltine and overwinters in the egg stage. Its eggs hatch on the slope of the Oishi Dam (38.03°N, 139.57°E, 160–170 m a.s.l.) in late June, adults begin emerging from late August, and oviposition lasts until early October. Oviposition is limited to the period when the water level of the Oishi Dam is low. The period from egg hatching to adult emergence is approximately 1 month shorter than that of the T. emma population on the Arakawa riverside (38.09°N, 139.57°E, 29 m a.s.l.), which is approximately only 7 km from the Oishi Dam. The egg and body sizes of T. emma on the slope of the Oishi Dam were smaller than those of T. emma on the Arakawa riverside, and the egg and nymphal periods were shorter; these variations were inherited by the next generation of T. emma. The egg period, nymphal period and head width of T. emma on the dam slope correspond to those of the populations near 40°N. Several traits of the T. emma population on the dam slope were naturally selected by adapting to the isolated environment, resulting in the genetic variations. However, their variations were small and the period after isolation is short, suggesting that it is in the early stages of speciation.