The growth characteristics according to temperature conditions were investigated in the breeding room of the Sericulture & Entomology Experiment Station for Oriental garden crickets(Teleogryllus emma Ohmachi et Matsuura) and Modeagali-crickests(Loxoblemmus doenitzi Stein) collected from the lawns of Byeonsan-myeon, Buan-gun, Jeollabuk-do. The temperature conditions were 6 treatments from 15°C to 40°C at 5°C intervals using a multi-incubator, and the development period and mortality rate by age were compared using the 28°C breeding room conditions as a control. For T. emma, the higher the temperature, the shorter the total development period was, and the same trend was observed for the growth period by age stage. However, at low temperatures of 15°C and 20°C, all died after the third instar, and at high temperatures above 35°C, all died during development. At 25°C and 30°C, they developed normally, and the mortality rate was about 25%. The L. doenizi had the same tendency as the T. emma, with the higher the temperature, the shorter the development period. The total development period was 57.7 days at 25°C, which was similar to the T. emma's 55.9 days, and the mortality rate was the lowest at 44% at 25°C.

Cryptic species are hardly distinguished by their morphology but reproductively isolated. To understand the evolution and speciation of cryptic species, differentiations between cryptic species should be studied using multiple approaches including morphological analysis. Two of three species under the genus Loxoblemmus in Korea are morphologically similar and may constitute the cryptic species. We studied the differentiations in morphology, calling songs, and genetic sequences to understand patterns of speciation in these three species. Although L.doenitzi was easily distinguished from the other two species based on morphology, the distributions of the number of file teeth and wing morphology overlapped in L. campestris and L. equestris. However, there were clear differentiations in some calling song characters among three cricket species. The number of pulses in a chirp was two in L.doenitzi and four in L. campestris, but that was greater than or equal to six in L. equestris. The genetic sequence analyses using 16S rRNA and COI barcode revealed that L. doenitzi diverged off earlier from the other two species. Calling songs of L. campestris and L. equestris largely differed in spite of their short divergence time. Our results suggest that the speciation processes may involve differentiation in calling songs in the Loxoblemmus complex.

Sexual dimorphism, the difference between sexes in secondary sexual characters, is in general driven by processes of sexual selection. The horn-headed cricket, Loxoblemmus doenitzi, exhibits sexual dimorphism in head shape, in which males have flat heads and triangular horns on both sides of their heads, whereas females have rounded heads and no horns. We hypothesized that male horns have been evolved due to intra-sexual selection in which males use these horns as weapons in aggressive interactions. To test this hypothesis, we conducted agonistic trials of field-caught males in L.doenitzi. Horn length was significantly correlated with thorax length and hind femur length. During agonistic males aggressively used their horns by beating the opponent’s horns with their horns or by poking the opponent’s body with their horns. However, the result of logistic regression analysis revealed that horn length or horn point frequency were not significant factors for contest outcome. Instead, body size was significant for determining contest outcome

The genus Loxoblemmus has three speices in Korea: L. doenitzi, L. campestris and L. equestris. Males of L. doenitzi have flat heads and triangular horns on both sides of their frons, whereas males of L. campestris and L. equestris have flat heads and no horns. The latter two species are not clearly distinguished based on morphology and thus may constitute cryptic species. We studied the divergence in morphology, calling songs, and genetic sequences to understand patterns of differentiation of these three species. Distributions of the number of file teeth and wing morphology overlapped in L. campestris and L. equestris. In calling songs, the number of pulses in a chirp was four in L. campestris, but that was greater than or equal to six in L. equestris. The genetic sequence analyses using 16S rRNA and COI barcode revealed that L. doenitzi diverged off earlier from the other two species. Thus, the genetic data were congruent with the calling song data in three Loxoblemmus species. Our results suggest that the speciation processes may be closely related to differentiation in calling songs in the Loxoblemmus complex.

Three species are described in the genus Loxoblemmus (Orthoptera: Gryllidae) in the Repulbic of Korea: L. campester, L. equester, and L. doenitzi. Although males of L. doenitzi are characterized by triangluar-shaped horns on the face, these three species are generally difficult to distinguish based on morphological characteristics. Here, we compared males of L. doenitzi and L. campester collected from Mokpo and Jeju Island, using morphological, calling song, and DNA sequences data. In the tegminal characters that may be responsible for calling song production, harp and mirror areas were significantly different between L. doenitzi and L. campester, whereas there was no significant difference in the number of files. In the calling song characters, pulse number per chirp and peak amplitude were significantly different between L. doenitzi and L. campester, whereas pulse duration, pulse period, chirp period, and phrase period were not. The phylogenic tree analysis based on 16s ribosomal RNA gene sequence, the genetic distance between L. doenitzi and L. campester was very close (0.1-0.15), suggesting that these two species recently diverged from the common ancestor.