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.

Male cicadas produced species-specific calling songs to attract conspecific receptive females. Male cicadas typically occupy tree trunks or tree branches during calling song production. We studied calling site preference in four species of cicada: Cryptotympana dubia, Meimuna opalifera, Oncotympana fuscata, and Meimuna mongolica. Several males were observed to sing together in a tree in C. dubia, but males of other species tended to sing singly in trees. There were also cases in which two or three individuals of different species sang together in a tree. Species differed significantly in height of and distance to trunk from calling site. Both tree height and tree crown were significant factors for calling site preference. The height of calling site was the highest in C. dubia, followed by M. opalifera, M. mongolica, and O. fuscata. The distance to trunk from calling site in M. opalifera was the farthest and was significantly different from those of other species. Males of other species tended to sing close to tree trunks. Males of M. opalifera were mobile when they produced calling songs, whereas males of other species were stationary. That is, males of M. opalifera sang only for short periods of time and moved around adjacent trees. Segregation of calling sites suggests that these four cicada species occupy different sections of trees, thereby avoiding competition for calling sites.

The nymphs of the lantern fly, Lycorma delicatula, typically aggregate on tree branches for feeding. We studied the agonistic interactions between nymphs in the field and investigated the effects of residence and size asymmetries on contest outcome. Resident nymphs took positions and engaged in feeding on tree branches, whereas intruding nymphs moved along tree branches. When intruders approached, residents typically raised their front legs as a threat sign. Intruders would decide to either move away or palpate residents, and residents often lowered their position when palpated. Then, intruders would attempt to shake residents back and forth, and the number of attempts varied from once to several. Residents either maintained its position or fled away. After a contest, the winner was determined as the one which occupied the position it fought over. Resident nymphs won 84.2 % of the agonistic encounters, and nymphs with bigger body size won 63.2 % of the agonistic encounters. The result of the logistic regression analysis revealed that residence was a significant factor for contest outcome, but body size was not

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 green peach aphid, Myzus persicae, is one of the most widespread insect pest worldwide. We documented all behaviors of this species during the pre-reproductive period to understand the behavioral repertoire, organization of behaviors, and the context in which they occur. The behaviors that we observed include honey-dew production, walking, wagging, and molting. Honey-dew production occurred regularly at every 30-60 min throughout all nymphal stages. Walking seemed to occur when the host condition was not good, probably related to searching for a new host. Wagging, which was the turning of abdomen with the stylet in the plant, was also frequently observed, but the function of this behavior was unclear. We also noted the frequency and the amount of time for each behavior at different nymphal stages.

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.

The nymphs of the lantern fly, Lycorma delicatula, typically aggregate on tree branches for feeding. We investigated effects of residence and size asymmetries on the agonistic interactions between nymphs in the field. Resident nymphs took positions and engaged in feeding on tree branches, whereas intruding nymphs moved along tree branches. When intruders approached, residents typically raised their front legs as a threat sign. Intruders would decide to either move away or palpate residents, and residents often lowered their position when palpated. Then, intruders would attempt to shake residents back and forth, and the number of attempts varied from once to several. Residents either maintained its position or fled away. After a contest, the winner was determined as the one which occupied the position it fought over. Resident nymphs had a winning rate of 84.61% in agonistic encounters, and the winning rate increased to 87.5% when residents had bigger body sizes than intruders. Bigger individuals had won 61.54 % of agonistic encounters. The behavioral analyses of the agonistic encounters suggested that asymmetry in residence had a strong effect on the outcomes of agonistic encounters, with asymmetries in body sizes producing a weaker effect.

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.

Males of many cricket species produce calling songs to attract receptive, conspecific females. Calling songs which affected by calling pattern are critical for male mating success, since male with no or limited calling songs are unable to attract female crickets. Investigating among- and within-individual variation in calling pattern may reveal the presence of alternative mating tactics such as attracting females by producing calling songs or being satellites in which males intercept females who are attracted to calling males. In this study, I investigated patterns of calling song production during the entire adulthood of 32 laboratory-reared and 24 field-captured individuals of Teleogryllu emma. Using recording system which can record acoustic signals from up to 32 individuals simultaneously, I measured daily calling output (DCO) and total calling output (TCO) in addition to acoustic parameters of calling songs and classified T.emma males into consistent and inconsistent singers based on the consistency of singing. Consistent singers lived longer, sang longer both in a day and during the lifetime than the inconsistent singers. These results suggest that the consistent singers in this study may be considered to employ the calling tactic. In lab-reared individuals, there seemed to be a trade-off between increasing pulse duration and length of phrases and ling chirp although older males produced calling songs with longer ling chirps and more multiple phrases.

Consistent individual difference in a behavior is recognized as an important evolutionary force in niche variation and may be a personality trait, an inherent property of the individual. To understand whether aggressiveness is a personality trait, independent of resource holding potential (RHP) and resource value in animal aggression assumed by game theory models, I determined individual variation in aggressiveness by measuringboth positive phonotactic and acoustic responses to the broadcast stimulus repeatedly over the three-week period in males of Gryllus rubens. Factors tested included amplitude levels of the broadcast stimulus, body size, wing dimorphism, and age. The analyses of the generalized linear mixed models revealed that RHP factors such as age, wing dimorphism, and body size, were not significant for both positive phonotactic and acoustic responses. However, there seemed to be more aggressive responses to higher levels of amplitudes. The significant variance-covariance structures of the models indicated that some individuals consistently aggressive or nonagressive during the experimental periods. Because potential factors for resource values were controlled, and because potential RHP factors would not explain variation in aggressive responses, I concluded that aggressiveness is a personality trait that is not characterized by factors that I tested.