In some cicada species, male calling songs are so loud that they become a nuisance to city dwellers in Korea. To understand the abundance of cicada species in central Korea, we conducted complete enumeration surveys of exuviae in Hyalessa fuscata, Cryptotympana atrata, Meimuna spp, and Graptopsaltria nigrofuscata. Exuviae collection was conducted in three representative habitats in central Korea: metropolitan, suburban, and country. We collected the exuviae twice with a 10-day interval between samplings in August 2010. Resource-weighted density of each species was calculated based on the area and the number of trees. H. fuscata was the dominant species in all three regions. Resource-weighted densities in metropolitan and suburban regions were much higher than those in the country region, due to H. fuscata and C. atrata. The results of the multivariate general linear models showed that region, date, and the interaction between these two variables were all significant for population densities of cicada species. Unlike the resource-weighted densities, the organism-weighted densities that indicated the intensity that an individual had to share its host with others were much larger than tree-weighted densities for cicada exuviae. Furthermore, there was no significant difference in organism-weighted densities among habitats. The difference between resource-weighted and organism-weighted densities implied that larger proportions of trees were not used by cicada juveniles in the country. Thus, the distributions and abundance of tree host species could be an important factor for cicada density in Korea.

An aphid usually stays at one feeding site for a long time for development and reproduction. The green peach aphids, Myzus persicae (Sulzer), feed consistently and regularly throughout all stages of nymphs and adult at one feeding site. In M. persicae, honey dew production, which indicates a state of feeding, occurs at regular intervals within a given stage, and moving, which may be related to escape or dispersal, interrupts feeding, The results of the playback experiments showed that acoustic stimuli with frequencies of 100 and 10000 Hz were effective in inducing feeding repression in M. persicae. That is, HDP occurred less often, and MV occurred more often and longer under acoustic stimuli. In this study, we tested whether the acoustic stimulus effective for inducing feeding suppression decreased reproductive rate in M. persicae. A group of 20 aphids were placed in a host plant and was subject to the acoustic stimulus with two frequency components, 100 and 10000 Hz, for a given time (1, 3, 6, and 12 hours) each day for four days. The result of this experiment showed that the acoustic stimulus did not affect the reproductive rate, regardless of exposure time, in M. persicae.

The green peach aphids, Myzus persicae (Sulzer), feed consistently and regularly throughout all stages of nymphs and adult. That is, honey dew production (HDP), which indicates a state of feeding, occurs at regular intervals within a given stage, and moving (MV), which interrupts feeding, tends to occur scarcely. We used these behaviors to test whether the sound stimuli acted as a stress in this species. We conducted the playback experiment in which acoustic stimuli with a combination of five frequency (100, 500, 1000, 5000, and 10000 Hz) and three intensity levels (66, 78, 90 dB SPL) were presented to all stages of aphids. Under all acoustic stimuli, HDP occurred less often, and MV occurred more often and longer. The results of two-way multivariate ANOVA showed that the stimulus frequency was a significant factor for variation in aphid behaviors in the playback experiment. However, there was no intensity effect on aphid’s behavior. Based on the electrical penetration graph experiment, aphid feeding was frequently stopped and lasted only for short durations under acoustic stimuli. The results of both experiments demonstrated that the acoustic stimuli were effective in inducing feeding suppression in this species. Thus, the acoustic stimuli may be a stressor in the green peach aphid. Furthermore, the behavioral bioassay employed in this study may be used to assess the effect of various stressors on aphids.

Many insects prefer lights with certain spectral properties, and such preferences may be associated with behavioral contexts such as mating, host-finding or dispersal. Lycorma delicatula (Hemiptera: Fulgoridae) is a newly invasive species in Korea and is spreading rapidly. They are diurnal and may rely on visual cues for orientation. We conducted a series of three experiments to determine possible cues of visual orientation in L. delicatula: light/dark choice, UV/white light choice, and spectral preference experiments. Nymphs of the third and final stages as well as adults were used for these three experiments. In the light/dark choice experiment where insects had a choice of white light and darkness in a T-maze, L. delicatula oriented toward the white light, regardless of stage and sex. In a choice of UV and white light, L. delicatula preferred the UV light with 395 to 410 nm in wavelengths, throughout all stages and sex. In the spectral preference experiment where insects had a choice of four monochromatic colors in a circular arena, L. delicatula stayed significantly longer in the blue light than in white, yellow and green lights. Overall, nymphs and adults of L. delicatula oriented toward lights with shorter wavelengths. It is necessary to investigate the behavioral contexts under which L. delicatula prefer the UV and blue lights.

The α-proteobacterium Wolbachia is maternally inherited and is known to induce reproductive distortions in a wide range of insect taxa such as cytoplasmic incompatibility, feminization, male killing and parthenogenesis (PI). When a female is infected with PI-Wolbachia, she does not need a male to produce female offspring, because the female can produce female offspring via gamete duplication without the aid of sperm. However, in the parasitoid wasp Trichogramma kaykai species, Wolbachia infected parthenogenetic females still produce a fraction of male offspring. Offspring sex ratio for 10 days are different according to each T. kaykai isofemale line that is infected with PI- Wolbachia. This may be caused by complex interactions between Wolbachia and the host genetic backgrounds on converting sex of infected eggs.

Final instars of cicada typically emerge from the ground and metamorphose into adults. Exuviae are typically left on tree branches or leaves where metamorphosis takes place. We investigated morphological characteristics of final instar exuviae for the most prevalent species of cicada that occur in urban areas of central Korea: Cryptotympana dubia, Meimuna opalifera, Oncotympana fuscata, and Graptopsaltria nigrofuscata. The characters analyzed were body length, body width, distance between compound eyes, proboscis length, antennal segmentation, femoral structure, and body coloration. The results of Principal Component Analysis for body-size related characters, body length, body width, distance between compound eyes, and proboscis length, revealed that only the first component (PCA1) was significant. The distribution of PCA1 showed that there were three non-overlapping groups: C. dubia, a complex of O. fuscata and G. nigrofuscata, and M. opalifera. Although O. fuscata and G. nigrofuscata were not distinguishable based on size-related characters, these two species differed in femoral structure. That is, the angle between the femur and femoral claw were generally 120° in G. nigrofuscata, whereas it was usually 90° in the other three species. Exuviae of M. opalifera were pale brown and non-polishing, whereas exuviae of three other species were all brown and highly polishing. Therefor, the exuviae of four cicada species can be easily distinguishable based on body size, femoral structure, and body coloration.

The green peach aphid, Myzus persicae (Sulzer), is one of the most important insect pests in the world. We have explored the possibility of using sounds as a stressor to control this species. Five sine wave frequencies (100, 500, 1000, 5000, 10000 Hz) with combination of three intensity (66, 78, 90 dB) were used as acoustic stimuli in the playback experiments. For behavioral bioassay, we examined frequencies of honeydew production (HDP) and wagging behavior, and duration of moving behavior. The HDP occurs regularly during each stage of nymphal or mature period, and rate of the HDP indicates a degree of food consumption. Aphids conduct wagging to determine a host plant or to find a feeding site. The moving behavior may be regarded as dispersal. As results, all acoustic stimuli significantly reduced rate of the HDP and increased rate of the moving behavior. There was a significant effect to induce the moving behavior in the test of 5000 Hz. In addition, the acoustic stimuli using 5000 Hz were the most effective to disturb feeding behavior of M. persicae at an individual level.

Aphids feed on host plants by penetrating the stems or leaves with stylets. The feeding behavior of aphids consists of probing, penetration, salivation, and sap ingestion. To assess the effects of sound on feeding behavior, we monitored the stylet activity of the green peach aphid, Myzus persicae (Sulzer), using electrical penetration graph (EPG). The use of EPG was critical for determining the stage, frequency, and duration of feeding in aphids. We played back four acoustic stimuli of sine waves with frequencies of 100, 500, 1000, and 5000 Hz to adult aphids. When the sound was treated, the frequencies of probing, penetration, and salivation increased, whereas the duration of sap ingestion decreased. The 100 Hz and 500 Hz was significantly effective to disturb ingestion of phloem sap. The results of EPG revealed that the acoustic stimuli may restrict aphid feeding by disturbing sap ingestion.

Male cicadas produce species-specific calling songs to attract conspecific receptive females, and they typically occupy tree trunks or branches during calling. We studied calling site preference in the natural environment for four species of cicada: Cryptotympana dubia, Meimuna opalifera, Oncotympana fuscata, and Meimuna mongolica. Males of M. opalifera tended to sing singly in trees, whereas other species were often observed singing together in one tree. In some cases, two or three individuals of different species sang together in one tree; the only possible pairwise combination not observed was M. mongolica with O. fuscata. Calling sites of the four species differed significantly in distance to the ground and distance to trunk, and both tree height and tree crown were significant factors for calling site preference in multivariate analysis of variance (MANOVA). Distance from calling site to the ground was highest in C. dubia, followed by M. opalifera, M. mongolica, and O. fuscata. The distance from calling site to the trunk was greatest in M. opalifera and differed significantly from those of other species, which 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 niches, thereby avoiding competition for calling sites as much as possible.

Haplodiploid sex determination occurs in a wide range of animals, especially in Hymenoptera, where a fertilized egg develops into a diploid female and unfertilized into a haploid male. However, recent studies on diploid functional males in some wasps suggest that the simple addition of paternal gene by fertilization may not be enough to explain female offspring production in the sex determination system. Recently, activation of sex determination gene (tra) was found to have a pivotal role in determining the sex of Nasonia vitripennis. In N. vitripennis, tra is activated only on the paternal genome (i.e. sperm) not on the maternal counterpart (i.e. egg). Such parent specific activation of a gene is controlled by a epigenetic factor, DNA methylation. However, in Trichogramma kaykai, Wolbachia induces female offspring production without sperm. Therefore all female offspring are clonal to the maternal gene. This violates the role of activated sex determination gene (tra) from sperm in the wasp. We hypothesize that Wolbachia has an ability to activate the gene by demethylation. This hypothesis indicates that the target of sex ratio distorting endosymbionts may be an upstream gene. It will enhance our understanding of evolution of haplodiploid sex determination.

Aphids feed on host plants by penetrating the stems or leaves with stylets. The feeding behavior of aphids consists of probing, penetration, salivation, and sap ingestion. To assess the effects of sound on feeding behavior, we monitored the stylet activity of the green peach aphid, Myzus persicae (Sulzer), using electrical penetration graph (EPG). The use of EPG was critical for determining the stage, frequency, and duration of feeding in aphids. We played back three acoustic stimuli of sine waves with frequencies of 100, 1000, and 5000 Hz to adult aphids. In the sound treatment group, the frequencies of probing, penetration, and salivation increased, whereas the duration of sap ingestion decreased. The results of EPG revealed that the acoustic stimuli may restrict aphid feeding by inhibiting sap ingestion.

The green peach aphid, Myzus persicae (Sulzer), is one of the most important insect pests in the world. We have explored the possibility of using sounds as a control agent in this species. Sine waves with four different frequencies (100, 500, 1000, 5000 Hz) were used as acoustic stimuli in the playback experiments. As a behavioral bioassay, we recorded honey dew production (HDP), wagging, and walking. HDP occurs regularly at each stage of nymphal and adult periods, and the rate of HDP may indicate a degree of food consumption. Aphids conduct wagging to determine a host plant or to find a feeding site. Walking may be regarded as dispersal. All acoustic stimuli significantly reduced the rates of HDP and increased the rates of wagging. There were no significant effect of acoustic stimuli on walking. Based on the bioassay, the acoustic stimulus with 5000 Hz seemed to be the most effective on inhibiting feeding behavior of this aphid species at an individual level.

To understand the evolution and speciation of closely related species, a multiple approach encompassing morphological, behavioral, and genetic analyses is necessary. In Korea, three species of Loxoblemmus crickets occur widely. L. campestris and L. equestris are morphologically indistinguishable, whereas males of L. doenitzi are different from the other two species in head morphology. The genetic analyses using the partial mitochondrial COI sequences showed that L. doenitzi diverged off earlier than L. campestris and L. equestris. The analyses of laboratory recordings revealed that distributions of calling song characters generally overlapped among three cricket species. However, the number of pulses in a chirp was two in L. doenitzi and four in L. campestris, but it was greater than or equal to six in L. equestris. Provided that females make mate choice based on this calling song character, the differentiation in this character may lead to premating reproductive isolation and may have evolved during the speciation proccess in these closely related species.

Lycorma delicatula (White 1845), which has been recently introduced into Korea, is a notorious pest on grapes. This invasive insect has rapidly spread throughout central and southern Korea. To date, we have no behavioral or population genetics information, such as invasion routes and subsequent dispersal rates in Korea, to help understand and control populations of L. delicatula. Here, we have developed 15 novel microsatellite loci for L. delicatula. The isolated loci were polymorphic, with 2 to 19 alleles in 42 individuals from a single population in Cheonan. The analyses revealed that all 42 individuals had different multilocus genotypes with heterozygosity ranging from 0.214 to 0.866. Eleven of the 15 loci did not deviate significantly from Hardy-Weinberg equilibrium. The isolated markers will facilitate population genetic studies of L. delicatula.

The α-proteobacterium Wolbachia pipientis infects a wide range of arthropods and filarial nematodes. Wolbachia is maternally inherited and is known to induce reproductive anomalies such as cytoplasmic incompatibility, feminization, male killing and parthenogenesis induction (PI). Trichogramma kaykai is a tiny wasp that parasitizes on lepidopteran eggs. When a female of the wasp is infected with PI-Wolbachia, the female produces female offspring via gamete duplication without the aid of sperm. As she ages, however, the fraction of male offspring increases. In this study, we investigated the effect of host genetic background on the expression of sex ratio between isofemale lines. Virgin females of six isofemale lines were allowed to lay eggs individually for 10 days. There was the positive relationship between female age and the offspring sex ratio. Furthermore, the sex ratio was significantly different among isofemale lines, implying that the host genetic background had an effect on the sex ratio. Based on the results, evolution of symbiosis in terms of sex ratio and future experimental design are discussed.

evolution of multicellular organisms. Especially in insects, a large amount of bacterial symbionts are illustrated. Among the insect taxonomic group, sap feeding insects, mostly Heteroptera, that feeds on poor nutrient sources from plants, have developed special organs where symbiotic bacteria can reside. The bacteria mainly provide the host insects with some essential amino acids. This has built evolutionarily unbreakable tie between the symbionts and the their hosts. Here we present an obligate symbiont from Lycorma delicatula (Heteroptera: Fulgoridae) being thought to invade the Korean penninsula recently. Based on the partial 16s rRNA gene sequence, the symbiotic bacterium is identified as Cadidatus Sulcia mullleri. The Genbank data indicates that the bacterium is found in various heteropteran families. This may imply the acquisition of the bacterium precedes the hosts' divergence, though there is an alternative postulation. We discuss its distribution in the sap-feeding insects and potential role on survival of L. delicatula and paratransgenetic application of the bacterium in controlling L. delicatula.

Plant penetration by aphids can be monitored electrically by the electrical penetration graph (EPG) technique. To confirm whether some behaviors are correlated to specific graph pattern in EPG, we analyzed the two synchronized data, EPG and video records. We recorded electrical penetration graph (EPG) and behaviors of aphids simultaneously. Then we compared the behaviors of aphids with the recorded EPG waveforms in order to match their visible behaviors and invisible behaviors with stylet. The visible behaviors were categorized for walking, wagging, honeydew production, and reproduction. When the aphids were generally motionless, the EPG denoted feeding-related waveforms (E1, E2, F and G). Whereas, probing waveforms (B and pd) frequently occurred when they were wagging. We aim to present the correlation between observed behaviors and EPG patterns.

The Green Peach aphid, Myzus persicae Sulzer, is one of the most widespread insect pests worldwide. We established the ethogram 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 honeydew production (HDP), walking, wagging, pre-molting and molting. We noted the frequency and the amount of time for each behavior at different nymphal stages. As the nymphal stage increased, the rate of HDP decreased. The HDP seemed to occurred at regular duration and interval in each nymphal stage, while the wagging and walking seemed to be irregular behaviors. When wagging occurred before HDP, the successive HDP was significantly delayed, suggesting that aphids might not feed during wagging. Due to regularity through all nymphal-stages, HPD can be used for a good behavioral indicator in the related bioassay.

The green peach aphid, Myzuspersicae Sulzer, is one of the most important insect pest in the world. To assess the efficiency of sound wave to control aphids, we treated a different combination of intensity (66dB, 78dB, 90dB) and frequency (100Hz, 500Hz, 1000Hz) of acoustic stimulus to the aphids. Then we analyzed aphid’s behaviors occurred in each different combination group of acoustic stimulus and control group, and compared them to confirm the most effective sound. We used honey-dew-production (HDP) for behavioral bioassay, which occurs regularly in each nymphal stage and adult period. The rate of HDP decreased in the whole experimental group when compared with control group (F1,358=79.415,P<0.0001). The most effective acoustic frequency was100Hz in which aphids reduced the rate of HDP to approximately 1/3 times lower than that of control group. The treatments of 1000Hz and 500Hz were effective in the order of appearance. The effect of acoustic stimulus seems irregular in the different intensities, and the highest intensity did not show the strongest effect in each frequency. Consequently, the rate of HDP seemed to be affected by the acoustic frequency more than the intensity.

The impotance of the color stimuli in foraging and host-finding by phytophagous insects are determined by various experiments. Since the lantern fly Lycorma delicatula (Hemiptera: Fulgoroidea) was first reported in Korea in 2006, damages on grapevine are growing annually. It is often observed that nymphs and adults of L. delicatula shift host plants several times during the course of the season. However, information about the dispersal behavior of L. delicatula is scarce. We conducted a series of three experiments to determine possible cues of visual orientation in L. delicatula. In the Light/Dark choice experiment, nymphs had a choice of light and no light conditions in the T-maze. In the color preference experiment, we measured the time spent in one of four colored lights: Yellow, blue, green, and white. In the UV experiment, more than 98% of 3rd and 4th nymphs had a choice of UV (395 - 410 nm) and white light conditions in the T-maze. As a result, 91% individuals in the 1st nymph stage before the first foraging oriented toward the light conditions. And after 7 days, 93% in 1st nymph choose the light arm. But only 63% in 2nd nymph chose the light and light preference was decreased by days. It represents that light response of L. delicatula could change among instars. In the color preference experiment, more than 60% of L. delicatula in 3rd and 4th nymph chose blue light. In the UV experiment, more than 90% of 3rd and 4th nymphs preferred the UV light to the white light. This result is suggested that nymphs are sensitive to light and oriented toward shorter wave light such as blue and green.