Development of Sex Pheromone Trap for Monitoring Matsumuraeses falcana (Walshingham) (Lepidoptera: Tortricidae)

This study was carried out to find out an effective formulation for monitoring the soybean podborer, Matsumuraeses falcana (Walshingham), using its sex pheromone in Korea. A 1 : 1 : 1 mixture of (E)-8-dodecenyl acetate (E 8–12: Ac), (E,E)-8,10-dodecadienyl acetate (E 8 E 10–12: Ac) and (E,Z)-7,9-dodecadienyl acetate (E 7 Z 9–12: Ac) was an effective composition in monitoring M. falcana. A binary mixture of E 8–12: Ac and E 8 E 10–12: Ac was essential to attract M. falcana male moths. E 7 Z 9–12: Ac showed a synergistic effect on the attractiveness of 1 : 1 mixture of E 8–12: Ac and E 8 E 10–12: Ac. These chemicals alone showed little or no attractiveness to M. falcana. The sticky-typed wing trap baited with sex pheromone captured significantly more males than the water-pan trap. Trap catches within a soybean field were much more than those in perimeter trap. The trap-baited with sex pheromone gave a distinct fluctuation pattern of male catches throughout the flight seasons. Therefore, it can be expected that pheromone-baited trap provides a simple tool for monitoring the soybean podborer, M. falcana in Korea.     

Economic Thresholds of Western Flower Thrips (Thysanoptera: Thripidae) for Unripe Red Pepper in Greenhouse

This study was conducted to develop economic thresholds of western flower thrips (Frankliniella occidentalis Pergande) for unripe red pepper in greenhouses. To investigate the relationship between the density of thrips and resulting damages, experimental plots with five treatments (0, 4, 16, 48, 96 adults per plot) as initial release densities were established at the National Institute of Agricultural Science and Technology, Suwon, Korea, in 2004. Western flower thrips density was monitored using flower samplings and yellow sticky trap (8×13 cm) counts. Western flower thrips density was directly related to increased numbers of damaged fruits and reduced fruit yield. The number of marketable fruits produced decreased as the thrips densities increased. The major damage to pepper fruits caused by thrips was cosmetic scars that resulted from immature feeding. When flower samples or yellow trap caches were used to determine the density of thrips, which were collected on a previous sampling date, thrips densities were determined to be related to the percentage of fruits that were damaged, and a significant relationship was found for the flower samples (y = 0.3219x + 1.0792, r² = 0.8640 and for trap catches (y = 11.9209 log(x) −2.158, r² = 0.8306). The economically-tolerable ratio of damaged fruits based on control cost and market values under current greenhouse cultivation was estimated as 3.4 to 8.0%. Economic thresholds of western flower thrips ranged from 0.7 to 2.1 adults or nymphs per flower, and 2.3 to 5.7 adults per four-day sticky card count.     

Identification of egg parasitoids of rice leafhoppers and planthoppers (Hemiptera: Cicadellidae and Delphacidae) of economic importance in Taiwan,part 1: Mymaridae (Hymenoptera)

Fairyfly egg parasitoids (Hymenoptera: Mymaridae) of rice leafhoppers and planthoppers (Hemiptera: Cicadellidae and Delphacidae) known from Taiwan are identified taxonomically, keyed, and illustrated. Their host associations are determined by rearings using sentinel eggs of mainly four key pest species. The previously published records of such egg parasitoids in Taiwan are critically analyzed in the unfortunate absence of almost any voucher specimens. Three species of Mymaridae are shown to be the predominant egg parasitoids of one leafhopper and three planthopper major pests of rice in Taiwan: Anagrus (Anagrus) incarnatus Haliday of the green rice leafhopper Nephotettix cincticeps (Uhler) and the delphacids Laodelphax striatella (Fallén) (small brown planthopper), Nilaparvata lugens (Stål) (brown planthopper), and Sogatella furcifera (Horváth) (whitebacked planthopper), as well as Gonatocerus aegyptiacus Soyka and Mymar taprobanicum Ward of N. cincticeps. The zig-zag leafhopper Maiestas dorsalis (Motschulsky), which is also common in paddy fields, is newly recorded as a host for A. incarnatus, G. aegyptiacus, Lymaenon litoralis (Haliday), and M. taprobanicum. Additional new records of some other Mymaridae in Taiwan, mostly from the rice field agroecosystems, are indicated. Litus assamensis Rehmat and Anis, syn. nov. from India, is synonymized with L. sutil Triapitsyn and Berezovskiy from Thailand, which is also newly recorded from Taiwan.     

Exploring the non-coding regions in the mtDNA of some honey bee species and subspecies

The sequence of the DNA contains coding and non-coding regions. The role of the non-coding regions is not known and is hypothesized to maintain the structure of the DNA. This study aimed to investigate the structure of the non-coding sequences in honey bees utilizing bioinformatics. The non-coding sequences of the mtDNA of three honey bee species Apis dorosata, Apis florea, Apis cerana, and ten subspecies of Apis mellifera were investigated. Different techniques were utilized to explore the non-coding regions of these bees including sequence analysis, phylogenetic relationships, enzymatic digestion, and statistical tests. Variations in size and sequences of nucleotides were detected in the studied species and subspecies, but with the same nucleotide abundance (i.e. nucleotides A were more than T and nucleotides G were less than C). The phylogenetic tree based on the non-coding regions was partially similar to the known phylogenetic relationships between these bees. The enzymatic digestion using four restriction enzymes confirmed the results of the phylogenetic relationships. The statistical analysis based on numerical codes for nucleotides showed the absence of significant variations between the studied bees in their sequences in a similar way to results of neutrality tests. This study suggests that the non-coding regions have the same functional role in all the studied bees regardless of the number of nucleotides, and not just to maintain the structure of the DNA. This is approximately the first study to shade lights on the non-coding regions of the mtDNA of honey bees.     

Nitidulidae (Coleoptera: Cucujoidea) of Vanuatu

A checklist to the Nitidulidae of Vanuatu is provided based on a combination of historical museum specimens and recent field expeditions. A dichotomous key to the described species recorded from the country is provided. Specific data per island is given where available; in addition, broader distributions are outlined for each described taxon. Several undescribed taxa are listed but not described until further work can be done in the region. A discussion of the movement of invasive Nitidulidae throughout Vanuatu is also included with an emphasis on the relationship between increases in human movement and commerce and the number of invasive species present. This discussion is extended to other islands in Vanuatu that have not yet been sampled in an attempt to predict the presence of invasive species.     

Olfactory responses of Aethina tumida murray (Coleoptera: Nitidulidae) to some major volatile compounds from hive materials and workers of Apis mellifera

The small hive beetle (Aethina tumida Murray) is an invasive pest affecting honey bee colonies. The beetles are known to be attracted to volatiles from hive products and honey bees like Apis mellifera L. Previously we reported the presence of five major compounds from the volatile extracts of hive materials; ethyl linolenate and ethyl palmitate from pollen dough, oleamide and tetracosane in fermenting honey, and oleamide and 5-methyl-2-phenyl-1H-indole from A. mellifera worker bees. This study tested the attractiveness of the aforementioned five volatile organic compounds to small hive beetles (SHB) by Y-tube olfactometric bioassay. Ethyl linolenate was highly attractive to both male and female adults of SHB. Ethyl palmitate was attractive to SHB only at higher concentration (0.01–01 mg/ml). Interestingly, tetracosane, 5-methyl-2-phenyl-1H-indole and oleamide were repellent for SHB of both sexes, but ethyl linolenate and ethyl palmitate as components of honey bee brood pheromone attracted SHB. The results highlight that SHB differentially utilizes volatile chemicals from hive materials and honey bees as cues to locate honey bee hives.     

Population genetic characterization of the endangered silver skipper,Leptalina unicolor (Lepidoptera: Hesperiidae), using novel microsatellite markers and mitochondrial DNA gene sequences

The silver stripped skipper, Leptalina unicolor, is listed as an endangered species with a paucity of leftover populations in Korea. Prior population genetic analysis is essential for the establishment of effective conservation strategies. In the present study, we investigated the genetic diversity and the relationships of L. unicolor populations in Korea using 12 newly developed L. unicolor-specific microsatellite markers and two mitochondrial DNA (mtDNA) sequences (a total of 1283 bp from COI and CytB). Due to the endangered status and rarity, a total of 33 individuals from two localities in Gangwon-do Province (Seohwa and Girin) and one in Gyeongsangnam-do Province (Danjang) were sampled. The concatenated mtDNA sequences revealed very low genetic diversity in each population, with only one to three independent haplotypes per population. F_ST, principal coordinate analysis, and independent structural analysis of the concatenated mtDNA sequences and the 12 microsatellite loci developed in this study showed that each L. unicolor population in Korea is nearly completely isolated, although inbreeding has not yet occurred. Long-term conservation habitat recovery that increases the available population appears to be important in the prevention of genetic drift and inbreeding, which occur in small isolated populations and reduce the viability of populations under fluctuating environmental conditions.     

Sex pheromone composition of the variegated cutworm,Peridroma saucia (Lepidoptera: Noctuidae), in Korea

This study was conducted to investigate the sex pheromone composition of the variegated cutworm (Peridroma saucia Hübner) in Korea. The sex pheromone components of P. saucia were identified as (Z)-9-tetradecenyl acetate (Z9-14:Ac) and (Z)-11-hexadecenyl acetate (Z11-16:Ac) through GC-EAD and GC–MS analysis. EAG tests of the male antennae revealed that the Z9-14:AC exerted significantly larger responses than other compounds. The female moths primarily called and copulated between 6 h and 7 h after the lights off, and the ratio of two pheromone components, Z9-14:Ac and Z11-16:Ac, in the sex pheromone gland during this period was 1:2.1 to 1:2.4. In the field trapping studies, a large number of male moths were caught in the traps baited with the mixtures of Z9-14:Ac and Z11-16:Ac at the ratios ranging from 2.3:1 to 1:4, with the highest trap catches at 1:1 to 1:2.3 ratios of the two components. The seasonal flight activities of P. saucia monitored by using pheromone lures revealed complicated patterns in Korea. Specifically, the first flight period was spread over a long period and irregular, while the second flight period differed among the localities examined.     

Enhancement of Riptortus clavatus (Thunberg) (Hemiptera: Alydidae) egg parasitism by a component of the bug's aggregation pheromone

Egg parasitism of the bean bug, Riptortus clavatus (Thunberg) (Hemiptera: Alydidae), was surveyed using individual egg bags in a sweet persimmon orchard and at Gyeongsang National University (GNU) campus, Korea in 2006. The effect of (E)-2-hexenyl (Z)-3-hexenoate (E2HZ3H), one component of R. clavatus aggregation pheromone, on the parasitism enhancement was tested at GNU campus and in a soybean field in 2005 and 2006, respectively. In 2006, two egg parasitoid species, Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae), emerged from R. clavatus eggs. Parasitism by O. nezarae was 9.4–48.3% in mid August to mid September in GNU campus and 6.7–30.0% at the orchard. Total parasitism by G. japonicum (2.5%) at both sites throughout the experimental period was lower than that by O. nezarae (12.5%). This survey revealed nearly no activity of the two species after October at both sites. G. japonicum was solitary and O. nezarae could be either solitary or gregarious. From a single R. clavatus egg, one female or one male G. japonicum emerged. However, an average of 4.3 O. nezarae emerged from one host egg. It took 12.6 d for G. japonicum and 12.0 d for O. nezarae to emerge from R. clavatus eggs in the laboratory. Treatment with E2HZ3H increased parasitism by O. nezarae in both years, but did not increase parasitism by G. japonicum. This suggests that E2HZ3H can be used as a kairomone to reduce the density of R. clavatus in the fields where natural parasitism by O. nezarae is high.