Search

To monitor and control the Japanese orange fly Bactrocera tsuneonis (Miyake) (Diptera: Tephritidae), it is important to determine their dispersal ability. Therefore, to determine the genetic structure of this species, we developed microsatellite markers at 17 loci for B. tsuneonis. A total of 80 adult females and males randomly collected from abandoned orchards in the Oita and Yamaguchi Prefectures, in the western part of Japan, were used for polymorphism analysis using the microsatellite markers. The average number of alleles was 2.65 for the 17 loci, in which two loci did not show polymorphism. The expected heterozygosity ranged from 0 to 0.663, although the observed heterozygosity was relatively low between 0 and 0.105. The null allele frequencies varied among populations. Moreover, no polymorphism was found in the three larval populations collected in the Oita Prefecture. These results suggested a high degree of inbreeding for this species. Significant genetic differentiation between females and males of the same population was not observed, although it was observed between the Oita and Yamaguchi populations. A bottleneck effect was detected in Yamaguchi but not in Oita, and this is congruent with the history of an expanding distribution in this species. These markers could be used for population discrimination and to expand the geographic history of this species, potentially contributing to the pest management of B. tsuneonis. [ABSTRACT FROM AUTHOR]

BACKGROUND The investigation of molecular mechanisms and evolution of resistance to insecticides is an ongoing challenge, as researchers must provide guidance to manage the resistance to achieve sustainable production in agriculture. Predicting, monitoring, and managing insecticide resistance requires information on the origins, selection, and spread of resistance genes. The resistance of Plutella xylostella (L.) against diamide insecticides is becoming an increasingly severe problem in east and southeast Asia. In this study, the evolution of resistance was investigated using a resistance allele [ryanodine receptor (RyR); G4946E mutation] and its flanking regions, as well as mitochondrial cytochrome c oxidase subunit I (mtCOI). RESULTS: The sequences of the flanking region of the G4946E and mtCOI suggested that the G4946E mutation has a key role in resistance. Furthermore, the G4946E mutation has multiple origins, and congenic resistant mutations have spread across east and southeast Asia, despite substantial geographical barriers. In addition, the susceptibility of field populations partially recovered during winter, based on the observed decrease in the G4946E (resistant allele) frequency. Finally, the resistance level indexed by the frequency of the E4946 allele was significantly lower in non‐overwintering regions than in overwintering regions. CONCLUSION: The information of the present study is useful to monitor resistance using molecular markers and to develop strategies to delay the evolution of diamide resistance. [ABSTRACT FROM AUTHOR]

Environmental risk assessments (ERAs) are required before utilizing exotic arthropods for biological control (BC). Present ERAs focus on exposure analysis (host/prey range) and have resulted in approval of many specialist exotic biological control agents (BCA). In comparison to specialists, generalist arthropod BCAs (GABCAs) have been considered inherently risky and less used in classical biological control. To safely consider exotic GABCAs, an ERA must include methods for the analysis of potential effects. A panel of 47 experts from 14 countries discussed, in six online forums over 12 months, scientific criteria for an ERA for exotic GABCAs. Using four case studies, a three-tiered ERA comprising Scoping, Screening and Definitive Assessments was developed. The ERA is primarily based on expert consultation, with decision processes in each tier that lead to the approval of the petition or the subsequent tier. In the Scoping Assessment, likelihood of establishment (for augmentative BC), and potential effect(s) are qualitatively assessed. If risks are identified, the Screening Assessment is conducted, in which 19 categories of effects (adverse and beneficial) are quantified. If a risk exceeds the proposed risk threshold in any of these categories, the analysis moves to the Definitive Assessment to identify potential non-target species in the respective category(ies). When at least one potential non-target species is at significant risk, long-term and indirect ecosystem risks must be quantified with actual data or the petition for release can be dismissed or withdrawn. The proposed ERA should contribute to the development of safe pathways for the use of low risk GABCAs. [ABSTRACT FROM AUTHOR]

To develop an augmentative biological control programme for Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and Thrips palmi Karny (Thysanoptera: Thripidae) using Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), we studied the life history traits of a Japanese strain of N. tenuis reared on B. tabaci and T. palmi in controlled environments. The lower developmental threshold during the nymphal period was far higher than those estimated for Spanish, Moroccan, and Iranian strains, indicating that the Japanese strain is better adapted to higher temperatures than the other three strains tested. The intrinsic rate of increase rm was highest at 30 °C and lowest at 20 °C. The rm value for individuals reared on T. palmi at 25 °C was lower than that for individuals reared on B. tabaci at the same temperature. Implications of these results for the biological control of B. tabaci and T. palmi in greenhouses are discussed. [ABSTRACT FROM AUTHOR]

We examined the utility of a non-destructive DNA extraction method for identification of Bradysia odoriphaga Yang and Zhang, 1985 (Diptera: Sciaridae) based on PCR using species-specific primers and DNA barcoding targeting the mitochondrial cytochrome c oxidase subunit I gene. Using species-specific primers, PCR success rates for adults and pupae were more than 90%, while those for larvae and eggs were 51% and 13%, respectively. The success rates of PCR for DNA barcode region were slightly higher than those of PCR using species-specific primers. In all sequenced samples, the 658 bp of sequences in the DNA barcode region were identical to the sequences from B. odoriphaga that we previously obtained using a destructive DNA extraction method. The adults were successfully identified based on morphological characters after non-destructive DNA extraction. The non-destructive DNA extraction method examined in this study is useful for the identification of adults and pupae of B. odoriphaga collected in the fields. [ABSTRACT FROM AUTHOR]

Minute pirate bugs of genus Orius (Wolff) are known important generalist predators of microinvertebrate pests and are therefore useful in many agricultural contexts. Effective sampling methods are thus of great importance to monitor Orius spp. populations. Sticky traps are one such sampling method; however, trap color must be carefully selected for the target insect species. In this study, we examined the most suitable sticky trap color (i.e. white, blue, or yellow) to capture Orius spp. individuals in eggplant Solanum melongena (Linnaeus) (Solanales: Solanaceae), Italian ryegrass Lolium multiflorum (Lamarck) (Poales: Poaceae), soybean Glycine max (Linnaeus) (Fabales: Fabaceae), and white clover Trifolium repens (Linnaeus) (Fabales: Fabaceae) fields. More Orius spp. adults were caught on blue and white traps than on yellow traps. The white traps also caught other insects, which hampered the counting of Orius spp. individuals and, therefore, reduced trapping efficiency. In addition, seasonal prevalence investigations showed that blue sticky traps had similar patterns to those of field observations. Thus, as the blue sticky trap can avoid capturing nontarget insects, we concluded that blue was the most suitable trap color for monitoring Orius spp. In addition, because blue sticky traps are more efficient and less-labor intensive, they can be useful as an alternative to field observations. [ABSTRACT FROM AUTHOR]

A new pest of Welsh onion and carrot, the dark-winged fungus gnat, Bradysia sp., was found in the northern region of Saitama Prefecture, Japan. DNA sequences of mitochondrial cytochrome c oxidase subunit I revealed that Bradysia sp. is identical to the Chinese chive gnat, Bradysia odoriphaga Yang and Zhang. This suggests that Bradysia sp. may be an invasive species that originates from continental East Asia. Direct sequencing analysis and PCR using a species-specific primer were found to be useful tools for discriminating Bradysia sp. from other native Japanese fungus gnats, such as Bradysia impatiens (Johannsen), Pnyxia scabiei (Hopkins), and Lycoriella ingenua (Dufour). [ABSTRACT FROM AUTHOR]

We designed a species-specific primer pair for Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae). In polymerase chain reaction (PCR), these primers amplified a fragment (118 bp) of the internal transcribed spacer 1 region of the ribosomal RNA gene of the target species but not those of any of the tested species of Lepidoptera (except H. armigera), Hemiptera, Thysanoptera, Araneae, and Coleoptera. Using the designed primer pair, we also analyzed the gut contents of Araneae and Orius spp. (Hemiptera: Anthocoridae) that were collected in estivo-autumnal tomato, Solanum lycopersicum L. (Solanaceae) and eggplant, Solanum melongena L. (Solanaceae), fields, respectively. Amplified fragments of H. armigera DNA were detected in seven of nine Araneae and in two of 183 Orius spp. individuals. Therefore, we confirmed that Araneae and Orius spp. prey on H. armigera in the field. In a laboratory experiment, we determined the period in which H. armigera consumed by O. strigicollis (Poppius) (Hemiptera: Anthocoridae) can be detected. The detection rate of H. armigera in the gut of O. strigicollis fed with a first-instar larva of H. armigera was 100 % at 8 h after feeding, 33 % at 12 h, and 17 % at 16 and 20 h; H. armigera DNA was undetectable at 24 h. [ABSTRACT FROM AUTHOR]

PCR is a useful technique to detect mutations in insecticide resistance genes or to analyze gene flow in pest insects. Plutella xylostella (L.) is one of the most important pests that develops insecticide resistance, and it is desirable to make efficient use of specimens obtained from pheromone-baited sticky traps. To estimate the period of DNA preservation in moths collected on traps in the field, we analyzed the probability of PCR success using mtCOI and microsatellite primers. The results suggested that moths caught by sticky traps would maintain DNA of sufficient quality for PCR analysis when the trap was changed weekly. DNA degradation was greater in moth specimens on traps exposed to ultraviolet (UV) radiation in direct sunlight than in the shade. DNA degeneration was greater in moths exposed to direct sunlight in summer than in winter. Therefore, setting traps in shade or using a UV light-shielding barrier over the trap might be an effective approach to prevent DNA degradation. [ABSTRACT FROM AUTHOR]

The frequent application of acaricides is necessary for the management of the two-spotted spider mite Tetranychus urticae because of its high tendency to rapidly develop resistance to the used chemicals. Here, we aimed to investigate the underlying mechanisms of the simultaneous development of acaricide resistance in multiple mite populations and assessing their genetic structure. To this end, we used four microsatellite loci to analyze the genetic structure of 11 T. urticae populations collected from eight commercial apple orchards, one apple tree nursery, one experimental apple orchard, and one hop farm. In the commercial orchards and nursery, acaricides were used frequently every year; in the experimental apple orchard, acaricides were not used after transplantation; and in the hop farm, a propylene glycol emulsion was used periodically. Allelic richness and heterozygosity were not highly different among the orchards. In most mite populations, the inbreeding coefficients were significantly higher than zero, indicating frequent occurrence of inbreeding. Inbreeding coefficient values were higher in populations collected from commercial orchards, suggesting that acaricide applications increased the frequency of inbreeding in mite populations. Overall, the results showed that the recurrent chemical treatments have a strong bottleneck effect on T. urticae populations, which probably accelerates the development of acaricide resistance. [ABSTRACT FROM AUTHOR]

RATIONALE: Discrimination of spider mite species is still performed using morphological information, although DNA and other biological approaches have been attempted for identification purposes. These techniques need much time, are expensive, and require specialist staff. As an alternative, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) analysis is applied for rapid discrimination of spider mite species. METHODS: Spider mites were analyzed using MALDI-TOFMS after extraction with 70% formic acid and acetonitrile. A single spider mite was also analyzed directly on double-sided carbon tape. A dendrogram was compiled from theMS data. RESULTS: Evolutionarily close and morphologically similar spider mites, the Kanzawa (Tetranychus kanzawai) and the two-spotted (T. urticae) spider mites, as well as three other related species of spider mites, could be discriminated by mass fingerprints. Although female adults were mainly used in this report, male adults and nymphs showed almost the same mass fingerprints and were not considered to affect discrimination capability. A single spider mite on double-sided carbon tape was analyzed directly by MALDI-TOFMS. CONCLUSIONS: Spider mites could be analyzed directly by MALDI-TOFMS, with evolutionarily and morphologically closely related spider mites showing different mass fingerprints, allowing for their identification. [ABSTRACT FROM AUTHOR]

The spider mite sub-family Tetranychinae includes many agricultural pests. The internal transcribed spacer (ITS) region of nuclear ribosomal RNA genes and the cytochrome c oxidase subunit I (COI) gene of mitochondrial DNA have been used for species identification and phylogenetic reconstruction within the sub-family Tetranychinae, although they have not always been successful. The 18S and 28S rRNA genes should be more suitable for resolving higher levels of phylogeny, such as tribes or genera of Tetranychinae because these genes evolve more slowly and are made up of conserved regions and divergent domains. Therefore, we used both the 18S (1,825–1,901 bp) and 28S (the 5′ end of 646–743 bp) rRNA genes to infer phylogenetic relationships within the sub-family Tetranychinae with a focus on the tribe Tetranychini. Then, we compared the phylogenetic tree of the 18S and 28S genes with that of the mitochondrial COI gene (618 bp). As observed in previous studies, our phylogeny based on the COI gene was not resolved because of the low bootstrap values for most nodes of the tree. On the other hand, our phylogenetic tree of the 18S and 28S genes revealed several well-supported clades within the sub-family Tetranychinae. The 18S and 28S phylogenetic trees suggest that the tribes Bryobiini, Petrobiini and Eurytetranychini are monophyletic and that the tribe Tetranychini is polyphyletic. At the genus level, six genera for which more than two species were sampled appear to be monophyletic, while four genera (Oligonychus, Tetranychus, Schizotetranychus and Eotetranychus) appear to be polyphyletic. The topology presented here does not fully agree with the current morphology-based taxonomy, so that the diagnostic morphological characters of Tetranychinae need to be reconsidered. [ABSTRACT FROM AUTHOR]

We studied the genetic diversity of Hygrobates fluviatilis collected from two different types of habitats (springs and streams) based on 653 bp sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene. Among 39 individuals collected from Iran, the Netherlands and Germany, 29 haplotypes were found. Deviation between the two types of habitats was not found, suggesting frequent gene flow between these habitats. Haplotypes from the same countries formed each clade, and a large genetic distance was found between the samples from different countries, which poses a question about the existence of cryptic species in the populations of this species. [ABSTRACT FROM AUTHOR]

Species identification is a basic issue in biosecurity. Polymera.se chain reaction (PCR) followed by restriction fragment length polymorphism (BFLP) is a useful molecular diagnostic tool for species identification. However, the lack of transferability of data has been a serious shortcoming of this method. A RFLP catalog, i.e., a graph of PCR-RFLP patterns expected from sequence data, was devised as a tool to facilitate PCR-RFLP data sharing among laboratories. Twelve species of Tetranychus spider mites have been recorded in Japan to date. In this study, we analyzed DNA sequences of the internal transcribed spacer (ITS) region in nuclear ribosomal DNA of 11 Tetranychus species. For the species identification using PCR-RFLP, we chose six candidates from 131 restriction endonucleases and developed an RFLP catalog of all known Japanese Tetranychus species except Tetranychus neocaleclonicus André. The RFLP catalog revealed that most Tetranychus species had diagnostic restriction fragments. The RFLP catalog is transferable and simple molecular diagnostic tool, and it has the ability to add more species and newly found intraspecific variations. Therefore, we believe that the RFLP catalog will contribute to biosecurity as a practical diagnostic tool for species identification of spider mites. [ABSTRACT FROM AUTHOR]

We developed multiplex polymerase chain reaction methods to identify five Orius (Heteroptera: Anthocoridae) species that occur commonly in Japan: Orius sauteri, Orius minutus, Orius strigicollis, Orius nagaii, and Orius tantillus. The method amplified internal transcribed spacer 1 of the nuclear ribosomal DNA by using five primers simultaneously and produced species-specific banding patterns upon agarose gel electrophoresis. Reliability of the method was tested for 350 individuals of 23 strains, and consistent results were obtained. Dichotomous keys are also provided for easy and quick species identification. [Copyright &y& Elsevier]

Genetic markers were searched using PCR with 40 kinds of decanucleotide primers to investigate DNA polymorphism in Panonychuscitri. A region consisting of a variable number of CT tandem repeats (microsatellite) was found in a fragment amplified with the OPB10 primer. The microsatellite differed in size by ca. 100 bp among several P. citri populations screened and was derived from at least seven alleles. This region was characteristic of P. mori and P. osmanthi, but was lacking in P. ulmi. The flanking regions were highly conserved among these species. [ABSTRACT FROM AUTHOR]

Establishing effective methods of rearing natural enemies can facilitate basic and applied studies on their use in biological pest control. Insect predators of four genera ( Oligota , Stethorus , Scolothrips and Feltiella ) and predatory mites are important natural enemies of pest spider mites in agricultural crops. However, fewer laboratory studies have focused on insect predators due to the difficulty of their rearing. To establish a simple rearing method, we compared the rearing efficiency of four insect predator groups ( Oligota spp., Stethorus spp., Scolothrips takahashii and Feltiella acarisuga ) on potted komatsuna plants ( Brassica rapa ) infested with the two-spotted spider mite Tetranychus urticae , a new plant-prey combination for predator rearing in large containers, with that on potted bean plants infested with T. urticae . Significantly more Feltiella acarisuga and Stethorus spp. adults were obtained when offered T. urticae -infested komatsuna plants than infested lima bean or kidney bean plants ( Feltiella : 70, 9 and 0 adults, respectively; Stethorus : 72, 3 and 0 adults, respectively). More adults of S. takahashii and Oligota spp. were obtained on T. urticae -infested komatsuna than on infested lima bean ( Scolothrips : 181 and 27 adults, respectively; Oligota : 152 and 16 adults, respectively). Many individuals of all four predator groups such as larvae of F. acarisuga and Stethorus spp. were entrapped by the hooked trichomes on lima and kidney bean leaves, whereas no entrapped predators were observed on the komatsuna plants. These results show potted komatsuna plants infested with T. urticae to be suitable for efficient rearing of all four predator groups. [ABSTRACT FROM AUTHOR]