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Background: Outbreaks of the casuarina moth, Lymantria xylina Swinehoe (Lepidoptera: Lymantriidae), which is a very important forest pest in Taiwan, have occurred every five to 10 years. This moth has expanded its range of host plants to include more than 65 species of broadleaf trees. LyxyMNPV (L. xylina multiple nucleopolyhedrovirus) is highly virulent to the casuarina moth and has been investigated as a possible biopesticide for controlling this moth. LdMNPV-like virus has also been isolated from Lymantria xylina larvae but LyxyMNPV was more virulent than LdMNPV-like virus both in NTU-LY and IPLB-LD-652Y cell lines. To better understand LyxyMNPV, the nucleotide sequence of the LyxyMNPV DNA genome was determined and analysed. Results: The genome of LyxyMNPV consists of 156,344 bases, has a G+C content of 53.4% and contains 157 putative open reading frames (ORFs). The gene content and gene order of LyxyMNPV were similar to those of LdMNPV, with 151 ORFs identified as homologous to those reported in the LdMNPV genome. Two genes (Lyxy49 and Lyxy123) were homologous to other baculoviruses, and four unique LyxyMNPV ORFs (Lyxy11, Lyxy19, Lyxy130 and Lyxy131) were identified in the LyxyMNPV genome, including a gag-like gene that was not reported in baculoviruses. LdMNPV contains 23 ORFs that are absent in LyxyMNPV. Readily identifiable homologues of the gene host range factor-1 (hrf-1), which appears to be involved in the susceptibility of L. dispar to NPV infection, were not present in LyxyMNPV. Additionally, two putative odv-e27 homologues were identified in LyxyMNPV. The LyxyMNPV genome encoded 14 bro genes compared with 16 in LdMNPV, which occupied more than 8% of the LyxyMNPV genome. Thirteen homologous regions (hrs) were identified containing 48 repeated sequences composed of 30-bp imperfect palindromes. However, they differed in the relative positions, number of repeats and orientation in the genome compared to LdMNPV. Conclusion: The gene parity plot analysis, percent identity of the gene homologues and a phylogenetic analysis suggested that LyxyMNPV is a Group II NPV that is most closely related to LdMNPV but with a highly distinct genomic organisation. [ABSTRACT FROM AUTHOR]

Invasive events by Bemisia tabaci (Gennadius) biotypes in various parts of the world are of continuing interest. The most famous is biotype B that has caused great economic losses globally. In addition, biotype Q has also recently been reported to be a new invasive pest. These two biotypes have been monitored for some time in the Western North Pacific region, but the invasive events and population genetic structures of these two biotypes are still not clear in this region. In this study, the mitochondrial cytochrome oxidase I (COl) gene was used to reconstruct a phylogenetic tree for identifying biotypes B and Q and to study the relationships between invasive events and ornamental plants. Population genetic analyses of mtCOI sequences were also used to study the genetic relationships within and between populations. A combination of a phylogenetic tree and haplotype analysis suggested the recent invasion of biotype Q in this region is related to the international ornamental trade from the Mediterranean region. Low levels of haplotype diversity and nucleotide diversity indicate that the presence of biotypes B and Q in the Western North Pacific region are caused by multiple invasions. Hierarchical analysis of molecular variance supports the hypothesis of multiple invasions. In addition, high sequence identities and low genetic distances within and between populations of the two biotypes revealed that these invasive events occurred recently. The low levels of genetic differentiation revealed by pairwise FST values between populations also suggests the invasions were recent. Therefore, results of this study suggested that biotypes B and Q entered this region through multiple recent invasions. A quarantine of agricultural crops may be necessary to prevent further invasions. [ABSTRACT FROM AUTHOR]

Microsporidiosis (nosema disease) of the honeybee, Apis mellifera, has spread worldwide and caused heavy economic losses in apiculture. We obtained a spore isolate from worker ventriculi of A. mellifera colonies kept on the campus of National Taiwan University and sequenced the ribosomal genes. The entire length of the ribosomal DNA is about 3828?bp and the organization is similar to that of Nosema apis. However, the SSUrRNA, ITS, and LSUrRNA sequences have comparatively low identities with those of N. apis (92, 52, and 89%, respectively) and the SSUrRNA has a 99% identity with Nosema ceranae. These results indicate that this isolate is not N. apis, but N. ceranae. Moreover, the morphological characteristics are identical to those of N. ceranae. These results show that nosema disease of the honeybee, A. mellifera, may not be caused solely by the infection of N. apis. [ABSTRACT FROM AUTHOR]

Distribution and biotypes of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) in eastern Asia are not clear. In this study, B. tabaci was collected from Taiwan and neighboring islands of eastern Asia. Host range records included 51 plant species from 15 families. The molecular marker of the mitochondrial cytochrome oxidase I (COI) gene sequence was used to distinguish biotypes. Phylogenetic analyses indicated three biotypes in eastern Asia: B, Nauru, and An. This is the first molecular evidence to demonstrate the B and An biotypes in Taiwan and that the Nauru and An biotypes are new to China. Therefore, at least the B, Q, Nauru, and An biotypes are now known from China. Phylogenetic trees revealed that the invasion event of the B biotype in Taiwan was recent, and multiple invasions may have occurred due to human trade activities. The B biotype is the most widely distributed biotype in Taiwan. Invasions by the Nauru and An biotypes in Taiwan may have included both natural movements and human trade activities. Otherwise, distributions of the Nauru and An biotypes overlap in Asia, and it is presumed they are closely related. The result supports that the Nauru biotype is of Asian origin, and the An biotype may be of Asian or Australian origin. In addition, the tree topology supports B. tabaci being differentiated into three major clades: the New World, Asia/Australia, and Mediterranean/Asia Minor/African groups. This study also provides some information on the relationships within the B. tabaci species complex. In addition, we hope this study will be helpful to crop protection and appropriate control materials of B. tabaci in eastern Asia. [ABSTRACT FROM AUTHOR]

We briefly described the morphology and transmission pathway of a Spiroplasma sp. isolated from the field cricket, Gryllus bimaculatus in Taiwan, followed by the phylogenetic analysis based on the 16S rRNA gene sequence. The cricket spiroplasma infected the hemolymph, gut, muscle tissues and tracheal cells; therefore we suggest that the pathogen invaded tissues and organs from the hemolymph through the tracheal system and the endoplasmic reticular system. Based on 16S rRNA gene sequences and the phylogeny, this spiroplasma was most closely related to Spiroplasma platyhelix (Identity = 95%) isolated from the dragonfly Pachydiplax longipennis and belongs to the Ixodetis clade. [ABSTRACT FROM AUTHOR]

One unique feature of the shrimp white spot syndrome virus (WSSV) genome is the presence of a giant open reading frame (ORF) of 18,234 nucleotides that encodes a long polypeptide of 6,077 amino acids with a hitherto unknown function. In the present study, by applying proteomic methodology to analyze the sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile of purified WSSV virions by liquid chromatography-mass spectrometry (LC-MS/MS), we found that this giant polypeptide, designated VP664, is one of the viral structural proteins. The existence of the corresponding 18-kb transcript was confirmed by sequencing analysis of reverse transcription-PCR products, which also showed that vp664 was intron-less. A time course analysis showed that this transcript was actively transcribed at the late stage, suggesting that this gene product should contribute primarily to the assembly and morphogenesis of the virion. Several polyclonal antisera against this giant protein were prepared, and one of them was successfully used for immunoelectron microscopy analysis to localize the protein in the virion. Immunoelectron microscopy with a gold-labeled secondary antibody showed that the gold particles were regularly distributed around the periphery of the nucleocapsid with a periodicity that matched the characteristic stacked ring subunits that appear as striations. From this and other evidence, we argue that this giant ORF in fact encodes the major WSSV nucleocapsid protein. [ABSTRACT FROM AUTHOR]