Evidence for Range Expansion and Origins of an Invasive Hornet Vespa bicolor (Hymenoptera, Vespidae) in Taiwan, with Notes on Its Natural Status.

The invasive alien species (IAS) Vespa bicolor is the first reported hornet that has established in Taiwan and is concerning as they prey on honeybee Apis mellifera, which leads to colony losses and public concerns. Thus, the aim of this study was to assess the current status of V. bicolor abundance, dispersal, and impact and to trace the origins of Taiwan's V. bicolor population. Our studies took place in five areas in northern to central Taiwan. We used mtDNA in the phylogenetic analyses. Field survey and ecological niche modeling (ENM) were used to understand the origins and current range of the invasive species. Two main subgroups of V. bicolor in the phylogenetic tree were found, and a clade with short branch lengths in Southeastern China and Taiwan formed a subgroup, which shows that the Taiwan population may have invaded from a single event. Evidence shows that V. bicolor is not a severe pest to honeybees in the study area; however, using ENM, we predict the rapid dispersion of this species to the cooler and hilly mountain areas of Taiwan. The management of V. bicolor should also involve considering it a local pest to reduce loss by beekeepers and public fear in Taiwan. Our findings highlight how the government, beekeepers, and researchers alike should be aware of the implications of V. bicolor's rapid range expansion in Taiwan, or in other countries.

Flower-visiting insects of genus Melastoma (Myrtales: Melastomataceae) at the Fushan Botanical Garden, Taiwan.

BACKGROUND: We investigated the diversity and behaviour of insects that visit flowers of four native Melastoma (Family Melastomataceae) species of Taiwan and a horticultural hybrid Melastoma species at the Fushan Botanical Garden, Taiwan biweekly from May to August 2020. Visits of flower-visiting insects were classified into seven behavioural categories, based on the insects' behaviour and positions on the flower. The data are further assigned into four insect-flower interactions, namely pollination, herbivory, commensalism and neutralism. Our goal is to provide baseline data of insect-plant interactions of Melastoma, which is a common, but understudied plant genus in the country. NEW INFORMATION: A total of 1,289 visits to flowers were recorded by at least 63 insect morphospecies belonging to seven orders. The number of insect species recorded per Melastoma species ranged from 9 to 39. Visiting, sonication and passing were the three most frequently recorded types of behaviour, collectively accounting for 90.2% (n = 1,240) of the total observations. Pollination was the most dominant insect-flower interaction, accounting for 70.2% of the total observations, followed by neutralism (20.0%), herbivory (6.3%) and commensalism (3.5%). Sweat bees of the genera Lasioglossum and Maculonomia (Hymenoptera: Halictidae) are considered key pollinators to Melastoma species in Fushan Botanical Garden, based on their high number of visits and sonication behaviour. Our study provides the first list of insects that visit the flowers of all Taiwan's known Melastoma species and description of their interactions with the plants.

Genetic Variation in Native Populations of the Laurel Wilt Pathogen, Raffaelea lauricola, in Taiwan and Japan and the Introduced Population in the United States.

Laurel wilt is a vascular wilt disease caused by Raffaelea lauricola, a mycangial symbiont of an ambrosia beetle, Xyleborus glabratus. The fungus and vector are native to Asia but were apparently introduced to the Savannah, GA, area 15 or more years ago. Laurel wilt has caused widespread mortality on redbay (Persea borbonia) and other members of the Lauraceae in the southeastern United States, and the pathogen and vector have spread as far as Texas. Although believed to be a single introduction, there has been no extensive study on genetic variation of R. lauricola populations that would suggest a genetic bottleneck in the United States. Ten isolates of R. lauricola from Japan, 55 from Taiwan, and 125 from the United States were analyzed with microsatellite and 28S rDNA markers, and with primers developed for two mating-type genes. The new primers identified isolates as either MAT1 or MAT2 mating types in roughly equal proportions in Taiwan and Japan, where there was also high genetic diversity within populations based on all the markers, suggesting that these populations may have cryptic sex. Aside from a local population near Savannah and a single isolate in Alabama that had unique microsatellite alleles, the U.S. population was genetically uniform and included only the MAT2 mating type, supporting the single introduction hypothesis. This study suggests the importance of preventing a second introduction of R. lauricola to the United States, which could introduce the opposite mating type and allow for genetic recombination.

Establishment of Vespa bicolor in Taiwan (Hymenoptera: Vespidae).

The establishment of a hornet, Vespa bicolor F., in Taiwan was confirmed based on successful field collection of adults of both sexes and two subterranean colonies. Information on nesting habitat, nest measurement, and colony composition of this species are provided in this article. V. bicolor is the ninth hornet species ever recorded from Taiwan. Possible pathway for the introduction of this alien species is also discussed.

Isolations from the redbay ambrosia beetle, Xyleborus glabratus, confirm that the laurel wilt pathogen, Raffaelea lauricola, originated in Asia.

The laurel wilt pathogen Raffaelea lauricola was hypothesized to have been introduced to the southeastern USA in the mycangium of the redbay ambrosia beetle, Xyleborus glabratus, which is native to Asia. To test this hypothesis adult X. glabratus were trapped in Taiwan and on Kyushu Island, Japan, in 2009, and dead beetles were sent to USA for isolation of fungal symbionts. Individual X. glabratus were macerated in glass tissue grinders, and the slurry was serially diluted and plated onto malt agar medium amended with cycloheximide, a medium semiselective for Ophiostoma species and their anamorphs, including members of Raffaelea. R. lauricola was isolated from 56 of 85 beetles in Taiwan and 10 of 16 beetles in Japan at up to an estimated 10 000 CFUs per beetle. The next most commonly isolated species was R. ellipticospora, which also has been recovered from X. glabratus trapped in the USA, as were two other fungi isolated from beetles in Taiwan, R. fusca and R. subfusca. Three unidentified Raffaelea spp. and three unidentified Ophiostoma spp. were isolated rarely from X. glabratus collected in Taiwan. Isolations from beetles similarly trapped in Georgia, USA, yielded R. lauricola and R. ellipticospora in numbers similar to those from beetles trapped in Taiwan and Japan. The results support the hypothesis that R. lauricola was introduced into the USA in mycangia of X. glabratus shipped to USA in solid wood packing material from Asia. However differences in the mycangial mycoflora of X. glabratus in Taiwan, Japan and USA suggest that the X. glabratus population established in USA originated in another part of Asia.