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  • Author or Editor: Bin Wu x
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Crapemyrtle bark scale (CMBS; Acanthococcus lagerstroemiae Kuwana), a fast-spreading invasive insect, has been causing damage to popular landscape plants in at least 17 states in the United States since 2004. This invasive insect has a list of documented plant hosts in ∼23 genera, which includes its primary hosts, crapemyrtles (Lagerstroemia spp.), as well as other important plant species, such as pomegranates, apple, and the native plant American beautyberry. Previous studies have shown CMBS causes different levels of feeding damage among its plant hosts, while the underlining plant defense mechanisms toward CMBS attacks remain elusive. A better understanding of plant–CMBS interactions and how CMBS performs under different plants (e.g., a susceptible vs. a resistant host) can provide valuable guidance for integrated pest management. Therefore, in this study, we conducted the age-stage, two-sex table study analysis to evaluate the biological parameters of CMBS on different species or cultivars of crapemyrtle under laboratory conditions (25 °C and 250 μmol·m−2·s−1 light with a photoperiod of 12 hours:12 hours (light:dark). Crapemyrtle bark scale development was found to be greatly influenced by the hosts. This study aims to provide important biological and ecological data on CMBS using a comprehensive life table study to gain a thorough understanding of its development, survival, and fecundity on different crapemyrtle species or cultivars.

Open Access

Crapemyrtle bark scale [CMBS (Acanthococcus lagerstroemiae)], a newly emerged pest in the United States, has spread to 16 U.S. states and unexpectedly spread on a native species american beautyberry (Callicarpa americana) in Texas and Louisiana in 2016 since it was initially reported on crapemyrtles (Lagerstroemia sp.) in Texas in 2004. The infestation of CMBS negatively impacted the flowering of crapemyrtles. We observed the infestation on the two most commercially available edible fig (Ficus carica) cultivars Beer’s Black and Chicago Hardy in a preliminary trial in 2018. To help estimate CMBS potential in aggravating risks to the ecosystem stability and the green industry, we conducted a host range and suitability test using ‘Bok Tower’ american beautyberry as a positive control with other eight beautyberry (Callicarpa) species [mexican beautyberry (C. acuminata), ‘Profusion’ bodinieri beautyberry (C. bodinieri), ‘Issai’ purple beautyberry (C. dichotoma), japanese beautyberry (C. japonica var. luxurians), ‘Alba’ white-fruited asian beautyberry (C. longissima), taiwan beautyberry (C. pilosissima), luanta beautyberry (C. randaiensis), and willow-leaf beautyberry (C. salicifolia)] and three fig (Ficus) species [creeping fig (F. pumila), roxburgh fig (F. auriculata), and waipahu fig (F. tikoua)] over 25 weeks. All the tested beautyberry species and waipahu fig sustainably supported the development and reproduction of nymphal CMBS and were confirmed as CMBS hosts. Furthermore, comparing with the control, mexican beautyberry, ‘Profusion’ bodinieri beautyberry, taiwan beautyberry, and willow-leaf beautyberry were significantly less suitable, while ‘Issai’ purple beautyberry, japanese beautyberry, ‘Alba’ white-fruited asian beautyberry, and luanta beautyberry were as suitable as ‘Bok Tower’ american beautyberry. Thus, when using beautyberries in landscapes, their different potential to host CMBS should be considered to minimize spreading CMBS through the native ecosystems.

Open Access

Pear plants (Pyrus pyrifolia var. Hengshen) showing symptoms of chlorotic spots on leaves were observed in orchards in central Taiwan in 2004. The sap of diseased leaves reacted positively to Apple chlorotic leaf spot virus (ACLSV) antiserum. A purified virus isolate (LTS1) from pear was characterized by host range, electron microscopy, phylogenetic analyses, serological property, and back-inoculation experiments to pear. Fifteen of 28 species of tested plants were susceptible to this virus after mechanical inoculation. Pathogenicity of ACLSV isolate LTS1 was verified by back-inoculating to pear seedlings. Filamentous virions of ≈12 × 750 nm were observed in the preparations of purified virus. Virus particles accumulated in the cytoplasm were observed in the ultrathin sections of LTS1-infected pear leaf tissue. Sequence analyses of the coat protein (CP) gene of LTS1 and the CP gene of LTS2, which originated from a distinct symptomatic pear sample, shared 81.4% to 92.6% nucleotide and 87.6% to 98.4% amino acid identities with those of the CP of 35 ACLSV isolates available in GenBank. ACLSV isolates were grouped into four clusters, i.e., Asia I, II, III, and Europe, and isolates LTS1 and LTS2 were classified as members of cluster Asia II and Asia I, respectively, based on phylogenetic data. Moreover, the variability of amino acid sequences of the CP gene of 37 ACLSV isolates showed geographically associated clustering in the phylogenetic tree. To our knowledge, this is the first study on the characterization of ACLSV causing the leaf chlorotic spot disease of pear in Taiwan. This study also provides the phylogenetic relationships among ACLSV populations based on amino acid sequences of CPs, which are correlated with their geographic origins.

Free access

Crapemyrtle bark scale (CMBS; Acanthococcus lagerstroemiae Kuwana) is an invasive insect that was first discovered in the United States in 2004. The polyphagous feeding habit of CMBS has allowed it to infest a wide range of plant species beyond its primary host, Lagerstroemia. Using molecular approaches, we studied the genetic relationships between CMBS specimens and their hosts from different geographic locations. Naturally occurring CMBS infestations were confirmed on American beautyberry (Callicarpa americana L.), a native plant species in the United States, and spirea (Spiraea L.). The new infestation of CMBS found on Spiraea raises the alarm that other economically important crops in the Amygdaloideae subfamily (subfamily under Rosaceae) might be susceptible to CMBS attacks.

Open Access