Co-occurring nonnative woody shrubs have additive and non-additive soil legacies.[Pubmed: 27755688]

To maximize limited conservation funds and prioritize management projects that are likely to succeed, accurate assessment of invasive nonnative species impacts is essential. A common challenge to prioritization is a limited knowledge of the difference between the impacts of a single nonnative species compared to the impacts of nonnative species when they co-occur, and in particular predicting when impacts of co-occurring nonnative species will be non-additive. Understanding non-additivity is important for management decisions because the management of only one co-occurring invader will not necessarily lead to a predictable reduction in the impact or growth of the other nonnative plant. Nonnative plants are frequently associated with changes in soil biotic and abiotic characteristics, which lead to plant-soil interactions that influence the performance of other species grown in those soils. Whether co-occurring nonnative plants alter soil properties additively or non-additively relative to their effects on soils when they grow in monoculture is rarely addressed. We use a greenhouse plant-soil feedback experiment to test for non-additive soil impacts of two common invasive nonnative woody shrubs, Lonicera maackii and Ligustrum sinense, in deciduous forests of the southeastern United States. We measured the performance of each nonnative shrub, a native herbaceous community, and a nonnative woody vine in soils conditioned by each shrub singly or together in polyculture. Soils conditioned by both nonnative shrubs had non-additive impacts on native and nonnative performance. Root mass of the native herbaceous community was 1.5 times lower and the root mass of the nonnative L. sinense was 1.8 times higher in soils conditioned by both L. maackii and L. sinense than expected based upon growth in soils conditioned by either shrub singly. This result indicates that when these two nonnative shrubs co-occur, their influence on soils disproportionally favors persistence of the nonnative L. sinense relative to this native herbaceous community, and could provide an explanation of why native species abundance is frequently depressed in these communities. Additionally, the difference between native and nonnative performance demonstrates that invasive impact studies focusing on the impact only of single species can be insufficient for determining the impact of co-occurring invasive plant species.

Fundamental Host Range of Leptoypha hospita (Hemiptera: Tingidae), a Potential Biological Control Agent of Chinese Privet.[Pubmed: 27325627]

Chinese privet, Ligustrum sinense Lour., is an invasive shrub within riparian areas of the southeastern United States. Biological control is considered the most suitable management option for Chinese privet. The potential host range of the lace bug, Leptoypha hospita Drake et Poor, was evaluated on the basis of adult feeding and oviposition, combined oviposition-nymphal development no-choice tests, nymphal development no-choice tests, multiple generation comparison on Forestiera pubescens Nutt. and L. sinense no-choice tests, and multiple-choice tests with 45 plant species in 13 families. No-choice tests showed that the host range of L. hospita was restricted to the tribe Oleeae. In adult feeding and oviposition no-choice tests, the bug fed and oviposited significantly more on Chinese privet than all other test plant species except for three native Forestiera spp., two nonnative Syringa spp., and another exotic Ligustrum sp. Among those, only F. pubescens supported complete development in numbers comparable to Chinese privet. However, when reared for multiple generations lace bugs reared on F. pubescens were smaller and had lower fecundity than those reared on L. sinense, suggesting F. pubescens is not an optimal host. In multiple-choice tests, L. hospita displayed a strong preference for feeding and ovipositing on Chinese privet over other test plant species, with the exception of the closely related nonnative Syringa spp. and its congenic species Ligustrum vulgare. The results of this study suggest that the risk to nontarget plant species in North America is minimal, and L. hospita would be a promising candidate for Chinese privet biological control.

Plant-soil interactions promote co-occurrence of three nonnative woody shrubs.[Pubmed: 26405753]

Ecosystems containing multiple nonnative plant species are common, but mechanisms promoting their co-occurrence are understudied. Plant-soil interactions contribute to the dominance of singleton species in nonnative ranges because many nonnatives experience stronger positive feedbacks relative to co-occurring natives. Plant-soil interactions could impede other nonnatives if an individual nonnative benefits from its soil community to a greater extent than its neighboring nonnatives, as is seen with natives. However, plant-soil interactions could promote nonnative co-occurrence if a nonnative accumulates beneficial soil mutualists that also assist other nonnatives. Here, we use greenhouse and field experiments to ask whether plant-soil interactions (1) promote the codominance of two common nonnative shrubs (Ligustrum sinense and Lonicera maackii) and (2) facilitate the invasion of a less-common nonnative shrub (Rhamnus davurica) in deciduous forests of the southeastern United States. In the greenhouse, we found that two of the nonnatives, L. maackii and R. davurica, performed better in soils conditioned by nonnative shrubs compared to uninvaded forest soils, which. suggests that positive feedbacks among co-occurring nonnative shrubs can promote continued invasion of a site. In both greenhouse and field experiments, we found consistent signals that the codominance of the nonnatives L. sinense and L. maackii may be at least partially explained by the increased growth of L. sinense in L. maackii soils. Overall, significant effects of plant-soil interactions on shrub performance indicate that plant-soil interactions can potentially structure the co-occurrence patterns of these nonnatives.

Combined treatment of Pseudomonas aeruginosa PA01 biofilm formation with the water-soluble extract of Ligustrum sinense and gentamicin sulphate.[Pubmed: 24620617]

Ligustrum sinense are commonly used for their anti-inflammatory, anti-rheumatic, diuretic, and hypotensive activities in traditional Chinese medicine. To observe the effects of the combined treatment of a water-soluble extract of Ligustrum sinense (WEL) and gentamicin sulphate (GS) on Pseudomonas aeruginosa PA01, the micro-dilution method was used to determine the minimal inhibitory concentration (MIC) of GS. Formation of a PA01 biofilm was observed under an optical microscope after treatment with different dosages of WEL and combined treatment with GS. The MIC of WEL was 8g l(-1), and permanent activity was also observed. The effect of WEL with GS was synergistic. The motility, biomass of biofilms, and production of pyocyanin of P. aeruginosa were strongly suppressed in the presence of WEL. The conclusion can be drawn that combined antibiotics can be used to treat the contamination due to the biofilm formation caused by P. aeruginosa.

Hydrothermal transformation of Chinese privet seed biomass to gas-phase and semi-volatile products.[Pubmed: 20149648]

Hydrothermal (HT) treatment of seeds from Chinese privet (Ligustrum sinense), a non-native and invasive species in the southeastern United States, was examined with respect to the generation of gas-phase and semi-volatile organic chemicals of industrial importance from a lipid-rich biomass resource. Aqueous seed slurries were transformed into biphasic liquid systems comprised of a milky aqueous phase overlain by a black organic layer. Present in the headspace were elevated levels of CO(2) and acetic acid. Analysis of the semi-volatiles by GC-MS showed the formation of alkyl substituted benzenes, oxygenated cyclic alkenes, phenol, substituted phenolics, and alkyl substituted pyridines. Compared to immature seeds, mature seeds gave high relative amounts of oxygenated cyclic alkenes (cyclopentenones) and alkyl pyridines. The presence of fatty acids in the HT products likely resulted from both lipid hydrolysis reactions and the inherent stability of fatty acids under HT treatment conditions. Estimates of lignin and protein contents showed no definite trend that could be linked to the HT data. The proportion of aromatic HT products appeared to derive primarily from the proportion of extractives. Thus, variations in extractives yields impact HT product yields and thereby demonstrate the importance of timing in feedstock collection to favor targeted HT products.

Host specificity of Argopistes tsekooni (Coleoptera: Chrysomelidae), a potential biological control agent of Chinese privet.[Pubmed: 18767722]

Chinese privet, Ligustrum sinense Lour., is a perennial semi-evergreen shrub that is a serious invasive weed in the United States. Classical biological control offers the best hope for controlling it in an economic, effective, and persistent way. Host specificity of one of the most promising biological control agents of Chinese privet, a flea beetle, Argopistes tsekooni Chen (Coleoptera: Chrysomelidae), was evaluated in China by using laboratory no-choice and choice tests on 13 species of Oleaceae and eight species in other families that have important economic value. In adult no-choice survival and oviposition tests, the flea beetle fed and survived for 30 d on Syringa oblata Lindl., Jasminum nudiflorum Lindl., and three species in the genus Ligustrum. Females also oviposited on these species, but only larvae from eggs laid on S. oblata and Ligustrum spp. developed successfully. In addition, the beetles did not feed or oviposit on the species of economic importance. In choice tests, adults preferred L. sinense for feeding and oviposition. These results show that A. tsekooni is relatively host specific and warrants further testing as a biocontrol agent of Chinese privet in the United States.

Brevipalpus mites Donnadieu (Prostigmata: Tenuipalpidae) associated with ornamental plants in Distrito Federal, Brazil.[Pubmed: 17934626]

Brevipalpus mites colonize a great number of fruit and ornamental plants. Mite species belonging to this genus have been associated with many plant viruses. Citrus leprosis (CiLV) is the most economically important virus transmitted by B. phoenicis mites. It has recently been shown that ornamental plant species can be alternative hosts of this virus. The high volume of trade and frequent movement of live ornamental plants make them efficient pest disseminators. Because of this, it is desirable to expand knowledge of potential pests aiming to guide the adoption of quarantine measures. This work reports ornamental plant hosts of Brevipalpus mites in the Distrito Federal (DF), as well the occurrence of symptoms consistent with Brevipalpus-borne plant viruses in these same hosts. Between July and September of 2005, five surveys were carried out in 14 localities within DF. Leaves and branches of fifty-five ornamental plant species were sampled. The species Pithecellobium avaremotemo Mart. is for the first time reported as a host for B. phoenicis (Geijskes), B. californicus Banks and B. obovatus Donnadieu species. Additionally, seven new species are reported as hosts for Brevipalpus within South America. New hosts are also listed for individual mite species. Typical symptoms of Brevipalpus-borne viruses were observed in Ligustrum sinense Lour., Pelargonium hortorum L.H. Bailey, Hibiscus rosa-sinensis L. and orchids (Dendrobium and Oncidium). The results of this work emphasize the potential role of the ornamental plants as vehicles for dissemination of Brevipalpus mites.

Anti-oxidative activity of glycosides from Ligustrum sinense.[Pubmed: 14577686]

Three active glycosides that afford protection to red blood cell membrane to resist hemolysis induced by a peroxyl radical initiator, 2,2'-azo-bis-(2-amidinopropane) dihydrochloride (AAPH) were isolated from the MeOH extract of Ligustrum sinense. The compounds are 10-hydroxyl-oleuropein (1), 3-O-alpha-L-rhamnopyranosyl-kaempferol-7-O-beta-D-glucopyranoside (4), and 8'-alpha-hydroxyl-lariciresinol-4'-O-beta-D-glucopyranoside (6). The structures of these glycosides were determined by 1D and 2D NMR spectral analysis.

Ecological studies of adult Ixodes scapularis in central Mississippi: questing activity in relation to time of year, vegetation type, and meteorologic conditions.[Pubmed: 1625300]

Adult Ixodes scapularis Say were collected weekly during two fall-winter-spring seasons from 1989 to 1991 to assess their temporal and spatial distribution as well as the effects of several meteorologic parameters on questing activity. Collections were made in three 0.4-ha sites in central Mississippi by flagging vegetation with a white flannel cloth. Adult I. scapularis were collected from 25 October through 11 April during the 1989-1990 season and 24 October-1 April in the 1990-1991 season. Peak I. scapularis questing activity occurred on 5 February and 4 February during the two seasons, respectively. Ticks were collected most often at approximately 20 degrees C but seven were collected on a day when the temperature was 6.9 degrees C. Ticks were clustered within the study sites and not evenly distributed. Most I. scapularis were collected from Ligustrum sinense and Chasmanthium sessiliflorum at a height of 31-40 cm. Statistical analyses of the meteorologic factors that affect questing activity are presented and discussed.