Bidens Alba Research Articles

Comparative Effects of Crude Extracts and Bioactive Compounds from Bidens pilosa and Bidens alba on Nonspecific Immune Responses and Antibacterial Activity Against Vibrio sp. in Coculture with Lactic Acid Bacteria in Hybrid Grouper (Epinephelus fuscoguttatus ♀ × Epinephelus lanceolatus ♂).

This study investigated the effect of substances on nonspecific immune responses of head kidney leukocytes, the antimicrobial activity against Vibrio sp., as well as the time-kill of Vibrio sp. by combining the substances with lactic acid bacteria (LAB) and Pediococcus sp. The substances are B. pilosa hot water extract, B. pilosa powder extract, B. pilosa methanol extract, B. pilosa ethanol extract, B. alba hot water extract, B. alba powder extract, B. alba methanol extract, B. alba ethanol extract, and bioactive compounds, namely cytopiloyne, flavonoid, phenol, ethyl caffeate, luteolin, chlorogenic acid, butein, and linoleic acid. The results showed that some of them were nontoxic to the head kidney leukocytes, which can increase the phagocytic rate, phagocytic index, and respiratory burst. These substances were able to inhibit the growth of Vibrio sp.; they can even completely kill the pathogenic bacteria. The largest of the inhibition zone formed from the EC group at a concentration range of 5-50 µg/mL against V. parahaemolyticus, V. alginolyticus, and V. harveyi with a value of 19.7 ± 0.56, 19.3 ± 1.53, and 20.6 ± 1.53 mm. Furthermore, the time-kill studies showed that the LAB and P. acidilactici can completely kill the Vibrio sp. at 6 h incubation time, mainly in the group of combination with EC.

Evaluation of Plant Growth and Flowering Performance of Florida Native and Non-native Ornamentals under Varying Irrigation

Pollinator gardening has gained momentum with an increased consumer interest in selecting native rather than non-native plant species to reduce water dependence and maximize the biodiversity value in both public greenspaces and residential gardens. Native plant species can enhance biological control and benefit ecosystems and wildlife. Often, they are also better-adapted to local environmental conditions, including temperature and rainfall, thus increasing their survival and reducing associated maintenance costs, primarily by requiring less water. Commercially available pollinator-friendly plant mixes often include both native and non-native species. A 2-year study was conducted to determine the main effects of plant provenance (native or non-native) and irrigation (full or partial irrigation) on landscape performance and flowering of 20 plants, including 10 congeneric pairs of native and non-native taxa that were planted in two locations (north and northcentral Florida). Native and non-native taxa were paired by genus to analyze the effect of the plant native status on vegetative and floral traits while controlling for variations in leaf and floral morphologies, growth habits, and blooming periods, which was a key and novel component of our study design. Represented native species included Spanish needles (Bidens alba), false rosemary (Conradina grandiflora), tickseed coreopsis (Coreopsis leavenworthii), blanket-flower (Gaillardia pulchella), swamp rosemallow (Hibiscus grandiflorus), inkberry (Ilex glabra), spotted beebalm (Monarda punctata), azure blue sage (Salvia azurea), Florida scrub skullcap (Scutellaria arenicola), and Walter's viburnum (Viburnum obovatum). Non-native taxa paired with native congeners included Beedance® painted red bidens (Bidens ferulifolia) or Goldilocks Rocks® bidens (Bidens ferulifolia ‘BID 16101’), barbeque rosemary (Salvia rosmarinus ‘Barbeque’), Jethro Tull coreopsis (Coreopsis × ‘Jethro Tull’), Arizona sun blanket-flower (Gaillardia ×grandiflora ‘Arizona Sun’), Ruffled Satin® rose of Sharon (Hibiscus syriacus ‘SHIMCR1’), dwarf Burford holly (Ilex cornuta ‘Dwarf Burford’), pardon my pink beebalm (Monarda didyma ‘Pardon My Pink’), big blue salvia (Salvia longispicata × S. farinacea ‘PAS1246577’), Malaysian skullcap (Scutellaria javanica), and Sandankwa viburnum (Viburnum suspensum). Overall, the results revealed that native plants outperformed non-native plants and exhibited greater survival, more vegetative growth, and greater floral abundance regardless of the irrigation treatment. Although there was no overall effect of irrigation on plant size or flower abundance, there were some species-specific responses, especially during the establishment year, and plants under full irrigation had greater survival in the establishment year. Thus, in general, the effects of plant provenance were stronger and more consistent across years than irrigation. Additional studies are underway to determine the floral rewards of these species and their attraction to diverse pollinators.

Allelopathic effects of Borreria latifolia on weed germination and identification of allelochemicals.

Borreria latifolia (Aubl.) K. Schum (Rubiaceae) is an annual weed with a strong allelopathic inhibitory effect on malignant weeds in orchards in southern China. This study was carried out to investigate its allelopathic potential and to identify allelochemicals present in B. latifolia. Aqueous extracts of B. latifolia inhibited the germination and radicle growth of Eleusine indica and the radicle growth of Bidens alba in a dose-dependent manner. However, only the high-concentration treatment at 50 mg mL-1 delayed the germination of B. alba and Digitaria sanguinalis. Among the root, stem, and leaf aqueous extracts of B. latifolia, the leaf extract had the strongest inhibitory effects on the germination and seedling growth of E. indica, followed by stem extract and then root extract. A total of 47 published allelochemicals, including coumarin, 4-hydroxybenzoate, salicylic acid, 4-hydroxycinnamic acid, and vanillic acid, were identified in the leaf extract. Among the five allelochemicals, coumarin was found to be present in the highest concentration in the leaf extract. Furthermore, coumarin exhibited a significantly greater inhibitory effect on E. indica (EC50 = 36.87 mg L-1) than did the other allelochemicals (EC50 = 100.87-156.30 mg L-1). This study indicates that the leaf extracts of B. latifolia and their allelochemicals have excellent potential as bioherbicides and that coumarin is one of the key allelochemicals in B. latifolia. © 2024 Society of Chemical Industry.

Importance of wildflowers in Orius insidiosus (Heteroptera: Anthocoridae) diet

Abstract The addition of non-crop floral resources is known to improve the fitness of many beneficial arthropods. Orius insidiosus (Say; Heteroptera: Anthocoridae) is a predator of several economically important pests and is known to feed on pollen. Spanish needles, Bidens alba L., and Leavenworth’s tickseed, Coreopsis leavenworthii Torrey & Gray (both Asteraceae), are two Florida native wildflowers that may serve as sources of pollen beneficial to O. insidiosus. The current study investigated the effects of adding flowers from C. leavenworthii and B. alba to the diet of captive O. insidiosus on longevity, nymphal development time, and cannibalism. A mixed diet of flowers and thrips prey increased O. insidiosus adult female longevity. Nymphal development time was reduced when B. alba was added to thrips when compared to a diet of thrips alone. Interestingly, cannibalism was low in all instances, suggesting a negligible effect of cannibalism on O. insidiosus except perhaps in extreme situations. These results indicate that B. alba and C. leavenworthii flowers can increase longevity and fitness of O. insidiosus, thus providing support for the use of these plants to enhance natural enemy services.

The genomes of Dahlia pinnata, Cosmos bipinnatus, and Bidens alba in tribe Coreopsideae provide insights into polyploid evolution and inulin biosynthesis.

The Coreopsideae tribe, a subset of the Asteraceae family, encompasses economically vital genera like Dahlia, Cosmos, and Bidens, which are widely employed in medicine, horticulture, ecology, and food applications. Nevertheless, the lack of reference genomes hinders evolutionary and biological investigations in this tribe. Here, we present 3 haplotype-resolved chromosome-level reference genomes of the tribe Coreopsideae, including 2 popular flowering plants (Dahlia pinnata and Cosmos bipinnatus) and 1 invasive weed plant (Bidens alba), with assembled genome sizes 3.93G, 1.02G, and 1.87G, respectively. We found that Gypsy transposable elements contribute mostly to the larger genome size of D. pinnata, and multiple chromosome rearrangements have occurred in tribe Coreopsideae. Besides the shared whole-genome duplication (WGD-2) in the Heliantheae alliance, our analyses showed that D. pinnata and B. alba each underwent an independent recent WGD-3 event: in D. pinnata, it is more likely to be a self-WGD, while in B. alba, it is from the hybridization of 2 ancestor species. Further, we identified key genes in the inulin metabolic pathway and found that the pseudogenization of 1-FEH1 and 1-FEH2 genes in D. pinnata and the deletion of 3 key residues of 1-FFT proteins in C. bipinnatus and B. alba may probably explain why D. pinnata produces much more inulin than the other 2 plants. Collectively, the genomic resources for the Coreopsideae tribe will promote phylogenomics in Asteraceae plants, facilitate ornamental molecular breeding improvements and inulin production, and help prevent invasive weeds.

Competition shifts the advantage of the invasive plant Bidens alba to a disadvantage under soil ammonia nitrogen

Competition shifts the advantage of the invasive plant Bidens alba to a disadvantage under soil ammonia nitrogen

Analysis of the chloroplast genome and phylogenetic evolution of Bidens pilosa

Chloroplast genomes for 3 Bidens plants endemic to China (Bidens bipinnata Linn., Bidens pilosa Linn., and Bidens alba var. radiata) have been sequenced, assembled and annotated in this study to distinguish their molecular characterization and phylogenetic relationships. The chloroplast genomes are in typical quadripartite structure with two inverted repeat regions separating a large single copy region and a small single copy region, and ranged from 151,599 to 154,478 bp in length. Similar number of SSRs and long repeats were found in Bidens, wherein mononucleotide repeats (A/T), forward and palindromic repeats were the most in abundance. Gene loss of clpP and psbD, IR expansion and contraction were detected in these Bidens plants. It seems that ndhE, ndhF, ndhG, and rpl32 from the Bidens plants were under positive selection while the majority of chloroplast genes were under purifying selection. Phylogenetic analysis revealed that 3 Bidens plants clustered together and further formed molophyletic clade with other Bidens species, indicating Bidens plants might be under radiation adaptive selection to the changing environment world-widely. Moreover, mutation hotspot analysis and in silico PCR analysis indicated that inter-genic regions of ndhD-ccsA, ndhI-ndhG, ndhF-rpl32, trnL_UAG-rpl32, ndhE-psaC, matK-rps16, rps2-atpI, cemA-petA, petN-psbM were candidate markers of molecular identification for Bidens plants. This study may provide useful information for genetic diversity analysis and molecular identification for Bidens species.

Short-term effects of asymmetric day and night warming on soil N2O, CO2 and CH4 emissions: A field experiment with an invasive and native plant

Global warming and biological invasion are the main aspects of global change. Understanding the effects of warming on soil greenhouse gas (GHG) emissions represents a challenge to comprehending the feedbacks associated with climate change. Asymmetric warming due to the greater warming during the night than during the day leads to decreased diurnal temperature range (DTR) which have lasted for several decades and are projected to continue over this century. However, few experimental studies have attempted to integrate the asymmetric warming and plant invasion with soil GHG emissions. A two-factor (warming and plants) field experiment was conducted herein using infrared heaters to increase temperatures. We set four warming treatments (no warming, symmetric warming, asymmetric warming with increased and decreased DTR) and three plant treatments (bare soil without plants, the invasive species Bidens alba, native species Eleusine indica). We found warming with decreased DTR induced higher nitrous oxide (N2O) emissions in the bare soil and with E. indica than symmetric warming at the early stage of warming, whereas such effects diminished with warming duration. In general, no significant differences in soil methane (CH4) or carbon dioxide (CO2) emissions were found between the symmetric and asymmetric warming. The observed different effects on soil GHG emissions between E. indica and B. alba were mainly due to altered soil nitrate (NO3−) and ammonia (NH4+) content resulted from their growth. Redundancy analysis indicated that soil NO3−, NH4+ and the functional gene nirS were the main factors driving the variance in soil GHG emissions, while soil pH and NO3− were the main driving factors of functional genes abundances. Overall, this study highlights the importance of effects of asymmetric day/night warming on soil GHG emissions associated with plant invasion.

Helical shoot-tip mines on three genera of Asteraceae in Jamaica are caused by different species of Melanagromyza – Implications for the biological control of Chromolaena odorata using Melanagromyza eupatoriella

Field host-range surveys and fixed plot trials were undertaken in Jamaica to gain an understanding of the host range of the fly Melanagromyza eupatoriella (Diptera: Agromyzidae), a potential biological control agent of the neotropical shrub Chromolaena odorata in South Africa. The fly larvae form helical mines in growing, vegetative stem tips, causing them to wilt and die. Seventy-seven sites at which C. odorata was present along with 30 other species of Asteraceae were surveyed for the presence of damage similar to that caused by M. eupatoriella. Twelve of these sites, chosen for the high (>10) number of M. eupatoriella mines present on C. odorata, were used to determine the abundance of 19 Asteraceae species encountered and the proportion of shoot tips with helical mines on each of these species. Similar mines were found on six species other than C. odorata: Mikania micrantha, M. cordifolia, Bidens alba, B. pilosa, B. reptans and Calea jamaicensis. Damaged plant material was field-collected from M. micrantha, C. odorata and B. alba and the causative herbivores (all Agromyzidae) were preserved for identification. Mines on Mikania species were longer than those caused by M. eupatoriella, and the species collected from M. micrantha was tentatively identified as Melanagromyza vulgata. Helical shoot-tip mines on Bidens species continued internally to completion further down the stem, unlike those of M. eupatoriella, where pupation occurs near the base of the helical mine. Only adult females were reared out of B. alba, therefore the fly could only be identified as a Melanagromyza species. The proportion of shoot tips with helical mines was highest on the two Mikania species, intermediate on C. odorata, and lowest on B. alba. For the quantitative, 12-site survey, five plant species in addition to C. odorata were present at four or more sites, and were significantly less likely than C. odorata to host M. eupatoriella. A fixed-plot trial was undertaken using two forms of C. odorata (plants from Jamaica and the southern African biotype), six Asteraceae (all encountered in the host-range surveys) and two crop species. Over 19 months, both C. odorata forms were attacked by M. eupatoriella and one mine was encountered on B. alba. The surveys, trials and identification of insects indicate that shoot-tip mines caused by M. eupatoriella were encountered only on C. odorata, out of 31 Asteraceae and two other plant species. Further laboratory-based host-range trials are required, should there be a need for this insect as a biocontrol agent in future.

A Preliminary Study on Insect Pollinators of New Forest Campus, Dehradun, India

The present study was undertaken to find out the insect pollinators associated with some plants in the New Forest Campus, FRI, Dehradun, India. The observations were taken by three different methods from April to July 2020. The study revealed that 45 insect pollinator species belonging to four orders and ten families were present in the campus. A total of 32 flowering plant species were observed to be visited by 45 insect pollinators among them species richness of butterflies was maximum followed by non apis bees, apis bees, wasps and syrphidflies, but bees were the most dominated species for pollination in the campus. Among the host plants flowers of Peltophorum pterocarpum was visited by maximum number of pollinators (11 species), followed by Lantana camara (8 species), Lichi chinensis (6 species), Bidens alba (4 species) and Mangifera indica (3 species), etc.

Interactive effects of allelopathy and arbuscular mycorrhizal fungi on the competition between the invasive species Bidens alba and its native congener Bidens biternata

AbstractAllelopathy is an invasion driver, and arbuscular mycorrhizal fungi (AMF) also play an important role in plant invasion. However, little is known about their interactive effects on plant invasion mechanisms. In this study, we have investigated the interactive effects of allelopathy and AMF on competition between the exotic invasive species, Bidens alba, and its native congener, Bidens biternata. A two‐factor (allelopathy, AMF) common garden experiment was conducted using sterilised soil with or without AMF inoculation and with or without activated carbon (AC) addition. The results showed that both AC and AMF had significant effects on the relative yield (RY) of invasive species and competitive aggressivity (AG) between invasive and native species. Both AC and AMF exerted interactive effects on the AG. Activated carbon significantly reduced AG (0.86 vs 0.15%) without AMF, while it had no significant effects on AG with AMF. Moreover, AC significantly reduced the mycorrhizal dependency of the native species (108.06% vs 23.62%) but did not affect the invasive species. The AMF increased the variety of organic compounds in the aqueous extracts of the rhizosphere soil of invasive species, regardless of the competition. Overall, allelopathy significantly increased the mycorrhizal dependency of the native species, while it promoted the competitive ability of the invader regardless of AMF inoculation. Conversely, AMF reduced the facilitation of allelopathy in the AG of the invasive species. These results suggest that AMF play a critical role in improving the resistance of the native species to the invader by mediating allelopathy.

Effects of Bidens alba and Plectranthus amboinicus dietary supplements on nonspecific immune responses, growth, and resistance to Vibrio alginolyticus in white leg shrimp (Penaeus vannamei)

Bidens alba and Plectranthus amboinicus are common medicinal plants. This study investigated the effects of a diet containing B. alba extract (BAE) and P. amboinicus extract (PAE) on the immune responses, growth, and their resistance to Vibrio alginolyticus in white leg shrimp (Penaeus vannamei). An in vitro experiment revealed that the BAE and PAE are nontoxic to white leg shrimp haemocytes, and the extracts increased phagocytic activity, superoxide anion (O2−) production, and phenoloxidase (PO) activity.In in vivo trials, shrimp were fed diets containing 10, 20, or 40 g of BAE (B1, B2 and B4) or PAE (P1, P2 and P4 group) per kg of regular feed for 28 days, and immune parameters were measured. All BAE and PAE groups exhibited enhanced nonspecific immune responses including increased total haemocyte count, phagocytic activity, O2− production rate, and PO activity. Shrimp fed the BAE or PAE diet for 7 days exhibited increased expression of Lysozyme (Lyz), Penaeidin 2 (Pen2), Penaeidin 3 (Pen3), and Penaeidin 4 (Pen4). After a V. alginolyticus challenge, the treated shrimp exhibited higher survival rates than exhibited by those fed the control diet. The growth performance results of 56 feeding trials revealed that shrimp fed BAE or PAE at 20 g/kg (B2 or P2 group) gained significantly more weight and has a significantly higher specific growth rate than did those on the control diet. Thus, these results suggest that administration of 20 g of BAE or PAE per kilogram of feed can enhance immunity, growth, and resistance to V. alginolyticus in white leg shrimp.

Foraging and mating behavior of the butterfly Archonias brassolis tereas (Godart, 1819) (Lepidoptera: Pieridae: Pierinae) in two sites in Southeastern Brazil

This study describes some aspects of the foraging and mating behavior of the butterfly Archonias brassolis tereas recorded in two sites at coast of São Paulo State, Brazil, near the hills of Serra do Mar. Adults of this species forage in ten species of Asteraceae: Cyrtocymura scorpioides, Bidens alba, Chromolaena maximiliani, Austroeupatorium inulaefolium, Vernonanthura beyrichii, Mikania hatschbachi, Mikania lundiana, Elephantopus mollis, Chromolaena laeve, Chromolaena laevigatum, and two non-asterace species: Cupania oblongifolia (Sapindaceae), and Inga marginata (Fabaceae). The sexual dimorphism is weak with females being slightly heavier than males. Females can copulate with more than one male. Although courtship displays where observed in females foraging on flowers it was not seen in the recorded mating.

The effects of Bidens alba invasion on soil bacterial communities across different coastal ecosystem land-use types in southern China.

Environments in both biotic and abiotic ecosystems have been affected by the colonization of non-native flora. In this study, we examined the effect of Bidens alba invasion on different land-use types along a coastline in southern China. Bacterial communities in each site were determined using 16S rDNA sequencing, and soil physicochemical properties were analyzed using standard methods. Although our results indicated that B. alba invasion did not have a significant effect on the alpha diversity of bacteria, it caused significant differences in soil bacterial community composition between invaded and uninvaded soil across different land-use types. Beta diversity and several physicochemical properties in forest, orchard and waterfront environments were recorded to be more susceptible to B. alba invasion. A high proportion of the variation of bacterial communities can be explained by a combination of environmental variables, indicating that environmental selection rather than plant invasion is a more effective process in coastal microbial assemblages. By comparing topological roles of shared OTUs among invaded and uninvaded soil, keystone taxa in invaded soil were identified. Acidobacteria was the major phyla involved in the invasive process which could be driven by environmental selection. How key phyla react in our experiment should be verified by further studies.

Allelopathic interactions between Borreria latifolia and two common Asteraceae species

Borrelia latifolia is an annual herb suitable to be used as cover crop for weed control in orchards in southern China. To understand the competition between B. latifolia and common weeds in orchards, we investigated the allelopathic interactions between B. latifolia and two Asteraceae species, Ageratum conyzoides and Bidens alba. The results showed that the aqueous extracts of B. latifolia at 10-50 mg·mL-1 significantly inhibited seed germination and seedling growth of A. conyzoides and B. alba, with the radicle length of A. conyzoides and B. alba being reduced by 57.4%-90.2% and 57.3%-62.3%, respectively. The aqueous extracts of A. conyzoides and B. alba also had strong allelopathic effects on seed germination of B. latifolia. Under the treatment of 50 mg·mL-1 aqueous extracts, the two Asteraceae species almost entirely inhibited the germination of B. latifolia. After treated with 10 mg·mL-1 aqueous extract of B. latifolia for 30 d, net photosynthesis, plant height and biomass of A. conyzoide were reduced by 15.2%, 20.6% and 41.5%, respectively, compared with the control, while the biomass of B. alba also showed a decreasing trend. Instead, the growth of B. latifolia was not affected. Under mixed culture, biomass of B. latifolia was comparable to that under monoculture, whereas those of A. conyzoides and B. alba were reduced by 86.0% and 27.1%, respectively. Compared with A. conyzoides and B. alba, the allelopathic advantage of B. latifolia is that it can inhibit growth of the two Asteraceae species as well as inhibit seed germination.

Germination and emergence of common beggar’s-tick (Bidens alba) seeds at two different stages of afterripening as affected by environmental factors

AbstractExperiments were conducted to determine the effect of various environmental factors and burial depth on germination and seedling emergence of common beggar’s-tick [Bidens alba (L.) DC.] seeds at two different stages of afterripening. Mature B. alba seeds were stored at 4 C for 3 to 5 mo (new seed lot) and 13 to 15 mo (old seed lot) until experiment initiation. Germination exponentially decreased with increasing moisture stress. Germination rate decreased from 87 ± 2.9% to 13 ± 6.1% as osmotic potential decreased from 0 to −0.5 MPa and was completely inhibited at osmotic potentials below −0.83 MPa. A large portion of the new seeds tested positively photoblastic, but seeds that had afterripened for 1 additional year were partially desensitized to the light requirement. New and old seeds still germinated to a greater percentage in the presence of light than under continuous dark at temperatures ranging from 15 to 35 C. Both new and old seeds germinated over a range of temperatures from 5 to 35 C, but the optimum temperatures for germination was 15 to 30 C in the presence of light. Regardless of seed lot, seedling emergence was the greatest when seeds were sown at the soil surface. Seedling emergence was abruptly reduced when burial depth was 1 cm or greater. Based on these results, we conclude that shallow cultivation could effectively suppress this population of B. alba from emerging when incorporated into an integrated control strategy. The information obtained in this research identifies some important factors that facilitate the widespread presence of B. alba in Florida and may contribute to weed management programs.

Pollinator Communities of Restored Sandhills: a Comparison of Insect Visitation Rates to Generalist and Specialist Flowering Plants in Sandhill Ecosystems of Central Florida

Globally, urbanization and other forms of land use change have been implicated in widespread pollinator declines and disruptions to plant–pollinator interactions. A growing body of literature, however, suggests that urban habitat fragments can provide oases for both plant and insect diversity. A micro-ecosystem on our college campus was created to represent the longleaf pine savannas (sandhills) that once dominated upland ridges throughout the Southeast. To assess the ability of this site to support wild insect pollinators, from May through August for three years (2016–2018) we compared visitation to two abundant flowering plant species, Bidens alba (a generalist-pollinated composite) and Chamaecrista fasciculata (a specialist-pollinated legume), between the campus micro-ecosystem and a nearby site within a large conservation area containing sandhill habitat undergoing restoration. We found that, for both plant species, total insect visitation rates did not differ between years or sites, suggesting that the small urban fragment is capable of maintaining abundant pollinators. The identity of generalist visitors to Bidens alba, however, differed dramatically between sites. Wild hymenopterans constituted more than two-thirds of all insect visits in the campus site but less than half in the conservation area, where butterflies, flies, and beetles were also common visitors. The high density of flowers in the campus site is likely at least partially responsible for the high abundance of hymenopterans, a result consistent with that of many other studies showing that hymenopterans are less sensitive to urbanization than are other insect groups.

Feeding Behavior of Asian Citrus Psyllid [Diaphorina citri (Hemiptera: Liviidae)] Nymphs and Adults on Common Weeds Occurring in Cultivated Citrus Described Using Electrical Penetration Graph Recordings.

Asian citrus psyllid, Diaphorina citri, transmits Candidatus Liberibacter asiaticus (CLas), the putative causal agent of Huanglongbing disease. Although they primarily feed on the phloem of Citrus and related plants, when grove or host conditions are unfavorable, D. citri may be able to use weed species as alternate food sources for survival. To explore this possibility, electrical penetration graph (EPG) recordings (18 h) were performed to investigate the feeding behavior of psyllid adults and nymphs on three common south Florida weeds (Bidens alba, Eupatorium capillifolium, and Ludwigia octovalvis). EPG recordings revealed that the proportion of time spent by D. citri feeding on xylem was similar on all tested weed species (19%–22%) and on the positive control (20%), the preferred host, Citrus macrophylla. Very little to no phloem feeding was observed on weed species by either nymphs or adults. Histological studies using epifluorescence microscopy showed that salivary sheaths were branched and extended into xylem of weed species, whereas they ended in phloem on citrus plants. No choice behavioral assays showed that adults can obtain some nutrition by feeding on weed species (xylem feeding) and they may be able to survive on them for short intervals, when host conditions are unfavorable.

Do arbuscular mycorrhizal fungi help the native species Bidens biternata resist the invasion of Bidens alba?

Arbuscular mycorrhizal fungi (AMF) play an important role in competition between exotic and native species, but we know little about the role of AMF in changing plant intra- and interspecific competition. Invasive alien species Bidens alba and native species Bidens biternata were selected. Five species proportions, 0:4, 1:3, 2:2, 3:1, and 4:0, of B. alba: B. biternata were examined to simulate inter- and intraspecific competition between the two plants. Glomus mosseae was selected as the AMF inoculum. The results showed that B. alba strongly inhibited B. biternata, and the effects of inhibition increased as the proportion of B. alba increased with up to 71% reduction in both shoot and root biomass. When inoculated with Glomus mosseae, the biomass of the two plants significantly increased, and B. biternata was no longer inhibited by B. alba, conversely B. biternata showed stronger competitiveness under the species proportion of B. alba: B. biternata = 1:3. This suggests AMF have the potential to help the native species B. biternata resist the invasive species B. alba under certain proportion. Under competition with the invasive species B. alba, AMF facilitated phosphorus (P) absorption of the native species B. biternata, whereas such facilitation by AMF decreased sharply under B. biternata monoculture. Our study indicates that AMF can alter the competitive relationship between native and invasive species through affecting the absorption of P between plants, and the role of AMF is associated with the inter- and intraspecies competition.

Secondary hosts of the Asian citrus psyllid, Diaphorina citri Kuwayama: Survivorship and preference

AbstractThe Asian citrus psyllid, Diaphorina citri Kuwayama, is the most economically important and difficult to manage citrus pest in Florida due to its role as vector of huanglongbing or citrus greening disease. Spread of the disease is a function of dispersal patterns and thus influenced by availability of suitable hosts. Young leaves of citrus or related plants are required for reproduction, but in their absence, secondary hosts may provide needed resources to enhance survival. Therefore, survivorship on and preference for three abundant weed species was investigated. The suitability of potential secondary host plants Bidens alba (L.), DC, Ludwigia octovalvis (Jacqu.) P. H. Raven, and Eupatorium capillifolium (Lam.) Small was compared to a reproductive host, Murraya paniculata (L.) Jack, in no‐choice tests by assessing survivorship of D. citri adults confined to these plants in cages. Preference was evaluated by choice tests where D. citri adults were released into cages containing all three secondary hosts alone or with M. paniculata. Both B. alba and E. capillifolium increased D. citri survivorship by twofold compared to starvation conditions with only water available. Choice trials revealed no difference in initial selection between true and secondary hosts; however, the true host was favoured over time. This result suggested that hosts were selected initially by sight, and only later by taste and/or smell. While secondary hosts are unable to support reproduction or long‐term survival, these findings establish the ability of D. citri to use secondary hosts that are ubiquitous in Florida citrus groves as temporary reservoirs for food and moisture when ideal host conditions are scarce or absent.