Facultative Associations Research Articles

Genetic diversity patterns of arbuscular mycorrhizal fungi associated with the mycoheterotroph Arachnitis uniflora Phil. (Corsiaceae).

Arachnitis uniflora is a mycoheterotrophic plant that exploits arbuscular mycorrhizal fungi of neighbouring plants. We tested A. uniflora 's specificity towards fungi across its large latitudinal range, as well as the role of historical events and current environmental, geographical and altitudinal variables on fungal genetic diversity. Arachnitis uniflora mycorrhizas were sampled at 25 sites. Fungal phylogenetic relationships were reconstructed, genetic diversity was calculated and the main divergent lineages were dated. Phylogeographical analysis was performed with the main fungal clade. Fungal diversity correlations with environmental factors were investigated. Glomeraceae fungi dominated, with a main clade that likely originated in the Upper Cretaceous and diversified in the Miocene. Two other arbuscular mycorrhizal fungal families not previously known to be targeted by A. uniflora were detected rarely and appear to be facultative associations. High genetic diversity, found in Bolivia and both northern and southern Patagonia, was correlated with temperature, rainfall and soil features. Fungal genetic diversity and its distribution can be explained by the ancient evolutionary history of the target fungi and by micro-scale environmental conditions with a geographical mosaic pattern.

Bacterial Endosymbionts of the Psyllid Cacopsylla pyricola (Hemiptera: Psyllidae) in the Pacific Northwestern United States

Insects often have facultative associations with bacterial endosymbionts, which can alter the insects' susceptibility to parasitism, pathogens, plant defenses, and certain classes of insecticides. We collected pear psylla, Cacopsylla pyricola (Förster) (Hemiptera: Psyllidae), from pear orchards in Washington and Oregon, and surveyed them for the presence of bacterial endosymbionts. Adult psyllids were collected on multiple dates to allow us to assay specimens of both the summer ("summerform") and the overwintering ("winterform") morphotypes. Two endosymbionts, Arsenophonus and Phytoplasma pyri, were detected in psyllids of both morphotypes in both states. A separate survey revealed similar associations present in psyllids collected in 1987. Arsenophonus was present in 80-100% of psyllids in all growing regions. A slightly lower proportion of summerform than winterform psyllids harbored the bacterium. Arsenophonus was present in the bacteriomes and developing oocytes of most psyllids, indicating that this endosymbiont is transovarially transmitted. This bacterium was also observed in the salivary glands and midguts of some psyllids. Phytoplasma pyri was present in a greater proportion of pear psylla from orchards near Yakima, WA, than from other regions, and was present in a higher proportion of winterforms than summerforms. We did not detect Wolbachia, Profftella, or Liberibacter europaeus, which are associated with other psyllid pests, including other species of Cacopsylla. Our study is the first to survey North American populations of C. pyricola for endosymbionts, and provides a foundation for further research on how bacterial associations may influence the ecology and management of this pest.

Symbiont Diversity of Aphis (Toxoptera) citricidus (Hemiptera: Aphididae) as Influenced by Host Plants.

Aphids are well known for their association with endosymbiont bacteria. Almost all aphids harbor Buchnera aphidicola as an obligate symbiont and several other bacteria as facultative symbionts. Associations of facultative symbionts and aphids are quite variable in terms of diversity and prevalence across aphid species. Facultative symbionts can have a major impact on aphid bioecological traits. A number of factors shape the outcome of the facultative symbiont-aphid association, including aphid clone, bacterial genotype, geography, and host plant association. The effects of host plant on aphid-facultative symbiont associations are the least understood. We performed deep sequencing of the bacterial community associated with field populations of the oligophagous aphid Aphis (Toxoptera) citricidus collected from different host plants. We demonstrate that (i) A. citricidus has low symbiont diversity, (ii) symbiont diversity is affected by host plant, and (iii) host plants affect the relative abundance of the obligate symbiont Buchnera and an unknown genus of Enterobacteriaceae.

Peripheral communities of the Eastern Lau Spreading Center and Valu Fa Ridge: community composition, temporal change and comparison to near‐vent communities

AbstractWestern Pacific hydrothermal vents will soon be subjected to deep‐sea mining and peripheral sites are considered the most practical targets. The limited information on community dynamics and temporal change in these communities makes it difficult to anticipate the impact of mining activities and recovery trajectories. We studied community composition of peripheral communities along a cline in hydrothermal chemistry on the Eastern Lau Spreading Center and Valu Fa Ridge (ELSC‐VFR) and also studied patterns of temporal change. Peripheral communities located in the northern vent fields of the ELSC‐VFR are significantly different from those in the southern vent fields. Higher abundances of zoanthids and anemones were found in northern peripheral sites and the symbiont‐containing mussel Bathymodiolus brevior, brisingid seastars and polynoids were only present in the northern peripheral sites. By contrast, certain faunal groups were seen only in the southern peripheral sites, such as lollipop sponges, pycnogonids and ophiuroids. Taxonomic richness of the peripheral communities was similar to that of active vent communities, due to the presence of non‐vent endemic species that balanced the absence of species found in areas of active venting. The communities present at waning active sites resemble those of peripheral sites, indicating that peripheral species can colonize previously active vent sites in addition to settling in the periphery of areas of venting. Growth and mortality were observed in a number of the normally slow‐growing cladorhizid stick sponges, indicating that these animals may exhibit life history strategies in the vicinity of vents that differ from those previously recorded. A novel facultative association between polynoids and anemones is proposed based on their correlated distributions.

Isolation of Endohyphal Bacteria from Foliar Ascomycota and In Vitro Establishment of Their Symbiotic Associations.

Endohyphal bacteria (EHB) can influence fungal phenotypes and shape the outcomes of plant-fungal interactions. Previous work has suggested that EHB form facultative associations with many foliar fungi in the Ascomycota. These bacteria can be isolated in culture, and fungi can be cured of EHB using antibiotics. Here, we present methods for successfully introducing EHB into axenic mycelia of strains representing two classes of Ascomycota. We first establish in vitro conditions favoring reintroduction of two strains of EHB (Luteibacter sp.) into axenic cultures of their original fungal hosts, focusing on fungi isolated from healthy plant tissue as endophytes: Microdiplodia sp. (Dothideomycetes) and Pestalotiopsis sp. (Sordariomycetes). We then demonstrate that these EHB can be introduced into a novel fungal host under the same conditions, successfully transferring EHB between fungi representing different classes. Finally, we manipulate conditions to optimize reintroduction in a focal EHB-fungal association. We show that EHB infections were initiated and maintained more often under low-nutrient culture conditions and when EHB and fungal hyphae were washed with MgCl2 prior to reassociation. Our study provides new methods for experimental assessment of the effects of EHB on fungal phenotypes and shows how the identity of the fungal host and growth conditions can define the establishment of these widespread and important symbioses.

New records and field observations support a facultative commensal association of <I>Thalamita longifrons</I> and <I>Thalamita murinae</I> with soft coral

New records and field observations support a facultative commensal association of <I>Thalamita longifrons</I> and <I>Thalamita murinae</I> with soft coral

New Records of Three Non-Native Darkling Beetles (Coleoptera: Tenebrionidae) Established in California and Nevada, USA

Recent California collection records for three adventive species of soil-dwelling darkling beetles (Coleoptera: Tenebrionidae) are provided, with observational notes on habitats and spread. Gonocephalum sericeum (Baudi), a widespread, synanthropic species in northern Africa and Middle East, is reported from the Western Hemisphere for the first time. The species is illustrated and diagnosed, and the genus is incorporated into a key to North American Opatrini. Gondwanocrypticus platensis (Fairmaire), a South American species of Crypticini often associated with nest debris of imported fire ants, has spread widely in southern California. Opatroides punctulatus Brulle, first discovered in the Sacramento area in 2003–2008, has recently been found in abundance in and around Reno, Nevada and is spreading to new California counties. All three species are thought to be facultative opportunistic ant associates in disturbed habitats.

Tank bromeliads as natural microcosms: A facultative association with ants influences the aquatic invertebrate community structure

Many tank bromeliads have facultative relationships with ants as is the case in French Guiana between Aechmea aquilega (Salib.) Griseb. and the trap-jaw ant, Odontomachus haematodus Linnaeus. Using a redundancy analysis, we determined that the presence of O. haematodus colonies is accompanied by a greater quantity of fine particulate organic matter in the water likely due to their wastes. This increase in nutrient availability is significantly correlated with an increase in the abundance of some detritivorous taxa, suggesting a positive bottom-up influence on the aquatic macroinvertebrate communities living in the A. aquilega wells. On the other hand, the abundance of top predators is negatively affected by a lower number of available wells due to ant constructions for nesting, releasing a top-down pressure that could also favor lower trophic levels.

Arsenophonus and Sodalis Symbionts in Louse Flies: an Analogy to the Wigglesworthia and Sodalis System in Tsetse Flies

Symbiosis between insects and bacteria result in a variety of arrangements, genomic modifications, and metabolic interconnections. Here, we present genomic, phylogenetic, and morphological characteristics of a symbiotic system associated with Melophagus ovinus, a member of the blood-feeding family Hippoboscidae. The system comprises four unrelated bacteria representing different stages in symbiosis evolution, from typical obligate mutualists inhabiting bacteriomes to freely associated commensals and parasites. Interestingly, the whole system provides a remarkable analogy to the association between Glossina and its symbiotic bacteria. In both, the symbiotic systems are composed of an obligate symbiont and two facultative intracellular associates, Sodalis and Wolbachia. In addition, extracellular Bartonella resides in the gut of Melophagus. However, the phylogenetic origins of the two obligate mutualist symbionts differ. In Glossina, the mutualistic Wigglesworthia appears to be a relatively isolated symbiotic lineage, whereas in Melophagus, the obligate symbiont originated within the widely distributed Arsenophonus cluster. Although phylogenetically distant, the two obligate symbionts display several remarkably similar traits (e.g., transmission via the host's "milk glands" or similar pattern of genome reduction). To obtain better insight into the biology and possible role of the M. ovinus obligate symbiont, "Candidatus Arsenophonus melophagi," we performed several comparisons of its gene content based on assignments of the Cluster of Orthologous Genes (COG). Using this criterion, we show that within a set of 44 primary and secondary symbionts, "Ca. Arsenophonus melophagi" is most similar to Wigglesworthia. On the other hand, these two bacteria also display interesting differences, such as absence of flagellar genes in Arsenophonus and their presence in Wigglesworthia. This finding implies that a flagellum is not essential for bacterial transmission via milk glands.

Productivity links morphology, symbiont specificity and bleaching in the evolution of Caribbean octocoral symbioses.

Many cnidarians host endosymbiotic dinoflagellates from the genus Symbiodinium. It is generally assumed that the symbiosis is mutualistic, where the host benefits from symbiont photosynthesis while providing protection and photosynthetic substrates. Diverse assemblages of symbiotic gorgonian octocorals can be found in hard bottom communities throughout the Caribbean. While current research has focused on the phylo- and population genetics of gorgonian symbiont types and their photo-physiology, relatively less work has focused on biogeochemical benefits conferred to the host and how these benefits vary across host species. Here we examine this symbiosis among 11 gorgonian species collected in Bocas del Toro, Panama. By coupling light and dark bottle incubations (P/R) with 13C-bicarbonate tracers, we quantified the link between holobiont oxygen metabolism with carbon assimilation and translocation from symbiont to host. Our data show that P/R varied among species, and was correlated with colony morphology and polyp size. Sea fans and sea plumes were net autotrophs (P/R>1.5), while nine species of sea rods were net heterotrophs with most below compensation (P/R<1.0). 13C assimilation corroborated the P/R results, and maximum δ13Chost values were strongly correlated with polyp size, indicating higher productivity by colonies with high polyp SA:V. A survey of gorgonian-Symbiodinium associations revealed that productive species maintain specialized, obligate symbioses and are more resistant to coral bleaching, whereas generalist and facultative associations are common among sea rods that have higher bleaching sensitivities. Overall, productivity and polyp size had strong phylogenetic signals with carbon fixation and polyp size showing evidence of trait covariance.

Infection prevalence of Sodalis symbionts among stinkbugs.

IntroductionDiverse insects and other organisms are associated with microbial symbionts, which often significantly contribute to growth and survival of their hosts and/or drastically affect phenotypes of their hosts in a variety of ways. Sodalis glossinidius was first identified as a facultative bacterial symbiont of tsetse flies, and recent studies revealed that Sodalis-allied bacteria encompass diverse ecological niches ranging from free-living bacteria through facultative symbionts to obligate symbionts associated with a diverse array of insects. Despite potential ecological and evolutionary relevance of the Sodalis symbionts, their infection prevalence in natural insect populations has been poorly investigated.ResultsHere we surveyed diverse stinkbugs and allied terrestrial heteropteran bugs, which represented 17 families, 77 genera, 108 species, 310 populations and 960 individuals, for infection with the Sodalis symbionts. Diagnostic PCR detected relatively low infection frequencies of the Sodalis symbionts: 13.6% (14/103) of the species, 7.5% (22/295) of the populations, and 4.3% (35/822) of the individuals of the stinkbugs except for those belonging to the family Urostylididae. Among the urostylidid stinkbugs, strikingly, the Sodalis symbionts exhibited very high infection frequencies: 100% (5/5) of the species, 100% (15/15) of the populations, and 94.2% (130/138) of the individuals we examined. Molecular phylogenetic analysis based on bacterial 16S rRNA gene sequences revealed that all the symbionts were placed in the clade of Sodalis-allied bacteria while the symbiont phylogeny did not reflect the systematics of their stinkbug hosts. Notably, the Sodalis symbionts of the urostylidid stinkbugs were not clustered with the Sodalis symbionts of the other stinkbug groups on the phylogeny, suggesting their distinct evolutionary trajectories.ConclusionsThe relatively low infection frequency and the overall host-symbiont phylogenetic incongruence suggest that the Sodalis symbionts are, in general, facultative symbiotic associates in the majority of the stinkbug groups. On the other hand, it is conceivable, although speculative, that the Sodalis symbionts may play some substantial biological roles for their host stinkbugs of the Urostylididae.Electronic supplementary materialThe online version of this article (doi:10.1186/s40851-014-0009-5) contains supplementary material, which is available to authorized users.

First report of Colacium vesiculosum Ehrenberg 1853 (Euglenophyceae), as epibiont on planktonic copepods (Crustacea, Copepoda), in a Brazilian floodplain lake

Epibiosis is a facultative association between two organisms: the epibiont, which colonizes the surface of living substrates, and the basibiont, which hosts the epibionts. Among protists, while numerous accounts exist for ciliates as epibionts of zooplankton, little information is available about the occurrence of this relationship between flagellates and microcrustaceans in the neotropics. During a survey on the epibiotic relationship between ciliated protists and planktonic copepods in a tropical floodplain, we reported for the first time the occurrence of Colacium vesiculosum as an epibiont on Thermocyclops minutus and Notodiaptomus amazonicus from southern Brazil. The mean infestation prevalence was significantly higher on adults 30.53% (± 2.85) in comparison with copepodites 0.87% (± 0.55). When hosts were separated by order (Calanoida and Cyclopoida) copepodites presented a mean infestation prevalence of 0.92% (± 0.85) and 0.83% (± 0.60) respectively, while adults had a mean prevalence of 29.55% (± 6.8) and 30.13% (± 5.83), which could be explained by the fact that adult copepods provide a more stable substrate for epibionts.

Behavioral differences among mutualist species in a shrimp-goby association

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 510:101-106 (2014) - DOI: https://doi.org/10.3354/meps10905 Behavioral differences among mutualist species in a shrimp-goby association Patrick J. Lyons* Department of Ecology and Evolution, Stony Brook University, 650 Life Sciences Building, Stony Brook, New York 11794-5245, USA Present address: CIEE Research Station Bonaire, 26 Kaya Gobernador N. Debrot, Kralendijk, Bonaire, Caribbean Netherlands *Corresponding author: patrick.lyons5@gmail.com ABSTRACT: Alpheid shrimps and gobiid fishes engage in a mutualism in which shrimp construct burrows that are co-habited with gobies and used as refuge from predators by both. Gobies act as sentinels for shrimp. In the western Atlantic, different goby species have been hypothesized to have a facultative (Ctenogobius saepepallens) and obligate (Nes longus) association with the shrimp Alpheus floridanus. I compared various behaviors among these 2 gobies and another goby that occasionally associates with shrimp (Coryphopterus glaucofraenum). The putatively obligate goby had the greatest preference for shrimp burrows versus other shelters, had the greatest partner fidelity, and facilitated more emergence by shrimp by remaining for longer periods at shrimp burrow entrances. These findings provide evidence that in shrimp-goby mutualism, the more specialized and dependent mutualist gobies provide greater services to their shrimp partners. KEY WORDS: Mutualism · Coevolution · Obligate · Facultative · Shrimp-goby · Nes longus · Ctenogobius saepepallens Full text in pdf format PreviousNextCite this article as: Lyons PJ (2014) Behavioral differences among mutualist species in a shrimp-goby association. Mar Ecol Prog Ser 510:101-106. https://doi.org/10.3354/meps10905 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 510. Online publication date: September 09, 2014 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2014 Inter-Research.

Social monogamy in the crab Planes major, a facultative symbiont of loggerhead sea turtles

Studying how host characteristics and ecology affect the mating systems of symbiotic crustaceans offers an opportunity to understand how ecological factors contribute to the evolution of different animal mating systems. In theory, symbiotic crustaceans should display social monogamy with long-term heterosexual pairing when hosts are relatively small in body size and structurally simple, and when hosts have relatively low abundance in habitats where the risk of mortality for symbionts (e.g., predation) away from hosts is high. We test this prediction in the mating system of the flotsam crab (Planes major) and its facultative association with loggerhead sea turtles (Caretta caretta). First, we found that the overall population and sex distributions were non-random and crabs inhabited host turtles as heterosexual pairs more frequently than expected by chance, which supports the hypothesis that P. major is socially monogamous on C. caretta. Second, we found that male crabs pair with females regardless of their reproductive state, male–female pairs do not display size-assortative pairing, crab body size and host turtle body size are not correlated, and crabs display reverse sexual dimorphism in body size and conventional sexual dimorphism in weaponry. These results do not support the hypothesis that social monogamy in P. major is always long term. Instead, our results suggest that the duration of social monogamy in P. major is likely variable and may involve some degree of host switching and intra-sexual (mostly male–male) competition. Our results were only partially consistent with theoretical considerations for how host characteristics and ecology affect the mating systems of symbiotic crustaceans, and future studies should focus on quantifying the degree and direction of host switching to better understand the factors that affect the duration of monogamous pairing when P. major associates with C. caretta.

Diversity of 175 Wheat Varieties from Yellow and Huai River Valleys Facultative Wheat Zone and Association of SSR Markers with Plant Height and Yield Related Traits

To understand the genetic diversity of wheat varieties planted in Yellow and Huai River Valleys Facultative Wheat Zone in China and identify SSR markers associated with important agronomic traits,we selected 108 pairs of SSR markers evenly distributed on wheat chromosomes to detect the diversity of 175 historical winter wheat varieties planted in this region.A total of 448 alleles were detected on the 108 loci,and the average alleles per locus were 4.15,which varied from 2 to 14.The polymorphism information content(PIC) value ranged from 0.075 to 0.869,with an average of 0.560.Clustering analysis showed that most of the varieties with shared parents,bred by the same institution,or planted in the same area were grouped together.Twenty-three markers were significantly associated with plant height and yield related traits(P0.01),among which three were associated with these traits at an extremely significant level(P0.001).Markers wmc128(1B) and wmc236(3B) could explain the variation of spikelet number by 10.5% and 8.0%(P0.001),respectively.Besides,marker Xgwm129(2B) showed significant association with 1000-kernel weight(P0.001) with the rate of phenotypic variation explained as high as 19.3%.

Trophic ecology of a freshwater sponge (Spongilla lacustris) revealed by stable isotope analysis

The vital roles that sponges play in marine habitats are well-known. However, sponges inhabiting freshwaters have been largely ignored despite having widespread distributions and often high local abundances. We used natural abundance stable isotope signatures of carbon and nitrogen (δ 13C and δ 15N) to infer the primary food source of the cosmopolitan freshwater sponge Spongilla lacustris. Our results suggest that S. lacustris feed largely on pelagic resources and may therefore link pelagic and benthic food webs. A facultative association between S. lacustris and endosymbiotic green algae caused S. lacustris to have significantly depleted carbon and nitrogen signatures that may reflect carbon and nitrogen exchange between sponges and their symbiotic algae. Isotopic data from specialist sponge consumers demonstrated that sponges hosting zoochlorellae were the major component of the diet of the spongillafly Climacia areolaris and the sponge-eating caddisfly Ceraclea resurgens suggesting that the symbiosis between freshwater sponges and algae is important to sponge predator trophic ecology. Our results help define the role of sponges in freshwater ecosystems and shed new light on the evolution and ecological consequences of a complex tri-trophic symbiosis involving freshwater sponges, zoochlorellae, and spongivorous insects.

Bacterial Infections across the Ants: Frequency and Prevalence ofWolbachia, Spiroplasma, andAsaia

Bacterial endosymbionts are common across insects, but we often lack a deeper knowledge of their prevalence across most organisms. Next-generation sequencing approaches can characterize bacterial diversity associated with a host and at the same time facilitate the fast and simultaneous screening of infectious bacteria. In this study, we used 16S rRNA tag encoded amplicon pyrosequencing to survey bacterial communities of 310 samples representing 221 individuals, 176 colonies and 95 species of ants. We found three distinct endosymbiont groups—Wolbachia(Alphaproteobacteria: Rickettsiales),Spiroplasma(Firmicutes: Entomoplasmatales), and relatives ofAsaia(Alphaproteobacteria: Rhodospirillales)—at different infection frequencies (at the ant species level: 22.1%, 28.4%, and 14.7%, resp.) and relative abundances within bacterial communities (1.0%–99.9%).Spiroplasmawas particularly enriched in the ant genusPolyrhachis, whileAsaiarelatives were most prevalent in arboreal ants of the genusPseudomyrmex. WhileWolbachiaandSpiroplasmahave been surveyed in ants before,Asaia, an acetic acid bacterium capable of fixing atmospheric nitrogen, has received much less attention. Due to sporadic prevalence across all ant taxa investigated, we hypothesize facultative associations for all three bacterial genera. Infection patterns are discussed in relation to potential adaptation of specific bacteria in certain ant groups.

Evolution of microhabitat association and morphology in a diverse group of cryptobenthic coral reef fishes (Teleostei: Gobiidae: Eviota)

Gobies (Teleostei: Gobiidae) are an extremely diverse and widely distributed group and are the second most species rich family of vertebrates. Ecological drivers are key to the evolutionary success of the Gobiidae. However, ecological and phylogenetic data are lacking for many diverse genera of gobies. Our study investigated the evolution of microhabitat association across the phylogeny of 18 species of dwarfgobies (genus Eviota), an abundant and diverse group of coral reef fishes. In addition, we also explore the evolution of pectoral fin-ray branching and sensory head pores to determine the relationship between morphological evolution and microhabitat shifts. Our results demonstrate that Eviota species switched multiple times from a facultative hard-coral association to inhabiting rubble or mixed sand/rubble habitat. We found no obvious relationship between microhabitat shifts and changes in pectoral fin-ray branching or reduction in sensory pores, with the latter character being highly homoplasious throughout the genus. The relative flexibility in coral-association in Eviota combined with the ability to move into non-coral habitats suggests a genetic capacity for ecological release in contrast to the strict obligate coral-dwelling relationship commonly observed in closely related coral gobies, thus promoting co-existence through fine scale niche partitioning. The variation in microhabitat association may facilitate opportunistic ecological speciation, and species persistence in the face of environmental change. This increased speciation opportunity, in concert with a high resilience to extinction, may explain the exceptionally high diversity seen in Eviota compared to related genera in the family.

Two sides of the same coin? Rare and pest plants native to the United States and Canada

Plant biodiversity is at risk, with as many as 10% of native species in the United States being threatened with extinction. Habitat loss has led a growing number of plant species to become rare or threatened, while the introduction or expansion of pest species has led some habitats to be dominated by relatively few, mostly nonindigenous, species. As humans continue to alter many landscapes and vegetation types, understanding how biological traits determine the location of species along a spectrum from vulnerability to pest status is critical to designing risk assessment protocols, setting conservation priorities, and developing monitoring programs. We used boosted regression trees to predict rarity (based on The Nature Conservancy global rankings) and pest status (defined as legal pest status) from data on traits for the native vascular flora of the United States and Canada including Hawaii, Puerto Rico, and the Virgin Islands (n approximately = 15,000). Categories were moderately to highly predictable (AUCpest = 0.87 on 25% holdout test set, AUCrarity = 0.80 on 25% holdout test set). Key predictors were chromosome number, ploidy, seed mass, and a suite of traits suggestive of specialist vs. generalist adaptations (e.g., facultative wetland habitat association and phenotypic variability in growth form and life history). Specifically, pests were associated with high chromosome numbers, polyploidy, and seed masses ranging from 0.1 to 100 mg, whereas rare species were associated with low chromosome numbers, low ploidy, and large (>1000 mg) seed masses. In addition, pest species were disproportionately likely to be facultatively associated with wetlands, and variable in growth form and life history, whereas rare species exhibited an opposite pattern. These results suggest that rare and pest species contrast along trait axes related to dispersal and performance in disturbed or novel habitats.

A leaf-rolling weevil benefits from general saprophytic fungi in polysaccharide degradation

Insects, especially those feeding on leaf litter, widely form symbiosis with fungi. As dead plant tissues provide insects with poor-quality diets, which contain relatively high levels of indigestible lignin and cellulose, some saprophytic fungi may increase nutrient availability by polysaccharide degradation. Although the inherited, obligate bacterial symbionts are well documented, the non-inherited, facultative fungal symbionts are relatively overlooked. Females of the leaf-rolling weevil Heterapoderopsis bicallosicollis, a specialist of Triadica sebifera, construct leaf-rolls that serve as retreats from which larvae feed internally. We found that fungi associated with leaf-rolls were not transported by the female, but likely originated from the soil. To determine the effects of fungi on H. bicallosicollis development, fungal growth was reduced by a dry treatment. This treatment decreased adult weight and survival, and prolonged larval duration significantly. We further tested the hypothesis that fungi degrade leaf-roll polysaccharides, by a fungus inoculation experiment. Three dominant fungi (Penicillium sp., Aspergillus sp. and Cladosporium sp.) decreased the levels of soluble carbohydrate, cellulose, and lignin in inoculation experiments. Soluble carbohydrate, cellulose, and lignin of leaf-rolls all were found to decrease gradually during insect development. We conclude that these saprophytic fungi form facultative associations with H. bicallosicollis and benefit weevil nutrition by polysaccharide decomposition. Our study highlights the significance of fungal symbionts in insect nutritional ecology.