Chemical defenses shift with the seasonal vertical migration of a Panamanian poison frog

Dendrobatid poison frogs sequester lipophilic alkaloids from their arthropod prey to use as a form of chemical defense. Some dendrobatid frogs seasonally migrate between the leaf litter of the forest floor in the dry season to the canopy in the wet season, which may yield differences in prey (arthropods) and therefore alkaloid availability over space and time. Here, we document a seasonal vertical migration of Andinobates fulguritus (the yellow‐bellied poison frog) from ground to canopy between dry and wet seasons. We observed turnover in alkaloid composition between seasons and found that dry season frogs contained a lower relative quantity of alkaloids; however, there was no change in alkaloid richness between seasons. The 77 alkaloids of 13 structural classes identified in this population appear to be derived mostly from mites and ants, though the two most common alkaloids were mite derived. Our observed shifts in defensive profiles are consistent with well‐documented turnover in mite and ant communities between seasons and vertical strata. As climate change is expected to lengthen and strengthen dry seasons in many tropical regions, our results suggest that arboreal poison frogs forced to the ground for longer periods of time may see a shift in the abundance of alkaloids, possibly decreasing their defensive potential. This study provides further predictions for the wide‐reaching effects of climate change, even as nuanced as charismatic poison frogs losing their poisons. Abstract in Spanish is available with online material.     

Review of oribatid mites as intermediate hosts of tapeworms of the Anoplocephalidae

A list of oribatid mites acting as intermediate hosts of tapeworms of the Anoplocephaldae is provided. to date, 127 species of oribatids included in 27 families, are implicated as intermediate hosts of the 14 genera and 27 species of anoplocephalid tapeworms. The most cited mites families are Oribatulidae with 35 species, Galumnidae with 22 species and Ceratozetidae with 15 species. Scheloribates laevigatus (Oribatulidae) is the species that demonstrated most susceptibility, both natural and experimental, to develop larval forms of anoplocephalid tapeworms. A theoretical-methodological model for parasitology based on the trophic characteristics of the intermediate and definitive mammalian hosts is reviewed.     

贵州施秉喀斯特地区林地土壤甲螨的群落组成及多样性（英文）

【目的】为了解施秉喀斯特地区林地土壤甲螨的分布和群落组成特点,明确中国西南喀斯特地区林地类型对土壤甲螨群落密度、组成和物种多样性的影响,对该区林地土壤甲螨的群落结构及多样性进行了的调查和分析。【方法】2012年8月选取了中国西南施秉喀斯特地区典型生境中的8个样地,每个样地9个取样点,用Berlese-Tullgren装置分离土样24 h。多样性分析采用常见的多样性指数;群落相似性分析采用Jaccard相似性系数(C_J);群落聚类分析分别采用Marczewski Steinhaus 距离(C_ms)和Bray-Curtis距离,应用R 2.11程序进行类平均法聚类。【结果】结果显示,中国西南喀斯特8个样地中土壤甲螨由少数的优势属和数量众多的稀有属组成。其中全菌甲螨属 Perscheloribates (22.48%)和长单翼甲螨属 Protoribates (11.45%)个体数量最为丰富。长单翼甲螨属 Protoribate、上罗甲螨属Epilohmannia、小奥甲螨属 Oppiella、小盾珠甲螨属 Suctobelbella 和盖头甲螨属 Tectocepheus 分布广泛。本区的甲螨组成（属级水平）表现出明显热带和亚热带地区特点。在天然常绿落叶阔叶林中,甲螨的个体数量和种类数较多,但多样性不高,而在人工针叶林中甲螨多样性最高。甲螨群落组成和分布特征多样,异质性高,特别是在天然常绿落叶阔叶林中突出。【结论】研究表明,施秉喀斯特生态系统的不同林分影响甲螨的物种多样性和群落稳定性,天然常绿落叶阔叶混交林是甲螨的“避难所”。     

New Species of Oribatid Mites of the Superfamily Oripodoidea Jacot, 1925 (Acari,Oribatida) from Trinidad and Tobago

Two new species of oribatid mites of the superfamily Oripodoidea (Acari, Oribatida) are described from Trinidad and Tobago. Scheloribates (Scheloribates) tobagoensis sp. n. (Scheloribatidae) differs fromS. (Scheloribates) papillaris Tseng, 1984 in the structure of the rostral and lamellar setae and leg solenidia, in the length of the prolamellae, the absence of aggenital setae, and in reduction of setae on tarsi III. Areozetes ryabinini sp. n. (Haplozetidae) differs from A. altimontanus Hammer, 1961 in the structure of the bothridial and notogastral setae and rostrum and in the number of claws on the tarsi.     

Expanding the ‘enemy-free space’ for oribatid mites: evidence for chemical defense of juvenile Archegozetes longisetosus against the rove beetle Stenus juno

Adult oribatid mites are thought to live functionally in ‘enemy-free space’ due to numerous morphological and chemical defensive strategies. Most juvenile oribatid mites, however, lack hardened cuticles and are thus thought to be under stronger predation pressure. On the other hand, the majority of oribatids have exocrine oil glands in all developmental stages, possibly rendering chemical defense the crucial survival strategy in juvenile Oribatida. We manipulated tritonymphs of the model oribatid mite Archegozetes longisetosus to completely discharge their oil glands and offered these chemically disarmed specimens to the polyphagous rove beetle Stenus juno. Disarmed specimens were easily consumed. By contrast, specimens with filled oil glands were significantly protected, being rejected by the beetles. This is the first direct evidence that oil gland secretions provide soft-bodied juvenile oribatids with chemical protection against large arthropod predators.     

广东鼎湖山自然保护区土壤甲螨的调查研究（蜱螨亚纲：甲螨亚目）

以种类名录报道广东鼎湖山自然保护区的土壤甲螨58种,并记述新种巨杆棱甲螨Mochlozetes grandis sp.nov.此外还对该地区甲螨区系的特点作了初步分析。     

Evolution of dietary specialization and chemical defense in poison frogs (Dendrobatidae): a comparative analysis

Defensive mechanisms, including noxious or toxic substances, are favored by predation-driven natural selection. The acquisition of noxious/toxic substances can be either endogenous, in which the substances are produced by the organism, or exogenous, in which the substances are produced by another organism and are sequestered. Evidence indicates that the defensive skin alkaloids of Neotropical poison frogs (Dendrobatidae) have an exogenous source: a diet of ants and other small alkaloid-containing arthropods, which we term the diet-toxicity hypothesis. A critical prediction of the diet-toxicity hypothesis is that independent origins of dietary specialization will be found to be correlated with independent origins of skin alkaloids. We tested this prediction in an integrated framework using comparative methods with new and published data on feeding ecology and chemical defense for 15 species of dendrobatids in five genera. We found a significant correlation between alkaloid profiles and degree of dietary specialization. This reveals a recurring association of dietary specialization and alkaloid sequestration in dendrobatids, which suggests parallel evolutionary trends in the origins of defensive mechanisms.     

亚热带不同树种组成森林中土壤甲螨群落结构特征: 以江西新岗山为例

在全球环境变化的大背景下, 生物多样性丧失日益加剧。土壤动物作为生物多样性重要组成之一, 受到广泛的关注。位于我国江西省新岗山的亚热带森林生物多样性与生态系统功能实验样地(BEF-China)是全世界25个森林生物多样性控制实验样地之一。本研究自2019年9月至2022年4月在BEF-China两个不同树种组成的样地(A样地和B样地)内采样, 共获得甲螨23,704头, 隶属于34科50属61种。本文分析和对比了两个样地内甲螨群落结构的差异, 及其多度、物种丰富度、Shannon多样性指数的季节性差异; 通过Pearson检验探讨了甲螨多度与环境因子的关系。结果表明: 在A、B两个不同树种组成的森林生态系统内, 土壤甲螨群落结构及其季节动态具有显著差异。具体表现在: A样地奥甲螨科、罗甲螨科、若甲螨科和尖棱甲螨科的相对多度高于B样地; B样地菌甲螨科、盖头甲螨科和礼服甲螨科的相对多度高于A样地。A样地中夏季和秋季甲螨多度、物种丰富度和Shannon多样性指数显著低于春季和冬季; 而B样地中秋季甲螨多度和物种丰富度与春季差异不显著。Pearson检验结果显示, 凋落物木质素含量与单翼甲螨科和菌甲螨科多度呈负相关关系, 而与奥甲螨科多度呈正相关关系。菌甲螨科多度与土壤和凋落物同一理化因子的相关性基本相同(碳氮比除外), 但与凋落物碳氮比呈正相关关系而与土壤碳氮比呈负相关关系。     

The effect of herbivore faeces on the edaphic mite community: implications for tapeworm transmission

Oribatid mites may be of epidemiological and medical importance because several species have been shown to serve as intermediate hosts for anoplocephalid tapeworms of wild and domestic animals. Despite their economic and conservation significance, relatively few studies examined factors influencing the effective number of oribatid mites that can serve as intermediate hosts. We examined variation in the structure of the edaphic arthropod community in functionally different territory parts of the Alpine marmot (Marmota marmota latirostris), a known definitive host of a prevalent anoplocephalid tapeworm, Ctenotaenia marmotae. We used a field experiment to test whether the abundance of oribatid mites in marmot pastures is affected by the presence of fresh herbivore faeces. We found that the abundance of soil and litter dwelling oribatid mites in marmot pastures did not change shortly after faeces addition. In contrast, numbers of other predominant soil–litter and phoretic microarthropods increased after faeces addition. The abundance of the two predominant phoretic mites colonizing the faeces was inversely related to the abundance of oribatid mites. In contrast, the abundance of a ubiquitous soil–litter mesostigmatid mite was a positive function of oribatid numbers. Although absolute numbers of oribatid mites did not change after faeces addition, our study suggests that, depending on soil quality or type, the probability of tapeworm egg ingestion by oribatid mites can be reduced due to increased interspecific prey-predatory and trophic interactions. Latrine site selection in Alpine marmots is consistent with a reduced probability of tapeworm transmission by oribatids.     

Links between prey assemblages and poison frog toxins: A landscape ecology approach to assess how biotic interactions affect species phenotypes

Ecological studies of species pairs showed that biotic interactions promote phenotypic change and eco‐evolutionary feedbacks. However, it is unclear how phenotypes respond to synergistic interactions with multiple taxa. We investigate whether interactions with multiple prey species explain spatially structured variation in the skin toxins of the neotropical poison frog Oophaga pumilio. Specifically, we assess how dissimilarity (i.e., beta diversity) of alkaloid‐bearing arthropod prey assemblages (68 ant species) and evolutionary divergence between frog populations (from a neutral genetic marker) contribute to frog poison dissimilarity (toxin profiles composed of 230 different lipophilic alkaloids sampled from 934 frogs at 46 sites). We find that models that incorporate spatial turnover in the composition of ant assemblages explain part of the frog alkaloid variation, and we infer unique alkaloid combinations across the range of O. pumilio. Moreover, we find that alkaloid variation increases weakly with the evolutionary divergence between frog populations. Our results pose two hypotheses: First, the distribution of only a few prey species may explain most of the geographic variation in poison frog alkaloids; second, different codistributed prey species may be redundant alkaloid sources. The analytical framework proposed here can be extended to other multitrophic systems, coevolutionary mosaics, microbial assemblages, and ecosystem services.     

Molecular phylogeny of oribatid mites (Oribatida, Acari): evidence for multiple radiations of parthenogenetic lineages

Nucleotide sequences of the D3 expansion segment and its flanking regions of the 28S rDNA gene were used to evaluate phylogenetic relationships among representative sexual and asexual oribatid mites (Oribatida, Acariformes). The aim of this study was to investigate the hypothesis that oribatid mites consist of species-rich clusters of asexual species that may have radiated while being parthenogenetic. Furthermore, the systematic position of the astigmate mites (Astigmata, Acariformes) which have been hypothesised to represent a paedomorphic lineage within the oribatid mites, is investigated. This is the first phylogenetic tree for oribatid mites s.l. (incl. Astigmata) based on nucleotide sequences. Intraspecific genetic variation in the D3 region was very low, confirming the hypothesis that this region is a good species marker. Results from neighbour joining (NJ) and maximum parsimony (MP) algorithms indicate that several species-rich parthenogenetic groups like Camisiidae, Nanhermanniidae and Malaconothridae are monophyletic, consistent with the hypothesis that some oribatid mite groups diversified despite being parthenogenetic. The MP and maximum likelihood (ML) method indicated that the D3 region is a good tool for elucidating the relationship of oribatid mite species on a small scale(genera, families) but is not reliable for large-scale taxonomy, because branches from the NJ algorithm collapsed in the MP and ML tree. In all trees calculated by different algorithms the Astigmata clustered within the oribatid mites, as proposed earlier.     

Oribatid mite (Acari: Oribatida) contribution to decomposition dynamic of leaf litter in primary forest, second growth, and polyculture in the Central Amazon.

We studied the contribution of oribatid mites in the dynamics of litter decomposition in an experiment using litterbags of three different mesh sizes (20 microns, 250 microns, and 1 cm). The experiment was carried out at a primary forest (FLO), a secondary forest (SEC), and at two polyculture systems (POA and POC). We compared the weight loss of the leaves of Vismia guianensis and the changes of the oribatid mite species community. We processed the samples after 26, 58, 111, 174, 278, and 350 days from the beginning of the experiment by using the Berlese-Tullgren to extract the animals. We hypothesized that: 1. the abundance and diversity of oribatid mites would exert an influence in the decomposition process; 2. there would be a successional changing of the species during decomposition; and 3. there would be differences in the colonization of species in relation to the mesh size of the litterbags. A total of 95 species of oribatid mites was found. The biomass data was the first registered for the Amazon region. The great dominance of oribatid mites did not exert an influence in the decomposition process. There was not a successional changing of the species during the course of the decomposition process, unlike those shown by results obtained in the temperate forest, because we found neither early colonizers nor species that prefer advanced decomposition stages. The oribatid mite community, which developed in the litterbags under tropical conditions, was atypical of the normal stages of leaf litter breakdown and decomposition. There were differences in the colonization of species in relation to the mesh size of the litterbags. These differences were very closely related to the specific habits and habitat of the dominant species.     

南岳衡山蕨类植物区系研究

南岳衡山蕨类植物共计235种(含种下等级),隶属于36科75属。区系分析表明:该地蕨类植物具有较强的热带性质,同时也显示出该区蕨类植物区系向温带渗透和过渡的性质,科、属的分布区类型均以热带、亚热带分布型为主,而种以温带分布型为主。热带、亚热带分布型在该区有18科38属69种,分别占科、属、种数的50.00%、50.67%和29.36%;其中泛热带分布型有14科21属5种,分别占科、属、种数的38.89%、28.00%和2.13%;温带性分布型有3科18属158种,分别占科、属、种数的8.33%、24.00%和67.23%。表明泛热带分布型是该区科、属最重要的分布类型;在种的区系上,温带性成分占明显优势,反映了该区热带成分与温带成分的交汇与兼容。该区虽没有自己的特有属,但具1种特有种,而且中国特有种丰富,共计46种,占总种数的19.57%。该区系与周邻联系广泛,地理成分以华东成分为主。在区系关系上,该区与武夷山、庐山的关系密切,而与万佛山的关系较为疏远。     

The palatability of Neotropical poison frogs in predator‐prey systems: do alkaloids make the difference?

Neotropical poison frogs sequester alkaloid‐based chemical defenses from their diet, which seem to repel invertebrate predators after contact. In this study, we tested the reaction of predatory ants toward skin secretions of captive‐bred poison frogs without alkaloids. Although the secretions had a smell and taste similar to those of wild‐caught frogs, the ants did not avoid them, but actually preferred them. We infer that amphibian secretions are attractive to invertebrate predators (probably due to palatable nutritive components), but that this attraction is overridden when unpalatable alkaloids are present.     

Global diversity of oribatids (Oribatida: Acari: Arachnida)

Oribatid mites are primarily terrestrial. Only about 90 species (less than 1% of all known oribatid species) from 10 genera are truly aquatic, with reproduction and all stages of their life cycle living in freshwater. Adaptation to aquatic conditions evolved independently in different taxa. However, many terrestrial species can also be found in aquatic habitats, either as chance stragglers from the surrounding habitats, or from periodic or unpredictable floodings, where they can survive for long periods. In spite of their low species richness aquatic oribatids can be very abundant in different freshwater habitats as in lentic (pools, lakes, water-filled microhabitats) or flowing waters (springs, rivers, streams), mainly on submerged plants. The heavily sclerotized exoskeletons of several species enables subfossil or fossil preservation in lakes or bog sediments. Guest editors: E. V. Balian, C. Lévêque, H. Segers & K. Martens Freshwater Animal Diversity Assessment     

Triggering chemical defense in an oribatid mite using artificial stimuli

Most oribatid mites are well known for their exocrine oil gland secretions, from which more than a hundred different chemical components (hydrocarbons, terpenes, aromatics and alkaloids) have been described. The biological functions of these secretions have remained enigmatic for most species, but alarm-pheromonal and allomonal functions have been hypothesized, and demonstrated in some cases. Here, we tested different experimental stimuli to induce the release of defensive secretions in the model oribatid mite Archegozetes longisetosus Aoki. Whereas various mechanical stimuli did not result in a reproducible and complete expulsion of oil gland secretions, repeated treatments with hexane led to complete discharge. Life history parameters such as survival, development and reproduction were not influenced by the hexane treatment. Repeated hexane treatments also resulted in a complete depletion of oil glands in Euphthiracarus cribrarius Berlese.     

湖北利川市种子植物区系研究

根据调查和统计,利川市共有野生种子植物145科750属2028种,其中裸子植物6科19属24种,被子植物139科731属2004种,木本植物1002种,草本植物1026种;本区系具有古老、孑遗、原始性,单种属和寡种属数量多;分布类型多样,地理成分复杂,仅属有15个分布类型和21个变型,科的热带成分占61.62%、温带成分占36.36%,属的热带成分占39.05%,温带成分占55.62%。利川种子植物区系具有以温带为主的亚热带性质。     

武功山地区种子植物区系研究

通过多次野外调查及资料整理,对武功山地区种子植物科、属、种的组成及区系特征进行了调查分析,为该区植物资源的保护以及植物分区提供理论依据。结果表明:(1)武功山地区共有种子植物166科、814属、2 079种,分别占江西省种子植物科、属、种总数的72.81%、61.11%、50.46%,其中裸子植物有7科、15属、19种,分别占江西裸子植物总数的77.78%、65.21%、54.28%。(2)武功山地区科包含12个分布区类型,热带成分占优势(70科,占57.96%),温带成分丰富(46科,38.65%);属包含14个分布区类型,热带成分略占优势(368属,49.40%),温带成分增加(354属,47.53%);种包含14个分布类型,热带分布性626种(31.04%),温带分布性663种(32.87%),温带成分略占优势;武功山地区植物成分具有热带向温带过渡的特点,并且热带和温带成分相互交融、渗透。(3)武功山地区种子植物具有单种和少种的科属较多,具有起源古老的特点,其中单种属有414属,占总属数的50.86%。中国特有成分有4科、23属、728种。(4)与相邻的15个代表性区系比较表明,武功山地区种类较为丰富,聚类分析表明该区系与黄山、庐山、武夷山、井冈山等地区的关系很密切,与秦岭、西双版纳和高黎贡山的区系关系最疏远。     

Differences in litter mass change mite assemblage structure on a deciduous forest floor

Few mechanisms that determine the assemblage structure of mites have been identified. Whilst the relative abundance of soil fauna is known to change with humus form, the degree to which the quantity of litter inputs play a part in these changes has not been investigated. We tested the response of oribatid and mesostigmatid mites in litter and soil layers to increasing levels of birch Betula pubescens litter to test whether litter mass could affect the mite assemblage. Six litter treatments (1, 2, 4, 8 and 12×natural litter mass and complete litter removal) were established in November 2004 and the soil and litter communities sampled in October 2005. Species composition of oribatids was distinct for the soil and litter. There was no apparent effect of increasing litter mass on the soil mite assemblage. In the litter layer, the number of oribatids g⁻¹ of litter showed a strong negative relationship with increasing litter mass whilst the number of mesostigmatids g⁻¹ of litter was unresponsive to litter mass. Hence, the relative abundance of these two groups altered with increasing litter mass. The response of the oribatid groups Oppiidae and Poronota followed this negative relationship with litter mass but Phthiracaridae appeared less affected. Consequently, there was a subtle shift in the relative abundance of these groups with increasing litter mass. Our results demonstrate that oribatids as a whole and within groups respond in a predictable manner to increases in litter mass whilst mesostigmatids are unresponsive. Whilst there are undoubtedly biological and physical aspects that vary with litter mass, litter mass itself, is able to explain some patterns in the assemblage of oribatid mites.     

Secondary succession, soil formation and development of a diverse community of oribatids and saprophagous soil macro-invertebrates

Investigations into different stages of secondary succession (from a wheat field to a beechwood on Threstone; Northern Germany) demonstrated the formation of a carbon rich top soil in later successional stages. Parallel to changes in plant species and soil formation, there were also changes in species composition and diversity of saprophagous macro-invertebrates (Lumbricidae, Diplopoda, Isopoda) and oribatid mites (Acari: Oribatida). Diversity of diplopod and isopod species increased after cessation of cultivation, but in a late successional stage (ca 50 y-old fallow, ash-dominated wood) species number of diplopods and isopods declined strongly. In comparison with the other soil invertebrate groups, species composition of earthworms among the sites was more similar. Accumulation of soil C was assumed to be related to wood formation and occurrence of woody debris and recalcitrant leaf litter of beech trees. Incorporation of recalcitrant litter materials by earthworm species living in the upper mineral soil presumably contributed significantly to accumulation of soil C. Accumulation of soil C was accompanied by the development of an oribatid mite community rich in species. In early successional stages oribatids predominantly colonized the litter layer, while most oribatid mites of the beechwood inhabited the upper mineral soil. Maximum diversity of oribatid mites in the beechwood is assumed to be related to instability of the mineral soil caused by earthworm activity. Changes in species composition and diversity are discussed considering succession theory. Even soil invertebrates of similar trophic groups appear to respond very differently to successional changes. It is concluded that conservation strategies to maintain high diversity of soil invertebrates are most likely to be successful if a wide range of habitats of different successional stages is included.