Search Results (9)

The highly variable ’leafscapes’ of plants across the world represent billions of square metres of mite habitat. The phytoseiid mites (Acari: Phytoseiidae), an extremely species-rich group of mostly generalist predators, are providers of ecosystem services for humanity worth many hundreds of millions of dollars annually by helping suppress phytophagous mites and insects in forests, agro-ecosystems, shade-houses and home gardens. In this study, the phytoseiid mite assemblages on the leaves of four species of common tree species, namely oak (Quercus cerris var. cerris), poplar (Populus deltoides, P. nigra) and walnut (Juglans regia), were compared. The three data sets used were generated in three independent seasonal studies in Samsun Province, Türkiye, between 2018 and 2022. In total, mite species in 18 families, including 15 families on walnut, were recorded. Nineteen phytoseiid species in 13 genera, Amblydromalus, Amblyseius, Euseius, Kampimodromus, Neoseiulella, Neoseiulus, Paraseiulus, Phytoseius, Transeius, Typhlodromina, Typhlodromips, Typhlodromus and Typhloseiulus, were collected. Only Eusieus amissibilis was collected from all three tree genera, whereas 14 species were collected from only one tree genus. Shannon diversity and Jaccard similarity indexes were calculated for mite families and phytoseiid genera and species. Potential reasons for the observed differences in the phytoseiid assemblages on the different host trees are explored in depth. In the ‘big picture’, global biodiversity, likely including many undescribed phytoseiid species, is threatened by widespread habitat degradation and destruction, especially in the tropics, and accelerating climate change, and rapidly stopping them is imperative. Full article

Mite communities inhabiting plants are known to be affected by several environmental factors, including temperature and humidity. This pilot study aimed to assess seasonal variation in mite abundance and species richness in three Southern African woody species: Gardenia thunbergia, Rothmannia globosa (both Rubiaceae), and Tecomaria capensis (Bignoniaceae). Furthermore, we investigated the influence of rainfall, maximum and minimum temperature, and relative humidity on mite abundance and species richness. The study was conducted in 2014–2015 in Makhanda, formerly known as Grahamstown, in the Eastern Cape, South Africa. Twenty mature leaves were collected from all aspects of the plant fortnightly over 34 weeks. Following sampling, the leaves were viewed under a dissecting microscope, and mites were collected from inside the domatia and surrounding leaf surface area. Species diversity and abundance were calculated for each season and compared. A multiple linear regression analysis was performed in R Studio to test relationships between species richness and abundance, minimum and maximum daily temperatures, relative humidity, rainfall the day before, and accumulative rainfall over the preceding two-week period. We found that mites were present in the leaves of the sampled plants across all seasons, but that mite abundance and species richness changed with each season. None of the environmental variables were correlated with mite abundance, and only relative humidity influenced species richness. These results were not consistent across the three plant species studied, and we point to weaknesses in our sampling approach for the observed results. This pilot study, one of the first from southern Africa, provides a window into the complex interactions between plants and mites. We advocate for more studies on mite seasonality to better understand if it is specific to a region, vegetation type, or host species. Full article

Many dicotyledonous plants produce structures called leaf domatia. Approximately 28% of 290 families have species with leaf domatia. These structures are abundant within the Rubiaceae and Vitaceae. 26% and 16% out of 206 representative species cited in literature from 48 plant families belong to the Rubiaceae and Vitaceae respectively. Leaf domatia are usually associated with mites and often mediate mutualistic relationships with predacious mites. These structures are pockets found in the underside of the leaf, where the secondary vein axils meet the major vein. In the present study, we examine the anatomical structures of leaf domatia from three plant species (Gardenia thunbergia Thunb., Rothmannia capensis Thunb., Rothmannia globosa (Hochst.) Keay) from the Rubiaceae family in order to find out if their internal tissues differ. These plants were sectioned and viewed under a Light Microscope in order to document their internal anatomy. A Transmission Electron Microscope was used to search for the presence of cuticular folds in their epidermis, which are thought to assist plant to communicate with mites. Results from this study suggested that the main features of domatial anatomy are the presence of an extra layer of tissue in the lower epidermis, a cuticle, cuticular folds, trichomes and the presence of an invagination. Cuticular folds were present inside the domatia but were not restricted to the domatial lamina. Thus, we conclude that these structures do not assist plant in plant-mite communication. This study provides a better understating of the anatomy of leaf domatia of the Rubiaceae. Full article

Black fungi of the order Chaetothyriales are grown by many tropical plant-mutualistic ants as small so-called “patches” in their nests, which are located inside hollow structures provided by the host plant (“domatia”). These fungi are introduced and fostered by the ants, indicating that they are important for the colony. As several species of Chaetothyriales tolerate, adsorb, and metabolize toxic volatiles, we investigated the composition of volatile organic compounds (VOCs) of selected domatia in the Azteca/Cecropia ant-plant mutualism. Concentrations of VOCs in ant-inhabited domatia, empty domatia, and background air were compared. In total, 211 compounds belonging to 19 chemical families were identified. Ant-inhabited domatia were dominated by ketones with 2-heptanone, a well-known ant alarm semiochemical, as the most abundant volatile. Empty domatia were characterized by relatively high concentrations of the monoterpenes d-limonene, p-cymene and β-phellandrene, as well as the heterocyclic sulphur-containing compound, benzothiazole. These compounds have biocidal properties and are primarily biosynthesized by plants as a defense mechanism. Interestingly, most of the latter compounds were present at lower concentrations in ant inhabited domatia than in non-colonized ones. We suggest that Chaetothyriales may play a role in reducing the VOCs, underlining that the mutualistic nature of these fungi as VOCs accumulation might be detrimental for the ants, especially the larvae. Full article

Indirect defenses are plant phenotypes that reduce damage by attracting natural enemies of plant pests and pathogens to leaves. Despite their economic and ecological importance, few studies have investigated the genetic underpinnings of indirect defense phenotypes. Here, we present a genome-wide association study of five phenotypes previously determined to increase populations of beneficial (fungivorous and predacious) mites on grape leaves (genus Vitis): leaf bristles, leaf hairs, and the size, density, and depth of leaf domatia. Using a common garden genetic panel of 399 V. vinifera cultivars, we tested for genetic associations of these phenotypes using previously obtained genotyping data from the Vitis9kSNP array. We found one single nucleotide polymorphism (SNP) significantly associated with domatia density. This SNP (Chr5:1160194) is near two genes of interest: Importin Alpha Isoform 1 (VIT_205s0077g01440), involved in downy mildew resistance, and GATA Transcription Factor 8 (VIT_205s0077g01450), involved in leaf shape development. Our findings are among the first to examine the genomic regions associated with ecologically important plant traits that facilitate interactions with beneficial mites, and suggest promising candidate genes for breeding and genetic editing to increase naturally occurring predator-based defenses in grapevines. Full article

Studies on carton nesting ants and domatia−dwelling ants have shown that ant–fungi interactions may be much more common and widespread than previously thought. Until now, studies focused predominantly on parasitic and mutualistic fungi–ant interactions occurring mostly in the tropics, neglecting less−obvious interactions involving the fungi common in ants’ surroundings in temperate climates. In our study, we characterized the mycobiota of the surroundings of Formica polyctena ants by identifying nearly 600 fungal colonies that were isolated externally from the bodies of F. polyctena workers. The ants were collected from mounds found in northern and central Poland. Isolated fungi were assigned to 20 genera via molecular identification (ITS rDNA barcoding). Among these, Penicillium strains were the most frequent, belonging to eight different taxonomic sections. Other common and widespread members of Eurotiales, such as Aspergillus spp., were isolated very rarely. In our study, we managed to characterize the genera of fungi commonly present on F. polyctena workers. Our results suggest that Penicillium, Trichoderma, Mucor, Schwanniomyces and Entomortierella are commonly present in F. polyctena surroundings. Additionally, the high diversity and high frequency of Penicillium colonies isolated from ants in this study suggest that representatives of this genus may be adapted to survive in ant nests environment better than the other fungal groups, or that they are preferentially sustained by the insects in nests. Full article

A banker plant system is a rearing and release method for biological control agents, and in recent years has gained serious attention among plant propagators for its use in regulating common greenhouse and nursery pests. In the current study, the suitability of four ornamental pepper (Capsicum annuum L.; Solanales: Solanaceae) banker plant candidates, Black Pearl (BP), Explosive Ember (EE), Masquerade (MA), Red Missile (RM), and a commercial pepper cultivar, Blitz (BL), were evaluated with three main objectives: (1) to assess host preference of three major arthropod pests of agricultural importance, Bemisia tabaci Gennadius, Polyphagotarsonemus latus Banks, and Frankliniella occidentalis Pergande among selected pepper cultivars; (2) to determine the susceptibility of plant cultivars to three different pests; and (3) to assess the effect of tuft domatia on the abundance of the predatory mite Amblyseius swirskii Athias–Henriot. In choice and no-choice assays, BL and BP were highly susceptible to P. latus with a moderately high damage rating index of >3.5/5; B. tabaci and F. occidentalis were abundant on BL and EE. A positive correlation was observed between the number of tuft domatia and the A. swirskii count. Although all ornamental pepper cultivars exhibited varying degrees of susceptibility to different arthropod pests, if used strategically, cultivars MA and RM can be used to develop a banker plant system and help reduce multiple pests in greenhouses or interiorscapes. Full article

Some plant species possess structures known as leaf domatia, which house mites. The association between domatia-bearing plants and mites has been proposed to be mutualistic, and has been found to be important in species of economic value, such as grapes, cotton, avocado and coffee. This is because leaf domatia affect the distribution, diversity and abundance of predatory and mycophagous mites found on the leaf surface. As a result, plants are thought to benefit from increased defence against pathogens and small arthropod herbivores. This study assesses the relative diversity and composition of mites on an economically important plant host (Coffea aribica) in comparison to mites found in a neighbouring indigenous forest in South Africa. Our results showed that the coffee plantations were associated with only predatory mites, some of which are indigenous to South Africa. This indicates that coffee plantations are able to be successfully colonised by indigenous beneficial mites. We also found an “edge effect”, in that coffee trees at the edge of the plantation hosted fewer mite species. These results are a snap-shot from a single sampling period. Nonetheless, they highlight the potential importance of this mutualism in commercial crop species and the possible role of faunal exchanges between indigenous and exotic crop species. This study expands our understanding of the mite–plant mutualism in Southern Africa, a region where acarological studies are sparse. Full article

Ant-associated microorganisms can play crucial and often overlooked roles, and given the diversity of interactions that ants have developed, the study of the associated microbiomes is of interest. We focused here on specialist plant-ant species of the genus Allomerus that grow a fungus to build galleries on their host-plant stems. Allomerus-inhabited domatia, thus, might be a rich arena for microbes associated with the ants, the plant, and the fungus. We investigated the microbial communities present in domatia colonised by four arboreal ants: Allomerus decemarticulatus, A. octoarticulatus, A. octoarticulatus var. demerarae, and the non-fungus growing plant-ant Azteca sp. cf. depilis, inhabiting Hirtella physophora or Cordia nodosa in French Guiana. We hypothesized that the microbial community will differ among these species. We isolated microorganisms from five colonies of each species, sequenced the 16S rRNA or Internal TranscribedSpacer (ITS) regions, and described both the alpha and beta diversities. We identified 69 microbial taxa, which belong to five bacterial and two fungal phyla. The most diverse phyla were Proteobacteria and Actinobacteria. The microbial community of Azteca cf. depilis and Allomerus spp. differed in composition and richness. Geographical distance affected microbial communities and richness but plant species did not. Actinobacteria were only associated with Allomerus spp. Full article