Host-plant specificity and specialization in eriophyoid mites and their importance for the use of eriophyoid mites as biocontrol agents of weeds

Eriophyoid mites, which are among the smallest plant feeders, are characterized by the intimate relationships they have with their hosts and the restricted range of plants upon which they can reproduce. The knowledge of their true host ranges and mechanisms causing host specificity is fundamental to understanding mite-host interactions, potential mite-host coevolution, and diversity of this group, as well as to apply effective control strategies or to use them as effective biological control agents. The aim of this paper is to review current knowledge on host specificity and specialization in eriophyoid mites, and to point out knowledge gaps and doubts. Using available data on described species and recorded hosts we showed that: (1) 80% of eriophyoids have been reported on only one host species, 95% on one host genus, and 99% on one host family; (2) Diptilomiopidae has the highest proportion of monophagous species and Phytoptidae has the fewest; (3) non-monophagous eriophyoids show the tendency to infest closely related hosts; 4) vagrant eriophyoids have a higher proportion of monophagous species than refuge-seeking and refuge-inducing species; (5) the proportions of monophagous species infesting annual and perennial hosts are similar; however, many species infesting annual hosts have wider host ranges than those infesting perennial hosts; (6) the proportions of species that are monophagous infesting evergreen and deciduous plants are similar; (7) non-monophagous eriophyoid species have wider geographic distribution than monophagous species. Field and laboratory host-specificity tests for several eriophyoid species and their importance for biological control of weeds are described. Testing the actual host range of a given eriophyoid species, searching for ecological data, genetic differentiation analysis, and recognizing factors and mechanisms that contribute to host specificity of eriophyoid mites are suggested as future directions for research.     

What’s “cool” on eriophyoid mites?

Fundamental knowledge on the morphology, biology, ecology, and economic importance of Eriophyoidea has been exhaustively compiled by Lindquist et al. (Eriophyoid mites—their biology, natural enemies and control; Elsevier, 1996). Since that time, the number of recognized species and the economic importance of the taxon have increased substantially. The aim of this paper is to analyze and briefly review new findings from eriophyoid mites’ literature after Lindquist et al. book, stressing persistent gaps and needs. Much recent attention has been given to sampling and detection, taxonomy and systematics, faunistic surveys, internal morphology, rearing techniques, biological and ecological aspects, biomolecular studies, and virus vectoring. Recommendations are made for integrating research and promoting broader dissemination of data among specialists and non-specialists.     

Adventive eriophyoid mites: a global review of their impact, pathways, prevention and challenges

Eriophyoids have high potential as adventive mite species (AMS) because their small size make them difficult to detect, and can be easily distributed in world trade. Economic, social and environmental impact from adventive eriophyoid mites has been significant. Considerable attention has been given to adventive insect species while adventive mites have received little attention and little information is available for eriophyoids. This paper summarizes information on adventive eriophyoid mites, their impact, and the history of some important invasions. The status of adventive species of eriophyoids introduced as biological control agents of weeds is presented. A list of eriophyoid mites reported as invasive species worldwide is given. Pathways of concern and biosecurity actions to reduce the risk of eriophyoid mites are discussed. The need to raise public awareness of the risk and importance of these tiny organisms as AMS is emphasized. Scientific and technical challenges to deal with adventive eriophyoids are discussed.     

The effect of the presence of quiescent female nymphs, males and their spermatophores on spermatophore placement in two species of eriophyoid mites

Under sex dissociated sperm transfer, females seek spermatophores and pick up sperm without male assistance. In several species males adjust spermatophore deposition rate to the presence of conspecifics. It is not known, however, which factors could favor such elasticity in non-pairing males. In this paper, we compare male response towards conspecifics between the sex dissociated eriophyoid mites Aculus fockeui (Nalepa and Trouessart) and Aculops allotrichus (Nalepa). The species differ significantly in male reproductive strategies and, consequently, the intensity of male–male-competition. Aculus fockeui males deposit spematophores all over the leaves and occasionally leave single spermatophores beside quiescent female nymphs (QFNs). In contrast, A. allotrichus males guard QFNs and encircle them with spermatophores. In this study, males of both species deposited spermatophores close to and apart from the rival spermatophores. Aculops allotrichus males had similar spermatophore output whether they were kept alone or in a group of seven males. They did not change spermatophore output in the presence of five rival spermatophores, a QFN or a QFN and varying number of rivals, either. In contrast, A. fockeui males increased spermatophore output in the presence of rival spermatophores or when on the arena with a QFN the male number increased to eight males. They did not respond, however, to the presence of a QFN and one rival or a QFN alone. The possible effect of the species-specific intensity of male–male competition, population density, the availability of receptive females and the rate of spermatophore output on the flexibility of eriophyoid spermatophore deposition is discussed.     

Repeated visitations of spermatophores and polyandry in females of eriophyoid mites

Eriophyoid females store sperm either asymmetrically in one spermatheca, or symmetrically in both spermathecae. Previous studies have suggested that species in which females store sperm asymmetrically pick up sperm from only one spermatophore, while those with symmetrical sperm storage pick up sperm from two or more spermatophores during their lifetime. The aim of this study was to examine spermatophore visitation behaviour and symmetry of sperm storage in Aculops allotrichus from the black locust tree and Cecidophyopsis hendersoni from the yucca. This would indicate monandry or polyandry in these species. In both eriophyoids, the spermatophore visitation consisted of three phases: mounting, lying on the spermatophore and dismounting. Aculops allotrichus stored sperm asymmetrically. However, nearly one-third of the observed females visited two spermatophores, rather than only one in their lives. When A. allotrichus females visited two spermatophores they spent a similar amount of time at the first and at the second visitation. Also, the times of visitation of the first of the two spermatophores and the single spermatophore in a female lifetime did not differ significantly. This would suggest that apart from monandry, double insemination also occurs in this species. By contrast, C. hendersoni females were polyandrous. They stored sperm symmetrically and visited several spermatophores, on average 1.54 (max 6) per day, and up to 33 spermatophores in their lives. The benefits of repeated spermatophore visitation and the possible mechanisms of sperm storage in both species are discussed.     

Collection and detection of eriophyoid mites

Methods for collecting and detecting eriophyoid mites are crucial components in research, taxonomical and biological studies, and control programs for these organisms. Their small size, their specific host-plant interactions and their hidden life-style make them difficult to find in routine inspections. This review examines successful and unsuccessful approaches for collecting eriophyoid mites, and makes recommendations for their detection, supporting studies in taxonomy, ecology, biology, molecular systematics and population genetics.     

Plant–eriophyoid mite interactions: cellular biochemistry and metabolic responses induced in mite-injured plants. Part I

This review is a comprehensive study of recent advances related to cytological, biochemical and physiological changes induced in plants in response to eriophyoid mite attack. It has been shown that responses of host plants to eriophyoids are variable. Most of the variability is due to individual eriophyoid mite–plant interactions. Usually, the direction and intensity of changes in eriophyoid-infested plant organs depend on mite genotype, density, or the feeding period, and are strongly differentiated relative to host plant species, cultivar, age and location. Although the mechanisms of changes elicited by eriophyoid mites within plants are not fully understood, in many cases the qualitative and quantitative biochemical status of mite-infested plants are known to affect the performance of consecutive herbivorous arthropods. In future, elucidation of the pathways from eriophyoid mite damage to plant gene activation will be necessary to clarify plant responses and to explain variation in plant tissue damage at the feeding and adjacent sites.     

Eriophyoid mites from Qinghai Province, northwestern China with descriptions of nine new species (Acari, Eriophyoidea)

Eriophyoid mites from Qinghai Province, northwestern China were studied herein. Up to now, only six species have been reported from Qinghai Province. In field surveys, 17 eriophyoid mite species were collected, among which nine species were found new to science. The new species and their host plants are listed as follows: Acaphyllisa tuberculumaesp. n. on Populus sp. (Salicaceae); Proiectus xiningensissp. n. on Pinus sp. (Pinaceae); Phyllocoptes beishaniensissp. n. on Spiraea mongolica Maxim. (Rosaceae); Tetra prunianasp. n. on Prunus tomentosa Thunb. (Rosaceae) Rupr. (Berberidaceae); Tetra pyrianasp. n. on Pyrus calleryana Decne. (Rosaceae); Tetra simoniasp. n. on Populus simonii Carr. (Salicaceae); Diptacus berberinussp. n. on Berberis amurensis Rupr. (Berberidaceae); Diptacus mengdaensissp. n. on Lonicera elisae Franch. (Caprifoliaceae); Rhyncaphytoptus spinussp. n. on Lonicera rupicola Hook. f. et Thoms. (Caprifoliaceae). Aculops ulmi Hong & Xue, 2005 was re-described.     

Genetic architecture of resistance to aphids and mites in a willow hybrid system

Hybrid plants often differ in resistance to arthropods compared to the parental species from which they are derived. To better understand the relative contribution of genetic effects in influencing plant resistance to arthropods, we examined the genetic architecture of resistance in a willow hybrid system, Salix eriocephala, S. sericea, and their interspecific hybrids. Resistance to two arthropods, a willow leaf aphid (Chaitophorus sp.: Aphididae) and an eriophyoid mite (Aculops tetanothrix: Eriophyidae), were compared because resistance to different herbivores may be controlled by different traits and influenced by different genetic effects. We found additive and nonadditive genetic effects to be important in explaining the difference between willow species in resistance to aphids and mites. F2 hybrids exhibited low resistance to aphids, suggesting breakdown of favourable epistatic interactions that confer resistance. F2 hybrids, however, exhibited high resistance to mites, suggesting either the breakdown of interactions that affect traits used by mites in host location or the creation of favourable epistatic interactions. This study demonstrates the potential role of herbivores in affecting plant genetic structure, such that selection by herbivores can potentially lead to the creation of gene interactions that influence host resistance traits or host recognition traits used by the herbivore.     

Limits to ambulatory displacement of coconut mites in absence and presence of food-related cues

Ambulatory movement of plant-feeding mites sets limits to the distances they can cover to reach a new food source. In absence of food-related cues these limits are determined by survival, walking activity, walking path tortuosity and walking speed, whereas in presence of food the limits are also determined by the ability to orient and direct the path towards the food source location. For eriophyoid mites such limits are even more severe because they are among the smallest mites on earth, because they have only two pairs of legs and because they are very sensitive to desiccation. In this article we test how coconut mites (Aceria guerreronis Keifer) are constrained in their effective displacement by their ability to survive in absence of food (meristematic tissue under the coconut perianth) and by their ability to walk and orient in absence or presence of food-related cues. We found that the mean survival time decreased with increasing temperature and decreasing humidity. Under climatic conditions representative for the Tropics (27 °C and 75 % relative humidity) coconut mites survived on average for 11 h and covered 0.4 m, representing the effective linear displacement away from the origin. Within a period of 5 h, coconut mites collected from old fruits outside the perianth moved further away from the origin than mites collected under the perianth of young fruits. However, in the presence of food-related cues coconut mites traveled over 30 % larger distances than in absence of these cues. These results show that ambulatory movement of eriophyoid mites may well bring them to other coconuts within the same bunch and perhaps also to other bunches on the same coconut palm, but it is unlikely to help them move from palm to palm, given that palms usually do not touch each other.     

捕食螨化学生态研究进展

捕食螨是重要的生物防治因子。早在20世纪70年代就发现了捕食螨的性信息素,许多研究证明植物挥发物在捕食螨向猎物定位过程中发挥着至关重要的作用,影响捕食螨寻找猎物的植物挥发物来源于未受害植物、机械损伤植物、猎物危害植物、非猎物危害植物。人工合成的植物挥发物组分对捕食螨具有引诱作用,但引诱活性低于虫害诱导植物释放的挥发性混合物。捕食螨的饲养条件、饥饿程度、学习与经验行为等会影响捕食螨对植物挥发物的反应。介绍了信息素与植物挥发物对捕食螨的作用,并讨论了目前存在的问题和研究前景。     

Eriophyoid mites (Acari: Eriophyoidea) on coniferous trees: is the occurrence of one species associated with the other?

Although Eriophyoidea is one of the most important phytophagous mite taxa owing to its negative impact on plants, reports on associations between occurrences of eriophyoid species are scarce. The aim of this paper is to test the hypothesis that the occurrence of one species is correlated with the occurrence of another in some predictive manner. Analyses are carried out for two popular coniferous trees in Poland, i.e., Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). Observations were made in four locations in Poland, from three age groups of trees, namely adult trees (thirty 15-cm shoot samples from each of ten trees), young trees (ten 15-cm shoot samples from each of ten trees) and seedlings (100 whole-seedling samples). The associations were estimated by Yule’s V index. Among four eriophyoid species observed on Scots pine, and the same number of species on Norway spruce, in general no association pattern was observed. It means that their occurrence is independent. The most likely explanation for the absence of co-occurrence is the abundance of microhabitats on coniferous trees for eriophyoid mites, combined with the low mite density on these plant hosts.     

An insight into some relevant aspects concerning eriophyoid mites inhabiting forests, ornamental trees and shrubs

Worldwide a great variety of eriophyoid mites inhabit forest canopy trees and ornamental plants that are used in city parks, squares and boulevards. An analysis of the relevant bibliography portrays only a fragmentary knowledge and the majority of our information concerns the temperate zone. Three case studies are presented as examples of different approaches to solve problems connected with eriophyoid mites of forest and ornamental trees. The first example deals with eriophyoids of a temperate zone forest in a natural environment, focusing on conifers which represent the largest component. The second case study documents a possible approach to obtain greater knowledge and control of the bud mite species, Trisetacus juniperinus (Nalepa) on Cupressaceae. This is a harmless species in the natural environment which becomes a serious pest in nurseries and young stands of Cupressus sempervirens in the Mediterranean region. The final case study reports on long-term studies carried out in Poland on injurious eriophyoid species that are found in nurseries, city greenery and parks. This paper also discusses future perspectives for research on eriophyoid mites living on forest and ornamental plants.     

Eriophyoid Mites (Acariformes,Eriophyoidea) from Rosaceae: Taxonomic Diversity,Host-Parasite Relationships,and Ability to Cause Galls

A review on the complex of species of eriophyoid mites associated with Rosaceae is given, focused on the phylogeny, biology, and distribution of their host plants and galls induced by these mites. About 200 species of 39 genera from 3 families ofEriophyoidea are known from Rosaceae. Among them, 6 species from 2 genera belong to Phytoptidae, 178 species from 27 genera, to Eriophyidae, and 28 species from 10 genera, to Diptilomiopidae; 7 genera of the latter family are represented on Rosaceae by a single species each. The ability to induce galls is discussed using the example of the most widespread and numerous genera of the family Eriophyidae from Rosaceae. Mites of two large subfamilies, Eriophyinae and Phyllocoptinae, include both vagrant and concealed forms. The types of galls caused by mites are related to the systematic position of mites and the distribution of mites and their host plants. The hypothesis of host shifts of eriophyoid mites from other plant families to Rosaceae is considered. Most of the species which presumably switched to Rosaceae have been described from Southeast Asia. Morphological similarity between vagrant and concealed forms from the paraphyletic tribes Eriophyini and Phyllocoptini, and also Aceriini and Anthocoptini is discussed. Their pairwise similarity might be the result of evolution (Eriophyini → Phyllocoptini and Aceriini → Anthocoptini) connected with change oflife style.     

Herbivore and pathogen damage on grassland and woodland plants: a test of the herbivore uncertainty principle

Researchers can alter the behaviour and ecology of their study organisms by conducting such seemingly benign activities as non-destructive measurements and observations. In plant communities, researcher visitation and measurement of plants may increase herbivore damage in some plant species while decreasing it in others. Simply measuring plants could change their competitive ability by altering the amount of herbivore damage that they suffer. Currently, however, there is only limited empirical evidence to support this `herbivore uncertainty principle' (HUP). We tested the HUP by quantifying the amount of herbivore and pathogen damage in 13 plant species (> 1400 individuals) at four different visitation intensities at Cedar Creek Natural History Area, Minnesota, USA. Altogether, we found very little evidence to support the HUP at any intensity of visitation. Researcher visitation did not alter overall plant herbivore damage or survival and we did not detect a significant visitation effect in any of the 13 species. Pathogen damage also did not significantly vary among visitation treatments, although there was some evidence that high visitation caused slightly higher pathogen damage. Based on our results, we question whether this phenomenon should be considered a `principle' of plant ecology.     

DNA-based methods for eriophyoid mite studies: review, critical aspects, prospects and challenges

Besides their potential for species identification, DNA-based methods are also routinely used for addressing ecological, evolutionary, phylogenetic and genetic questions to study several groups of Acari. However, in contrast to other plant-feeding mites and despite the economical relevance of many species of Eriophyoidea, very few scientists have dared so far to use DNA methods for the study of this group of mites; their very small size certainly has influenced this. In this review we examine the main techniques that have been used to study eriophyoid mites and discuss the results from the literature where DNA methods have provided significant advances to address several essential questions of the eriophyoid biology, e.g., to clarify suspect synonymies, to test hypothesis of cryptic species, to examine the occurrence of biotypes, especially in relation to virus ability or host-plant associations, to understand colonization patterns of invasive species, and for uses as biological control agents against invasive plants. We discuss these questions which might be related to agricultural issues, together with more fundamental aspects as the revision of the phylogeny of the Eriophyoidea. We discuss on the advantages as well as limitations of the most commonly used genetic markers and emphasize prospects and challenges of new molecular approaches. Much is now expected from molecular techniques in many fields of biology and for virtually all taxa. Eriophyoids should not be the exception.