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a) Plant infestation with A0 mites (infestation time, TI), b) Emergence of the silk-ball at the stick apex (emergence time, TE) and, c) Harvesting of the silk-ball after 24 or 4 hours (harvest time, TH).
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The two-spotted spider mite is a worldwide phytophagous pest displaying a peculiar dispersal. At high density, when plants are exhausted, individuals gather at the plant apex to form a collective silk-ball. This structure can be dispersed by wind or phoresy. Individuals initiating the ball are enclosed in the centre and have a high risk to die. For...
Citations
... Spider mites from genus Tetranychus produce silk webs while walking (Saito 1977;Clotuche et al. 2012a). The dense webs may protect mites from predation (McMurtry et al. 1970;Sabelis 1985;Tien et al. 2009;Dittmann and Schausberger 2017), bad weather conditions (Davis 1952;Linke 1953) and pesticides (McMurtry et al. 1970) and serve as modes of dispersal (Saito 1977;Gerson 1985;Yano 2008;Clotuche et al. 2013b). Additionally, silk may act as the substrate for sex pheromones (McGregor 1950;Saito 1977Saito , 1979Sabelis 1985;Sabelis and Bakker 1992;Zhang et al. 2002;Yano 2008;Clotuche et al. 2009Clotuche et al. , 2011Clotuche et al. , 2012bClotuche et al. , 2014Tien et al. 2009;Le Goff 2011). ...
Selection of a suitable habitat by animals before settlement is critical for their survival and reproduction. In silk-spinning arthropods like spider mites, denser webs offer protection from predation and serve as a dispersal mode. Settling in habitats with the presence of conspecifics and silk webs can benefit the habitat-searching females. Silk and conspecifics usually coexist, but their distinct effects on female colonization have received little attention. In this study, we used a haplodiploid spider mite, Tetranychus ludeni Zacher (Acari: Tetranychidae), to examine the impact of conspecific cues, including cues from ovipositing conspecifics and silk, on habitat selection and subsequent reproductive performance of females. Results show that females significantly preferred habitats with cues from neighboring conspecifics and silk and neighboring conspecifics induced additive effect to that of silk on habitat selection. Conspecific cues did not boost female reproduction but facilitated females laying larger eggs that were more likely to be fertilized and to develop into daughters. When given a choice between silk-covered and clean habitats, females preferred silk-covered habitats, laid a similar number of eggs with similar size, but produced more daughters, suggesting that T. ludeni females can adjust the size threshold for fertilization in response to the current social environment. Knowledge of this study improves our understanding of spider mite habitat selection and post-settlement reproductive performance behaviors.
... It usually thrives on the abaxial side of the plant and feeds on the plant juice by penetrating the leaf tissues with its piercing and sucking mouthparts. T. urticae possess a precipitous population growth rate, a short developmental time, high fecundity, and a long lifespan (Clotuche et al., 2011). The egg-to-adult lifecycle of female T. urticae takes around 6.5 days at 30°C, while the male completes just before female (Clotuche et al., 2013). ...
... T. urticae possess a precipitous population growth rate, a short developmental time, high fecundity, and a long lifespan (Clotuche et al., 2011). The egg-to-adult lifecycle of female T. urticae takes around 6.5 days at 30°C, while the male completes just before female (Clotuche et al., 2013). ...
The two-spotted spider mite (Tetranychus urticae Koch ) is the most pronounced polyphagous non-insect pest, wreaking havoc on agricultural and horticultural crops. In cucumber, the infestation by various pests jeopardises effective cultivation, with two spotted spider mites causing great harm to the crop. Six different chemical acaricides were tested for their effectiveness against T. urticae in cucumber cultivated under protected cultivation system at the farmer’s field. The results revealed that none of the acaricides exhibited a tangible decrease over the control, but spiromesifen (59.50 %) recorded a rather excellent reduction over the other investigated chemicals (40 to 54.47 %). The experimental bioassays were performed to determine the effective dosage, which resulted in a significant mite population reduction and the results revealed that tested chemical acaricides were found to be effective at their higher dose, ranging nearly from 3X to 4X of recommended by CIB&RC. The pot culture and field study was conducted to determine the effectiveness of fixed doses from bioassay investigations. A good reduction in mite population was observed for all tested chemicals with spiromesifen recorded a 100 per cent reduction in mite population. Residue analysis of harvest time samples of cucumber after spiromesifen application revealed residues below quantification limit of 0.025 µg/kg.
... One of the possibilities of maintenance of population heterozygosity would be to increase the variation of immigrants' gene pool, which allows transferring a sufficiently high proportion of allelic variance of the parental population, enabling the successful establishment of a new population. The gene pool increase may be ensured by collective dispersal, where a group of individuals is moved together 21,22 . Another possibility is fertilisation before dispersal, as sexual reproduction increases the number of alleles transferred to the new (founding) population and thereby decreases the probability of the reduction of fitness and adaptive potential (which otherwise could lead to population extinction). ...
... Hence the collective dispersal behaviour can reduce the costs of risky aerial dispersal, and such a phenomenon has been previously documented in e.g. haplodiploid phytophagous spider mites 21,22 . However, Yearsley et al. 37 concluded that collective dispersal may have knock-on consequences for the population genetic structure, because it can reduce the mixing effect of dispersal (even in systems with high rates of migration), which slows down the rate at which related lineages (e.g. ...
Dispersal and colonisation determine the survival and success of organisms, and influence the structure and dynamics of communities and ecosystems in space and time. Both affect the gene flow between populations, ensuring sufficient level of genetic variation and improving adaptation abilities. In haplodiploids, such as Aceria tosichella (wheat curl mite, WCM), a population may be founded even by a single unfertilised female, so there is a risk of heterozygosity loss (i.e. founder effect). It may lead to adverse outcomes, such as inbreeding depression. Yet, the strength of the founder effect partly depends on the genetic variation of the parental population. WCM is an economically important pest with a great invasive potential, but its dispersal and colonisation mechanisms were poorly studied before. Therefore, here we assessed WCM dispersal and colonisation potential in relation to the genetic variation of the parental population. We checked whether this potential may be linked to specific pre-dispersal actions (e.g. mating before dispersal and collective behaviour). Our study confirms that dispersal strategies of WCM are not dependent on heterozygosity in the parental population, and the efficient dispersal of this species depends on collective movement of fertilised females.
... Furthermore, when the plant offers protection and it is also a food source, A. lycopersici and T. merganser form groups in order to protect them from their predators, resulting in aggregated distribution (Taylor 2019). However, competition for the same food promotes dispersal among mites in search for new food sources (Mitchell 1970;Clotuche et al. 2013). ...
Ecological interactions between mites (predatory and phytophagous) and wild plants growing in undisturbed environments play a crucial role to understand their natural settlement, development and dispersion patterns. Pequin chili pepper, Capsicum annuum L. var. glabriusculum, is a low-cost natural resource for local communities living inside Natural Protected Areas (ANP) of Tamaulipas State in Mexico. The aims of this research work were: 1) determine the spatial distribution pattern of predatory and phytophagous mites, 2) determine the spatiotemporal association between predatory and phytophagous mites, and 3) determine the association among different mite species and some phenological stages of Pequin chili pepper. The most abundant phytophagous mites were Tetranychus merganser and Aculops lycpoersici, and the predatory species
were Amblyseius similoides, Euseius mesembrinus and Metaseiulus (Metaseiulus) negundinis. Most mite species showed an aggregated distribution pattern according to the plant phenological stages. However, the distribution of mite species throughout time showed different types of aggregation. On the other hand, we found positive associations among A. lycopersici and T. merganser phytophagous mites with A. similoides, E.
mesembrinus and M. (M.) negundinis predators mites. The association between plants and mite species were
influenced by the phenological stages of Pequin chili pepper. This is an indication of the complexity among
trophic-chain interactions that depend largely on the available resources and competition. These two factors
serve as foundations for settlement, development and dispersion patterns of certain species
... Furthermore, when the plant offers protection and it is also a food source, A. lycopersici and T. merganser form groups in order to protect them from their predators, resulting in aggregated distribution (Taylor 2019). However, competition for the same food promotes dispersal among mites in search for new food sources (Mitchell 1970;Clotuche et al. 2013). ...
... Besides ambulatory dispersal, Tetranychus females also disperse aerially, either alone (Smitley and Kennedy, 1985;Margolies, 1987) or as part of a woven ball (dubbed ballooning; Bell et al., 2005), which may contain both adults and immatures. Ballooning mites can also be phoretic if the balls are carried away by other animals (Brandenburg and Kennedy, 1982;Clotuche et al., 2011Clotuche et al., , 2013b. For collective ballooning, mites start to move to the apex of leaves and plants, and others follow the spinning threads to jointly produce webbing and form balls on the apex. ...
... Collective dispersal via ballooning could represent cooperation based on the expression and recognition of green beard alleles that may indicate kinship or not. Clotuche et al. (2013b) observed that Tetranychus individuals did not discriminate and segregate with kin during ball formation; however, this may have been due to mixed rearing before the experiment, allowing familiarization among kin and non-kin. Also, these experiments do not rule out a possible role of kin selection, because on a local scale Tetranychus individuals live more likely with kin than non-kin and, thus, may not need to discriminate who initiated or joins in ball formation. ...
... Whether mites dying inside balls sacrifice themselves to aid in ball formation or are trapped accidentally by other mites requires close scrutiny. In any case, dying inside the balls just occurs if there is a long delay between initiating ball formation and being carried away by the wind; if the take-off occurs soon after initiation of ball formation, there are no dead individuals inside the balls (Clotuche et al., 2013b). One likely selective force of collective ballooning may be immediately acting Allee effects on the new host plant (byproduct cooperation), i.e., collective colonization of a new host plant increasing individual fitness because of positive group effects (synergism sensu Queller, 1985) as compared to solitary colonization (Clotuche et al., 2013a,b). ...
Cooperative behaviors are evolutionary stable if the direct and/or indirect fitness benefits exceed the costs of helping. Here we discuss cooperation and behaviors akin to cooperation in subsocial group-living species of two genera of herbivorous spider mites (Tetranychidae), i.e., the largely polyphagous Tetranychus spp. and the nest-building Stigmaeopsis spp., which are specialized on grasses, such as bamboo. These spider mites are distributed in patches on various spatial scales, that is, within and among leaves of individual host plants and among individual hosts of single or multiple plant species. Group-living of spider mites is brought about by plant-colonizing foundresses ovipositing at local feeding sites and natal site fidelity, and by multiple individuals aggregating in the same site in response to direct and/or indirect cues, many of which are associated with webbing. In the case of the former, emerging patches are often composed of genetically closely related individuals, while in the case of the latter, local patches may consist of kin of various degrees and/or non-kin and even heterospecific spider mites. We describe and discuss ultimate and proximate aspects of cooperation by spider mites in host plant colonization and exploitation, dispersal, anti-predator behavior, and nesting-associated behaviors and conclude with theoretical and practical considerations of future research on cooperation in these highly rewarding model animals.
... Two-spotted spider mites are groupliving and although wild colonies are typically composed of only a few individuals, much larger groups are formed in greenhouse environments (Yano 2008). Spider mite silk provides protection against biotic (e.g., predators) and abiotic (e.g., rain) agents (Gerson 1985;Sabelis and Bakker 1992;Yano 2012), a substrate for sex pheromone (Cone et al. 1971;Penman and Cone 1974), and facilitates dispersal (Saito 1977;Gerson 1985;Yano 2008;Clotuche et al. 2013b). ...
Tetranychus urticae (the two-spotted spider mite) is a phytophagous agricultural pest that affects many economically important crops. Two-spotted spider mites are group-living arachnids that produce silk webbing which is used for protection and dispersal, and also influences settlement behavior of conspecifics. We investigated the effects of conspecific silk and frass on microhabitat selection of these mites and whether these materials are substrates for semiochemicals. Two-choice behavioral assays gave mites the option of settling in the presence or absence of cues produced by conspecifics. Both sexes of mites preferred to settle in the presence of silk produced by conspecific females, and males also responded positively to silk produced by other males. Frass alone had no effect on mite settlement choices, but mites tended to prefer frass in combination with silk over silk alone. Female mites did not respond to conspecific silk after it was washed with methanol, and a crude methanol extract of the silk was sufficient to elicit settlement behavior, confirming that a semiochemical is responsible for the effect. We conclude that silk-bound semiochemicals provide cues used by both male and female mites when selecting a microhabitat, and that frass may also provide relevant social cues.
... Spider mites can also migrate in groups. At high densities, when plants are overexploited, individuals gather at the plant apex to form a collective silk ball, and this structure can also be dispersed by wind [31]. Aphids disperse as winged morphs (alates) that are produced as a response to crowding or reduced host-plant quality [32], and those alates can travel long distances by wind. ...
One of the ecosystem services of biodiversity is the contribution to pest control through conservation and stimulation of natural enemies. However, whether plant diversity around greenhouses is beneficial or a potential risk is heavily debated. In this review, we argue that most greenhouse pests in temperate climates are of exotic origin and infest greenhouses mainly through transportation of plant material. For indigenous pests, we discuss the potential ways in which plant diversity around greenhouses can facilitate or prevent pest migrations into greenhouses. As shown in several studies, an important benefit of increased plant diversity around greenhouses is the stimulation of indigenous natural enemies that migrate to greenhouses, where they suppress both indigenous and exotic pests. How this influx can be supported by specific plant communities, plant characteristics, and habitats while minimising risks of increasing greenhouse pest densities, virus transmission, or hyperparasitism needs further studies. It also requires a better understanding of the underlying processes that link biodiversity with pest management. Inside greenhouses, plant biodiversity can also support biological control. We summarise general methods that growers can use to enhance pest control with functional biodiversity and suggest that it is particularly important to study how biodiversity inside and outside greenhouses can be linked to enhancement of biological pest control with both released and naturally occurring species of natural enemies.
... Attraction to conspecifics in phoretic nematodes might also arise to avoid the impact of Allee effects (i.e. decreased fitness due to low population density at the destination) as proposed in other species (Clotuche et al., 2013;Courchamp et al., 1999;Fronhofer et al., 2013;Kramer et al., 2018). unpubl. ...
Hitchhikers (phoretic organisms) identify their vehicles using species‐specific visual, chemical and vibrational cues. However, what factors influence their choice between vehicles of the same species has rarely been investigated.
Hitchhikers must not only avoid overcrowded vehicles but may also need to travel with conspecifics to ensure mates at their destination. Hence, a trade‐off between overcrowding and presence of conspecifics likely determines the choice of a vehicle especially when destination sites are distant, ephemeral and unique.
Here, we investigate whether a trade‐off between the presence of conspecifics versus overcrowding by conspecifics or heterospecifics on a vehicle affects hitchhiker choice. We also investigate the sensory modality responsible for this choice. We experimentally examine these questions using a phoretic nematode community (containing plant‐ and animal‐parasitic taxa) obligately associated with a brood‐site pollination mutualism. In this model system, nematodes co‐travel with conspecifics and heterospecifics on pollinators as vehicles, between ephemeral plant brood sites to complete their developmental life cycle. In this system, hitchhiker overcrowding has proven negative impacts on vehicle and plant fitness. We expected nematodes to respond to conspecifics and heterospecific density on offered vehicles when making their choice.
We found that animal‐parasitic nematodes preferred vehicles containing some conspecifics within a certain density range. However, plant‐parasitic nematodes preferentially boarded vehicles that were devoid of conspecifics or had few conspecifics. Plant parasites that preferred empty vehicles likely hitchhiked in pairs. Both nematode types employed volatile cues to discriminate between vehicles with different conspecific nematode densities. Our results suggest that vehicle overcrowding by conspecifics, most likely, guaranteed access to mates at the destination determined hitchhiker choice. Surprisingly, and contrary to our expectations, plant‐ and animal‐parasitic nematodes did not respond to heterospecific crowding on vehicles and did not discriminate between vehicles with different heterospecific nematode densities. The reason for this lack of response to heterospecific presence is unknown.
This study not only shows that phoretic organisms use different strategies while choosing a vehicle but also confirms that density‐dependent effects can ensure the stability and persistence of phoretic interactions in a mutualism by balancing overcrowding against reproductive assurance.
... At high population levels, T. ogmophallos individuals move to the upper part of their food plants to form collective silk balls which serve to facilitate aerial dispersal (Clotuche et al. 2013). They produce a structure consisting of silk and mites, both dead and alive, which can be carried away by the wind (Weeks et al. 2000). ...
... Such a gregarious dispersal behavior confers many advantages to the population (Lioni and Deneubourg 2004), such as increased chances of mating (Hambäck 2010;Clotuche et al. 2011), and lower predation risk (Dittmann and Schausberger 2017). On the other hand, clustering also has disadvantages, such as higher competition for food and space (Clotuche et al. 2013). Dispersal of mites, either as single individuals being carried away by the wind or as groups of individuals being collectively transported inside silk balls, is an essential factor for T. ogmophallos population dynamics. ...
... The studies of Clotuche et al. (2011Clotuche et al. ( , 2013 on two-spotted spider mites, Tetranychus urticae Koch, were used as a model for our experiments. A total of 40 potted peanut plants were used, each plant constituting a replicate. ...
Peanut red spider mite, Tetranychus ogmophallos, exhibits a peculiar dispersal behavior using silk balls, which involves clustering of mites and spinning of webs at the top of plants. Such a dispersal mechanism has not been studied for this species yet. Therefore, this study aimed at using mathematical models to describe aerial dispersal and silk ball formation of peanut red spider mite on peanut plants. The influence of wind speed, generated by a wind tunnel, on the dispersal of mites was studied in two experiments, one with 500 mites per plant and one with 1000 mites per plant, and six wind speeds (5, 10, 15, 20, 25, and 30 km h−1) for each mite density. The proportion of displaced mites and the distance they were blown were measured. Another series of experiments considered the formation of silk balls to assess how fast balls were formed as a function of time and the number of mites present on a peanut plant. Data from the wind tunnel experiments were analyzed by logistic regression and multiple regression to assess the proportion of displaced mites and the distance moved, respectively, as functions of wind speed and the initial density of mites on the donor plant. The distribution of dispersal distances from the donor plant was fitted by a mathematical model proposed by Ricker (J Fish Res Board Can 11:559–623, 1954). The number of mites moving upwards on a plant to be involved in silk ball formation was modeled as a function of time based on the initial number of spider mites and their estimated birth, death and movement rates per capita. Logistic regression was used to analyze the presence of balls as a function of time elapsed since a plant was infested with spider mites. Finally, non-linear regression was applied to link ball size to the total number of mites occupying the ball. The data analyses revealed that wind speed had a significant positive effect on take-off probability and distance moved by individual mites, whereas mite density had little influence. Ricker’s model adequately described the distribution of dispersal distances. The models describing silk ball formation also described data very well. Ball size was found to increase almost linearly with the number of mites found in the ball. We expect that the knowledge provided by the present study will help to develop efficient management strategies against T. ogmophallos in peanut crops as dispersal seems to be a key factor in the species’ capability to become a serious pest.