FNZ 52 - Raphignathoidea (Acari)
Fan, Q-H; Zhang, Z-Q 2005. Raphignathoidea (Acari: Prostigmata). Fauna of New Zealand 52, 400 pages.
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ISSN 0111-5383 (print),
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no.
52.
ISBN 0-478-09371-3 (print),
).
Published 20 May 2005
ZooBank: http://zoobank.org/References/5F7C5C50-9D70-459B-BE40-F7CB5D5E5DFE
Biology
Feeding habits
According to our current knowledge, the majority of the Raphignathoidea are free-living predators (Table 2). Some species of Stigmaeidae and Dasythyreidae are found on insects, and a few species of Stigmaeidae are phytophages, feeding on moss. A couple of species of Xenocaligonellididae are possibly microphytophages, probably feeding on substances on the outer layer of tree bark.
Predators. Relatively little is known about the predatory habit of the Raphignathoidea (Table 3). Species of the two genera of Caligonellidae, Molothrognathus and Paraneognathus, are known to prey on spider mites on plants and on acarid mites and cheyletid mites in stored products. Species of the Camerobiidae are known to feed on crawlers of the scale insects and tarsonemid mites (Table 3). Members of Eupalopsellidae are mainly predators of mites and scale insects (Table 3). Species of Stigmaeidae feed on spider mites and other mites, as well as on small insects such as crawlers of scale insects (Table 3).
Parasites. Five species of Eustigmaeus, three species of Stigmaeus (both Stigmaeidae), and one species of Dasythyreus (Dasythyreidae) have been found on insects. Stigmaeids have so far been recorded on sandflies only (Table 4). Whether these species have any negative effects on insect hosts is yet to be shown, although feeding scars were commonly observed and the nature of the mite-insect relationship was assumed to be parasitism by most authors (Table 4). A species of Dasythyreus was found on the pronotal-mesonotal interface of the eyed-click beetle Alaus myops (F.) and it is not known whether this mite feeds on the beetle (Walter & Gerson 1998).
Phytophages and microphytophages. Some members of Eustigmaeus (Stigmaeidae) were observed feeding on mosses (Gerson 1972a). Xenocaligonellidus ovaerialis De Leon (Xenocalignoellididae) was observed probing a tree bark surface (De Leon 1959). Another species, Xenocaligonellidus smileyi Hu & Liang, was observed scrubbing the substance on the outer layer of oliver tree bark (Fan 2000).
Microhabitats
Members of the superfamily are found on foliage, branches, trunks (tree bark and holes), moss and lichen, litter, soil, animal nests (birds, possum, and honeybee), stored products, and house dust (Table 5). A few are aquatic or sub-aquatic: Annerosella and Homocaligus of Homocaligidae; and some species of Caligohomus, Cheylostigmaeus, Eustigmaeus, and Ledermuelleriopsis of Stigmaeidae.
Biology
Compared with the Phytoseiidae, relatively little is known about the biology of the Raphignathoidea. Published records concern a handful of species from two main families, Stigmaeidae and Eupalopsellidae. The biology of the Stigmaeidae was reviewed by Santos & Laing (1985) in relation to their role as predators of Tetranychidae. Thistlewood et al. (1996) discussed the biology of Stigmaeidae in relation to their role as predators of the Eriophyoidea. The biology and application of Stigmaeidae, Camerobiidae, and Eupalopsellidae in biological control were reviewed by Gerson & Smiley (1990) and updated by Gerson et al. (2003).
Life history. The life cycle has been studied for only a few species: Agistemus exsertus, A. floridanus, A. industani, and Zetzellia mali. In general, development from egg to adult can be completed in 1–3 weeks, although the duration is affected by abiotic factors such as temperature and biotic factors such as the type and quantity of food (Collyer 1964; ElBadry et al. 1969a; Gerson & Blumberg 1969; Muma & Selhime 1971; Gerson 1972a; Inoue & Tanake 1983; Osman & Zaki 1986; Yue & Childers 1994; White & Laing 1977; El-Laithy 1998; Jamali et al. 2001; Arbabi & Singh 2002). The egg stage is invariably the longest among immature stages and often takes at least twice as long as the larval or each nymphal stage. The males develop slightly faster than females.
Reproduction is arrhenotokous and the offspring sex ratio of mated females is female-biased (Gerson 1972a; Arbabi & Singh 2002). Unmated females produce males only and start to lay eggs one day later than mated females (Rasmy & Hussein 1996). Multiple-mated females have shorter life spans but consume more prey and lay more eggs than single-mated females (Abou-Awad & Reda 1992; Rasmy & Hussein 1995). After a pre-ovipositional period of a few days, most females start to lay eggs for 1–2 weeks. Female reproductive rates (mostly between 1 to 4 eggs per day) are strongly affected by food type/quantity (ElBadry et al. 1969a; Yousef et al. 1982; Nawar 1992) and temperature (Inoue & Tanake 1983). The intrinsic rate of increase of Agistemus exsertus is 0.229 female offspring/female/day at 25°C when feeding on eggs of Panonychus citri (Yue & Childers 1994) and 0.150 individuals/female/day at 27–29°C when feeding on Tetranychus urticae (Abou-Awad & Elsawi 1993), and that of Z. mail is 0.109 female offspring/female/day at 24±1°C when feeding on Aculus schlechtendali (White & Laing 1977).
Adult females of Agistemus industani live about as long as adult males but consume three times as many prey as males (Arbabi & Singh 2002).
Diapause. There appears to be a lack of diapause in raphignathoid mites, at least for the limited number of studies reported so far. Eustigmaeus frigidus apparently reproduces under both long-day (16 h) and short-day (9 h) photoperiodic regimes, without a reproductive diapause (Gerson 1972a). In Auckland, Agistemus longisetus breeds throughout the year on non-deciduous plants, without an overwintering phase (Collyer 1964).
Feeding behaviour and predation
Unlike the phytoseiids, which can respond to kairomones associated with prey, Zetzellia mali does not detect kairomones and appears to search for prey by random encounters (Santos 1991). Once inside a prey patch or leaf, Z. mali increases its residence time in response to the presence of prey, but it also leaves a patch before all prey are consumed (Lawson & Walde 1993). Saniosulus nudus holds its prey by its anterior legs while inserting the chelicerae into the body of the prey; it then sucks the body fluids for 30–40 min or more and when finished pushes the shrivelled prey off the chelicerae with its long palps (Gerson & Blumberg 1969). Agistemus exsertus punctures tetranychid eggs but does not necessarily suck their contents completely (ElBadry et al. 1969b).
As generalist predators, most stigmaeids show some degrees of prey preference. Zetzellia mali tends to prefer the eriophyids over the economically more significant tetranychids (Santos 1976a; Clements & Harmsen 1993; Walde et al. 1995). Agistemus exsertus prefers immatures of Tenuipalpus granati to those of Tetranychus urticae (Yousef et al. 1982), and Tetranychus cinnabarinus to Eutetranychus orientalis (ElBadry et al. 1969b). When feeding on tetranychids, Zetzellia mali prefers eggs and only occasionally attacks resting and nymphal stages; this species never attacks adult spider mites (Santos 1976b; Clements & Harmsen 1990). Agistemus exsertus also develops faster and produces more eggs when feeding on eggs than it doeswhen feeding on larvae or nymphs of Tetranychus urticae and T. cucurbitacearum (Hafez et al. 1983); it also develops faster when feeding on the eggs of T. urticae than it does on the eggs of T. cucurbitacearum, although the eggs of the latter prey were more attractive to the predator.
Predation rates vary with a number of biotic and abiotic factors. Within a certain range, the number of prey consumed increases with temperature (Afify et al. 1969) and prey density (Nawar 1992; Yue & Tsai 1995). Agistemus exsertus, for example, can consume 5.8 larvae per day of Tetranychus urticae at a prey density of 7 larvae; very high levels of prey decreased predator oviposition and feeding capacity (Nawar 1992). At very low prey densities, females of Zetzellia mali disproportionately reduce their predation and oviposition rates compared with high densities (Santos 1982). This response, as well as its ability to become cannibalistic, allows Z. mali to persist on apple leaves when few prey are present.
Intraguild predation and competition
Stigmaeids feed on and are fed upon by phytoseiids, especially when phytophagous mites are scarce — this may have both positive and negative impacts on their interactions and their roles in biological control (Clements & Harmsen 1992; Croft & MacRae 1993; Croft 1994; Slone & Croft 2001). At low prey densities, stigmaeids are more effective than phytoseiids because of their higher preference for prey eggs, higher oviposition relative to prey consumption, and the ability to consume their own eggs, whereas at high prey densities the higher maximum predation rate of phytoseiids gives them a higher efficacy (Clements & Harmsen 1992); a combination of stigmaeids and phytoseiids has greater efficacy than either alone over a wide range of prey densities. Zetzellia mali is usually less important than the phytoseiid Typhlodromus pyri in the direct reduction of the population growth rate of the eriophyid Aculus schlechtendali and acts later in the season than T. pyri, and the interference between these predator species is only occasionally strong enough to affect A. schlechtendali population dynamics (Walde et al. 1997). In the Northern U.S.A., where the phytoseiid mites Typhlodromus pyri and Metaseiulus occidentalis are common in apple orchards, Z. mali has a stronger impact on M. occidentalis than on T. pyri only (Croft & MacRae 1993), because M. occidentalis lays significantly more eggs in the primary foraging area of adult female Z. mali than T. pyri does (MacRae & Croft 1996).
Spatial distribution and seasonal fluctuations
Stigmaeids are unevenly distributed in orchards. The patterns of aggregation vary among different predator species and change with the season and population densities of their prey, competitors and predators (Holdsworth 1972; Hu et al. 1994; Slone & Croft 1998, 2001). Agistemus terminalis, for example, was more aggregated in the lower and western portions of the tree than in other portions (Hu et al. 1994). Zetzellia mali multiplied on the fruit-cluster leaves to become more numerous on the outside of the tree than on watersprouts (Holdsworth 1972). It is unknown how these mites move from tree to tree and disperse from orchard to orchard.
Raphignathoid seasonal fluctuations have been studied for Zetzellia mali (Rice et al. 1976; Hu et al. 1996), and for Agistemus longisetus in orchards (Collyer 1964). In apple orchards in Massachusetts, Z. mali was present in early spring and increased slowly until reaching peak levels in autumn (Hu et al. 1996). In apple and plum orchards in Auckland, Agistemus longisetus first appears in late December or early January, becomes abundant in February and sometimes reaches densities as high as 100 mites per leaf (Collyer 1964).
Diet and rearing
The diets of most raphignathoids are too poorly known to allow rearing. Most stigmaeids that have been studied have relatively broad ranges of food and are generalist predators (Table 3). In addition to mites and small insects, some stigmaeids can also develop and reproduce on pollens of some plants (Abo Elghar et al. 1969; Wafa et al. 1969; Rasmy 1975; Rasmy et al. 1996). When feeding on the pollen of Phoenix dactylifera, Zea mays, and Ricinus communis, Agistemus exsertus does not develop as well as when feeding on Tetranychus cinnabarinus, but lays more eggs when feeding on the pollen of dates than on T. cinnabarinus (Wafa et al. 1969). This species can also develop normally on artificial diets composed of yeast, milk, amino acids, and sugar, but the number of eggs laid per female per day is two-thirds of that for mites reared on a natural diet of pollen (Reda 1990). The adult female lifespan on the artificial diet is equal to that on the standard diet.
Economic importance and role in biological control
Raphignathoid mites are important biological control agents of spider mites, eriophyid mites, and scale insects in agriculture and forestry. Most species of the families Eupalopsellidae, Stigmaeidae, Caligonellidae, and Camerobiidae are free-living predators (Meyer & Ueckermann 1989; Gerson & Smiley 1990). Among them the genera Agistemus and Zetzellia of the Stigmaeidae and Saniosulus of the Eupalopsellidae are well-known biological control agents on plants. Gerson et al. (2003) reviewed the role and application of Eupalopsellidae and Stigmaeidae in biological control.
Geographical distribution
Mites of the superfamily are worldwide in distribution, and abundant in the Palaearctic, Nearctic, Neotropical, Afrotropical, Oriental, and Australian Regions. Raphignathus johnstoni Womersley was even discovered in the Antarctic region (Womersley 1937). The raphignathoid faunas of the Palaearctic, Nearctic, Afrotropical, and Oriental Regions are relatively well known, but the Neotropical Region has only a few species recorded or described (Table 6).