New records of Phytoseiidae ( Acari : Mesostigmata ) from Mauritius

Mauritius is one of the three islands constituting Mascareignes Archipelago, with La Réunion and Rodrigues. So far, onIy three mite species of the family Phytoseiidae are known from Mauritius, namely Amblyseius caudatus, Euseius ovalis and Phytoseius coheni. We report in this paper the results of a brief survey recently conducted onMauritius Island, in which four additional species were found, namely Paraphytoseius orientalis, Phytoseiulus persimilis, Scapulaseius reptans and Typhlodromips culmulus.


Introduction
Mites of the family Phytoseiidae are best known for their predatory habits on phytophagous mites and on small insects. Some of them are used for the control of pest organisms in open fields and protected crops all around the world (McMurtry and Croft 1997;McMurtry et al. 2013). This family is widespread around the Globe, consisting presently of 2,521 valid species of 94 genera belonging to three sub-families (Demite et al. 2018).
Biodiversity surveys in poorly investigated areas might result in the discovery of additional species potentially useful for biological control as well as having more information on the biodiversity of these areas.
Most of the Indian Ocean constitutes one of the world biodiversity hotspots. The concept of biodiversity hotspot was defined by Myers (1988) in order to identify the most immediately important areas for biodiversity conservation. These hotspots hold high endemism levels and have lost at least 70% of their original natural vegetation (Myers et al. 2000). Knowledge of the phytoseiid diversity in these areas may contribute to future establishment of conservation programs.
Located in the Indian Ocean at 1,000 km from the eastern coast of Madagascar, together with La Réunion and Rodrigues, Mauritius is one of the three main islands constituting Mascareignes Archipelago. Only three phytoseiid species have been reported from this island (Moutia 1958, Schicha 1984, Demite et al. 2018. The objective of this paper is to present the phytoseiid species found in brief survey recently conducted in Mauritius.

Material and methods
The survey was conducted in September 2017 on cultivated plants of two locations. Mites were directly collected from leaves and transferred to vials with 70 % ethanol, and later mounted on microscope slides in Hoyer's medium. They were examined under a phase and DIC (differential interference contrast) microscope (DMLB, Leica Microsystèmes SAS, Nanterre, France). Measurements were done using a graded eyepiece. Chant andMcMurtry's (1994, 2007) concepts of Phytoseiidae taxonomy and the world catalogue database of Demite et al. (2018) were used for faunistical and biogeographical aspects. The chaetotaxy terminology used followed that proposed by Lindquist and Evans (1965) as adapted by Rowell et al. (1978) for Phytoseiidae for dorsal and by Chant and Yoshida-Shaul (1991) for ventral idiosomal setae, respectively.
Numbers of teeth on the fixed and movable cheliceral digits do not include the respective apical teeth. Setae not referred to in the Results section should be considered as absent.
All measurements are given in micrometers and presented as the mean in bold followed by the range in parentheses. All mites collected were measured. They were deposited in the mite reference collection of Montpellier SupAgro conserved in UMR CBGP INRA/ IRD/ CIRAD/ SupAgro/ Université de Montpellier.
Previous Records -Widely distributed in all the tropical area of Africa, South America and South-East Asia.
Remarks -Measurements of most setae of the single female collected (Table 1) agree with measurements provided in the literature, except for the longer r3, R1, ventrianal shield, and macrosetae of telotarsus IV. It also has shorter JV5 and Scw than reported for Kenyan specimens. This species belongs to a genus included in the great polyphagous generalist group named type III among phytoseiid mites (McMurtry and Croft 1997;McMurtry et al. 2013). Navasero and Navasero (2016) have studied the life history of P. orientalis on the broad mite as prey [Polyphagotarsonemus latus (Banks)]. The authors reported high predation rates of this predator on eggs of that prey, suggesting its potential for the control of this pest.
Remarks -(tables 2 & 3) -Measurements of the 14 adult females collected in this work (Table 2) agree very well with measurements of the literature, especially with those of Ueckermann et al. (2007) obtained with a great number of specimens (29) from various African countries.
Macrosetae on basitarsus of leg IV are not serrated but macrosetae of genu and tibia are serrated and there is no pre-anal macrosetae on the ventrianal shield. These are key characters of P. persimilis in comparison to the closely related species Phytoseiulus macropilis (Banks) (Okassa et al. 2010).
Only few measurements of adult males are available in the literature and consequently measurements of the four males found in Mauritius are of great interest.
Four males and 14 females in a collected population with a sex ratio of nearly 4 females to one male is not exceptional for that species (Laing 1968).
Phytoseiulus persimilis is a Mediterranean / subtropical predatory mite that is a type I species, i.e. a specialist predator of the urticae species group of the genus Tetranychus (McMurtry and Croft 1997;McMurtry et al. 2013). Considerable research has been conducted on this predator-prey interaction (see review by Kostiainen and Hoy 1996), and numerous Table 2 Comparison of measurements of adult females of Phytoseiulus persimilis collected in this study with those in previous studies (localities followed by the number of specimens measured between brackets).

Characters
Mauritius ( biological control programs have used P. persimilis against T. urticae on a wide range of ornamental and vegetable crops. Phytoseiulus persimilis was the first greenhouse biological control agents available commercially and it is one of the most successful biological control agents. It can also be used in temperate climates on open-field crops such as strawberries. Optimum conditions are 20-27°C and relative humidity of 60-90 %. Cooler or warmer temperatures may have a negative effect on reproduction, development and efficiency of this predatory mite. This species is present in Mauritius probably because of its commercial introduction and uses in vegetable and ornamental greenhouses, dispersion of some specimens released and establishment in the environment. This species is actually reared and sold in La Réunion and commercialised in Mascareignes since a long time (Quilici, personal communication).
Remarks -Measurements of collected females are consistently longer than reported for the type specimens (Table 4). Measurements of the only male specimen collected (Table 5) are more variable in comparison with the type specimens. In Mauritius specimen, setae s4, Z4, Z5 and macrosetae SgeIV are longer but setae z2, z4, S2, S4, and S5 are shorter than type specimens. The rest of the measurements however agree well with the original description of Blommers (1974) and with our own measurements of females and males collected in La Réunion Island (Quilici et al. 2000 and Kreiter et al. in prep.).
agents, namely P. persimilis and P. orientalis, and may have great interest for agriculture of the island. The first species for the history of success in the control of T. urticae, and the second has apparently high potential for the control of P. latus. The biology of the two other species remains unknown and consequently their potential for biological control. Finding local species potentially useful for biological control purpose is particularly important nowadays because new regulations of many countries of the world makes more difficult the importation of macro-organisms for biological control purposes. Importation permits must be requested, but it is expensive and chances to obtain are generally very low in many countries (Kreiter et al. 2016). Hence, knowledge of the biodiversity, especially of efficient biological control agents becomes progressively more important, not only for conservation, but also for agricultural and economic reasons.