Parasitus fimetorum and Macrocheles muscaedomesticae (Acarina:Parasitidae, Macrochelidae) as Natural Predators of the Root Knot Nematode, Meloidogyne javanica Treub

The potential use of two predacious mites, Parasitus fimetorum (Berlese 1904) and Macrocheles muscaedomesticae (Scopoli 1972), for controlling the root knot nematode, Meloidogyne javanica Treub 1885 was evaluated under laboratory and semi-field conditions. Obtained results revealed that the 2 predators significantly reduced the root knot nematode numbers. In addition, the highest reduction percentage (57.24%) in nematode juveniles was recorded at the treatment of (1000 nematode + 10 mites). For M. muscaedomesticae, the highest mortality percentage (50.83%) in nematode juveniles was recorded at the treatment of (1000 nematode + 50 mites), followed by (1000 nematodes + 20 mites) 48.88%, while the treatment of (1000 nematode + 10 mites) gave (47.13%). The combination of the 2 mite species (1000 nematodes + 50 mites/species) caused the highest mortality percentages in nematode juveniles (69.29%), followed by (1000 nematodes + 20 mite/species) 50.51% and the treatment of (1000 nematode + 10 mite/species) (37.66%). At the pot experiments, the highest overall mortality percentage in M. javanica juveniles was recorded at the treatment of P. fimetorum + M. muscaedomesticae giving (57.07%), followed by the treatment of P. fimetorum (39.17%), and then, by M. muscaedomesticae alone that recorded only (17.47%). In conclusion, predacious mites can be partially considered a control tool of the parasitic nematodes.


Background
The root knot nematode, Meloidogyne javanica (Treub 1885), is one of the most serious pests, attacking large numbers of field, vegetable, and fruit plants in Egypt. It can be found in all types of soils and cultivated regions of Egypt. The use of chemical compounds for the control of nematodes is costly and negatively affecting the environment as well as human and animal health. Meanwhile, nematodes have a diverse range of natural enemies. Therefore, scientists are constantly exploring other biological control methods, rather than the use of chemical compounds.
Biological control of plant-parasitic nematode using predatory mites has been explored in several countries, especially in protected crops (Carrillo et al. 2015). Cosmopolitan mites of the families Laelapidae, Parasitidae, and Macrochelidae are free-living predators feeding on eggs and immature stages of other soil-inhabiting micro-arthropods and nematodes (Kazemi et al. 2013).
In Egypt, Taha et al. (1988) studied the effect of feeding Neocunaxoides andrei (Baker and Hoffmann) on the nematode, Panagrolimaus rigidus (Schneider 1866) Thorne 1937, on its developmental time and fecundity under laboratory conditions of 30°C and 70% RH, and found that cunaxids are generalist predators because they feed on diverse prey, such as plant mites and other small arthropods and nematodes. In addition, Walter and Kaplan (1991) found that Coloscerius simplex Ewing colonized in greenhouse pot cultures fed on Meloidogyne spp. Mostafa et al. (1997) reported that Lasioseius dentatus Fox 1946 could develop on Meloidogyne javanica egg masses under laboratory conditions. El-Khateeb (1998) reared Coloscerius aegyptiacus Gomaa and El-Khateeb on the free living nematode, Rhabditis (Rhabditella) muscicola (Andrássy 1986), while Sholla Salwa (2000) reared Coloscerius buratus Den Heyer on the same previous nematode species. El-Hady Mona and El-Naggar (2001) studied the possibility of using the predacious laelapid mites, Hypoaspis bregetovae (Shereef and Afifi) and H. sardous (Canestrini 1884), as biological control agents of root knot nematode infesting sunflower plants. Maareg et al. (2005) evaluated the potentiality of 7 predacious mite species in feeding on the juveniles of Meloidogyne incognita and found that all the tested mites fed successfully on nematode stages except Cunaxa sp.
Although the acarina communities in Egyptian soils have not been widely studied, limited information is available on the mesostigmatid fauna. Owing to their numerical importance, the gamasid mites have received more attention than other soil Acari. The majority of these species are predators and found associated with small and immature stages of insects and nematodes inhabiting soil surface (El-Hady Mona and El-Naggar 2001; Mostafa et al. 2013;Carrillo et al. 2015). The natural enemies of plant parasitic nematodes include fungi, bacteria, and predacious invertebrates. These natural enemies of nematodes are often used in agricultural practices to suppress the populations of plant parasites (Kerry and Hominick 2002). Mostafa et al. (2013) indicated that the type of tested nematode food and temperatures had a slight significant difference on the incubation period of uropodid mite, Uroobovilla krantzi Zaher and Afifi (both sexes), when fed on free living and plant parasitic nematodes. However, predacious mites and predacious nematodes can be essential control agents for certain nematodes (Yeates and Wardle 1996). Nevertheless, the practice of using predacious mites as control agents in agriculture is still limited.
The aim of the present work was to study the efficacy of the predatory mites, P. fimetorum (Berlese 1904) and M. muscaedomesticae (Scopoli 1972), against the root knot nematode, M. javanica, under laboratory and greenhouse conditions.

Root knot nematode culture
Root knot nematode, M. javanica, juveniles were obtained from a pure culture reared at the Biological laboratory of Economic Entomology and Agricultural Zoology Department at the Faculty of Agriculture, Menoufia University, Egypt, by incubating egg masses in modified Baermann units. Newly hatched nematode juveniles were used for conducting experiments.

Culture of Parasitus fimetorum
The predatory mite, P. fimetorum, was collected from soil samples including leaf litter and farmyard manure and extracted by using modified Tullgren funnels for 72 h (Lindquist et al. 1979). The extracted predators were collected in distilled water and then transferred into plastic rearing units (Fouly 1996;Al-Rehiayni and Fouly 2005). Samples were taken from the experimental farm at the Faculty of Agriculture, Menoufia University, Egypt.

Laboratory experiments
To study the efficacy of both mite species and their potential in feeding on the root knot nematode juveniles, plastic Petri dishes (5 cm) were filled with 50 g pure fine sand to conduct different treatments: 1. First and second experiments were as follows: 1000 J2 M. javanica + 10, 20, and 50 ind. P. fimetorum or M. muscaedomesticae (15 dishes) 1000 J2 of M. javanica only (15 dishes) (control) Treated dishes were randomized arranged and moistened with 30 ml water every 5 days. Ten days later, 5 dishes from each treatment were examined for mites and nematodes by extraction, using the modified Baermann units and Tullgren funnels. Numbers of juveniles of root knot nematode and mite individuals were counted under dissecting stereomicroscope. The previous step was repeated 20 and 30 days after beginning.

Greenhouse experiments
Seventy plastic pots, each contained 2 kg of pure sand soil, were prepared for the following treatments: 5000 J2 M. javanica + 100 ind. P. fimetorum, M. muscaedomesticae, 100 ind. from each species together (10 pots each). 100 individuals of P. fimetorum and M. muscaedomesticae (10 pots) 5000 J2 of M. javanica only (control) (10 pots) Check treatment without any additives (10 pots) Each pot was transplanted with two tomato seedlings (25 days old) and received the required populations of nematodes and mites as previously mentioned. Pots were randomized and arranged in the greenhouse at 23 ± 2°C and 65 ± 5% RH. Pots were watered as required and received a standard nutritional solution. Thirty days later, the soils of 5 pots/ treatment were examined for nematode and mites, using the modified Baermann units and Tullgren funnels.

Statistical analysis
Data were analyzed using CoStat Soft Program 6.400 (CoStat version 6.400 Copyright © 2008) and ANOVA test with LSD (5%) and mean ± SD. Mortality percentages were computed according to Abbott's formula (Abbott 1925).

Results and discussion
Laboratory experiments Efficacy of Parasitus fimetorum against Meloidogyne javanica juveniles Statistical analysis of the obtained data indicated that there were significant differences in the numbers of nematode juveniles between the treatment with the nematode only (control) and each of the other treatments at the 3 periods of examination. Moreover, there were significant differences in nematodes' population among the 3 rates of the released predatory mite, P. fimetorum (Table 1). As shown in the table, there were significant differences between numbers of predatory mites, along experimental sampling, among the 3 ratios of release. Numbers of P. fimetorum were relatively low after 30 days at the treatment of (1000 nematodes + 10 mites), while it increased at other treatments.
The previous data revealed that there were significant differences in the activity of the predatory mite species towards the root knot nematode. The results are similar to those reported by Van de Bund (1972) with the predatory mite, Hypoaspis aculeifer (Canestrini 1884), which decreased the population of nematode M. javanica by 42%. Also, Imbriani and Mankau (1983) Dmowska et al. (1997) proved that it was still premature to evaluate the effectiveness of Parasitus bituberosus Karg 1972 against rhabditid nematodes because the life table parameters did not seem to be totally convincing.
Efficacy of Macrocheles muscaedomesticae feeding on Meloidogyne javanica juveniles Data in Table 2 indicated that there were significant differences in numbers of nematode juveniles between the treatments in which the predatory mite, M. muscaedomesticae, was released and control at the 3 intervals of examination. Moreover, there were significant differences in nematode population among the 3 rates of the released mite. The obtained data also indicated that there were significant differences in the numbers of M. muscaedomesticae mite among the 3 rates of the predator. Mortality percentages of M. javanica juveniles presented in Table 2 showed that the highest mortality rate (50.83%) was recorded at the treatment of (1000 nematodes + 50 mites), followed by (48.88%) at (1000 nematodes + 20 mites) and then by (47.13%) at (1000 nematodes + 10 mites). Obtained results are in agreements with Beaulieu and Weeks (2007)

Efficacy of P. fimetorum and M. muscaedomesticae mites in feeding on Meloidogyne javanica juveniles
Statistical analysis of the obtained data indicated that there were significant differences in the numbers of nematode juveniles at the 3 periods of examination between the treatment of nematode only (control) and other treatments of mites releasing (Table 3).
Statistical analysis of the obtained data indicated that there were significant differences in the numbers of the 2 mite species among the 3 rates of the predator ( Table 3). The highest mortality percentages in nematode juveniles (69.29%) was recorded at the treatment of (1000 nematodes + 50 mite/species), followed by (50.51%) at (1000 nematodes + 20 mite/species) and (37.66%) at (1000 nematodes + 10 mite/species).

Greenhouse experiments
At the pot experiments in the greenhouse, there were several interactions between the population of predacious mites and nematodes under such semi-field conditions. Tomato seedlings were used during the course of the study. Statistical analysis of the obtained data revealed that there were significant differences in the numbers of nematode juveniles extracted from different treatments, as well as between the 2 periods of examination (Table 4). The highest nematode juvenile numbers were recorded at the treatment of M. muscaedomesticae mite, giving 3236 and 4308.67 J2 at 30 and 60 days of nematode inoculation (LSD 5% = 354.2 and 502.4, respectively, followed by the treatment with P. fimetorum mite, giving 2264 and 3316 J2 at 30 and 60 days of nematode inoculation (LSD 5% = 354.2 and 502.4), respectively, while the lowest nematode juvenile numbers were found at M. muscaedomesticae + P. fimetorum mite treatments, giving 1752 and 2162 J2 at 30 and 60 days of nematode inoculation (LSD 5% = 354.2 and 502.4), respectively.
As for the mean numbers of mite species summarized in (Table 5), extracted from tomato soil, 30 and 60 days after planting, results show that there were significant differences in the numbers of mites, as well as between the 2 periods of examination (Table 5).
Data in Table 6 show that the highest overall mortality percentage in M. javanica juveniles (57.07%) was recorded at the treatment of P. fimetorum and M. muscaedomesticae, followed by (39.17%) at the treatment with   Table 7 show the average numbers of root knot nematode galls in tomato roots (60 days) at different treatments of predatory mites in comparison with control. The statistical analysis of the data indicated that there were significant differences in gall numbers among treatments.
Results in Table 7 indicated that the highest decrease percentage in root knot nematode galls (56.3%) was recorded at the treatment of P. fimetorum and M. muscaedomesticae mites, followed by P. fimetorum (44.3%), while the least (30%) was obtained at the treatment of M. muscaedomesticae. The obtained results are in agreements with (McSorley and Wang 2009) who reported that bioagent treatments reduced numbers of M. javanica was greater in tomato soil, especially mites, collembola. Also, Manwaring et al. (2015) stated that Macrocheles matrius and Onychiurus armatus (collembolan) are known to feed on nematodes and other plant parasites and decrease the root knot nematode galls and egg masses.

Conclusion
Using combined treatment of two predatory mites, P. fimetorum and M. muscaedomesticae, showed a high potential in reducing the number of M. javanica than using each predatory mite alone. Moreover, the results confirmed that parasitic nematodes can be safely controlled by predacious mites in an attempt to reduce depending upon chemical pesticides.

Authors' contributions
The author collected and identified predacious mites and nematode and wrote the manuscript. The author read and approved the final manuscript.

No funding
Availability of data and materials All data generated and/or analyzed during the present study are available in the manuscript, and the corresponding author has no objection to the availability of data and materials.
Ethics approval and consent to participate Not applicable. The study was conducted on mites and nematode species that are abundant in the environment and does not require ethical approval.

Consent for publication
The author agrees to publish this paper. The data has not been published in completely or in part in other journal.