Evaluate the Feeding Preference of Some Predator Mites Towards Red Spider Mites Untreated and Treated With Beauveria bassiana

Citation: Egypt. Acad. J. Biolog. Sci. (A. Entomology) Vol. 10(5)pp: 1120(2017) Egyptian Academic Journal of Biological Sciences is the official English language journal of the Egyptian Society for Biological Sciences, Department of Entomology, Faculty of Sciences Ain Shams University. Entomology Journal publishes original research papers and reviews from any entomological discipline or from directly allied fields in ecology, behavioral biology, physiology, biochemistry, development, genetics, systematics, morphology, evolution, control of insects, arachnids, and general entomology. www.eajbs.eg.net Provided for non-commercial research and education use. Not for reproduction, distribution or commercial use.


INTRODUCTION
The two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae), is a major agricultural pests, which often causes severe damage to a variety of crops (Gotoh et al., 2004).It frequently occurs in glasshouse and outdoor crops (Kennedy and Store, 2000).Spider mites are major pests in a wide range of protected crops across the world.It is one of the most serious pests responsible for yield losses of many horticultural ornamental and agronomic crops, causing considerable crop damage and economic loss (Puinean et al., 2010).A major problem in the control of T. urticae is the response to develop resistance to many acaricides.T. urticae is known for its ability to develop rapid resistance to pesticides.Among arthropods it has the highest incidence of pesticide resistance (van Leeuwen et al., 2010).
The use of multiple natural enemies has been recommended to control insect pests in integrated pest management programs (IPM) (Jacobson et al., 2001).Predatory mites are often used as an alternative to conventional pest management on a variety of plants (Gerson and Weintraub, 2007).The predatory mite, Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) and Neoseiulus californicus were used in integrated pest management programs for T. urticae suppression (Cote, 2001;Skirvin and Fenlon, 2001 ;Fitzgerala and Easter, 2003).
Microbial control of pests is an important approach to reduce the dependence on chemical pesticides for increased agricultural sustainability.Entomophthoralean is highly virulent, exhibiting fast pathogenesis and epizootics are common in nature, therefore playing an important role in controlling insect and mite populations (Milner, 1997;Lacey et al., 2001;Pell et al., 2001 ;Ravensberg, 2011).
The entomopathogenic fungus Beauveria bassiana is known to be effective in controlling many arthropod pests (Ferron 1978), Previous studies on the interaction between fungal pathogens and predatory mites have focused on the fungal infectivity to predators (Donka et al., 2008;Vergel et al., 2011), or on the sub lethal effects of ingesting pathogen treated prey on predators (Seiedy et al., 2012a ;Wu et al., 2015).
In the present study, host preference of P. persimilis and N. californicus were investigated when offered T. urticae treated adults by B. bassiana vs. untreated T. urticae on the leaf.The aim was to understand if the predatory mite was able to detect the presence of an entomopathogenic fungus and avoid feeding on fungus treated prey.

Rearing of Tetranychus urticae (Koch)
The original colony of the red spider mites T. urticae in this study was supplied from Acarology Laboratory in Plant Protection Research Institute, A.R.C at Dokki.It was reared as a test mite for several generations at 25±1°C and 70 ± 5% R.H. away from any pesticide contamination.T. urticae was maintained on detached mulberry leaves with the lower surface upwards placed on moist cotton wool pads in fiber-dishes (20cm in diameter).The cotton pads were moistened daily to avoid disc dryness, and to prevent mite escape.Mulberry leaves were changed by fresh one from time to time when necessary (Hassan, 2008;Sewify et al., 2015).
To obtain adult T. urticae of uniform age, 25 adult females were taken from the mite culture and put on leaf discs placed on wet cotton in Petri dishes (20cm in diameter), and allowed to lay eggs for 24h.After which the females were removed and the eggs remained till adult (Seiedy et al., 2012a).The prey used in the present study was the adults of T. urticae.Two factors were our reason to choose adults stage, because of their relatively big size, disease diagnosis in adults of T. urticae is easier in contrast with the other stages.Also, the adults of the two predators aggressively attack to adults of T. urticae (Cote, 2001;Seiedy, 2014).

Rearing of the predaceous mites
The predaceous mites, Phytoselies persimilis and Neselious californicus were obtained from rearing lab, Kaha Research Station, Agriculture Research Center.The predatory mites were maintained at 25± 1°C and 70 ± 5% R.H with a photoperiod of 16:8h (L:D) and away from any pesticide contamination.
The predatory mites were maintained on detached mulberry leaves with the lower surface upwards placed on moist cotton wool pads in fibber-dishes (20cm in diameter).The cotton pads were moistened daily to avoid disc dryness, and to prevent mite escape.The colony of the predator was fed on a mixture of various stages of T. urticae day after day.Also mulberry leaves were changed by fresh one from time to time when necessary (Nadimi et al., 2008;Seiedy et al., 2012a).

Preparation of conidia
B. bassiana isolate (B4) which was observed to cause non-significant mortality on P. persimilis and N. californicus (Unpublished data) percentage of mortality for both predators P. persimilis and N. californicus were recorded as 17.9 and 28.6 %, respectively.

Experimental Procedures
Experimental arenas were constructed by placing a mulberry leaf disks (2.5cm in diameter) excised from mulberry plants on top of a layer of cotton in a 12 cm Petri dish filled with sterile distilled water.A layer of cotton put around the leaf in order to prevent predatory mites from escaping.
Adults of the spider mites, T. urticae were placed on experimental disks at densities 25 per disk using 5 replicates were conducted for each prey density.Conidial suspension of B. bassiana (B4) was prepared at 5x10 6 conidia/ml as calculated LC 50 (Seiedy, 2014).
Two millilitre of the conidial concentration was applied against the adults of T. urticae in Petri dish with different densities by using the direct spray technique a glass atomizer at 30cm high with 2ml spore suspension for each treatment and 2ml sterilized distilled water of 0.1% Tween 80 as control (Abo-Shabana, 1980;Hassan, 2008 ;Sewify et al., 2015 ).
Four time intervals: 0, 24, 48 and 72h post-inoculation of mite adults were considered for introducing predators.A single P. persimilis or N. californicus female (starved for 24 h) was introduced to T. urticae adults.All predator females were in the early stage of adult.Eggs of prey were removed from Petri dishes for the duration of the experiment.The number of consumed T. urticae adults in each Petri dish was assessed after 24 h.The experiments were conducted at 25±1 °C, 60-70 % R.H. and a photoperiod of 16:8 h (L: D) (Seiedy, 2014)

Statistical analysis
Predator preference was calculated using Manly's preference index (Manly, 1974).Manly's preference index (β) calculates the number of consumed prey.The sum of Manly's β for all prey species is from 0 to1 and prey species with large values of Manly's β indicates preference for that species.


A 1 and A 2 : The number of treated and untreated prey presented to the predator.If the preference index is close to 1, the predator prefers Type I prey, if close to 0, it prefers Type II prey.An index value close to 0.5 indicates no preference.

RESULTS AND DISCUSSION
Adults of both untreated T. urticae and treated T. urticae by B. bassiana were offered simultaneously, after zero time, 24, 48 and 72h.P. persimilis and N. californicus consumed more untreated T. urticae than the treated preys.The percentage of predation for P. persimilis was (36.8, 28.8, 8 and 4%) after 0, 24 ,48 and 72h respectively compared to the control that was 37.6%, and for the other predator N. californicus the percentage of predation was (37.6, 27.2, 11.2 and 6.4%) after 0, 24, 48 and 72 h respectively compared to the control that was 38.4%.Table (1) and Table (2).Data analysis in Table (3) indicated that P. persimilis in all treatments exhibited type П response to T. urticae.The Manly's preference index (β) for the treated adult T. urticae by B. bassiana (B4) were (0.5, 0.42, 0.2 and 0.08) that had been treated for zero time, 24, 48 and 72h respectively.These results indicated that P. persimilis prefers untreated T. urticae and the predator was able to detect the presence of B. bassiana in 48 and 72 h treatments, These results are in agreement with Seiedy (2014) who found that P. persimilis prefers untreated T. urticae rather than T. urticae adults treated by strain DEBI008 of B. bassiana with interval 72h after infection.Results of the present study indicated that N. californicus in all treatments exhibited type П response to T. urticae The Manly's preference index (β) for treated adult T. urticae by B. bassiana (B4) were (0.49, 0.4,0.19 and 0.12) that had been treated for zero time, 24, 48 and 72h respectively, Table (4).These results indicated that P. persimilis and N. californicus prefer the untreated T. urticae and the predators were able to detect the presence of B. bassiana in 48 h and 72 h treatments.Seiedy (2014) explained that, the quality of the prey seems to have been significantly P. persimilis.In the present study we speculated that the presence of fungal conidia on prey body alter the behaviour of P. persimilis and N. californicus by increasing grooming.This based on other studies by (Pell et al., 2001;Inglis et al.,2001), who stated that the fungi primarily enter the host through direct penetration of the cuticle, virulence of fungal entomopathogens involves four steps: adhesion, germination, differentiation and penetration.Each step is influenced by a range of integrated intrinsic and external factors, which ultimately determine the pathogenicity.A successful infection is achieved by the attachment or adhesion of spores to the host.Adhesion is necessary and normally achieved through the secretion of mucilage.Spores attach to the cuticle, germinate and penetrate the integument by means of a combination of physical pressure and enzymatic degradation of the cuticle death of the host usually taking place 4-7 days after infection (Shah and Pell, 2003).
This was a possible reason for the decrease in prey consumption at 48h and 72h treatment, so it was probably that these treated mites had not taste good enough to be eaten in comparison with 0, 24 h after infection and control because after 48 and 72 h, the fungus grew on mites, so predator may be able to recognize the fungus spores and as a result, predators are indisposed for any feeding.Seiedy et al.,(2013) showed that P. persimilis was attracted to the control plants that contain untreated T. urticae more than plants contain T. urticae treated with B. bassiana after 72h.This indicated that the predator was able to detect the presence of B. bassiana in the 72h treatment.Baverstock et al. (2009) showed that entomopathogenic fungi produce a range of volatile chemicals, so it is possible to assume that the fungus produces one or more compounds that the predatory mite can detect and that trigger the avoidance behaviour.Faraji et al. (2001) mentioned that the predatory mite has capability to recognize dangerous conditions based on the odor, and to adjust its foraging behaviour accordingly.Seiedy et al. (2013) reported the avoidance of feeding of the predatory mite on T. urticae adults treated by B. bassiana, and showed that P. persimilis was attracted towards control plants if tested against plants with spider mites treated with B. bassiana for 72 h This indicated that the predator was able to detect the presence of B. bassiana in the 72 h treatments.Therefore, live T. urticae treated with the fungus for 72 h caused avoidance behaviour of the predator.
An insect or mite may gain selective advantage if it is able to detect entomopathogenic fungi from a distance and respond via behavioural avoidance or through post-contact responses such as grooming (Chouvenc et al., 2008 ;Seiedy et al. 2012b).Gao et al.,(2012), evaluated the insecticidal activity of strain B. bassiana (RSB) which was highly virulent to the western flower thrips Frankliniella occidentails and was not insecticidal against the predator Orius sauteri, and found that the larva of F. occidentails contaminated by B. bassiana may be poor quality prey for O. sauteri because infection makes the larvae deficient in certain essential nutrients, (Simelane et al., 2008) or creates a build up of fungal toxins or metabolites, which may slow development and shorten adult longevity of O. sauteri.(Leckie et al., 2008).Wekesa et al. (2007), demonstrated the effect of entomopathogens on mite behaviour, entomopathogenic fungus Neozygites floridana has no ability to affect the predator mite Phytoseiulus longipes but the behaviour of phytoseiid can be affected due to the presence of an excessive number of capilliconidia on their bodies.This change in their behaviour can be shown by their self-grooming and reducing their searching activity.
In other study, it has been shown that the behavioural factors such as feeding preference and activity of predator were affected by the presence of fungus on the treated prey , intensive decreasing in feeding of predator Anthocoris nemorum on aphid treated with B. bassiana was clearly detected (Meyling and Pell, 2006).Pell and Vandenberg (2002) , observed that the predator Hippodamia convergens Guerin-Meneville, did not feed on Russian wheat aphid Diuraphis noxia treated with Paecilomyces fumsoroseus fungi.
This conclusion comes parallel to Roy and Pell (2000) who stated that fungal control agents have the potential to negatively affect insect natural enemies through direct infection, or indirectly , by depleting the prey population or changing quality extent of prey population.In turn, insect natural enemies could negatively affect fungal control agents by consuming preys that are treated with the fungus, by removing the fungus from the system.While, Seiedy et al., (2012a) reported that fungal control agents have the potential to negatively affect natural enemies through their effects on the quality of prey, and P. persimilis showed increased handling time of B. bassiana treated adults of T. urticae if treated for 48 and 72 h.Therefore, B. bassiana strain (B4) and the predators mites P. persimilis and N. californicus appear to be compatible and complementary biological control agents for spider mite T. urticae in the IPM program.
B. bassiana strain (B4) could be used for rapid, short term suppression of spider mites populations, and predator mites could be used for long term suppression of spider mites population.

 β :
The preference to prey Type I (T.urticae treated adults by B. bassiana), Type II (untreated T. urticae ). e 1 and e 2 : The number of treated and untreated prey remaining after the experiment.