Mite Fauna (Arachnida: Acari) on Peach Cultivars in Presidente Prudente, São Paulo, Brazil

This study aimed to determine the mite diversity, population dynamics and to conduct a fauna analysis in plantations from four peach varieties established in the municipality of Presidente Prudente, SP, Brazil. The mite fauna from ‘Jóia 4’, ‘Ouromel 3’, ‘Regis’ and ‘Rei da conserva’ cultivars over the rootstock Okinawa were determined from December 2002 to February 2006. Samples composed by 72 leaves were collected fortnightly from upper, middle and lower third of each tree and four trees per cultivar. A total of 3,084 mites were recovered during the experiment, with the following distribution: 2,638 phytophagous, 373 predators and 73 of unknown feeding habit. The mites recovered were related to 18 species from 12 mite families. Aculus fockeui (Eriophyidae) occurred sporadically, not causing symptoms on the canopy. Euseius citrifoluis was the most abundant species among the Phytoseiidae, with predominance on cultivar ‘Regis’.


Introduction
Fruit plants are infested by several species of insects and mites, which in some cases are considered pests. The knowledge about the mite diversity can determine the degree of importance of phytophagous species and also of predatory species, as a scientific basis for the integrated pest management in several crops (Vasconcelos et al., 2005). It can also help in the evaluation of the species potential to become pests or natural enemies, foreseeing their impact on the environment (Moraes & Flechtmann, 2008).
The mite species are considered major pests on peaches, because their severe infestation destroys the superficial tissues of the leaves, which cause the loss of cell juice from the first tissue layers. This results in a color alteration, a yellowing or bronzing of the leaves, which provokes a qualitative and quantitative product reduction (Salles, 1998).
In another study on the population of predatory mites in peaches, especially the Phytoseiids family, Moraes et al. (1986) reported the occurrence of Euseius concordis (Chant, 1959), Iphiseiodes zuluagai Denmark & Muma, 1972, Phytoseiulus macropilis (Banks, 1904 and Ricoseius loxocheles (De Leon, 1965). The predatory mites were considered effective in the biological control of phytophagous mites on roses. Their occurrence may be influenced by cultural management, which affects their establishment in the plants when released in the field (Monteiro, 2002).
The introduction of peach orchards in Presidente Prudente, in the western region of São Paulo State, aimed at the diversification of fruit cropping for the family-based farm. The knowledge about the mites' fauna in peach plantations in the western São Paulo State is very much incipient. The present research aimed to determine the mite diversity, the population dynamics and to conduct a fauna analysis in peaches orchards in western São Paulo State, with the purpose to subsidize pest management.

Materials and Methods
The survey was conducted in the municipality of Presidente Prudente, São Paulo,Brazil (UTM N 7,545,288.76 m,E 459,930.31  Except for the application of insecticides and miticides, other cultural practices employed in this study were those recommended for conventional peach trees (Pereira et al., 2002), such as artificial dormancy break performed with hydrogen cyanamide (0.5% a.i.) + oil (1%), fruit thinning, fertilization, weed control (glyphosate, 0.5% a.i), green and dry pruning, and micro sprinkler irrigation.
In order to obtain the complete mite diversity, samplings were performed every fifteen days by collecting 12 leaves from the upper, middle and lower thirds of the plant (both internal and external parts). A total of 72 leaves were collected biweekly from each tree, from four trees per cultivar, was collected to guarantee a representative sample, but without compromising the plants development. The samples were placed into paper bags and kept in polystyrene boxes containing ice to decrease the mite activity. The mite extraction was performed at the Plant Health and Quality Laboratory at "APTA Alta Sorocabana", in Presidente Prudente, SP, Brazil. To accomplish the extractions, the samples were placed individually in plastic containers and immersed for five minutes in a 70% alcohol solution and then stirred to displace the mites. The leaves were discarded and the solution was passed through a 0.038 mm sieve and the mites collected were transferred to 30 ml capacity glass vials for later screening and identification. No leaves were sampled between May and August, due to plant natural defoliation. The mites collected were mounted in Hoyer's medium for identification, except the eriophids, which were mounted in modified Berlese medium (Krantz, 1978). A representative sample of the species found was deposited at the "Geraldo Calcagnolo Mites Reference Collection", at Laboratory of Acarology, Biological Institute, Campinas, SP.
A faunistic analysis and the characterization of mites' occurrence (accidental, accessory and constant) and dominance indices (accidental, accessory and dominant) were conducted to determine the mite species importance status (Palma, 1975).

Results and Discussion
Eighteen mite species were recorded in our survey, and the species were related to 12 distinct mite families (Table 1). A total of 3,084 mites were collected: 2,638 phytophagous, 373 predators, and 73 mites with unknown eating habits.  (120) were A. fockeui was (Table 2). Another eriophyid, Catarhynus sp. was detected in very low number (Table 1). A. fockeui is reported in several regions around the world as the major peach-associated mite (Kondo & Hiramatsu, 1999;Ferreira & Carmona, 1997;Kunugi et al., 1993), causing decrease in fruit weight, sugar content (Kunugi et al., 1993;Kondo & Hiramatsu, 1999), defoliation and reduced plant vigor, and resulting in poor fruit quality in subsequent years (Kondo & Hiramatsu, 1999). Contradictorily observations made elsewhere in the world, in the present study there were no detected visual symptoms associated with the occurrence of this mite. Eichelberger et al. (2011) also reported that A. fockeui has little relevance in peach orchards in Rio Grande do Sul.
In Italy, Castagnoli & Nannelli (1987) found high densities of A. fockeui in a peach orchard, but these authors did not find apparent damage, probably due to biological control by predators mites. However, according to Ashihara et al. (2004), injuries on the peach leaves caused by A. fockeui reduce the sugar content of the fruit, promoting intense leaf fall just after harvesting. The resurgence of A. fockeui registered there was probably due to the negative effects of synthetic phyrethroid on predator mites.
Among the predators collected in our study, Cheyletidae and Phytoseiidae species were reported (Table 1). The highest species richness and numbers of individuals registered was from the Phytoseiidae family.
A. fockeui was constant in Rei da conserva cultivar and intermediate in the remaining cultivars (Table 4), representing more than 80% of the total mites. The occurrence of M. planki (the most abundant species in the beginning of the study in December 2002) became intermediate for all cultivars along the study, while the occurrence of T. urticae was constant for Rei da conserva cultivar (Table 4).
In Portugal, Ferreira & Carmona (1997) recorded 27 mite species: seven phytophagous, eleven predators and nine designated as indifferent. The most representative phytophagous populations were A. fockeui (41.6%) and Tetranychus cinnabarinus (Boisduval, 1987) (20%), which in contrast with our study observations, it caused silvering of the foliage by the first species, and tanning, by the second species, respectively.
Studies about phytophagous and predator mites population on soil cover plants should be accomplished to clarify the role of other plant species as alternative hosts, as well as essays to determine pesticide with little effect on predator mites, in order to support the management of mites incidence on peach.

Conclusion
Eighteen mite species belonging to 12 families were detected on peach cultivars in Presidente Prudente, western Sao Paulo State, with the predominance of the phytophagous species A. fockeui and the predator E. citrifolius.