A Method to Estimate the Population Level of <I>Aceria litchii</I> (Prostigmata: Eriophyidae) and a Study of the Population Dynamics of This Species and Its Predators on Litchi Trees in Southern Brazil

Abstract

Litchi (Litchi chinensis Sonnerat) is native to Southeast Asia, where most of the world cultivation of this crop is done. Its commercial cultivation in Brazil is recent and concentrated in the state of São Paulo. This crop has been severely damaged in Asia and Brazil by the litchi erineum mite, Aceria litchii (Keifer) (Eriophyidae). The objectives of this study were the adaptation of a method to estimate the density of A. litchii, an evaluation of the population dynamics of this pest and of its associated predators in the state of São Paulo, and an estimation of its injury levels to litchi trees. To estimate the density of A. litchii, an adaptation of a method commonly used to evaluate nematode densities in plant roots was performed. This method was shown to be adequate for the estimation of the number of A. litchii, and it might also be useful for similar evaluations of other erineum forming mites. Field samples to determine the pest population dynamics were collected monthly from August 2011 to July 2012. Sampled leaves were examined under a stereomicroscope for removal of predators and subsequent extraction ofA. litchii by the adapted method. A. litchii reached maximum densities in November 2011 and June 2012, being found at low densities between January and March 2012. The pattern of variation of A. litchii injury levels was similar to that of the density of A. litchii. The main predatory mite co-occurring with A. litchii was the phytoseiid Phytoseius intermedius Evans and McFarlane. However, high injury levels due toA. litchii suggest that the predator was unable to prevent visible damages to the trees, indicating that control activities should be adopted by growers.

Detection of the Lychee Erinose Mite, Aceria litchii (Keifer) (Acari: Eriophyidae) in Florida, USA: A Comparison with Other Alien Populations

“…Several natural enemies have been reported in association with LEM in India [45], Australia [46,47], Brazil [42,48] and China [49]. However, predation on LEM has only been confirmed for a few species of phytoseiid mites, including Amblyseius largoensis (Muma) in China [50], and Phytoseius intermedius Evans and MacFarlane in Brazil [48]. In Florida, A. largoensis, Euseius membrasicus, Hemycheyletia bakeri and Cheylotogenes ornatus have been found to be associated with LEM.…”

Manejo del ácaro Aceria litchii (Acari: Eriophyidae) en Litchi chinensis

“…The behavior and small size of A. litchii hampers the verification of population density. This mite lives in erineos, which impedes direct observation (Azevedo et al 2014). Methods to estimate lychee mite populations and others insects that form erineos have been adapted from one used to evaluate nematode densities in plant roots (Coolen and D 'Herde 1972) consisting of blending litchi infested leaves in a blender for 1 min in 250 ml distilled water and screening the material with a set of sieves with openings of 2, 0.2 and 0.037 mm, respectively, from top to bottom.…”

“…The estimate is made by extrapolating the count of three aliquots of 1 ml. This procedure is progressive with higher precision as the A. litchii infestation level increases (Azevedo et al 2014). The highest A. litchii density on plants in Brazil is recorded at the beginning of the rainy season (October) and in the middle of the dry season (May-June) (Azevedo et al 2014).…”

“…This procedure is progressive with higher precision as the A. litchii infestation level increases (Azevedo et al 2014). The highest A. litchii density on plants in Brazil is recorded at the beginning of the rainy season (October) and in the middle of the dry season (May-June) (Azevedo et al 2014). Aceria litchii density can also be determined by stirring 2 cm 2 leaf pieces with erineos in a 0.5 % neutral detergent solution for five seconds to dislodge this mite from the erineos.…”

“…Practices for litchi mite control should be adopted throughout most of the year (Azevedo et al 2014) mainly in the development of the inflorescence and the expansion of new leaves when the mites migrate to young organs to take refuge, feed themselves and multiply by establishing new erineos (Arthur and Machi 2016). Several chemical products are widely used to control the mite (Azevedo et al 2013), but the adoption of other control methods is desirable.…”