Phytoseiid mites in cashew trees: diversity and seasonality

One of the main factors limiting the growth of cashew (Anacardium occidentale) crops is the incidence of pests, which is even more problematic because of the limited number of pesticides available. Thus, the biodiversity of beneficial organisms deserves special attention for improving the development of pest management programs. These faunae include predatory mites of the family Phytoseiidae, which are recognized as biological control agents. In the present study, the diversity and seasonality of phytoseiids in cashew plants were investigated during one year in two crop areas in Brazil (one of the main producers and likely place of origin). Species diversity was analysed at both sites and seasonality data only in the area with greater abundance and diversity. In one of the areas, seven species of phytoseiids were found, with Euseius concordis the most prevalent species; in the other area, nine species were found, and Iphiseiodes zuluagai was the most prevalent species. Phytoseiids were found throughout the year, and their population dynamics were influenced by temperature and tydeid populations. Lower phytoseiid population densities were recorded during the dry period, when high temperatures were associated with reduced precipitation and humidity. This period also coincided with high tydeid population densities, represented only by the species Lorryia formosa. Twelve phytoseiid species were found on cashew plants, with a predominance of generalist phytoseiids (types III and IV), which may be potentially used as biological control agents not only for phytophagous mites but also for small insects.