ABSTRACT
Southern red mite, Oligonychus ilicis McGregor (Acari: Tetranychidae), is an important polyphagous spider mite pest that causes economic damage to many ornamentals, coffee, and fruit crops. Blueberry growers in the Southeastern United States, including Florida and Georgia, have experienced severe losses due to outbreaks of O. ilicis. Predatory mites are an important management tool used for controlling spider mites; however, predators have not been studied and successfully evaluated in blueberry systems. Amblyseius swirskii Athias-Henriot, Phytoseiulus persimilis Athias-Henriot, and Neoseiulus californicus (McGregor) (Acari: Phytoseiidae) are among the most economically important arthropod agents used in augmentative biological control worldwide. To evaluate the potential of these 3 commercially available predatory mites for use in blueberry plantings, we conducted experiments under controlled laboratory conditions and in the greenhouse. In preliminary laboratory experiments, P. persimilis and N. californicus significantly reduced the number of O. ilicis motile stages below those found in the untreated control, indicating the potential for these 2 predatory mite species to suppress O. ilicis populations. Amblyseius swirskii did not perform well controlling O. ilicis motiles in the laboratory. Under greenhouse conditions, N. californicus and P. persimilis significantly reduced the number of eggs after 7 days of release and the number of motile stages after 14 days of release. This is the first report of using phytoseiid mites to suppress O. ilicis in blueberry systems in the United States. Further studies on predator behavior, feeding preferences, and acaricide compatibility with predators are required to investigate the possibility of using P. persimilis, and N. californicus as biological control agents of O. ilicis in blueberry systems.
Subject(s)
Blueberry Plants , Pest Control, Biological , Predatory Behavior , Tetranychidae , Animals , Tetranychidae/physiology , FemaleABSTRACT
Oligonychus ilicis (McGregor) (Acari: Tetranychidae), commonly known as the southern red mite, or as the coffee red spider mite in Brazil, is one of the main species of herbivorous mites that causes serious damage to coffee plants (Coffea spp.) and thus negatively affects coffee production. Among the biocontrol agents, predatory mites of the family Phytoseiidae play an important role in many biological control programs worldwide due to their potential as suppressor of mite populations mainly from the family Tetranychidae. One of the phytoseiid mites usually associated with O. ilicis is Euseius concordis (Chant), which often occurs abundantly in the coffee crops of Minas Gerais State, Brazil. This study was conducted to assess the predation potential of E. concordis feeding on the larvae and nymph stages of O. ilicis on coffee plants (Coffea arabica L.). Logistic regression analysis revealed a Holling type II functional response, showing that the number of O. ilicis killed by E. concordis increased gradually as the density of O. ilicis increased. Average daily oviposition also increased with prey densities above 6.3 mites/cm2, indicating that maximum oviposition rate is about 1 egg/day. Results of this study suggest that E. concordis has the potential to reduce O. ilicis populations, and this predatory mite can therefore be considered an important natural enemy of the pest O. ilicis in coffee plantations.