Prey-stage preference, functional and numerical responses of Amblyseius largoensis (Acari: Phytoseiidae) to Raoiella indica (Acari: Tenuipalpidae)

Raoiella indica Hirst (Acari: Tenuipalpidae) is a phytophagous mite that recently invaded the Western Hemisphere. This mite is a multivoltine and gregarious species that can reach very high populations and cause significant damage to a variety of palm species (Arecaceae). The native predator Amblyseius largoensis (Acari: Phytoseiidae) has been found associated with R. indica in Florida. This study was designed to gain insight into the potential of A. largoensis to control R. indica. We determined the preference of A. largoensis for the different stages of R. indica and estimated the functional and numerical responses of this predatory mite to varying densities of its preferred prey-stage. In no-choice experiments A. largoensis consumed significantly more eggs than other stages of R. indica. When given a choice A. largoensis showed a preference for R. indica eggs over other developmental stages (P<0.01). The predator had a type II functional response showing an increase in the number of prey killed with an increase in the prey population density. Prey consumption stabilized at approximately 45 R. indica eggs/day, which corresponded to a maximum fecundity of (1.85 ± 0.09 egg/day; mean ± SE). Results of this study suggest that A. largoensis has the ability to reduce R.indica populations; however, results of the functional response study suggest that this predator could be especially efficient at regulating low R. indica population densities.