Foraging behaviors of <i>Amblyseius swirskii</i> Athias-Henriot and <i>Euseius scutalis</i> (Athias-Henriot) (Acari: Phytoseiidae) feed on the invasive pest, <i>Eutetranychus orientalis</i> (Klein) (Acari: Tetranychidae)

BackgroundRecent population outbreaks of citrus brown mite, Eutetranychus orientalis (Klein) (Acari: Tetranychidae), were observed in the cukurova region, a region that supplies approximately 80% of total citrus production in Turkey. Therefore, to obtain preliminary data, regarding biological control of this pest, functional and numerical responses of two commonly found predatory mites, Amblyseius swirskii Athias-Henriot and Euseius scutalis (Athias-Henriot) (Phytoseiidae) in citrus orchards, to egg and protonymph stages of E. orientalis were determined under laboratory conditions.ResultsIn the experiments, six different prey densities (1, 5, 10, 20, 40 and 80) for each selected biological stage of the prey were provided to the predatory mite for 24 h. According to results, the proportion of prey consumed by A. swirskii decreased with increasing egg and protonymph stages of the prey densities. Similarly, the proportion of protonymph consumption of E. scutalis decreased with increasing prey densities, but egg consumption of the predator showed no discernible response to increasing densities. A. swirskii exhibited a type II functional response in both prey stages, whereas E. scutalis showed a type II response only for the protonymph stage of the prey. The attack rate (alpha) and the handling time (Th) varied between the biological stages and also predatory mite species. The highest alpha (0.066 h(-1)) and the lowest Th (0.536 h) values were determined when the A. swirskii was fed on protonymph stage of E. orientalis. The numerical response curves were found to be similar to those of Type II functional response. The efficiency of conversion of ingested food (ECI) of the both predatory mite species females decreased on both tested stages when prey density increased. The highest and the lowest average daily mean number of eggs laid by E. scutalis was found as 0.20 and 1.40 when it fed on eggs and protonymphs of its prey, respectively.ConclusionBoth predatory mite species were evaluated as potential and promising biological control agents in the sustainable control of E. orientalis in citrus orchards.