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

AbstractBackgroundRecent population outbreaks of citrus brown mite,Eutetranychus orientalis(Klein) (Acari: Tetranychidae), were observed in the Çukurova 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 swirskiiAthias-Henriot andEuseius scutalis(Athias-Henriot) (Phytoseiidae) in citrus orchards, to egg and protonymph stages ofE. orientaliswere 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 byA.swirskiidecreased with increasing egg and protonymph stages of the prey densities. Similarly, the proportion of protonymph consumption ofE.scutalisdecreased with increasing prey densities, but egg consumption of the predator showed no discernible response to increasing densities.A. swirskiiexhibited a type II functional response in both prey stages, whereasE.scutalisshowed a type II response only for the protonymph stage of the prey. The attack rate (α) and the handling time (Th) varied between the biological stages and also predatory mite species. The highestα(0.066 h−1) and the lowestTh(0.536 h) values were determined when theA.swirskiiwas fed on protonymph stage ofE.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 byE.scutaliswas 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 ofE.orientalisin citrus orchards.