Predation by Euseius scutalis (Acari: Phytoseiidae) on Tetranychus urticae and Eutetranychus orientalis (Acari: Tetranychidae): effect of prey density and developmental stage

Predation ability is a key component determining the suppression of agricultural pests by natural enemies. The aim of this study is to evaluate the effect of prey density and developmental stage on the predation of Euseius scutalis (Acari: Phytoseiidae) on the two-spotted spider mite, Tetranychus urticae (Acari: Tetranychidae) and the oriental red mite, Eutetranychus orientalis (Acari: Tetranychidae). For this purpose, laboratory functional response experiments were conducted using female adults of E. scutalis. Results indicated that the predator causes an inverse density dependent mortality to larvae, nymphs and adults of the two-spotted spider mite, as well as the oriental red mite. The random predator equation was used to fit the data. E. scutalis handling time increased significantly with T. urticae and E. orientalis developmental stage. The maximum number of T. urticae prey consumed was 48.3 larvae, 28.5 nymphs and 11.0 adults, where the corresponding values for E. orientalis were 48.8, 32.2 and 18.2 larvae, nymphs and adults, respectively. Estimated handling times and attack rates of E. scutalis on larvae, nymphs and adults of T. urticae were 0.4970 h and 0.1058 h-1, 0.8435 h and 0.1395 h-1, and 2.1834 h and 0.0835 h-1, respectively. The corresponding values on larvae, nymphs and adults of E. orientalis were 0.4920 h and 0.1166 h-1, 0.7452 h and 0.1361 h-1, and 1.3186 h and 0.0597 h-1, respectively. The results of this study may be indicative of the predation ability of adults of E. scutalis on these notorious pests, providing a basis for determining release rates appropriate for various pest densities.

Amblyseius swirskii Athias-Henriot ve Euseius scutalis Athias-Henriot (Acari:Phytoseiidae)’e Tau-Fluvalinatin Etkisi

Amblyseius swirskii Athias-Henriot (Acari:Phytoseiidae) and Euseius scutalis Athias-Henriot (Acari: Phytoseiidae) are important predatory mites for citrus orchards in Turkey. The side effects of insecticides on these predatory mites have been rarely studied. In this study was investigated to the effect of tau-fluvalinate on A. swirskii and E. scutalis. The studies have conducted both laboratory and field. Field studies were carried out detecting of the side effects of tau-fluvalinate on the mixed stages of A.swirskii. and E scutalis. at Seyhan and Kozan districts in Adana, while laboratory studies were evaluated the side effects of tau-fluvalinate on the nymph stages of A. swirskii The studies were carried out following the standard guidelines which were adopted and issued by the IOBC-WPRS Working group ‘Pesticedes and Benefical Organism’. In the field studies, the effects of the pesticides were calculated according to the Henderson-Tilton formula. As a result of study, tau-fluvalinate was determined as toxic on predatory mites in the laboratory studies. Side effects of abamectin, one of the standard toxic acaricides, on predatory mites were found to be “T” (Toxic) according to IOBC class value. Side effects of tau-fluvalinate were found to be ’M’’ (Moderately Harmful) on 7th days while were detected to be “N” (Harmless) on 28th days according to IOBC class value in field condition. The fields studies at Kozan and Seyhan districts showed similar results.