The developmental, survival, predation rates, and reproduction of Amblyseius swirskii (Phytoseiidae), as affected by feeding on the motile stages of Phyllocoptruta oleivora (Eriophyidae) and nymphs of Eutetranychus orientalis (Tetranychidae), were studied in the laboratory at six constant temperatures and relative humidities: 9°C and 70% RH; 16°C and 65% RH; 23°C and 60% RH; 30°C and 55% RH, 37°C and 50% RH and 40°C and 45% RH. The maximum daily consumption rate was recorded at 30°C and occurred during the oviposition period, when the females consumed an average of 169.40 specimens of P. oleivora and 24.58 of E. orientalis. The maximum reproduction rate (4.20, and 3.84 eggs/♀/day, on P. oleivora and E. orientalis, respectively) was recorded at 30°C and 50% RH, while the minimum one (1.20 and 0.86 eggs/♀/day, on P. oleivora and E. orientalis, respectively) was observed at 16°C and 65% RH. It is demonstrated in the life-table parameters that when the predatory mite A. swirskii is fed on P. oleivora, the highest reproduction rates (r_m = 0.144, 0.195, 0.280, and 0.181 females/female/day) are obtained, while feeding on E. orientalis gave the lowest reproduction rates (r_m = 0.121, 0.172, 0.204, and 0.141) at 16°C and 65% RH, 23°C and 60% RH, 30°C and 55% RH, and 37°C and 50% RH, respectively. The results suggest that A. swirskii is a promising control agent for P. oleivora and E. orientalis on orange trees.

Studies on the life history and life table parameters of Neoseiulus cucumeris Oudemans (Acari: Phytoseiidae) were carried out under laboratory conditions of 25 ± 1 °C and 65 ± 5% RH; 30 ± 1 °C and 60 ± 5% RH; 35 ± 1 °C and 55 ± 5% RH. As prey, immature stages of tetranychid spider mite T. urticae Koch (Acari: Tetranychidae) and the moving stages of the Tomato Russet Mite A. lycopersici (Massee) (Acari: Eriophyideae) were selected. The predatory phytoseiid mite, Neoseiulus cucumeris (Oudemans) was able to develop successfully from egg to adult stage through the entire life history on both preys. The higher of different temperatures and relative humidities shortened the development and increased reproduction and prey consumption and vice versa. The maximum reproduction (3.91, and 3.09 eggs/♀/day) was recorded at 35 °C and 65% RH, while the minimum (2.12, and 1.90 eggs/♀/day) was at 25 ± 1 °C and 55 ± 5% RH. when N. cucumeris fed on A. lycopersici and T. urticae, respectively. The reproductive rate on eriophyid was significantly higher than previously recorded on tetranychid. Life table parameters indicated that feeding of phytoseiid mite N. cucumeris on tomato russet mite A. lycopersici led to the highest reproduction rate (rm = 0.268, 0.232 and 0.211 females/female/day), while feeding on T.urticae gave the lowest reproduction rate (rm = 0.159, 0.143 and 0.131) at 35 °C and 55% RH, 30 °C and 60% RH and 25 °C and 65% RH, respectively. The population of N. cucumeris multiplied (36.81, 28.71 and 20.47) and (24.60, 19.58 and 14.62 times) in a generation time of (20.10, 23.20 and 25.14) and (22.35, 25.36 and 27.79 days) when a predator fed on A. lycopersici and T. urticae at the same temperature above mentioned, respectively. These results suggest that the two mites, particularly A. lycopersici, proved to be suitable prey for N.cucumeris, as a facultative predator.

Use of acaricides has become a common practice to control pests all over the world including Saudi Arabia. In spite of killing the targeted pests, such insecticides also effect growth of predatory mites. Present study has been conducted to evaluate the impact of two acaricides, abamectin and hexythiazox, on seven species of predatory mites. Standard solutions of abamectin (8.4% w/v) and hexythiazox (10% w/w) were purchased and prepared for direct spray. Acaricides were tested at three serial concentrations of recommended dose (RD), half of the recommended dose (HRD) and double the recommended dose (DRD). Trials were made on eggs, nymphs and adults of the seven species of predatory mites under laboratory conditions. Effect of the applied acaricides was determined one week after the application. The results of the study revealed that all doses of hexythiazox and abamectin are toxic to the nymphs and adults of all seven species of predatory mites but to the variable extent. Furthermore, it was observed that hexythiazox and abamectin reduced the percentage of egg hatching for all seven species of predatory mites. Hexythiazox was found to be more toxic than abamectin to all seven predatory mites. Higher mortality was recorded at DRD and RD, while minimum mortality was recorded at HRD. Acaricidal effect is less severe on hatching eggs than on immatures and adults of the predatory mites. Species vary in susceptibility to acaricides and in some populations resistance has been observed. Based upon this study, it is recommended that the frequent use of acaricides against phytophagous mites should be avoided and feasibility of biological control programs should be promoted to protect the environment, health of living individuals and the non-target organisms.

The date palm mite, Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae), is a serious pest of dates in the Middle East and North Africa, inflicting severe economic damage if not controlled early. As predaceous mites are known to be potential biocontrol agents against several pests, so predation capacity, life table, reproduction, and survival of Amblyseius swirskii Athias-Henriot and Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), collected from date palm farms in Qassim Saudi Arabia, were studied under laboratory conditions (25 °C, 30 °C, 35 °C and 50 ± 5% RH) against all motile stages of O. afrasiaticus. For both predators, mean developmental time, oviposition period, and longevity were inversely related to temperature from 25 to 35 °C. Various parameters were studied for A. swirskii and N. cucumeris at 25 °C, 30 °C and 35 °C, i.e. the female developmental time, 9.37, 7.29, 5.56, and 10.67, 8.38, 6.45 d; oviposition period, 19.77, 16.18, 13.94 and 15.90, 13.84, 10.64 d; longevity, 29.39, 24.79, 20.64 and 25.42, 21.94, 17.39 d; fecundity, 31.91, 37.10, 42.16 and 21.75, 26.84, 30.56 eggs per female, respectively. The maximum daily predation rate for both the predators was recorded at 35 °C during the oviposition period. The total predation of A. swirskii and N. cucumeris female was 370.86, 387.54, 405.83, 232.14, 263.32, 248.85 preys at 25 °C, 30 °C and 35 °C respectively. The maximum reproduction rate of A. swirskii and N. cucumeris (3.02, 2.87 eggs/♀/day) was recorded at 35 °C while the minimum (2.00, 1.36 eggs/♀/day) was recorded at 25 °C. The life table parameters were estimated as net reproductive rate (R_o) 21.68, 25.94, 29.52 and 18.95, 20.25, 22.78; the mean generation time (T) 24.92, 21.82, 18.24 and 26.30, 23.60, 20.56 d; the intrinsic rate of increase (r_m) 0.181, 0.232, 0.248 and 0.170, 0.185, 0.196; the finite rate of increase (λ) 1.365, 1.551, 1.706 and 1.126, 1.324, 1.428 for A. swirskii and N. cucumeris at 25 °C, 30 °C and 35 °C respectively. The results of this study suggested that the two phytoseiid species are promising biological control agents of O. afrasiaticus at a wide range of temperatures.

The predacious mite \ud Typhlodromips swirskii\ud (Athias-Henriot) completed its life-span when fed on the motile stages of the mango bud mite \ud Aceria mangiferae\ud Sayed, the mango rust mite \ud Metaculus mangiferae\ud (Attiah), the leaf coating mite \ud Cisaberoptus kenyae\ud Keifer and nymphs of mango red mite \ud Oligonychus mangiferus\ud (Rahman and Sabra) in the laboratory at different temperatures and relative humidities. The increase of different temperatures and decrease relative humidities from 25°C and 60% to 30°C and 55% and 35°C and 50% shortened development and increased reproduction and prey consumption. Life table parameters indicated that feeding \ud T. swirskii\ud on \ud A. mangiferae\ud led to the highest reproduction rate (rm = 0.216 females/female/day), while feeding on \ud O. mangiferus\ud gave the lowest reproduction rate (rm= 0.183) at 35°C and 50% R. H. Different prey species of eriophyid mango mites, especially \ud A. mangiferae\ud , have a high nutritional value for \ud T. swirskii\ud , as a facultative predator, than the tetranychid mango mite

Promising bioactivities of silver nanoparticles SNP urged researchers of different specialties to evaluate their field-respective activities. Bioactivity towards agricultural pests were the subject of limited publications. In the current study, SNP were synthesized and miticidal activity was evaluated towards old world date mite Oligonychus afrasiaticus (McGregor) (Acari: Tetranychidae) and an associated predatory mite Neoseiulus barkeri Hughes (Phytoseiidae). Under laboratory conditions, SNP displayed significantly higher activity towards O. afrasiaticus (LC₅₀ was 39.7 µg/mL) than N. barkeri (LC₅₀ was 1587.9 µg/mL) which accounts for about 40 folds of selectivity against the pest. SNP exhibited ovicidal activity against laid eggs of O. afrasiaticus (LC₅₀ was 67.8 µg/mL). In field, SNP (at 216 µg/mL) achieved slightly higher efficiency than in laboratory study, 86.5% of population reduction of O. afrasiaticus was achieved and only 18.5% of N. barkeri population was affected. SNP suppressed hatching of 57.1% of laid eggs of O. afrasiaticus. Residues of silver were determined using ICP-OES spectrometry. Initial residues reached 1.83 µg/mL after application then declined with time passing. Estimated daily intake (EDI) reached 1.28 µg/kg/day, calculated for the highest residues obtained and the highest consumption rate of date in the world. Hazard index (Hi) was 0.17 in average. The obtained level of residues appeared to be safe in terms of acute and chronic toxicity references.