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Parameters that describe foraging behavior play a key role in selection of natural enemies used in biological control programs. These parameters are greatly affected by patch condition and food source type. This study was carried out to evaluate foraging behavior in Neoseiulus barkeri (Hughes) (Acari: Phytoseiidae), a predatory mite of Tetranychus urticae Koch under different patch and diet conditions. The predation rate of N. barkeri at different egg and nymph densities of T. urticae (2, 4, 8, 16, 32, 64, 128) was investigated in both limited and unlimited patches either in the presence or absence of pollen as an additional food source under laboratory conditions. A Type II functional response was determined for N. barkeri on eggs or nymphs of T. urticae in both unlimited and limited patches. The type of functional response was not affected by presence or absence of pollen. The numerical response, in terms of eggs laid, increased curvilinear with increasing prey density. The numerical response was similar in shape to a Type II functional response. The efficiency of conversion of ingested food (ECI) of female N. barkeri decreased in all treatments when prey density increased. The type of patch (limited or unlimited) and prey stage (egg or nymph in the presence or absence of pollen) can affect searching efficiency (a) and handling time (Th) (functional response) as well as daily fecundity and ECI (numerical response) of the phytoseiid predator mite, N. barkeri with implications for its use in biological control.

Knowledge of the impact of acaricides on predatory mites is crucial for integrated pest management (IPM) programs. The sublethal effect of propargite was assessed against the subsequent generation of treated Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) fed on Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions [26 ± 1 ̊C, 70 ± 3 % RH and 16:8 (L:D) h]. A leaf disc bioassay was employed to assess the sublethal concentrations (LC10, LC20, and LC30) of propargite (Omite® 57% EC, MAHAN, Iran) on A. swirskii. The results revealed that sublethal concentrations of propargite significantly affected the total life span and longevity of the treated females of A. swirskii. Reproductive and total fecundity of the subsequent generation were also affected by sublethal concentrations. All concentrations caused a significant reduction in oviposition days, compared to the control. The intrinsic rates of increase (r) of A. swirskii treated with sublethal concentrations of propargite and distilled water were 0.126, 0.122, 0.115, and 0.129 d-1, respectively. Our findings revealed that propargite had no significant effect on life table parameters of treated mites in comparison to the control. Sublethal effects of propargite and its impact on A. swirskii are discussed.

Better performance of generalist predators, as well as an increase in their density, may be an incentive factor in the ability of the predators to exploit more than one food item or mixed diets. In this study, the effects of four pollen grains (cedar, pear, apricot, and pistachio) when provided to Neoseiulus californicus in mixed diets with prey, Tetranychus urticae, were evaluated. The result indicated that the fastest female developmental time was observed on pistachio pollen + T. urticae, together with apricot pollen + T. urticae. Females reared on the mixed diet comprising pistachio pollen reflected the longest total life span duration, while the shortest total life span was observed in those on the diet that included pear pollen. Furthermore, the lowest fecundity, as well as the shortest reproduction period, was determined on the diets that included pear pollen, while the highest fecundity and the longest reproduction period were observed in pistachio pollen + T. urticae. In addition, the intrinsic (r) and finite rate of increase (λ), net (R0) and gross (GRR) reproductive rates were highest in pistachio pollen + T. urticae. These findings have important implications for developing a comprehensive biological control program of T. urticae, which will be discussed.

Knowledge of the effects of pesticides on biological control agents is necessary for the successful implementation of integrated pest management programs. Laboratory bioassays were conducted to evaluate the effects of Biomite®, a natural acaricide, on the life table parameters of Neoseiulus californicus McGregor (Acari: Phytoseiidae), as one of the most important natural enemies of Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions at 25 ± 2°C, 65 ± 5% RH and a photoperiod of 16:8 (L:D) h. The raw data were analyzed based on the two-sex life table theory. Biomite® concentrations LC10 and LC20 gradually and significantly reduced the longevity and total life span of both sexes, as well as total fecundity. Besides, concentration LC20 significantly reduced the gross reproductive rate (GRR) and the net reproductive rate (R0). However, the intrinsic rate of increase (r) and the finite rate of increase (λ) were not significantly affected. Thereby, due to an unfavorable shortened in life history characters of N. californicus such as total life span, reproductive periods and biological parameters (such as R0 and GRR), as a consequence of Biomite® treatment, it can be concluded that this acaricide should not be used with N. californicus in integrated pest management programs.

The present study first evaluated the sublethal effects of diflovidazin (Flumite®) with three concentrations (LC5, LC10, and LC20) on life table parameters of Neoseiulus californicus (McGregor...

Amblyseius swirskii Athias-Henriot is a well-known predator that is used for controlling the population of two-spotted spider mites (TSSM), Tetranychus urticae Koch, and greenhouse whitefly (GHWF), Trialeurodes vaporariorum Westwood, in strawberry greenhouses. To find the effective factors that influence the efficiency of this predator, the predation rates of A. swirskii fed on (Ι) TSSM in the presence and absence of the pollen, webbing, and GHWF, as well as on (II) GHWF in the presence and absence of the pollen, and GHWF-produced honeydew were determined. Furthermore, developmental time, fecundity, and population growth rate of this predator under the same conditions were measured. Our results showed that A. swirskii was able to reduce TSSM population, while the spider mite webbing had an adverse effect on the performance of the predator. Therefore, the presence of the predator population at the time of the infestation is crucial to the success of biological control. It can be concluded that the alternative food sources such as pollen and GHWF-produced honeydew play an important role in maintaining the predator population in the absence of pests. Moreover, the results indicate that using the pollen and another pest along with the target pest can promote the predator density. A. swirskii consumed lower numbers of TSSM when concurrently offered with GHWF and/or maize pollen, and lower numbers of GHWF in the presence of pollen. On the other hand, in the presence of alternative food or alternative prey, the fecundity of the predator was much higher.

Alternative foods such as pollen may help predators to maintain their populations even when their prey is scarce or absent. In order to develop an appropriate spider mite management strategy using Neoseiulus californicus McGregor and optimize laboratory rearing, its biological parameters on four types of pollen (cedar, pistachio, pear, and apricot) were determined and compared on Tetranychus urticae Koch. Our results indicated that the developmental times of females and males varied from 6.06 to 7.32, and 6.00 to 7.15 d, respectively. The highest fecundity was obtained on pistachio pollen, followed by apricot pollen and T. urticae. Feeding on cedar pollen caused the lowest fecundity. In contrast to T. urticae and pistachio pollen, which resulted in the highest intrinsic and finite rates of increase, feeding on cedar pollen produced the lowest value. Pistachio and apricot pollen appear to have the highest nutritional value. From an ecological perspective, in the presence of pistachio pollen, a more rapid population increase of N. californicus could be expected, when the prey is scarce or absent in greenhouses or fields. This may provide valuable information for the design of a comprehensive program for conservation and/or mass production of N. californicus to control T. urticae and other pests.

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is a serious pest of many agricultural crops. Using chemical pesticides is one of the main methods for its management. I...

Predation rate is basic to any investigation of prey–predator interaction. The predation rate of Phytoseiulus persimilis Athias-Henriot and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) fed on the two-spotted spider mite (TSSM), Tetranychus urticae Koch, reared on the susceptible (Yellow) and resistant (Roulette) rose cultivars was determined under laboratory conditions at 25 ± 1°C, 60 ± 5% RH and a photoperiod of 16:8 (L:D) h. The value of total prey consumption in different life stages of both predators was higher on TSSM reared on the resistant rose cultivar than those on the susceptible one. In addition, the value of total prey consumption in different life stages of P. persimilis was higher than A. swirskii on both susceptible and resistant rose cultivars. The net predation rate (C0) of both predators on TSSM reared on the resistant rose cultivar was higher than those on the susceptible one. The stable predation rate (ψ) on the susceptible and resistant rose cultivars was 2.50 and ...

The predatory mite Amblyseius swirskii Athias-Henriot (Acari, Mesostigmata: Phytoseiidae) has been used to control greenhouse pests including thrips, whiteflies and the two-spotted spider mite (TSSM), Tetranychus urticae Koch (Acari, Trombidiformes: Tetranychidae). This study evaluated A. swirskii’s potential to control TSSM by determining the functional response, numerical response, mutual interference, and prey switching behavior of the predator in the presence or absence of pollen under laboratory conditions. Type II and III functional responses were determined for A. swirskii fed on TSSM in the absence or presence of pollen, respectively. The highest predation rate and searching efficiency (a) was observed on eggs of TSSM compared with nymphs in all experiments. The numerical response of the predator showed a rapid and significant increase in oviposition with increasing TSSM density (both eggs and nymphs) but the rate gradually declined at higher densities of TSSM in both the presence and absence of pollen. The efficiency of conversion of ingested food (ECI) was highest at low prey density, and decreased at higher prey densities. The per capita searching efficiency of the predator also decreased significantly with increasing predator density. The interference coefficient for A. swirskii in the presence of pollen was less than that in the absence of pollen. Switching behavior was observed in A. swirskii in which the predator switched from one life stage of TSSM when it became rare to another, more abundant stage. The results of this study revealed high performance of A. swirskii on TSSM and the importance of pollen in its efficiency.

The effect of 12 greenhouse cucumber cultivars (Royal, Amitral, Ariya, Sultan, Vida, Bahman, Storm, Nasim, Negin, PS-29, Tornado and Caspian) on life history and demographic parameters of the two-spotted spider mite (TSSM) (Tetranychus urticae Koch) was determined under laboratory conditions at 25 ± 1oC, 60 ± 5% RH and a photoperiod of 16:8 (L:8) hours using age-stage, two-sex life table procedure. The longest development time was 8.28 ± 0.09 days on Caspian and the shortest period was obtained on Vida and PS-29 (5.45 ± 0.12 and 5.54 ± 0.07 days, respectively). The TSSM fecundity varied from 64.83 ± 5.33 to 98.38 ± 5.65 eggs per female, which was minimum on Negin and maximum on Amitral. The shortest female longevity was observed on Negin (16.08 ± 1.15 days) and the longest on Amitral (26.82 ± 1.36 days). The net reproductive rate (R0) varied from 42.30 ± 4.90 on Negin to 75.72 ± 6.64 eggs per individual on Amitral. The lowest value of the intrinsic rate of increase (r) and finite rate of increase ...

Knowledge of the impact of acaricides on predatory mites is crucial for integrated pest management programs. The present study evaluated the sublethal effect of fenazaquin (Pride® 20 % SC, Behavar, Iran) on life table parameters of the subsequent generation of the predatory mite, Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae), fed on Tetranychus urticae Koch under laboratory conditions [26 ± 1 °C, 70 ± 3 % RH and 16:8 (L:D) h]. The sublethal concentrations including LC10, LC20 and LC30 were determined using a dose–effect assay. The total development time of both sexes enhanced with an increase in concentration. The oviposition period and total fecundity decreased in dose-dependent manner. The intrinsic rate of increase (r) and finite rate of increase (λ) significantly descended with concentration enhancing from LC10 to LC30, compared with the control. The net reproductive rate (R 0) ranged between 2.76 and 7.37 offspring. Overall, the results indicated that fenazaquin had negative effects on development and life table parameters of the subsequent generation of A. swirskii. In conclusion, fenazaquin is not a compatible acaricide with A. swirskii and should not be used with this predatory mite in integrated management of T. urticae.

This study was carried out on the ability of predatory thrips Scolothrips longicornis Priesner to feed on 2 phytoseiid species and vice versa. Also the effect of predation of Neoseiulus californicus (McGregor) on Typhlodromus bagdasarjani Wainstein and Arutunjan and vice versa was evaluated. The larvae, prepupae, and pupae of thrips and the eggs, larvae, and protonymphs of phytoseiids were selected as intraguild prey. The intraguild predation (IGP) among S. longicornis and 2 phytoseiid species was unidirectional and in favor of phytoseiids, i.e., S. longicornis was not able to feed on larval stages of 2 phytoseiids. However, N. californicus and T. bagdasarjani fed on the 1st instar larvae (1.39 and 0.80 per day), 2nd instar larvae (0.87 and 0.55 per day), prepupae (0.51 and 0.48 per day), and pupae of thrips (0.51 and 0.49 per day, respectively). Both phytoseiids fed on eggs, larvae, and protonymphal stages of each other. Females of N. californicus consumed more phytoseiid larvae (2.49 per day) than T. bagdasarjani, which consumed 1.08 N. californicus larvae per day. When Tetranychus urticae was presented as an extraguild prey, intensity of IGP between 2 species of phytoseiids and on larval stages of S. longicornis reduced significantly. Therefore, it is concluded that (i) IGP existed among the 3 examined species and lack of feeding of S. longicornis on 2 phytoseiid species can be justified by its feeding type (monophagy), (ii) N. californicus was much more prone to IGP than was T. bagdasarjani.

Tritrophic interactions can provide important insights for improving the efficacy of pest control programs. We studied three cucumber, Cucumis sativus, cultivars for their effects on the life table and predation parameters of the predatory mite, Phytoseiulus persimilis Athias–Henriot, when feeding on eggs and nymphs of the two-spotted spider mite (TSSM), Tetranychus urticae Koch. These cultivars were TSSM-susceptible (cv. Vida), semi-resistant (cv. Sultan), and resistant (cv. Caspian). Under laboratory conditions, the intrinsic rate of increase (r) and net reproductive rate (R0) of P. persimilis was significantly higher on the susceptible cultivar than on the resistant ones. In contrast, the age-stage-specific predation rate (cxj), net predation rate (c0) and finite predation rate on the resistant cultivar were all higher than on the semi-resistant or susceptible ones. Although the susceptible cultivar produced the most favorable life table parameters for P. persimilis, the resistant cultivar supported more P. persimilis individuals and had higher levels of predation on TSSM. Resistant cultivars in combination with P. persimilis can improve control of TSSM on cucumber, despite some negative life history impacts on the predator.

The life table parameters of the two-spotted spider mite (TSSM), Tetranychus urticae Koch, were determined on seven eggplant cultivars (“Isfahan”, “Dezful”, “Shend-Abad”, “Neishabour”, “Bandar-Abbas”, “Jahrom” and “Borazjan”) at 25 ± 1°C, 60 ± 5% RH and a photoperiod of 16:8 (L:D) h. The age-stage, two-sex life table and the traditional female age-specific life table were constructed by using demographic data. There was a significant difference between the duration of different life stages of TSSM on different eggplant cultivars. Using the age-stage, two-sex life table, the intrinsic rate of increase (r) on the above-mentioned cultivars varied from 0.022 day−1 on “Neishabour” to 0.157 day−1 on “Isfahan”. The value of the net reproductive rate (R0) of TSSM on different eggplant cultivars varied from 1.425 offspring on “Neishabour” to 11.585 offspring on “Isfahan”. Furthermore, the values of the gross reproductive rate (GRR) were significantly different on the tested cultivars, and the lowest and highest va...

International audience; The lifetime-dependent functional response and predation rate of Phytoseiulus persimilis Athias-Henriot on eggs of the two-spotted spider mite, Tetranychus urticae Koch was determined under laboratory conditions using cucumber leaf discs. Densities of 2, 4, 8, 16, 32, 64 and 128 prey were offered to 4 (protonymph), 5 (deutonymph), 6 (1-day-old adult), 10 (5-day-old adult), 15 (10-day-old adult), 20 (15-day-old adult), 25 (20-day-old adult), 30 (25-day-old adult), 35 (30-day-old adult) and 40 (35-day-old adult) P. persimilis individuals. The results of logistic regression analyses showed that on the 15th, 35th and 40th days of predator age, predation rate of T. urticae eggs increased, resulting in the type III functional response, while at the other ages, the functional response was type II. The Rogers model was used to estimate searching efficiency (a) and handling time (Th). The longest handling time was obtained in the protonymphal stage with 2.377 +/- 0.192 h. The shortest handling time and the highest value of estimated maximum attack rate (T/Th) were estimated at the age of 20 days (0.494 +/- 0.009 h and 48.57prey/day). At the highest prey density used (128 eggs), our findings showed that the highest number of prey was eaten by 15, 20, 25 and 30 days old P. persimilis (39.3, 41.7, 39.3 and 38.1 eggs per day, respectively). The results of this study revealed that P. persimilis especially at the middle and late ages has a good predation potential on T. urticae eggs at higher prey densities.

The two-spotted spider mite, Tetranychus urticae Koch, is one of the most economically important pests on a wide range of crops over the world. This study was carried out to evaluate the efficacies of two predatory mite species, Neoseiulus californicus (McGregor), an introduced species in Iran, and Typhlodromus bagdasarjani Wainstein & Arutunjan, a native species, as biocontrol agents of Te. urticae. The functional response and mutual interference of these two phytoseiid mites were determined under laboratory conditions at 25°C, 65% RH and a photoperiod of 16 h light:8 h dark. The functional response of the two predator species to eggs or nymphs of Te. urticae was type II. The highest attack rate (0.0936 h–1) and the lowest handling time (1.6451 h) were recorded for N. californicus on eggs and the lowest attack rate (0.0473 h–1) and the highest handling time (2.399 h) were estimated for T. bagdasarjani on nymphs of Te. urticae. Nicholson's model and linear regression were used to determine the per capita ...

The life table parameters of Phytoseius plumifer Canestrini & Fanzago fed on corn pollen and nymphal stages of Tetranychus urticae Koch were determined at eight constant temperatures (10, 15, 20, 25, 27, 30, 35 and 40 ± 1°C), 50 ± 5% relative humidity and a photoperiod of 16:8 h (L:D). Fifty 1-day-old eggs of P. plumifer were kept individually in a growth chamber at each temperature and all events were recorded daily for all immature and adult stages. Adult female longevity decreased from 73.42 days at 15°C to 34.73 days at 35°C. The net reproductive rate (R 0) increased with increasing temperature from 15°C (8.70 females/female) to 27°C (29.6 females/female) and then decreased noticeably. The values of the intrinsic rate of increase (rm ) and finite rate of increase (λ) were recorded to be highest at 30°C (0.257 day–1 and 1.29 day–1, respectively), which decreased at 35°C (0.244 day–1 and 1.28 day–1, respectively). The mean generation time (T) decreased significantly with increasing temperature from 15°C...

Typhlodromus bagdasarjani Wainstein and Arutunjan (Acari: Phytoseiidae) is a generalist predator frequently reported in plants infested by phytophagous mites or insects. In this study, we determined the daily and total prey consumption of different life stages of Ty. bagdasarjani on Tetranychus urticae Koch nymphs at constant temperatures of 15, 20, 25, 30 and 35°C, relative humidity of 60 ± 10% and a photoperiod of 16: 8 h (light : dark). The results showed a significant effect of temperature on food consumption by Ty. bagdasarjani. The number of prey consumed daily by protonymphs increased with increasing temperature from 15 (0.8 preys) to 25°C (3.5 preys), and then decreased at 30 (2.8 preys) and 35°C (3.1 preys). The daily predation of the other life stages of Ty. bagdasarjani followed a similar trend as that which occurred in protonymphs, with the exception of post-oviposition period, in which the highest values for the mean prey consumption were observed at 30°C (6.6 preys/day). The highest...

The effect of seven constant temperatures of 15, 20, 25, 27, 30, 35 and 37°C on developmental time of Neoseiulus barkeri Hughes were determined in laboratory conditions under 65%± 5% RH and a photoperiod of 12 : 12 (L : D) h on nymphal stages of Tetranychus urticae Koch. Total developmental time of females (from egg to adult emergence) at the above-mentioned temperatures was 26.59, 14.43, 6.32, 5.64, 4.59, 3.98 and 4.67 days, respectively. Developmental rate of the N. barkeri increased as temperature increased from 15 to 35°C, but declined at 37°C. A linear and two nonlinear models were fitted to developmental rate of immature stages of N. barkeri to predict the developmental rate as a function of temperature, as well as to estimate the thermal constant (K) and critical temperatures (i.e., Tmin, Topt and Tmax). The estimated values of the Tmin and K for total developmental time using the linear model were 12.07°C and 86.20 degree-days (DD), respectively. The Tmin and Tmax estimated by the Sharpe-Schoolfield-Ikemoto (SSI) model were 11.90°C and 37.41°C, respectively. The estimated Topt for overall immature stage development of N. barkeri by the Lactin and SSI models were 33.89°C and 24.51°C, respectively. Based on the biological criteria of model evaluation, the linear and SSI models were found to be the best models for describing the developmental rate of overall immature stages of N. barkeri and estimating the temperature thresholds.

Coccinella septempunctata Linnaeus, 1758 (Coleoptera: Coccinellidae) is an aphidophagous ladybird beetle species with cosmopolitan distribution. However, it may also thrive on arthropods other than aphids, when the latter are not readily available. Certain life history traits and demographic attributes of C. septempunctata were determined using seven different diets with different alternations and proportions of an aphid, Lipaphis erysimi (Kaltenbach,1843) and a mite, Tetranychus urticae Koch, 1836, in the laboratory (at 25±0.5°C, 65±5% RH and a photoperiod of 16 h L:8 h D).The larval duration was longest (12.61±6.17 days) when fed an alternating diet of two days aphid/two days mite. Adult longevity was longest (78.65±1.09 days) when fed aphids only and shortest (3.17±1.25 days) when fed mites only. Life expectancy (ex) was highest (111 days) when adults were fed only aphids and lowest (11.3 days) when fed only mites. Survival rates of ladybird beetles were positively related to an increasing rat...

The life table parameters of two-spotted spider mite (TSSM), Tetranychus urticae Koch, on 14 soybean genotypes (Sari, Sahar, Tellar, Zane, Ks3494, L17, Dpx, 032, 033, Clark, Hill, I27, Tms and Williams) were evaluated at 28 ± 1°C, 65%± 5% RH and a photoperiod of 16 : 8 h L : D. The survivorship data (lx) of adult females were fitted to the Weibull frequency distribution model in all genotypes tested. Based on the Weibull parameters, the survival curve was type I on all genotypes, which indicated that the mortality mostly occurred in old individuals. Furthermore, two mathematical models (Analytis and Enkegaard) were fitted to age-specific fecundity data (mx). The highest intrinsic rate of increase (rm) was recorded on L17 (0.392) and the lowest values of this parameter were obtained on Tms (0.233), Hill (0.236), 032 (0.236), I27 (0.237) and Clark (0.240). In addition, net reproductive rate (R0) and finite rate of increase (λ) of the TSSM had the highest value on L17 as 45.521 and 1.475, respectively. The lowest values of these parameters were recorded on Tms as 12.149 and 1.258, respectively. Doubling time (DT) varied significantly on different genotypes and the shortest and longest values of this period were obtained on L17 and 032, respectively. Our findings revealed that Tms, Hill, 032, I27 and Clark were less suitable genotypes, suggesting that they are more resistant to the TSSM than the other genotypes.

Bio-ecological parameters of the two-spotted spider mite (TSSM), Tetranychus urticae Koch and its predators depend on the quality of its host plants. In this study, the life table parameters of TSSM and its main predator Phytoseiulus persimilis Athias-Henriot during different generations (1st, 5th, and 10th generations) were determined on the susceptible (‘Beth-Alpha’) and resistant (‘HED’) greenhouse cucumber cultivars. The results indicated that the longest total development time of TSSM was allocated to the first generation on the susceptible cultivar, but there was no significant difference among different generations on the resistant cultivar. The total development time of the 1st and 10th generations of P. persimilis on each of the susceptible and resistant cultivars had not significant difference. Total fecundity of TSSM was higher in the 10th generation on both cultivars tested than that of the former generations. However, the total fecundity of the predator drastically reduced after long-term rearing (10 generations) on both cultivars. The intrinsic rate of increase (r) of the 1st, 5th, and 10th generations of TSSM on the susceptible cultivar was 0.178, 0.238 and 0.319 day-1, respectively, and 0.157, 0.166 and 0.168 day-1 on the resistant cultivar, respectively which indicates the significantly negative effect of the resistant cultivar on this parameter. In P. persimilis, the value of the intrinsic rate of increase in the first and tenth generations on the susceptible cultivar was 0.275 and 0.267 day-1, respectively, and on the resistant cultivar was 0.244 and 0.210 day-1, respectively. By understanding these interactions in the long term, we will be able to develop suitable strategies for biological control of TSSM on cucumber.

Notwithstanding the advantageous traits of Typhlodromus bagdasarjani Wainstein and Arutunjan to feed on alternative food such as pollen ensuring the long-term control of greenhouses pests, the nutritional ecology and the role of this predator in biological pest control are rarely addressed. In the current study, the predator’s development and reproduction on three food sources including Tetranychus urticae Koch, almond pollen, as well as T. urticae+ almond pollen; and the no food condition were evaluated. Additionally, all diets were tested on both artificial and leaf-based substrates to assess the potential host plant effects on the predator’s performance. Although all larvae on both rearing substrates successfully developed into protonymphal stage, they did not succeed to reach the next stage. Development of T. bagdasarjani was shorter, both female and male, on artificial substrate mainly feeding on almond pollen. Females feeding on almond pollen and almond pollen + T. urticae on artificial substrates had the highest intrinsic and finite rate of increase as well as oviposition rate. Consequently, almond pollen could be used as a conservation management tool to support the early buildup of pre-established natural populations of T. bagdasarjani in open field crops.

Knowledge of the lethal and sublethal effects of pesticides on biological control agents is necessary for successful implementation of integrated pest management programs. The sublethal effect of acaricide fenpyroximate (Ortus®) on performance of females and their offspring of Phytoseius plumifer (Canestrini & Fanzago), an efficient predator of Tetranychus urticae Koch, was determined under laboratory conditions. The adult predators were exposed to the residues of the acaricide on fig leaves and the LC50 value was determined based on a concentration–response analysis. The results showed that sublethal concentrations of fenpyroximate significantly affected the fecundity and longevity of the treated females of P. plumifer. Reproductive and life table parameters of the subsequent generation were also affected by sublethal concentrations. It could be concluded that sublethal concentrations can significantly reduce the population growth of P. plumifer and this should be considered in integrated pest management programs.

Environmental variables like temperature are important factors that affect the efficiency of biological control agents in greenhouse crops. This study examined the effect of temperature on the functional response of an acarophagous thrips Scolothrips longicornis Priesner to different densities of two spotted spider mite, Tetranychus urticae Koch in laboratory conditions. Five constant temperatures (15, 20, 26, 30, and 35 °C) and seven prey densities (2, 4, 8, 16, 32, 64, and 128) were used in the experiments. At each temperature, 2 to 128 adult of T. urticaue were exposed to a female S. longicornis for a 24 h period. The results indicated that the predatory thrips exhibited type II functional response to different densities of T. urticae at all examined temperatures. Temperature had significant effect on the predation capacity of the adult thrips over the range of 15–35 °C. Instantaneous attack rate (a) of the predator increased linearly with increasing temperature from 15 to 35 °C. At 35 °C, the highest instantaneous attack rate was estimated to be 0.0579 day− 1 using the Holling model and 0.1480 day− 1 using Rogers model. The estimated value of handling time (Th) using both Holling and Rogers models decreased linearly with increasing temperature from 15 to 35 °C. Scolothrips longicornis achieved higher predation at higher temperature (16.1 preys/day at 35 °C). This observation suggested that S. longicornis may be more effective for biological control of two spotted spider mite in warmer conditions.

Development of Stethorus gilvifrons (Mulsant), a predator of two spotted spider mite (Tetranychus urticae Koch), was studied under laboratory conditions at constant temperatures of 15, 20, 25, 28, 30, 35 and 40°C. No development occurred at 40°C. The total development time at temperatures tested was 56.47, 31.19, 18.53, 17.54, 12.49, and 9.27days, respectively, which indicated a significant decrease of development time with increasing temperature. Using the linear model, the estimated low temperature threshold for egg, larva, prepupa, pupa, and total immature stage of S. gilvifrons was 14.11, 10.86, 11.33, 17.04, and 12.47°C, respectively while the thermal constant for these stages was 36.36, 153.14, 11.63, 25.25, and 222.72 degree-days, respectively.

The influence of temperature on life-table parameters, fecundity and survivorship of the predatory ladybird, Stethorus gilvifrons, fed on Tetranychus urticae was determined at seven constant temperatures of 15� C, 20� C, 25� C, 28� C, 30� C, 35� C and 40� C. No development was observed at 40� C, thus being regarded as the threshold for the development of S. gilvifrons. The results indicate a significant decrease in male and female longevity with increasing temperature from 15� Ct o 35� C. The longest and shortest longevity were 18.40 and 12.75 days for males and 17.40 and 8.80 days for females, respectively. The intrinsic rate of natural increase (rm) and the net reproductive rate (R0 )o fS. gilvifrons linearly increased with increasing temperatures from 15� Ct o 35� C, while the mean generation time (T) and doubling time (DT) decreased linearly within this temperature range. The highest values of rm (0.240 females/ female/day) and R0 (59.27 females/female) and the lowest mean generation time (17.01 days) and DT (2.88 days) were recorded at 35� C. The maximum (185.50 eggs) and minimum (25.50 eggs) measurement of total fecundity was also recorded at 35� C and 15� C, respectively. The results indicate that temperature greatly affected fecundity, survivorship and life-table parameters of S. gilvifrons, and that 35� C is a suitable temperature for population growth of this predator. J. Appl. Entomol.

The interspecific competition is a widespread phenomenon among the herbivores and is an important factor in shaping the herbivore communities. Plants usually mediate competition among herbivores via induced resistance, which can affect pest density, either by altering the performance or host preference of herbivores. The strawberry plants host the two-spotted spider mites (TSSM), Tetranychus urticae Koch and greenhouse whitefly (GHWF), Trialeurodes vaporariorum (Westwood) in greenhouses. We clearly observed the adverse effect of TSSM or GHWF prevalence on colonization and outbreak of the other one, therefore the possibility exists that feeding-induced changes in plant and interspecific competition are the effective factors in shaping their densities. In this study, laboratory experiments were carried out to determine whether previous feeding by TSSM on strawberry (Camarosa variety) affects the performance and oviposition preference of GHWF (as a competitor), and vice versa. Lower egg number, and the slower development as well as delayed oviposition were observed when the pests fed on infested leaves than control leaves. Furthermore, when the pests were given the choice between the non-infested and infested leaves, both pests significantly preferred the non-infested leaves. Our study concluded that feeding-induced changes in quality of host plant adversely affected the performance and oviposition preference of both pests. We suggested that these results can help to explain the different population densities of pests in presence and absence of other species and can attract the attention of farmers to the effects of interspecific competition on the densities of pests.

Using the most suitable alternative diets that are easily available and less expensive than the natural diets may give rise to reduce the rearing costs of natural enemies. Alternative or additional food used for this purpose should be in accordance with the food spectrum of the respective mite species. To our knowledge no information is accessible on the comparison between natural diets and factitious prey for Amblyseius swirskii Athias-Henriot. Therefore, the objective of this study was to evaluate the nutritional value of three natural diets including almond pollen, maize pollen and Tetranychus urticae Koch, as well as four factitious prey comprising eggs of Ephestia kuehniella Zeller, Tyrophagus putrescentiae (Schrank), decapsulated and encapsulated cysts of Artemia franciscana Leach for A. swirskii. The data would seem to suggest that developmental time of individuals fed on pollens was shorter than that of those fed on factitious prey. The gross and net reproductive rate, intrinsic and finite rate of increase of the individuals consumed factitious prey were lower than those of mites fed on natural food diets, for the simple reason of shorter developmental time and higher oviposition rate of this predator on the latter. In conclusion, our results showed that natural foods were more favorable than factitious prey and among them almond pollen and maize pollen were the most suitable for A. swirskii, and thus it should be taken into account for application in its mass production, and supporting its population in greenhouse or field conditions when used in an augmentative approach.