Tetranychus Turkestani Ugarov Research Articles

Demographic parameters of Tetranychus turkestani (Trombidiformes: Tetranychidae) on different cultivars of greenhouse cucumber

ABSTRACT Demographic parameters of Tetranychus turkestani Ugarov & Nikolskii, which is a serious pest of cucumber crop worldwide, were evaluated on nine cultivars of greenhouse cucumber (Cucumis sativus) (Royal, Negin, Radvin, Vihan, Arya, Sina, Piro, Karim, and Kurazh). The study was carried out under laboratory conditions at 25 ± 1°C, 60 ± 10% RH and 16:8 (L:D) h. The results of this study showed that the longest development time of T. turkestani was observed on the Piro cultivar (10.86 ± 0.46 days) and the shortest on the Radvin cultivar (8.57 ± 0.35 days). The female longevity on different cultivars varied from 18.57 ± 0.31 to 20.19 ± 0.35 days. Our results indicated differences in the population growth rate of T. turkestani on different cucumber cultivars. The net reproductive rate (R 0) varied from 22.32 ± 3.99 to 52.90 ± 6.12 eggs per individual, which was minimum on Piro and maximum on Radvin. The comparison of biological parameters of T. turkestani on different cucumber cultivars demonstrated that Radvin was the most susceptible and Piro was the most resistant cultivar to this pest. The findings of this research can be used to develop integrated management of T. turkestani by considering its performance on different cucumber cultivars.

Life history traits and population parameters of the predatory mite Euseius scutalis (Acari: Phytoseiidae) fed on Tetranychus turkestani (Acari: Tetranychidae) and pollen from three different plants

Development, reproduction, and demographic parameters of the predatory mite Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae) were determined in the laboratory at 25±1 °C, with a 16L:8D photoperiod and 60 ±5% RH, to evaluate its response to four different diets: Tetranychus turkestani Ugarov and Nikolskii (Acari: Tetranychidae), caster bean pollen, date palm pollen, and hopbush pollen. Male and female mites raised on T. turkestani had a shorter mean pre-adult duration than those grown on date palm, castor, and hopbush pollen. Pre-adult mortality was found to be greater in either the larval stage or protonymphal stage than other stages. The highest and lowest pre-adult mortality rates were recorded on castor bean pollen (31.87%) and T. turkestani (2.94%), respectively. The total pre-oviposition periods (TPOP) on hopbush and castor bean pollen were significantly longer than those on T. turkestani and date palm pollen. The highest egg production and oviposition period were determined when T. turkestani were provided as diet. Overall, the individuals lived considerably longer when provided with T. turkestani and hopbush pollen than the two other diets. The gross reproductive rate (GRR) and net reproductive rate (R<sub>0</sub>) on T. turkestani were greater than the values attained on other diets. The highest intrinsic (r) and finite rates of increase (λ) were found to be 0.2537 and 1.2888 on T. turkestani, respectively. However, R<sub>0</sub>, GRR, r, and λ were almost similar between all pollen diets tested. In general, all diets tested in this study were adequate for development and oviposition in E. scutalis, but T. turkestani was the most favorable diet.

Effects of different pollen diets in comparison to a natural prey, Tetranychus turkestani (Acari: Tetranychidae), on development, survival, and reproduction of Euseius scutalis (Acari: Phytoseiidae)

The development, survival, and reproduction of the predatory mite Euseius scutalis (Athias-Henriot) (Acari: Phytoseiidae) were studied under laboratory conditions (25 ±1 °C, 65 ± 5% RH, 16:8 (L: D) h) on strawberry spider mite, Tetranychus turkestani Ugarov and Nikolski (Acari: Tetranychidae), and four different pollen including date palm, cattail, golden shower tree and caper bush pollen. Our results showed that E. scutalis mites successfully developed into the adult stage and reproduced on natural prey and plant pollen tested. Diet type significantly affected the developmental time of immature stages of both females and males. Females reared on T. turkestani had a considerably shorter total developmental time than those raised on other diets. Date pollen and spider mites-fed females began laying eggs much earlier than other females. The lower number of laid eggs was recorded for the females raised on golden shower tree, followed by caper bush pollen. The net reproductive rate (R0) of the predators fed golden shower tree was significantly lower than those provided cattail pollen and T. turkestani. Intrinsic and finite rates of increase (r and λ, respectively) were highest in the females fed T. turkestani (0.3300 ± 0.018 and 1.3910 ± 0.0247, respectively) followed by cattail pollen (0.2721 ± 0.0178 and 1.3126 ± 0.0233, respectively). Based on the current findings, it can be concluded that rearing of E. scutalis on the immatures of T. turkestani was considerably better than on other diets with higher values of egg production and population growth rate under laboratory conditions. Furthermore, cattail pollen followed by date palm pollen are suitable alternative diet sources for easy and cost-effective rearing of E. scutalis in the laboratory.

Comparison of natural prey Tetranychus turkestani, date palm pollen, and bee pollen diets on development, reproduction, and life table parameters of the predator Amblyseius swirskii

The predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) is produced commercially for biological control of insects and mites on crop plants around the world. The aim of this study was to compare the effects of a diet of natural prey, Tetranychus turkestani Ugarov and Nikolskii (Acari: Tetranychidae), date palm pollen, or bee-collected pollen on A. swirskii development, reproduction, and life table parameters. Completely randomized, no-choice experiments were conducted in replicated experimental units, i.e., 3 x 3 cm plastic sheets inside Petri dishes. A life table analysis was also conducted. Results indicated that diet type did not affect A. swirskii preimaginal survival; it ranged from 97-100% on T. turkestani and both pollen diets. However, total development time was significantly shorter for A. swirskii females fed date palm pollen than T. turkestani or bee pollen. Adult females fed T. turkestani lived longer, had longer oviposition periods, and produced more eggs. The intrinsic rate of natural increase (0.396 d<sup>-1</sup>) was higher for A. swirskii fed date palm pollen than T. turkestani or bee pollen. The finite rate of increase, net reproductive rate, and gross reproductive rate did not differ significantly between A. swirskii fed date palm pollen or T. turkestani. Mean generation time (7.56 d) and population doubling time (1.043 d) were shorter for A. swirskii fed date palm pollen than T. turkestani or bee pollen. This study suggests that the T. turkestani diet or date palm pollen diet is suitable for A. swirskii. Date palm pollen has great potential as a cost effective diet to mass produce A. swirskii in the absence of natural prey. Future research could determine whether long-term rearing on date palm pollen reduces the ability of A. swirskii to locate, capture, and consume T. turkestani or other Tetranychus species on crop plants.

Functional and numerical responses of the predator Amblyseius swirskii to its prey Tetranychus turkestani in the laboratory

The tetranychid Tetranychus turkestani Ugarov and Nikolskii is a serious pest of many important crops around the world. Management of T. turkestani by augmentative biological control using predators such as the phytoseiid Amblyseius swirskii (Athias-Henriot) is envisioned as an environmentally safe alternative to acaricides. Foundational knowledge on T. turkestani – A. swirskii interactions in the laboratory are necessary to predict the outcome of A. swirskii augmentative releases in the field. In this study, the functional and numerical responses of adult A. swirskii females feeding on immature stages of T. turkestani were determined in the laboratory. Prey densities were 2, 4, 8, 16, 32, 64, or 128 individuals per Petri dish arena. The functional response of A. swirskii to prey showed a Holling's type II response. The attack rate and handling time estimates from the random predator equation were 0.1148/h and 0.3146 h, respectively, indicating that A. swirskii consumed 76.28 individuals per day at the maximum level. The number of eggs laid by the predator, i.e., the numerical response, increased as host density increased up to a maximum of 33.10 eggs per female; then oviposition rate leveled-off. This study suggests that A. swirskii is a suitable candidate for augmentative biological control of T. turkestani but follow-up experiments in greenhouses or open fields are necessary.

Development, reproduction and life table parameters of Tetranychus turkestani (Acari: Tetranychidae) on three different host plants

The strawberry spider mite, Tetranychus turkestani Ugarov and Nikolski, is one of the most important pests of different field and glasshouse crops in Iran. The objectives of the current study were to determine developmental time, survival, reproduction and life table parameters of T. turkestani on three plant species: cowpea (Vigna unguiculata L.), white bean (Phaseolus lunatus L.) and red bean (Phaseolus calcaratus Roxb.) at 25 ± 1 °C, 60 ± 10 % RH and a photoperiod of 16:8 (L:D). The mean developmental time from egg to adult on cowpea, white bean and red bean were 11.99, 10.43 and 10.46 days, respectively. The total preadult survival rates varied from 75% to 80%. Females of T. turkestani oviposited means of 65.13, 44.03 and 32.69 eggs on cowpea, white bean and red bean, respectively, and had a mean longevity of 13.92, 9.08 and 7.23 days on the same three host plants. The intrinsic rate of increase (rm) varied from 0.18 to 0.21. The net reproductive rate (R0) was higher on cowpea (42.33) than on white bean (24.95) or red bean (14.16). Using these measures, T. turkestani performance was best on cowpea, worst on red bean, and intermediate on white bean.

Molecular characterization of Cardinium, Rickettsia, Spiroplasma and Wolbachia in mite species from citrus orchards.

Tetranychidae spider mites are considered key citrus pests in some production areas, especially Tetranychus urticae Koch. Over the past decades, pesticide overuse seems to have promoted T. urticae population selection in citrus orchards. However, the microbiota has also been pointed out as a plausible explanation for population structure or plant host specialisation observed in several arthropod species. In this work, we have determined the incidence of Cardinium, Rickettsia, Spiroplasma and Wolbachia as representatives of major distorter bacteria genera in Aplonobia histricina (Berlese), Eutetranychus banksi (McGregor), Eutetranychus orientalis (Klein), Panonychus citri (McGregor), Tetranychus evansi Baker and Pritchard, Tetranychus turkestani Ugarov and Nikolskii, and T. urticae populations from Spanish citrus orchards. Only Wolbachia was detected by PCR. The multilocus alignment approach and phylogenetic inference indicated that all detected Wolbachia belong to supergroup B. The deep analysis of each 16S rDNA, ftsZ and wsp gene sequences allowed identifying several phylogenetically different Wolbachia sequences. It probably indicates the presence of several different races or strains, all of them belonging to supergroup B. The wsp sequence typing analysis unveiled the presence of the two already identified alleles (61 and 370) and allowed to contribute with five new alleles, supporting the presence of different but related B-races in the studied mite populations. The results are discussed and related to T. urticae population structure, previously observed in Spanish citrus orchards.

<p class="Body"><strong>Effects of alternative and natural prey on body size, locomotion and dispersal of <em>Neoseiulus bicaudus</em> (Acari: Phytoseiidae)</strong></p>

Prey are very important for the mass rearing of natural enemies and can affect the efficiency and quality of natural enemy products. Locomotion is important in dispersal of predatory mites on plants, and such activity is affected by body size and prey availability. The study evaluates the effects of prey (alternative prey: Tyrophagus putrescentiae Schrank and natural prey: Tetranychus turkestani Ugarov & Nikolskii) on the body size, locomotion and dispersal of the predatory mite Neoseiulus bicaudus Wainstein. When fed the alternative prey, the body size and locomotion of N. bicaudus were significantly lower than when fed the natural prey. However, the dispersal of N. bicaudus fed the two prey types was similar. The results suggest that long-term feeding on alternative prey could decrease the body size and locomotion of N. bicaudus. Nevertheless, the negative effects of alternative prey did not appear to affect the dispersal of N. bicaudus. The likely reason is that the type of prey does not affect the ability of the predatory mite to locate spider mites. In other words, when it fed alternative prey, N. bicaudus could still successfully disperse and locate spider mite-infested plants in the same way as when fed the natural prey.

<p class="Body"><strong>Cucumber cultivar responses to two tetranychid mites, two-spotted spider mite and strawberry spider mite in greenhouses </strong></p>

Cultivating resistant host plants has been considered as an important strategy for sustainable pest management of mites. The current study was conducted to evaluate the response of 43 cucumber (Cucumis sativus L.) cultivars against two important tetranychid species, two-spotted spider mite (Tetranychus urticae Koch.) and strawberry spider mite (Tetranychus turkestani Ugarov & Nikolski). The experiment was implemented in a Randomized Complete Block design (RCB) with 43 treatments replicated 4 times in a greenhouse during 2015-2016. Two main evaluation criteria, cultivar injury rate (from 1 to 5) and number of eggs/female/day (EFD) on each cultivar, were used to compare responses. The results revealed that the highest number of eggs/female/day (EFD) for both mites was observed on Taha cultivar (9.0±0.40 and 9.5±0.28 for T. urticae and T. turkestani, respectively). The highest injury rate was also observed on this cultivar (4.8±0.26 and 5.0±0.0 for T. urticae and T. turkestani, respectively). In contrast, the lowest EFD number for T. urticae (2.8±0.47) and T. turkestani (2.5±0.28) was seen on Samer star and Davos cultivars, respectively. However, no host preference for egg-laying was observed on Iver and Samer star cultivars for T. turkestani. These two cultivars had the lowest injury level too (1.2±0.25 for Samer star and 1.5±0.28 for Negeen to T. urticae and T. turkestani, respectively). The obtained results demonstrated that Taha was the most susceptible cultivar colonized easily by both two tetranychid species. In contrast, Samer star and Negeen were the most resistant cultivars, strongly recommended for cultivation in greenhouses.

Productivity of Neoseiulus bicaudus (Acari: Phytoseiidae) Reared on Natural Prey, Alternative Prey, and Artificial Diet.

The predatory mite, Neoseiulus bicaudus (Wainstein), is a potential biological control agent against spider mites and thrips. The objective of this experiment was to compare the effects of three diets on the life table of N. bicaudus. The three diets were 1) Tetranychus turkestani (Ugarov & Nikolskii) (Acari: Tetranychidae), the natural prey of N. bicaudus; 2) Tyrophagus putrescentiae (Schrank) (Acari: Acaridae), an alternative prey; and 3) artificial diet primarily consisting of decapsulated shrimp cysts, egg yolk, and honey. The computer simulation was used to project the population growth of N. bicaudus fed on different diets. The preadult developmental time (3.83 d) of N. bicaudus was shortest, and the intrinsic rate of increase (r = 0.2782 d-1) and the net reproductive rate (R0 = 18.98 offspring) were highest when reared on the alternative prey Ty. putrescentiae. The total development time (7.37 d) was longest, and the population parameters were the lowest (r = -0.0081 d-1, R0 = 0.85 offspring) when N. bicaudus was reared on artificial diet. The population projection showed that the population of N. bicaudus reared on Ty. putrescentiae could increase fast. Our results showed that the Ty. putrescentiae was the most suitable prey for mass rearing of N. bicaudus. The artificial diet could not support the N. bicaudus population and needs to be improved.

Spider mites (Acari: Tetranychidae) in protected natural areas of Serbia

Despite economic importance of Tetranychidae, knowledge regarding diversity of spider mites in the Balkan Peninsula and Southeast Europe is incomplete, especially in protected natural areas. This study presents diversity of spider mites (Acari: Tetranychidae) collected over five growing seasons at 296 locations in 38 protected natural areas of Serbia. A total of 31 spider mite species were found, 10 from Bryobiinae and 21 from Tetranychinae. The species Eotetranychus fagi Zacher was recorded as new to Serbia and this record was also the first one for Southeast Europe. Spider mites were found on host plants in five basic types as well as many subtypes of terrestrial habitats, with woodland as the most dominant one. A total of 151 plant species from 44 families were recorded as hosts for spider mites including new world records: 60 new hosts for family Tetranychidae and 41 new hosts for 21 spider mite species. Host plants from Rosaceae family harbored the highest number of spider mite species (16). A considerable number of species was found on host plants from the families Betulaceae (11), Asteraceae (10) and Sapindaceae (10). Two cosmopolitan spider mites, Tetranychus urticae Koch and Tetranychus turkestani Ugarov & Nikolskii, were clearly distinguished with 67 (7 new) and 43 (13 new) recorded host species, respectively; among newly recorded hosts for Tetranychidae family, these two mite species were found on 27 and 12 hosts, respectively. After the two most common species, the most striking was the presence of Bryobia praetiosa Koch with 24 (4 new) recorded host plants, followed by Amphitetranychus viennensis (Zacher), Eotetranychus carpini (Oudemans) and Bryobia rubrioculus (Scheuten), with 21 (7 new), 20 (6 new) and 16 (2 new) hosts, respectively. The remaining tetranychids were found on 1–9 host plant species. This study provided the first insight into diversity of tetranychids in Serbian protected areas. Further research in this field should focus on mites from host plants representative of specific areas and habitats, including endangered, endemic and relict species.

Synthesis, Insecticidal, Fungicidal Activities and Structure⁻Activity Relationships of Tschimganin Analogs.

For the first time, a novel series of tschimganin analogs were designed, synthesized, and evaluated for their insecticidal and fungicidal activities. Their structures were characterized by 1H-NMR, 13C-NMR and HRMS. Some of these compounds displayed excellent insecticidal and fungicidal activities, suggesting that they have potential to be used as bifunctional agrochemicals. Compound 3d and 3g with electron donating groups showed better inhibitory activity and growth inhibition activity towards Helicoverpa armigera (Hübner). The properties and positions of the substituents on the benzene ring have an important influence on the acaricidal activity of tschimganin analogs. Topomer comparative molecular field analysis (CoMFA) was employed to develop a three-dimensional quantitative structure-activity relationship model for the compounds against Tetranychus turkestani Ugarov et Nikolski. It was indicated that higher electronegativity was beneficial for acaricidal activity. Moreover, compound 3r having a 2-hydroxy-3,5- dinitrophenyl moiety displayed a fungicidal spectrum as broad as azoxystrobin against these phytopathogens.

<p><strong>Sublethal effects of Biomite® on the population growth and life table parameters of <em>Tetranychus turkestani</em> Ugarov and Nikolskii on three cucumber cultivars</strong></p>

The strawberry spider mite Tetranychus turkestani Ugarov & Nikolskii (Prostigmata: Tetranychidae) is an important pest on greenhouse cucumber. Therefore, understanding the effect of sublethal concentration of acaricides using demographic toxicological analysis is important for successful management of this pest. Laboratory studies were conducted to assess sublethal (LC25) effects of Biomite®, a natural based miticide, on the population growth and life-table parameters of T. turkestani. Three commonly greenhouse cucumber cultivars including Milad, Khasib and Puia were used in the study. Developmental times of T. turkestani immature stages were decreased on treated cultivars, while total life spans were significantly increased on treated cultivars when compared with the control groups. For Milad cultivar, adult pre-oviposition period (APOP) was significantly decreased when females were treated with LC25 of Biomite®. However, the total pre-oviposition period (TPOP) increased in the treated females. The intrinsic rates of increases (r) were higher in all the treated cultivars in comparison with control. The r values were 0.20, 0.21 and 0.18 day-1 in the control group of Milad, Khasib and Puia cultivars which increased to 0.36, 0.38 and 0.37 day-1 in the treated females, respectively. The age-stage survival rates of the female adults increased in the Biomite® treated cultivars. The life expectancies of one-day-old female adults of T. turkestani were estimated to be 5.73, 6.54 and 6.14 days on the control group of Milad, Khasib and Puia and 8.96, 10.46 and 10.19 days on the Biomite® treated cultivars, respectively. It could be concluded that sublethal concentrations of Biomite® stimulated fecundity of females and as a result increased population development. However, further studies in greenhouses and in the field are required to confirm the results.

Sublethal effects of Biomite® on the population growth and life table parameters of Tetranychus turkestani Ugarov and Nikolskii on three cucumber cultivars

Abstract The strawberry spider mite Tetranychus turkestani Ugarov & Nikolskii (Prostigmata: Tetranychidae) is an important pest on greenhouse cucumber. Therefore, understanding the effect of sublethal concentration of acaricides using demographic toxicological analysis is important for successful management of this pest. Laboratory studies were conducted to assess sublethal (LC25) effects of Biomite®, a natural based miticide, on the population growth and life-table parameters of T. turkestani. Three commonly greenhouse cucumber cultivars including Milad, Khasib and Puia were used in the study. Developmental times of T. turkestani immature stages were decreased on treated cultivars, while total life spans were significantly increased on treated cultivars when compared with the control groups. For Milad cultivar, adult pre-oviposition period (APOP) was significantly decreased when females were treated with LC25 of Biomite®. However, the total pre-oviposition period (TPOP) increased in the treated females. ...

Effects of six greenhouse cucumber cultivars on reproductive performance and life expectancy of Tetranychus turkestani (Acari: Tetranychidae)

The strawberry spider mite Tetranychus turkestani Ugarov & Nikolskii is an important pest of greenhouse cucumber. Reproductive parameters, life expectancy and life table entropy of this mite on six greenhouse cucumber cultivars (Puia, Hedieh, Milad Jadid, Milad Ghadim, Khasib and Negin) were evaluated. These parameters were estimated by a leaf disc bioassay with six treatments and 40 replications under laboratory conditions (Tempt. 28 +/- 1 °C, RH: 60 +/- 5%, L:D = 16:8 h) in a walk-in growth chamber. The results of this study show that the highest total fecundity of the strawberry spider mite was observed on the Hedieh cultivar (29.784 egg/ female) and the lowest on the Puia cultivar (15.773 egg/ female). The highest gross and net fecundity rates of this pest were seen on the Hedieh cultivar (91.721 and 41.171 egg/female) and the lowest on the Puia cultivar (35.765 and 9.154 egg/female, respectively). The strawberry spider mite had the highest gross and net fertility rates on the Hedieh cultivar (44.913 and 26.720 egg/ female, respectively). Moreover, T. turkestani gross hatching rate on the six cucumber cultivars differed significantly, varying from 0.18 on Negin to 0.48 on Hedieh. The life expectancy of one-day-old adults of the strawberry spider mite was estimated to be 6.140, 7.800, 5.733, 6.551, 6.543 and 6.822 days on the above-mentioned cultivars, respectively. The values of the entropy parameter (H) of the strawberry spider mite on the cultivars were 6.600, 1.177, 8.468, 2.300, 1.249 and 0.247, respectively. These results suggest that Puia, Milad Jadid, Milad Ghadim, Khasib and Negin cultivars may have the highest resistance levels to this mite compared to the Hedieh cultivar. The use of resistant host plants is one of the most important components of an integrated pest management program.

Evaluation of five essential oils as botanical acaricides against the strawberry spider mite Tetranychus turkestani Ugarov and Nikolskii

The strawberry spider mite, Tetranychus turkestani Ugarov and Nikolskii (Acari: Tetranychidae), is a serious pest of agroecosystems in southwestern Iran and some other tropical regions. Records show that it has developed resistance to some chemical acaricides. In this study, the chemical composition of five Lamiaceae plant essential oils was examined, and their activity against T. turkestani was evaluated. The essential oil composition of savory (Satureja hortensis L.), penny royal (Mentha pulegium L.), spearmint (Mentha viridis L.), rosemary (Rosemarinus officinalis L.), and a thyme-like plant (Zataria multiflora Bioss) was analyzed by GC–MS and fumigant bioassays were performed to determine their acaricidal activity. The results showed that all the essential oils have acaricidal activity at all the tested concentrations. The calculated LC50 values were 5.5, 9.4, 14.5, 15.3, and 29.8 μl l−1 air for Z. multiflora, S. hortensis, M. pulegium, M. viridis, and R. officinalis, respectively. These results showed that Z. multiflora and S. hortensis essential oils, with carvacrol, thymol, and γ-terpinene as their main compounds, were the most effective oils. In another experiment designed to find the effects of exposure time on the mortality of T. turkestani females, nearly all females died in 20 μl l−1 of all the essential oils after 24 h, except in the case of R. officinalis oil, which caused 90% mortality in mites. This study demonstrated that all the tested essential oils have the ability to control T. turkestani and could be useful in the development of new agents for mite control.

Species complexes of predatory mites and spider mites (Acari: Phytoseiidae, Tetranychidae) on cultivated and wild apple trees in Serbia

The species complexes of leaf-inhabiting mites on apples were studied on actively cultivated and neglected apple orchards as well as on wild apple trees in Serbia, from 1981 to 2013. Thirty-nine species of 11 families were found on Malus domestica Borkh; 25 species of 6 families were found on Malus sylvestris (L.) Miller and Malus pumila Miller. A complex of 18 phytoseiid and 9 spider mite species was detected. Four phytoseiid and three spider mite species were found in commercial apple orchards, 13 phytoseiid and 5 spider mite species in neglected apple stands, and 12 phytoseiid and 7 spider mite species in forest habitats. Predatory mites Euseius finlandicus (Oudemans) and Amblyseius andersoni (Chant) and spider mites Panonychus ulmi Koch and Amphitetranychus viennensis (Zacher) had the highest constancy of occurrence. Positive and significant (or very significant) association was detected for 16 pairs of species. The pairs of phytoseids-spider mites Amb. andersoni–Pan. ulmi, Amb. andersoni–Tetranychus turkestani Ugarov et Nikolskii, and Typhlodromus (Anthoseius) rhenanus (Oudemans)–Te. turkestani had the highest interspecific association indices. Higher mite diversity was found on wild than on cultivated apples, and higher diversity on neglected than on cultivated apples. The complexes of phytoseiids and spider mites had uniform composition in the cultivated orchards, while their composition in the neglected stands was nonuniform and extremely heterogeneous on the wild apple trees.

Development and life table parameters of Tetranychus turkestani (Acarina: Tetranychidae) at different constant temperatures

Selected life history characteristics of the strawberry spider mite (Tetranychus turkestani Ugarov and Nikolski, Acarina: Tetranychidae) were studied at four constant temperatures (15, 20, 25 and 30 °C). Egg-to-adult developmental time of females ranged from 50.11 +/- 0.79 days at 15 °C to 7.73 +/- 0.14 days at 30 °C. An average of 140.33 +/- 5.49 degree-days was required to complete development above the lower thermal threshold (11.89 °C). Preimaginal mortality was 62.92, 16.67, 41.82 and 42.31% at 15, 20, 25 and 30 °C, respectively. Mean longevity of female T. turkestani ranged from 30.22 +/- 2.88 days at 15 °C to 5.78 +/- 0.10 days at 30 °C. Mean total fecundity ranged from 23.11 +/- 3.14 to 49.95 +/- 5.54 eggs / female. The sex ratio (% females) ranged from 69.00 +/- 0.04 to 83.01 +/- 0.02%. The intrinsic rate of population increase (rm) ranged from 0.272 +/- 0.010 at 30 °C to 0.033 +/- 0.002 (female per female per day) at 15 °C. The population doubled most quickly at 30 °C (2.54 +/- 0.09 d) and most slowly at 15 °C (20.46 +/- 1.59 d). Based on these results, we can predict the presence of the different stages of the strawberry spider mite on cucumber over time. This information will therefore enable us to determine more precisely the best time to control this pest.

Host plant effects on the functional response of Stethorus gilvifrons to strawberry spider mites

The functional response of adult females of the coccinellid beetle Stethorus gilvifrons Mulsant to juveniles of strawberry spider mite, Tetranychus turkestani Ugarov & Nikolski was determined on cowpea, castor bean and cucumber leaves in the laboratory at 25°C and a 14 h L: 10 h D photoperiod. Beetles were isolated singly for 24 h in 9-cm Petri dishes with either 2, 4, 8, 16, 32, 64, or 128 nymphal stages of T. turkestani. Results showed a typical type II response on all plants tested, with up to 110.7, 100.8, and 53.0 prey attacked when 128 nymphal stages were provided on cowpea, castor bean, and cucumber leaves, respectively. Based on the Rogers random attack equation, the highest estimated attack rate and the lowest handling time were obtained on cowpea. It was therefore concluded that the host plant species can affect the predation rate and functional response components of S. gilvifrons, a specific and effective predator of spider mites.

The effect of Tetranychus turkestani and Eutetranychus orientalis (Acari: Tetranychidae) on the development and reproduction of Stethorus gilvifrons (Coleoptera: Coccinellidae)

Stethorus gilvifrons Mulsant, native to the Mediterranean region, is often observed feeding on Tetranychus turkestani Ugarov & Nycolsky and Eutetranychus orientalis Klein on different host crops. Fecundity of S. gilvifrons on T. turkestani and E. orientalis was evaluated by placing newly emerged pairs on leaf discs infested with different developmental stages of T. turkestani or E. orientalis. They were maintained at 30 °C and changed daily until death of the female. Adult female mean longevity was 58 days on T. turkestani and 45 days on E. orientalis. Mean fecundity was 175 eggs per female on T. turkestani and 318 eggs per female on E. orientalis. No significant differences were detected in the duration of life stages between T. turkestani and E. orientalis. Mean preimaginal mortality was 20% on T. turkestani and 24% on E. orientalis, with no statistical differences. Mean generation time ( T) was 26.76 and 22.83 days on T. turkestani and E. orientalis, respectively. Net reproductive rate ( R o) was significantly greater on E. orientalis (154.08) than on T. turkestani (97.6), but the estimate of intrinsic rate of increase ( r m) was not statistically different (0.221 and 0.171, respectively). Our results suggest that both T. turkestani and E. orientalis are essential prey for S. gilvifrons development and reproduction and that E. orientalis is slightly more suitable than T. turkestani.