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.

Evaluation of Artemia franciscana Cysts to Improve Diets for Mass Rearing Stethorus gilvifrons, a Predator of Tetranychus turkestani

Stethorus gilvifrons is an acarophagous coccinellid distributed in the Mediterranean region and could potentially be mass-reared for the augmentative biological control of Tetranychus turkestani and related species on crop plants. The hypothesis that brine shrimp Artemia franciscana cysts can improve diets for rearing of S. gilvifrons was tested in laboratory experiments. The diet treatments included A. franciscana cysts (D1), A. franciscana cysts plus a vitamin B complex (D2), A. franciscana cysts plus date palm pollen (D3), and A. franciscana cysts plus date palm pollen and Ephestia kuehniella eggs (D4). The results indicated that D1 did not support immature development. D2 supported egg–larval development but not pupal–adult development. Both D3 and D4 supported development to the adult stage and reproduction. However, D4 was the most effective diet, determined by observations of S. gilvifrons oviposition behavior and fecundity. A life table analysis corroborated these results; an intrinsic rate of increase, net and gross reproductive rates, and mean generation time were best for S. gilvifrons fed D4 rather than D3. A mixed diet composed of A. franciscana cysts, date palm pollen, and E. kuehniella eggs can be used to mass rear S. gilvifrons.

Lethal and sublethal effects of several plant compounds compared to spiromesifen against Tetranychus turkestani

Summary Tetranychus turkestani Ugarov and Nikolski is one of the main agricultural pests of southwestern Iran and some other tropical regions. In the present study, fumigant activity of three essential oils extracted from Rosmarinus officinalis L., Mentha longifolia L. and Eucalyptus globulus Labill., and contact toxicity of two biopesticides (Tondexir and Palizin) on T. turkestani mite females were investigated and compared with that of spiromesifen, a chemical acaricide. Also, sublethal effects of the tested compounds at 50% lethal concentration (LC50) were estimated on the biological parameters of T. turkestani. The LC50 values for E. globulus, R. officinalis and M. longifolia essential oils were 12.50, 11.52 and 4.00 μl/l air and for spiromesifen, Tondexir and Palizin were 10.98, 327.34 and 858.13 ppm, respectively. All tested compounds significantly reduced adult female longevity, equally to the chemical acaricide spiromesifen. Fecundity also decreased in all treatments and this reduction was even higher for plant essential oils than the other compounds. Palizin, E. globulus and M. longifolia significantly reduced the hatchability of T. turkestani eggs similarly to spiromesifen. According to the results, the tested plant compounds are effective against T. turkestani and may be applied as suitable alternatives to synthetic pesticides against this crop pest.

Creation of resistant specimens of cotton (Tetranychus turkestani) using marker-based selection method in Uzbekistan

This article discusses the damage caused by pests to agricultural crops, including cotton, the importance of their control, the advantages of using modern biotechnological methods in the development of new pest-resistant varieties and foreign experience in this field, as well as preliminary research in this case was also briefly illuminated.

Entomocomplex of peach plantations in the vegetation period

Goal. Study of the entomocomplex of peach plantations in order to plan appropriate measures to limit their harmfulness. Methods. Laboratory field. The population of peach trees by pests was determined according to generally accepted methods in the Research Garden of the Dmytro Motorny Tavriya State Agrotechnological University. Census counts were conducted in peach plantations of the Crimean Fireworks, Jubilee Sidorenko, Redhaven, Skazka, Vireney and Ambassador of Peace varieties. Results. It was found that in the agrocenosis of peach plantations during 2018—2019, three permanent species of pests were registered: California thymus (Quadraspidiotus perniciosus Comst.), Turkestan mite (Tetranychus turkestani Ud. Net Nik.) And eastern fruit eater (Grapholitha molesta Busck). The adult age of the last phytophagous began with the beginning of flowering peach trees and lasted until September. The number of butterflies in pheromone traps varied during the growing season from 24.7 to 48.5 specimens / trap, ie significantly exceeded the economic threshold of harmfulness. It should be noted that despite the very high age of the pest in the experiment, damage to peach shoots in all varieties (except Crimean fireworks and the Ambassador of Peace) was below the economic threshold of harmfulness (0.1—1.0%). The population of peach leaves by Turkestan mite on different varieties was 0.1—1.5 specimens / leaf. Studies on the peculiarities of the development of the Californian thyroid have shown that the beginning of the flight of males of the first generation was recorded in pheromone traps in the second decade of May. In 2019, this phase of development is marked a week later. The revival of traveling larvae also occurred at different times, with slight fluctuations. The number of California thyme on peach varieties ranged from 0.8 to 17.2 specimens / shield. Conclusions. On peach cultivars the California thyme (up to 17.2 specimens/shield), oriental fruit fly (from 0.3 to 2.5 specimens/shoot) and Turkestan spider mite (up to 23.8 specimens / leaf) were noted, depending on The high potential of California thyme reproduction in peach plantations on the Crimean Fireworks, Virenea and Ambassador of Peace varieties has been recorded.

The predatory mite Neoseiulus bicaudus (Mesostigmata: Phytoseiidae), a promising biocontrol agent of whitefly Bemisia tabaci (Hemiptera: Aleyrodidae)

Neoseiulus bicaudus (Wainstein) (Acari: Phytoseiidae) is a native predatory mite species in Xinjiang, China, and a biological control agent for some small pests, such as Tetranychus turkestani (Acari: Tetranychidae) and Thrips tabaci (Thysanoptera: Thripidae) in greenhouse. However, little is known whether N. bicaudus could be an effective natural enemy of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae). A series of laboratory and greenhouse experiments were conducted to evaluate the efficiency of N. bicaudus on B. tabaci. The present data showed that each stage of N. bicaudus demonstrated type II functional response when fed on B. tabaci. The adult females showed the highest consumption rate and attack rate, and the shortest handling times were obtained when they preyed on eggs and 1st instar nymphs. The 1st instar of B. tabaci was preferred for the feeding of N. bicaudus adult females than eggs, followed by 2nd instar nymphs of B. tabaci. Under greenhouse conditions, this predator effectively suppressed the population growth of B. tabaci throughout the experimental period. Accordingly, N. bicaudus could be an efficient predator for B. tabaci.

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.

Effects of alternative and natural prey on body size, locomotion and dispersal of Neoseiulus bicaudus (Acari: Phytoseiidae)

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.

Cucumber cultivar responses to two tetranychid mites, two-spotted spider mite and strawberry spider mite in greenhouses

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.