Evaluation of the effectiveness of Neoseiulus cucumeris (Oudemans) as a predator of Tuta absoluta (Meyrick)

The leaf miner, Tuta absoluta is continue to be a serious threat to solanaceous plants, especially tomato plant worldwide. Tomato crop in Saudi Arabia has been recently affected by T. absoluta, which is difficult to control due to its unique biological features, such as high fecundity and its potential to develop resistance to chemical pesticides. In this article, the suitability and effectiveness of the predatory mite, Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae), an indigenous species usually found in tomato greenhouses of northcentral Saudi Arabia, has been evaluated on eggs and 1st instar larvae of T. absoluta in the laboratory. All experiments were conducted in an incubator at three constant temperatures of 22, 27 and 32°C ± 1°C, 50 ± 4% R.H. and L12:D12 h photoperiod. Adult females and males of N. cucumeris were able to feed and sustain oviposition on eggs and 1st instar larvae of T. absoluta, and could be an effective biocontrol agent against T. absoluta. The N. cucumeris had a clear preference for eggs compared to 1st instar larvae of T. absoluta. The results showed the obvious effect of the temperature on the consumption rate of the predatory mite. The maximum daily consumption rate occurred during the oviposition period, when the females of the predatory mite consumed an average of 4.26 eggs and 2.44 1st instar larvae of T. absoluta. In general, total fecundity was high with T. absoluta eggs as a food source when temperature increased from 22 to 32°C. The highest fecundity rate (42.92 and 20.97 eggs /female) was recorded at 32°C, while the lowest one (26.77 and 10.12 eggs / female) was recorded at 22°C, when N. cucumeris female fed on eggs and 1st instar larvae of T. absoluta, respectively. The results of this study indicated that the predatory mite, N. cucumeris can be considered a promising potential candidate for controlling the leaf miner T. absoluta, and further research is required to assess its effectiveness under greenhouse conditions.

Selection of suitable predatory mites against, Panonychus citri (McGregor) (Acari: Tetranychidae) using relative control potential metrics and functional response

Background Selection of suitable predators for the control of the spider mite, Panonychus citri is always a challenge due to the lack of their reliable predicted efficacy. In this laboratory study, biological control potential of Neoseiulus californicus, N. cucumeris and Scapulaseius newsami, against P. citri using the “Relative Control Potential” (RCP) metric to compare their efficacies was evaluated. The functional response type was determined at different prey densities (after 24 h). Results The type II functional responses were observed from all the tested predators feeding on 3 different life stages of P. citri, except N. cucumeris, which was fed only on eggs. All predatory mites preferred eggs of P. citri with a higher attack rate (1.397) in N. cucumeris, followed by N. californicus (1.238) and S. newsami (0.975). Handling time was also lower in N. cucumeris than other mites, with a trend as: for N. cucumeris, eggs > adults > immature stages; for N. californicus, immature stages > eggs > adults, while for S. newsami, eggs > immature stages > adults. The integration of greenhouse abundance and fecundity (%) data resulted in a higher RCP for N. cucumeris than other predators. Conclusion Neoseiulus cucumeris was selected as the most suitable predatory mite for the control of P. citri with a higher RCP and potential to maximum reproduction. S. newsami, which was used for the first time, gave almost similar results compared to N. californicus but with lower efficacy.

Modifications of Phytoseiidae mite breeding methods to suppress spider mite

Populations of mites from the Tetranychidae family are characterized as high-resistant to acaricides, which, in turn, leads to an increase in the pesticide load on the agrocenoses ecosystem. Carnivorous arthropods from the Phytoseiidae family can be used as an alternative pest control. Our research aimed at improving the methods of breeding, storage and use of predatory mites against Tetrahychus urticae Koch. In 2015–2018, work was being undertaken to define the optimum thickness of the substrate layer (2.0, 4.0 and 6.0 cm) for breeding the food object – Acaris farus Oud. We also assessed the effect of the fodder substrate composition (wheat bran – control, wheat bran + soybean meal – experimental variant) on the population density of Amblyseius andersoni Chant. In 2016–2019, experiments on the storage of Neoseiulus barkeri Hughes, Neoseiulus cucumeris Oud. and Amblyseius swirskii Athias-Henriot at 4 °C (control – no storage) were carried out. In 2018–2019, to control Tetrahychus urticae Koch. in the soybean field, a mixture of N. cucumeris and A. andersoni was used according to the method of introduction into natural foci of prey. The optimum thickness of the substrate layer was found to be 4 cm. In this case, it was possible to obtain 6,983 mites in 1 cm3 for 7 days. Soybean meal addition increased the number of A. andersoni by 22.3 % compared to control (263 ind. vs 204 ind. per cm3). 30–45 days – an effective storage period for N. barkeri, 30 days – for N. cucumeris, no more than 10 days – for A. swirskii. On average, in 2018–2019, N. cucumeris and A. andersoni mixture reduced the number of T. urticae. The number of spider mites in the control variant was 14.6, in the experimental one – 5.3 ind./leaf. No predatory activity was observed on eggs. To prevent the development of spider mites, it is necessary to use N. cucumeris and A. andersoni at least twice with an interval of 5–7 days.

Pollen grains are suitable alternative food for rearing the commercially used predatory mite Neoseiulus cucumeris (Acari: Phytoseiidae)

The generalist predatory mite, Neoseiulus cucumeris (Oudemans) is one of the most effective natural enemies on many crops in indoor cultivations. As supply of alternative food such as pollen is generally thought to enhance the reproductive and biological control performance of generalist predatory mites, the life table parameters of the predatory mite, N. cucumeris were determined in laboratory at 25±1°C, 60±5% RH, and a photoperiod of 16:8 (L: D) hours when fed on seven different pollen (almond, bitter orange, maize, date palm, castor bean, sunflower, and bee-collected). Our results indicated that feeding the predator on castor bean, almond, date palm, and sunflower pollen led to better performance in terms of higher oviposition (38.18, 33.53, 32.87, and 29.48 eggs/female, respectively), intrinsic rate of increase (0.146, 0.129, 0.152, and 0.123 day-1, respectively) and net reproductive rate (19.55, 12.58, 14.93, and 14.06 eggs/individual, respectively), and shorter development time (7.08, 7.73, 7.19, and 9.30 days, respectively). Bitter orange and bee-collected pollen were not suitable diets for both development and reproduction of N. cucumeris. The shortest (7.08 days) and longest (16.09 days) development times were observed on castor bean and bee-collected pollen, respectively. Adult longevity varied from 6.88 days on maize to 60.4 days on castor bean pollen. The highest fecundity was obtained on almond, followed by date palm, and castor bean pollen, while feeding on maize pollen did not lead to oviposition. Overall, we found that castor bean along with date palm, almond, and sunflower pollen are suitable diets for large scale rearing of N. cucumeris for subsequent use in biological control of pests in greenhouses.

Immature development and survival of Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae) on eggs of Tyrophagus curvipenis (Fain & Fauvel) (Acari: Acaridae)

Establishment and maintenance of the natural enemy are critical for successful biological control of pests on plants without alternative food for predators. Great efforts have been devoted to exploring suitable supplementary food for predators. In this study, we evaluated the feasibility of using Tyrophagus curvipenis (Fain and Fauvel) (Acari: Acaridae) as a supplementary food source for Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae) by investigating the survival and development of N. cucumeris at different prey densities with the influence of conspecifics. Furthermore, we investigated predation rates and their body size at adult emergence. The results showed that N. cucumeris developed from egg to adult in approximately six days. Survival rates of immature predators increased significantly with the given prey density. No significant difference in body size was found between the survived adults fed at different prey density, but the females were always larger than males. To conclude, T. curvipenis can be an excellent alternative food source for the biological control agent N. cucumeris.

Responses of avermectin-resistant and susceptible strains of Neoseiulus cucumeris (Oudemans) (Acari: Phytoseiidae) to Tetranychus urticae Koch (Acari: Tetranychidae) on sweet potato

To identify the searching ability of avermectin-resistant and susceptible strains of Neoseiulus cucumeris (Oudemans), the responses of the two strains to stimuli from Tetranychus urticae Koch on sweet potato leaves were examined in the laboratory. The results showed that avermectin-resistant and susceptible adult N. cucumeris females responded to different stages and intact webs (spider mite, egg, feces, and leaf damage) of T. urticae, but not to the destroyed webs and feces of and feeding damage by T. urticae. Moreover, no significant differences were observed in the responses of the avermectin-resistant and susceptible strains of N. cucumeris. Both strains of N. cucumeris were often observed inside the intact webs of T. urticae. These results show that the avermectin-resistant and susceptible strains of N. cucumeris have the ability to search actively for T. urticae on sweet potato leaves. This behavior clearly increases the searching efficiency of N. cucumeris and may help its use in the biocontrol of T. urticae.