Efficacy of Neoseiulus californicus and Phytoseiulus persimilis in suppression of Tetranychus urticae in young clementine plants

Combined application of entomopathogenic fungi and predatory mites for biological control of Tetranychus urticae on chrysanthemum

BACKGROUND

Most studies on efficacy of fungal pathogens and predatory mites against Tetranychus urticae have been done on individual species in the laboratory. We evaluated fungi and predatory mites separately and together against glasshouse populations of T. urticae on chrysanthemum plants. First, effectiveness of the fungal pathogens Beauveria bassiana (Bb88) and Metarhizium anisopliae (Ma129) was compared; then, effectiveness of the predatory mites Phytoseiulus persimilis and Neoseiulus californicus. Based on the results, N. californicus and isolate Ma129 were selected and evaluated in combination. In all experiments, treatment effects were assessed for eggs and motile stages of T. urticae.

RESULTS

The first experiment showed no significant effect of either fungal isolate on T. urticae populations, except on plants initially infested with 20 mites, where more eggs were found in the control compared to the fungal treatments. In the second experiment, both predatory mites were equally effective at reducing T. urticae populations compared with the control, regardless of initial T. urticae population density. The last experiment demonstrated that populations of T. urticae were reduced most when M. anisopliae (Ma129) and N. californicus were applied together, compared with the control and when each natural enemy was applied separately.

CONCLUSIONS

Metarhizium anisopliae (Ma129) and B. bassiana (Bb88) isolates did not have a significant effect on reducing T. urticae populations. Both predatory mites reduced T. urticae populations, regardless of T. urticae density. Combined application of M. anisopliae (Ma129) and N. californicus were more effective against T. urticae than the control or when each agent was applied separately. © 2024 Society of Chemical Industry.

Lethal and sublethal effects of carlina oxide on Tetranychus urticae (Acari: Tetranychidae) and Neoseiulus californicus (Acari: Phytoseiidae)

BACKGROUND

Tetranychus urticae Koch, is a polyphagous and damaging pest, presenting several resistant populations worldwide. Among new and more environmentally friendly control tools, botanical pesticides represent a valuable alternative to synthetic ones within integrated pest management strategies. Accordingly, we investigated the lethal and sublethal effects of carlina oxide isolated from Carlina acaulis (Asteraceae) roots on T. urticae and its natural enemy, the predatory mite, Neoseiulus californicus (McGregor).

RESULTS

Carlina oxide (98.7% pure compound) was used for acaricidal tests on eggs, nymphs, and adult females of T. urticae (concentrations of 312.5, 625, 1250, 2500 and 5000 μL L-1 ), and eggs and females of N. californicus (1250 and 5000 μL L-1 on eggs and females, respectively). Behavioral two-choice tests were also conducted on phytoseiid females. Carlina oxide toxicity was higher on T. urticae females than nymphs (median lethal dose 1145 and 1825 μL L-1 , respectively), whereas egg mortality and mean hatching time were significantly affected by all tested concentrations. A decreasing daily oviposition rate for T. urticae was recorded with concentrations ranging from 625 to 5000 μL L-1 , whereas negative effects on the population growth rate were recorded only with the three higher concentrations (1250, 2500 and 5000 μL L-1 ). No toxic effect on N. californicus females was found, but a strong repellent activity lasting for 48 h from application was recorded.

CONCLUSION

Carlina oxide reduced longevity and fecundity of T. urticae adults, but not of N. californicus. This selective property allows us to propose it as a novel active ingredient of ecofriendly acaricides for T. urticae management. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Air temperature optimisation for humidity-controlled cold storage of the predatory mites Neoseiulus californicus and Phytoseiulus persimilis (Acari: Phytoseiidae)

BACKGROUND

Humidity-controlled cold storage, in which the water vapour pressure is saturated, can prolong the survival of the predatory mites Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae). However, information on the optimum air temperature for long-term storage by this method is limited. The authors evaluated the survival of mated adult females of N. californicus and P. persimilis at 5.0, 7.5, 10.0 and 12.5 °C under saturated water vapour condition (vapour pressure deficit 0.0 kPa).

RESULTS

N. californicus showed a longer survival time than P. persimilis at all the air temperatures. The longest mean survival time of N. californicus was 11 weeks at 7.5 °C, whereas that of P. persimilis was 8 weeks at 5.0 °C. After storage at 7.5 °C for 8 weeks, no negative effect on post-storage oviposition was observed in N. californicus, whereas the oviposition of P. persimilis stored at 5.0 °C for 8 weeks was significantly reduced.

CONCLUSION

The interspecific variation in the response of these predators to low air temperature might be attributed to their natural habitat and energy requirements. These results may be useful for the long-term storage of these predators, which is required for cost-effective biological control.

Comparative toxicity of pesticides in three phytoseiid mites with different life-style occurring in citrus: Euseius stipulatus, Neoseiulus californicus and Phytoseiulus persimilis

Conservation and augmentative biological control strategies have been developed to take full advantage of the natural enemies that occur in Spanish citrus orchards. Among them, the predatory mites Euseius stipulatus, Neoseiulus californicus and Phytoseiulus persimilis play an important role in the biological control of tetranychid mites. However, these predatory mites are often affected by pesticides and information about the side-effects of these products against these beneficial arthropods is essential to guarantee their efficacy. The side-effects of some pesticides remain unknown and the primary aim of this study was to fill this gap. We have further used this information and that collected from other sources to compare the response of these three mite species to pesticides. Based on this information, E. stipulatus has the most tolerant species, followed by N. californicus and P. persimilis. Therefore, using E. stipulatus as an indicator species in citrus may have led to the paradox of selecting presumed selective pesticides resulting in excessive impact on N. californicus and, especially on P. persimilis. Because these two latter species are considered key for the biological control of T. urticae in citrus, especially clementines, in Spain, we propose to use P. persimilis as the relevant indicator of such effects on predacious mites occurring in citrus instead of E. stipulatus. This change could have a dramatic impact on the satisfactory control of tetranychid mites in citrus in the near future.

Environmental Engineering Approaches toward Sustainable Management of Spider Mites

Integrated pest management (IPM), which combines physical, biological, and chemical control measures to complementary effect, is one of the most important approaches to environmentally friendly sustainable agriculture. To expand IPM, we need to develop new pest control measures, reinforce existing measures, and investigate interactions between measures. Continued progress in the development of environmental control technologies and consequent price drops have facilitated their integration into plant production and pest control. Here I describe environmental control technologies for the IPM of spider mites through: (1) the disturbance of photoperiod-dependent diapause by artificial light, which may lead to death in seasonal environments; (2) the use of ultraviolet radiation to kill or repel mites; and (3) the use of water vapor control for the long-term cold storage of commercially available natural enemies. Such environmental control technologies have great potential for the efficient control of spider mites through direct physical effects and indirect effects via natural enemies.