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Abstract

From 1995 to 1999, four experiments were conducted on greenhouse roses to assess the effectiveness of the nC24 petroleum spray oil (PSO), D-C-Tron Plus, against two-spotted mite, Tetranychus urticae Koch (Acarina: Tetranychidae), and to determine how the oil could be most efficiently and effectively used in combination with the predatory mite Phytoseiulus persimilis Athias-Henriot (Acarina: Phytoseiidae) in an integrated pest management program. The results showed that 0.5% PSO applied fortnightly to roses gave excellent protection from T urticae infestation when the mite population was not already established. However, PSO applied after roses were infested with T. urticae above the economic threshold only stabilised populations without reducing them below that threshold. Populations of P. persimilis in the upper and lower canopies were unchanged after two sprays of PSO at 7-day intervals, and application of PSO to the upper canopy was as effective in controlling T. urticae in the presence of P persimilis as spraying the entire plant. Combining PSO with P. persimilis gave better control of T. urticae than using P. persimilis alone. The most cost-effective use of PSO in the presence of P. persimilis is, therefore, to apply spray only to the upper canopy. This will not affect control of powdery mildew with PSO. Comparison of a control program for T urticae based on the monitored use of synthetic miticides with that based on calendar application of PSO revealed that both gave equally effective control. The benefits of combining PSO and P. persimilis in an integrated pest management program for T. urticae on roses over a program based on synthetic fungicides are discussed.

The influence of sublethal deposits of agricultural mineral oil on the functional and numerical responses of Phytoseiulus persimilis (Acari: Phytoseiidae) to its prey, Tetranychus urticae (Acari: Tetranychidae)

“…In conclusion, it appears that the presence of sublethal quantities of AMO significantly changes the predation dynamics of the predatory mite P. persimilis in the presence of T. urticae, but in a way that is advantageous to techniques of integrated pest management, such as the partial spraying of plants as advocated by Nicetic et al (2001). P. persimilis would be even more effective if it had a strong aggregative response to high prey density in previously sprayed crops but further research is required to establish whether or not that is the case.…”

“…If the lower parts of the plants are left as an unsprayed refuge, as suggested by Nicetic et al (2001), the mites must be tolerant of sublethal overspray reaching the refuge and also tolerant of sublethal residues when reinvading the previously sprayed parts of the plants and the predator must still be able to cause mortality to the pest.…”

Current Situation of Tetranychus urticae (Acari: Tetranychidae) in Northern Africa: The Sustainable Control Methods and Priorities for Future Research

“…Experiments were conducted on greenhouse roses to evaluate the efficacy of the nC24 petroleum spray oil (PSO), D-C-Tron in combination with Phytoseiulus persimilis (Acarina: Phytoseiidae) against Tetranychus urticae in the context of developing an integrated management program. Results showed that 0.5% PSO applied fortnightly to roses provided excellent protection against T. urticae infestation and did not affect the population density of P. persimilis in the upper and lower foliage [129]. In Brazil, on strawberry crops, control of T. urticae in the program based on release of Neoseiulus californicus (McGregor) and reduction of the frequency of acaricide applications (IPM) was effective in maintaining a significantly lower level of pest infestation, resulting in a six-fold reduction in the frequency of acaricide applications and, consequently, a reduction in selection pressure for acaricide resistance [130].…”

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