Silica provides expanded possibilities for use in horticultural crops. However, there are many crop pests on the lower surface of plant leaves. This is particularly challenging when silica is used because the material must have a direct contact with the insect to be effective. In this study, we evaluate the efficacy of two traditional forms for SiO2 and SNPs against two different pests Bemisia tabaci, Aphis gossybsii under laboratory conditions. LC50 concentrations were measured after 24, 48, 72 and 96 hours, respectively. The SiO2 residues of traditional and their Nano particles were studied in leaves of mint, thyme, stems and soil, as well as the effect of drying and boiling techniques in the pesticide removal were also studied.
The results indicated that the cumulative mortality rate of white fly and cotton aphid increased with increased pesticide concentration and/or increased time. The highest value of mortality in the tested insects was recorded in 96 hours of traditional SiO2 application. In case of silica Nano particles (SNPs), the highest mortality rate of white fly values were observed at concentration of 2.50 µg/ml after 48 hours of treatment. While, the same mortality value was observed at 2.50 µg/ml after 24h of treatment for A. gossybsii. These results indicate that A. gossybsii was more susceptible to silica and Nano-silica particles SNPs than B. tabaci and that the Nano-silica particles SNPs are more effective than the traditional silica.
Conclusively, the results indicated that SiO2 of two forms plays the effective roles in integrated pest management and will be more effective when applied direct against white flies and aphis.