The agricultural use of silica (SiO2) nanoparticles (NPs) has the potential to control insect pests while the safety and tritrophic effects on plants and beneficial natural enemies remains unknown. Here, we evaluate the effects of silica NPs on insect pests with different feeding niches, natural enemies, and a plant. Silica NPs were applied at different concentrations (75–425 mg/L) on field-cultivated faba bean and soybean for two growing seasons. The faba bean pests, the cowpea aphid Aphis craccivora and the American serpentine leafminer Liriomyza trifolii, and the soybean pest, the cotton leafworm Spodoptera littoralis, were monitored along with their associated predators. Additional laboratory experiments were performed to test the effects of silica NPs on the growth of faba bean seedlings and to determine whether the rove beetle Paederus fuscipes is attracted to cotton leafworm-infested soybean treated with silica NPs. In the field experiments, silica NPs reduced the populations of all three insect pests and their associated predators, including rove beetles, as the concentration of silica NPs increased. In soybean fields, however, the total number of predators initially increased after applying the lowest concentration. An olfactometer-based choice test found that rove beetles were more likely to move towards an herbivore-infested plant treated with silica NPs than to a water-treated control, suggesting that silica NPs enhance the attraction of natural enemies via herbivore-induced plant volatiles. In the laboratory, while silica NPs inhibited the development of faba bean roots at 400 mg/L, they did not affect germination percentage, germination time, shoot length, or vigor index compared to the control.

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This experiment was carried out at El-Riad region, Kafr El-Sheikh Governorate during two sugar beet successive seasons, 2013 and 2014. The aim of this study examined the efficiency of silica nanoparticles, bioinsecticides (Dipel 2X and Biofly), peppermint extract and insecticide (Match 50% EC) in controlling the cotton leafworm, Spodoptera littoralis (Boisd.) and their effects on some associated natural enemies in sugar beet. Results showed that the chemical insecticide (marshal) was the highest efficiency in controlling the cotton leafworm flowed by silica nanoparticles in high rate. Data showed also the extract of peppermint attractive the natural enemies to sugar beet filed and made moderate control the cotton leafworm.

Since nanotechnology entered the field of agriculture, its safety impact on crops has been a high priority interest. Here, we aimed to evaluate the effect of two different types of nanoparticles (n-), n-SiO 2 and n-TiO 2 , on the above-and belowground growth and the root-tip cell mitosis of broad beans (Vicia faba L.), one of the major carbohydrate food sources as well as an ecotoxicological model plant. Seeds were soaked in n-SiO 2 and n-TiO 2 each at different concentrations (25, 50 and 75 mg/L) for 24 h. Nano-TiO 2 decreased vigor index, reflecting shorter shoots at all concentrations studied. By contrast, germination percentage and root length were not affected by any treatments. Cytological analysis suggested no significant difference in mitotic index (index for cell division activity) from the control. However, total chromosomal aberrations (%) were increased dose-dependently by n-SiO 2 and dose-independently by n-TiO 2. Also, different types of chromosomal abnormalities were induced by the nanomaterials; n-SiO 2 induced bridges at 50 and 75 mg/L, whereas n-TiO 2 induced breaks at 50 mg/L. In addition, cells in prophase were more frequently observed and those in anaphase less frequently seen with decreasing n-SiO 2 concentrations. We concluded that n-TiO 2 was more toxic than n-SiO 2 for broad bean chromosomes and early plant development at the concentrations studied. Finally, our review indicates the lack of evidence of germination enhancement by n-TiO 2 in Poaceae, a large monocotyledon family, which may require further attention.

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