Silica nanoparticles and variety: their efficacy and interaction on the tomato fruit worm (Helicoverpa armigera hubner) population infesting tomato (Solanum lycopersicum L.)

Field experiments were conducted at the Teaching and Research Farms of the University of Maiduguri and Mohamet Lawan College of Agriculture, Maiduguri, Nigeria to determine the effects of silica nanoparticles and tomato variety on the tomato fruit worm (Helicoverpa armigera Hübner) (Lepidoptera: Noctuidae). The treatments each replicated thrice were factorially combined and laid out in a split-plot design with four tomato varieties namely: UC-82, Dan Syria, Roma VF and Tima and three concentrations of amorphous silica nanoparticles (1000 ppm, 2000 ppm and 3000 ppm) and cypermethrin (as a check). Insecticides were applied during the fruiting stage at 7 days interval for 8 weeks. Larval holes and marketable fruit yield were recorded. Silica nanoparticles at 3000 ppm resulted in fewer larval population (39.25) at p < 0.05 with a resultant decrease in number of damaged fruits (36.58) as compared to lower doses of 1000 ppm and 2000 ppm. Cypermethrin also gave minimum population of larvae (39.12). In all tested varieties, Roma VF had the lowest larval population (28.79). Variety Roma VF in combination with both cypermethrin and silica nanoparticle at 3000 ppm resulted in lower larval population (19.67) and (28.67) respectively. These results show that silica nanoparticle at 3000 ppm acting together with Roma VF appreciably controls H. armigera in tomato, making both practices important components of IPM against this larval pest.