Using Silica Nanoparticles and Neemoil Extract as New Approaches to Control Tuta absoluta (Meyrick) in Tomato under Field Conditions

Aims: This study aimed to evaluate the efficacy of silica nanoparticles and neem oil extract at different concentrations compared with recommended chemical insecticide (imidacloprid) against T. absoluta under field conditions.
Study Design: Seven treatments plus control in randomized complete block design (RCB) at four replicates.
Place and Duration of Study: This experiment was carried out at El-Ryiad region, Kafr El-Sheikh Governorate under field conditions during two tomato growing seasons; 2012 and 2013.
Methodology: About 0.14 hectar (1400 m2) was transplanted with Star variety seedlings as one of the most common variety cultivated at Kafr El-Sheikh region. Recommended agricultural practices were adopted normally. The nano silica size was 20 nm with a purity of 99.99% at three concentrations and neem oil at three concentrations also compared with chemical insecticide with recommended dose. To calculate the percentage of T. absoluta reduction, Henderson Tilton's formula was used. Also, the number and the weight of tomato fruits at harvest from 20 plants (5 plants/replicate) were recorded and estimating the Vitamin C (mg/100 g of sample) and Total Soluble Solids percentage (TSS %) as a quality parameters.
Results: Using silica nanoparticles reduced significantly the numbers of T. absoluta larvae followed by neem oil extract compared with check (without any treatments). There were not significant differences between using silica nanoparticles and imidacloprid (p>0.05) in control T. absoluta. There were not significant differences when analyzing the content of tomato fruits resulting from the different treatments compared to the check, however, must be taken into account the residual impact of the chemical pesticide. The results also showed a significant increase in the weight and size of tomato fruits as a result of the silica nanoparticles treatment.
Conclusion: Silica nanoparticles was effective in control T. absoluta under field condition with high yield in tomato. Also, we need more study to showed the side effects on natural enemies during using silica nanoparticles.