Silica Nanoparticles Boosted Abamectin's Acaricidal Bioactivity Against Tetranychus urticae Koch's Two Spotted Spider Mite Developmental Stages

Under laboratory conditions, the sub-lethal effects of four agents [silica bulk, silica nanoparticles (NPs), two synthesis agents (silica bulk-abamectin, silica NPs-abamectin)] were compared to one synthetic acaricide (abamectin) against Tetranychus urticae immature stages. Sublethal concentrations (LC₂₅) of the tested agents against adult females of T. urticae were determined using standard bioassay procedures. The effects of sublethal concentrations of the investigated compounds on egg deposition and egg hatchability were measured over five days at 22 and 28 degrees Celsius, respectively. The effects of the investigated substances on the duration (in hours) of T.urticae developmental phases were evaluated at two different temperatures 22 and 28 ^oC. The results showed that silica nanoparticles (NPs) coated with abamectin had a significant influence on egg deposited decrease by T. urticae adult females. By the way, silica NPs-abamectin was the most effective therapy for egg deposition and hatchability over five days at 22 and 28 ^oC respectively, followed by abamectin. Furthermore, silica NPs-abamectin was found to be very beneficial in prolonging the length (in hours) of T.urticae developmental stages at different temperatures. This research reveals that silica bulk and silica nanoparticles (NP) might be employed as replacements for conventional acaricides and are compatible with IPM approaches. They could be useful in the future for pest management.