Evaluation of selected biorational and synthetic chemical insecticides for controlling Phenacoccus solenopsis (Hemiptera: Pseudococcidae) under field conditions

Phenacoccus solenopsis Tinsley, commonly known as the cotton mealybug, is a significant pest found in various regions worldwide. This polyphagous insect has become a serious problem on agricultural crops, ornamental plants, and certain trees in Khuzestan province. The primary method of controlling this pest is through the use of insecticides. However, applying insecticides, especially in urban green spaces, presents challenges due to direct exposure to the public and various restrictions. In this study, the effectiveness of six biorational and conventional synthetic chemical insecticides (azadirachtin, indoxacarb, flupyradifurone, spinosad, Lecanicillium muscarium as an entomopathogenic fungus, and imidacloprid) against this pest was evaluated under field conditions. The results showed that flupyradifurone had the greatest impact on reducing the population of P. solenopsis compared to the control (85.41% the insect abundance reduction comparing to control). The insecticides demonstrated a significantly higher efficacy when applied at the recommended field concentration of 100% compared to 50% of the recommended concentration. Furthermore, over time (from 1 to 14 days after application), there was a gradual decrease in pest density, indicating a progressive effect of the pesticides on the pests. Azadirachtin can be considered as an effective insecticide against this pest, but it requires a minimum two-week delay for optimal results.