Field Assessment of Certain Chemical and Biological Control Agents against the Mealybug Phenacoccus solenopsis (Tinsley)

This study was conducted as a field application to assess the efficacy of using some chemical and biological control agents against the cotton mealybug Phenacoccus solenopsis Tinsley, nymphs and adults. The findings indicated that the highest densities of P. solenopsis, nymphs and adults were recorded in July, 46.12 and 33.18 insects per square inch respectively, whereas the lowest densities occurred in January, with 6.31 and 1.24 insects per square inch, respectively. The results revealed notable seasonal variation in infestation rates. The highest infestation rate (94.00%) was observed in July, while the lowest (20.16%) was observed in November. Evaluation of chemical and biological pesticides showed that the most effective treatment was the insecticide (Lambda-cyhalothrin 5% EC), which resulted in mortality rates of (85.82%) for nymphs and (83.13%) for adults. While, the Trichoderma harzianum, recorded mortality rates for nymphs and adults (70.43%) and (61.97%), respectively. Statistical analysis showed significant differences between the chemical insecticides and the biological agents. Among the biological treatments, the biopesticide mixture containing Trichoderma viride, Trichoderma harzianum, and Bacillus subtilis proved to be the most effective against both life stages.