Evaluation of Cell-Free Supernatant from Xenorhabdus nematophila Bacteria and Two Insecticides against Mealybug Phenacoccus solenopsis under Laboratory and Field Conditions
Evaluation of Cell-Free Supernatant from Xenorhabdus nematophila Bacteria and Two Insecticides against Mealybug Phenacoccus solenopsis under Laboratory and Field Conditions
Ahmed Shamkhi Jabbar1* and Saadoon Murad2
ABSTRACT
Mealybug Phenacoccus solenopsis is one of a group of highly aggressive and invasive insect pests. Leaving large numbers of P. solenopsis on host plants can cause significant economic losses and damage. The effectiveness of commercially available chemical insecticides and biopesticides against cotton mealybugs was evaluated under lab and field conditions by using the secreted toxins of symbiotic bacteria Xenorahbdus nematophlia, Blaiser® as a biopesticide, and chemical pesticide Sivanto®. Our results indicate that the efficacy of secreted toxins by symbiotic bacteria X. nematophlia was the highest after the chemical pesticide Sivanto® and superior to the biopesticide Blaiser®, as the effectiveness recorded was (98.72%), while it was (100%) and (93.3%) for the chemical and biological pesticides, respectively, during the test period of 24-72 hours. The LC50 values after 48 and 72 hours of spraying free cell suspension of X. nematophila bacteria were 29.178 and 17.788. In contrast, the LC50 values for Blaiser® were 28.118 and 25.907, respectively. The more toxicity increased with the increase in the exposure period compared to the chemical compound Sivanto®. The results confirmed that the use of a free cell suspension of X. nematophlia bacteria gave excellent and promising results in controlling the mealybug P. solenopsis, comparable to and sometimes superior to pesticides of chemical origin.
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