Efficiency of Metarhizium spp. (Sorokin) Strains and insecticides against cotton mealybug Phenacoccus solenopsis (Tinsley)

We conducted a study to assess the insecticidal potential of the hypocreales entomopathogenic fungi (epf) metarhizium spp. strains,insecticides and their mixture for control of cotton mealybug (cmb) under laboratory,screen house and field conditions. the strain pdrl526 was the most effective amongst the strains of metarhizium spp. at laboratory bioassays. it caused 50% mortality (lt50 value) of adult cotton mealybug at 5.2 days (lt50 value = median lethal time) after the application of 1.57x105 spore/cm2 (6.3x1012 spores/acre) inside the bioassay chamber. therefore,the strain pdrl526 was selected to study at the screen house and field trials. the insecticide lambda-cyhalothrin was highly effective with 50% lethal concentration (lc50 value) (1.12 μg/ml) followed by acetamiprid (1.17 μg/ml),abamectin (1.62 μg/ml),imidacloprid (1.67 μg/ml),chlorpyrifos (2.09 μg/ml) and bifenthrin (3.05). the insecticide imidacloprid showed the best compatibility (95.2%) to the strain pdrl526; therefore,imidacloprid was selected for screen house and field trials. the strain caused adult cmb mortality after (lt50) 13.8 and 19.6 days by using 6.3 x1012 spores/acre,under screen house and field conditions,respectively. the strain's application in combination with insecticide imidacloprid (20 g a.i./acre + 6.3x1012 spores/acre) showed a positive toxicity/virulence to cmb population at screen house and field trials with lt50 6.57 and 8.4 days,respectively. along with the pest mortality,the yield of seed cotton/plant,increased with the spray of spores of the strain pdrl526,alone or in combination with imidacloprid,at screen house and field trials as compare to control treatments. the study confirmed that m. anisopliae strain pdrl526 is effective against cmb. copyright © 2015 zoological society of pakistan.