Efficacy of Cryptolaemus montrouzieri in Biological Control of Planococcus citri on Solenostemon scutellarioides Under Greenhouse Conditions

Citrus mealy bug، Planococcus citri (Risso) is one of the most common and well known pest insects of ornamentals. Coleus، Solenostemon scutellarioides (L.) Codd is a suitable host of the mealybugs. Mealybug destroyer، Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) is a polyphagous predatory coccinellid، employed in biological control programs against citrus mealy bug. The present work was carried out to study the efficacy of this predator (biological control agent of citrus mealy bug) on coleus (red variety) and to determine the most suitable releasing rate of the predatory coccinelid in greenhouse conditions. The same-aged coleus plants were infected by 2nd and 3rd in stars of the mealy bug nymphs. Following the pest establishment، mealy bug destroyers were released on plants at the rates 1، 2، 3 and 4 coccinelid/ plant as four treatments along with a non-treated plant used as check. Any of the treatments was replicated 4 times. Efficacy in each treatment was determined through Handerson-Tilton method within the period of one to 15 days after releasing the predator. ANOVA revealed statistically significant differences within treatments. The treatments bearing 2، 3، and 4 coccinellids / plant exerted the highest effect in biological control of the mealy bug and were statistically placed in one group. On the 15th day following the release of the predator، there was no statistically significant difference observed between the treatments of 3، vs 4 coccinellid/ plant. Based on the achieved results، releasing 2 coccinelid/ coleus plant in greenhouse conditions can provide more than 92% efficacy in biological control of the mealy bugs.