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 citrusmealy 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 under 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.