INVESTIGATIONS ON INSECTICIDAL ACTIVITIES OF SOME PLANTS TO MEALYBUG (Pseudococcus sp.) UNDER LABORATORY CONDITIONS

Mealybug Pseudococcus is a serious insect pest of many crops. They can damage plant by sap sucking directly or by transmission of many dangerous viruses. The toxicity of six plant methanol and aqueous extracts were investigated for insecticidal and repellent properties against second nymph of mealybug collected from sour sop under laboratory conditions. In bioassay, soursop methanol seed extract (20 % vol/vol concentration) was the most toxic to mealybug (caused 98.33 % mortality at three days after treating), followed by a tobacco methanol leaf extract (75 % mortality) at 10 %, chinaberry methanol leaf extract (61.67 %) at 20 %, wedelia methanol all plant extract (26.67 %) at 20 %, zanzibar gem aqueous leaf extract (25 %) at 20 % then onion aqueous bulb extract (16.67 % mortality) at 20 % concentration. LC50 of methanol extract of soursop seed, tobacco methanol leaf and chinaberry leaf to Pseudococcus sp. nymphs was 5.364, 4.436 and 11.809 %, respectively.