Mealy bugs are pests of

Step 1: Analyze the question The question asks which crop is attacked by mealy bugs. These are small, soft-bodied, sap-sucking insects covered with a white, powdery or waxy coating, which looks like flour or meal. That coating is how they got their name.

Step 2: Explain the concept Mealy bugs (order Hemiptera) feed on plant sap and weaken the plant. In Nigerian agriculture, the cassava mealybug (Phenacoccus manihoti) is a famous, serious pest. It causes stunted growth, leaf curling, and a "bunchy top" appearance, which leads to heavy yield losses. This pest was controlled in West Africa through a biological control programme led by IITA in Ibadan, which used a parasitic wasp, Apoanagyrus lopezi.

Step 3: Check the options

• A. Cassava: Correct. The cassava mealybug is a major pest of this crop.
• B. Cotton: Cotton is mainly attacked by bollworms, stainers and aphids. Some mealybugs do attack cotton in other regions, but they are not the classic answer for this question.
• C. Maize: Common pests are stem borers and armyworms.
• D. Rice: Common pests are stem borers, rice weevils and gall midge.
• E. Yarn: Yarn is a processed thread, not a crop.

Step 4: Answer The correct option is A. cassava.

Exam tip: Link the pest with its crop using a pair of words:

• Mealybug → Cassava
• Stem borer → Maize
• Bollworm → Cotton
• Weevil → Stored grains

Pairing pests and crops like this will help you answer many NECO and JAMB agricultural biology questions quickly.