Cassava mealybug

Systematic position: The cassava mealybug (Phenacoccus manihoti) is a member of the order Hemiptera and the family Pseudococcidae. It is a highly destructive insect pest that has had significant economic impacts on agricultural production throughout its introduced range in Africa and other tropical regions.

Host plants: The primary host is the cassava plant (Manihot esculenta). The pest shows a high degree of host specificity, exclusively targeting cassava crops, which makes the management of this insect a major priority for food security in countries heavily dependent on this staple root crop.

Biology and life cycle: Phenacoccus manihoti reproduces mainly through parthenogenesis. Females lay eggs within a white, waxy ovisac located on the stems or leaf undersides. Upon hatching, the first-instar nymphs (crawlers) are highly mobile and disperse across the plant or are carried to neighboring plants by wind currents, allowing for rapid colonization.

Damage and severity: The pest feeds on the sap of young stems and leaves using its piercing-sucking mouthparts. This feeding process induces severe stunting, leaf curling, and apical necrosis. The accumulation of honeydew secreted by the insects often promotes the growth of sooty mold, which impairs photosynthesis and leads to significant reductions in root tuber yield.

Control measures: The most successful control strategy has been classical biological control using the parasitoid wasp Anagyrus lopezi. Integrated pest management (IPM) practices also emphasize the use of clean, pest-free planting material, strict quarantine protocols to prevent further spread, and the selection of resistant cassava varieties to minimize potential losses.