Mango seed weevils are a hidden but highly destructive pest that infest the seeds of mango fruits. Unlike fruit flies, which damage pulp, these weevils target the seed itself, impacting both reproduction and commercial value.
The Interior Saboteur: Mango Seed Weevils
The Mango Seed Weevil (Sternochetus mangiferae) is a specialized pest that presents a unique challenge to fruit growers: its presence is often completely undetectable until the mango is sliced open. This small, dark-brown snout beetle is a major quarantine pest, restricting the international trade of mangoes from infested regions due to its ability to hitchhike inside the fruit’s stone.
Invisible Infestation and Life Cycle
The life cycle of the Mango Seed Weevil is perfectly synchronized with the development of the mango fruit. The female lays her eggs on the surface of very young, green fruit. Once the larvae hatch, they bore through the flesh with incredible speed, heading directly for the soft, developing seed. Remarkably, the tiny entry wound heals over almost immediately, leaving no external scar or sign of entry on the ripening fruit.
- Seed Destruction: The larva spends its entire life inside the seed, consuming the embryo. While the fruit flesh usually remains edible, the seed is rendered non-viable for planting.
- Pupation: The weevil transforms into an adult within the hollowed-out shell of the seed.
- Post-Harvest Emergence: In many cases, the adult only emerges after the fruit has fallen and decayed, though in some varieties, the weevil may tunnel out through the ripe flesh, causing premature rotting.
Management and Sanitation
Because the larvae are shielded by both the fruit and the hard seed coat, foliar sprays are largely ineffective once the eggs have hatched. The most critical control measure is orchard sanitation. Fallen fruit must be collected and destroyed (burned or deeply buried) to prevent the adults from emerging and overwintering in bark crevices. In commercial settings, some success has been found using “culling” techniques and strict heat treatments to ensure exported fruit is weevil-free.
Identification
Adult weevils are small beetles with elongated snouts typical of the Curculionidae family. Larvae develop inside the seed, making detection difficult.
Life Cycle
Females lay eggs on fruit surfaces. Larvae penetrate the fruit and bore into the seed, where they develop. Pupation occurs within the seed, and adults may remain dormant until conditions are favorable.
Damage
Damage includes reduced seed viability and compromised fruit quality. Infested fruit may be rejected in export markets due to quarantine concerns.
Control
Control focuses on sanitation, inspection, and removal of infested fruit. Heat treatment and strict quarantine measures are often necessary in commercial production.