SAVE FLORIDA'S BROMELIADS CONSERVATION PROJECT
The Mexican Bromeliad Weevil
The Mexican bromeliad weevil (Metamasius callizona (Chevrolat)) (Coleoptera: Curculionidae) is a bromeliad-eating weevil (Frank and Cave 2005). The weevil is a specialist herbivore of bromeliads and consumes only those plants in the family Bromeliaceae. In its native range (Mexico, Guatemala, and Belize), the weevil does not cause damage to its host bromeliad populations. But in Florida, where the weevil was discovered in 1989, the weevil is causing great damage to Florida's native bromeliads.
The adult Mexican bromeliad weevil is 1 - 1.5 cm (0.4 - 0.6 in) long, black, and has a strip across its wings. The stripe may be red, yellow, or orange, or occasionally not present or minimally present. The weevil has elbowed antannae and the classic weevil snout.
Weevil Life History
Egg and adult
The Mexican bromeliad weevil has 4 life stages: egg, larva, pupa, and adult. After mating, an adult female will lay an egg in the leaf of a bromeliad (Salas and Frank 2001). About 8 days after the egg is oviposited (at 25 degrees C, 65% RH), a larva hatches from the egg and begins mining the leaf. Eventually, the weevil grows too large for the leaf and begins eating the stem of the plant. The larva eats and grows for about 5 weeks, then creates a pupal chamber from plant material and pupates. About 12 days later, an adult emerges from the pupal chamber and the cycle starts over.
Arrival and Spread of the Weevil in Florida
In 1989, inspectors from the Florida Department of Agriculture found weevils in bromeliads in a nursery in Ft. Lauderdale, Broward County (Frank and Cave 2005). Surveys in surrounding natural areas showed that the weevil was already established in native bromeliad populations and could not be eliminated (Frank and Thomas 1994). The weevils in the nursery were killed using chemicals, but it was too late to contain or kill the weevils that had escaped to the wild.
The 12 species of Florida's bromeliads that are attacked by the weevil range from central to southern Florida. The bromeliads are restricted by cool weather; the range of the weevil is restricted by the range of the bromeliads (Cooper and Cave 2016).
Since 1989, the weevil has spread to nearly fill its new range (Frank 1996). Within the first year of its arrival, the weevil was found on the west coast of Florida, probably transported on infested bromeliads carried by humans. The weevil is capable of spreading on its own quite well, however.
The weevil is now in 22 counties. Those counties without weevil sightings (Hardee, Monroe, and Miami-Dade, where the weevil was found in a park in 1991 but, after Hurricane Andrew in 1992, was not found in the park) may be due to a lack of surveys.
The weevil is native to Mexico, Guatemala, and Belize and came to Florida on ornamental shipments of bromeliads. In 1992, Frank and Thomas (1994) traced the probable origin of those bromeliads to infested shade houses in the state of Veracruz, Mexico.
Weevil Damage on Bromeliads
Weevil larvae kill the plant by chewing the meristematic tissue (Frank and Thomas 1994). This action causes the core of the bromeliad to fall out of the plant to the forest floor. When the weevil first arrived in Florida, fallen bromelaid cores were found littering the floors of weevil infested forests.
The fallen core has a very distinctive look. The leaves are loosely held together and they have an "exploded" look. If you pick up the core, the base is without roots, and there are large, ragged chew marks on the bases of the leaves (made by the weevil larva).
Sometimes you will find a brown gelatinous substance that is thought to be a defensive response made by the plant (Frank and Thomas 1994). It does not protect the plant from the weevil.
The weevils have a preference for larger plants and even mine the inflorescence of reproducing plants (Frank and Thomas 1994, Cooper 2006), destroying seeds that are much needed to create the next generation of plants. The weevil is able to persist on the smaller, younger plants.
Weevil specimens can often be found in freshly fallen bromeliad cores. In large bromeliads, several specimens of different life stages may be found in a single plant.