No formal trials of chemicals have been conducted against any stage of M. callizona - the potential market is too small for a chemical company to be interested in funding such a study.
On general principles, Short (1992) recommended use of Dursban for controlling weevil larvae and adults in ornamental bromeliads. He suggested mixing half an ounce of Dursban 50W per gallon of water for application as a preventive spray every two to three months. Dursban 50W may be used also as a dip for bromeliads at reduced concentration (a third of an ounce per gallon of water).
Some bromeliad enthusiasts have been reluctant to use Dursban because they fear it may be phytotoxic. Some of them have told us they have used Sevin successfully to kill M. callizona, but we do not know the dosages that were used. Cygon is ineffective (McKenzie 1990). Marathon (imidacloprid), has been reported as effective in treating Mexican bromeliad weevil larvae on Alcantarea imperialis and native Tillandsia utriculata. No phytotoxicity was seen on plants treated twice (in early spring and early summer) with the systemic, granular insecticide (McAlpin 2003).
Chemical pesticides can be used successfully to kill weevil larvae and adults on ornamental bromeliads in greenhouses, shade-houses, and even outdoors when the plants are grown near to the ground and can be reached by directed chemical sprays. Directed spraying of plants that are growing high in trees is difficult because the plants are hard to reach by ground-based equipment, so is expensive. Aerial (non-directed) spraying of such plants at effective dosages of chemicals would kill many many non-target organisms, so will not be permitted in parks and natural areas.
Chemical pesticides can be used to kill Metamasius weevils attacking fields of pineapples, but restrictions on use of such chemicals are much more stringent because pineapples are a food crop. In Hawaii, the pesticide Thiodan is labelled for use against pests of pineapples, and might be useful to kill weevils, though, because there are no weevils attacking pineapples in Hawaii, there is no practical experience. Thiodan 2EC at 1 tablespoon per gallon of water (or 1.5 quarts per 100 gallons of water) should be legal to use and effective (D.E. Short, pers. com.).
For the control of the sporadic outbreaks of M. callizona in pineapple fields in Mexico, a recent recommendation was Sevin 5% G (carbaryl) at 1 gram per fruit, or 2.5 liters of methyl parathion 50% per hectare to be sprayed on the stem and base of the plant (Rebolledo et al. 1998). Residues of these chemicals on pineapples exported to the USA would make them unacceptable.
Use of chemical pesticides as a dip to treat bromeliads before shipment is a recommended way to reduce the risk of shipping weevils.
We have no license for dispensing advice on chemical control, so we cannot make recommendations. We can only report what others have told us.
revised 01/03
