Presentation on theme: "BIOLOGICAL CONTROL OF THE MEXICAN BROMELIAD WEEVIL Ronald D. Cave Indian River Research & Education Center Ft. Pierce, FL."— Presentation transcript:
BIOLOGICAL CONTROL OF THE MEXICAN BROMELIAD WEEVIL Ronald D. Cave Indian River Research & Education Center Ft. Pierce, FL
How long has the weevil been in Florida? The weevil was first discovered in 1989 in a bromeliad nursery in Fort Lauderdale and is believed to have arrived on plants imported from Veracruz, Mexico. Via movement of infested plants and its own flight capabilities, it is now widespread in south Florida
Mexican Bromeliad Weevil Distribution in Florida Reported in 22 Florida counties from 1989 to 2006 (2 new county infestations in 2006) Currently known to occur in 21 counties (not seen in Miami- Dade County since before Hurricane Andrew) Pinellas Orange
Which of Florida’s native bromeliads are under weevil attack? Tillandsia fasciculata cardinal airplant (endangered) Tillandsia utriculata giant airplant (endangered)
Tillandsia paucifolia potbelly airplant Tillandsia balbisiana northern needleleaf (threatened) Tillandsia flexuosa twisted airplant (threatened) Which of Florida’s native bromeliads are under weevil attack?
After hatching from the egg, the developing larva (the immature stage) tunnels into the base of the stem. WEEVIL LARVA AND PUPA Before changing to an adult, the mature larva becomes a pupa, resting within a chamber it constructs inside the stem from shredded plant material.
WEEVIL ADULT Feeds mainly on leaves; may feed on the inflorescence. Females lay eggs in slits in the leaves close to where they feed.
What are the symptoms of weevil damage? Gel produced by plant Browning of leaves Decomposition of leaves at base (center leaves of plant can be pulled out easily)
How are bromeliad populations in parks and other natural areas being affected? In many county and state parks, bromeliads are disappearing at an alarming rate. For example, in the Savannas Preserve State Park in St. Lucie County, an area of terrestrially-growing T. utriculata was reduced to debris within a matter of months.
What federally protected natural areas is the weevil affecting? The weevil is destroying Tillandsia fasciculata populations in the Loxahatchee National Wildlife Refuge and the Big Cypress National Preserve. B. Larson / UF
Chemical control is not appropriate, because the weevil is found in parks and other natural areas where chemicals would adversely affect other organisms. Bromeliads are also inaccessible, due to their tree- dwelling lifestyle. Parasites that kill the weevil naturally have not been found in Florida. Classical biological control offers the most likely option. How can we manage the weevil?
How does classical biological control work? A natural enemy (called a biological control agent) is brought from the pest’s homeland. After testing shows the biological control agent will NOT attack beneficial organisms and appropriate permits are obtained, it is released where pest densities are greatest, with the hope it will become established in the area. The pest population is not eradicated completely, but is maintained over the long term at a very low level.
It is a species of parasitic fly called Lixadmontia franki. It specializes in eating bromeliad weevils ONLY. It does parasitize larvae of Metamasius mosieri, a native bromeliad-eating weevil, but prefers M. callizona larvae. What biological control agent can we use against the weevil? A potential biological control agent was found in Honduras and is now colonized in quarantine.
Fly Biology Preferably parasitize 3 rd and 4 th instar hosts Development time is 5-6 weeks Adult females live up to six weeks when provided hummingbird food and honey Adults are only attracted to bromeliads damaged by weevils
What has been done so far? A thriving colony maintained at the Panamerican School of Agriculture in Honduras, financed in large part by the Florida Council of Bromeliad Societies
>2,000 puparia received during 2005-2007 and a fly colony established at the Biological Control Research and Containment Laboratory in Ft. Pierce Space Hosts Food
What needs to be done? 1. Increase the fly colony and produce large quantities. 2. Release the fly in areas of high weevil concentration. 3. Evaluate the fly’s effectiveness (Teresa Cooper et al.)
Sites for release of Lixadmontia Savannas Preserve State Park Highlands Hammock State Park Myakka River State Park Bear Island area Big Cypress National Preserve Loxahatchee NWR 59 females on July 20 NASA Enchanted Forest Northwest Equestrian Park 27 females on June 29
QUESTIONS? Release of Lixadmontia franki at Loxahatchee NWR July 20, 2007