Submitted to: Controlled Release Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/8/1997
Publication Date: N/A
Interpretive Summary: The apple maggot is a major pest of apples in eastern and central North America. To control apple maggot flies, growers apply synthetic pesticides in spray formulations using large volumes of water. In efforts to reduce pesticide use, scientists have been examining the behavior of the adult fly to develop devices that might lure and kill the fly before it can lay eggs that develop into the damaging stage of the pest. We have discovered a new device that aids this effort. Cornstarch, sugar and other ingredients were molded into the shape of an apple and then coated with a mixture of paint, sugar and a very small amount of pesticide. Apple maggot flies, attracted to the area by a volatile scent placed in the orchard, are attracted to the device by color and shape and will alight on the surface. The sugar in the paint entices the fly to feed on the surface, thus the fly ingests a lethal dose of pesticide. Pesticide residue levels on the surface of the artificial apple are less than those found on leaves of a tree sprayed through conventional practices. Current forms of the artificial apple remain intact for approximately 11 weeks and then start to degrade. This new device has the potential to be used for a variety of insect control applications through manipulating its shape, color and texture into forms known to be attractive to target insects and by employing toxicants designed to be effective against specific pests.
Technical Abstract: A novel biodegradable device, designed for long-lasting residual effectiveness of feeding stimulant (sugar) and insecticide (dimethoate) against apple maggot flies and other insects, was formulated. The device is an 8-cm diameter fruit-mimicking sphere, consisting of 42-50% sugar entrapped in a mixture of gelatinized corn flour and wheat flour in the presence of glycerine, and coated with a layer of latex paint containing dimethoate and sugar. We found that the outer layer of paint prevents cracking of the sphere upon drying and creates a barrier to control the release of both sugar and dimethoate. Releases of each ingredient were screened first by chemical analysis and then by bioassays in the laboratory and in field cages against apple maggot flies. Chemical analysis demonstrated strong potential for controlled release of water-soluble feeding stimulant and water-insoluble insecticide measured as a function of the amount of rainfall and duration of exposure time. Field results showed greater than 70% insecticidal activity after 11 weeks of sphere exposure in an orchard. This device has the potential to be used for a variety of insect control applications through manipulating its shape, color, and texture into forms known to be attractive to target insects, and by employing various toxicants designed to be effective against such insects.