CONTROLLED-RELEASE OF SUGAR AND TOXICANT FROM A NOVEL DEVICE FOR CONTROLLING PEST INSECTS

A novel biodegradable device, designed for long-lasting residual effec tiveness of feeding stimulant (sugar) and insecticide (dimethoate) aga inst 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 t he presence of glycerin, and coated with a layer of latex paint contai ning dimethoate and sugar. We found that the outer layer of paint prev ents cracking of the sphere upon drying and creates a barrier to contr ol the release of both sugar and dimethoate. Releases of each ingredie nt were screened first by chemical analysis and then by bioassays in t he 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. F ield results showed greater than 70% insecticidal activity after 11 we eks of sphere exposure in an orchard. This device has the potential to be used for a variety of insect-control applications through manipula ting its shape, color and texture into forms known to be attractive to target insects, and by employing various toxicants designed to be eff ective against such insects. (C) 1998 Elsevier Science B.V.