Xp. Hu et al., CONTROLLED-RELEASE OF SUGAR AND TOXICANT FROM A NOVEL DEVICE FOR CONTROLLING PEST INSECTS, Journal of controlled release, 50(1-3), 1998, pp. 257-265
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.