Diflubenzuron is an insecticide from the benzoylurea chemical class. It controls insect pests in forests, agricultural fields, and animal housing by interfering with insect development. Available in forms like suspension concentrates, wettable powders, or granules, it allows for diverse application methods.
Understanding How Diflubenzuron Works
Diflubenzuron functions as an insect growth regulator (IGR) by inhibiting chitin synthesis. Chitin, a complex sugar molecule, is a primary building block for the exoskeleton of insects and other arthropods. Without enough chitin, insects cannot properly form their outer shell during molting.
When insects, particularly larvae or nymphs, ingest or contact diflubenzuron, their chitin production is disrupted. This interference leads to deformities during molting, preventing them from developing a new, hardened exoskeleton. Consequently, affected insects cannot survive this developmental stage and die.
This mechanism is specific to chitin-producing organisms, primarily impacting insect larvae, nymphs, and eggs, rather than adults. It is understood to involve the disruption of chitin synthetase, an enzyme involved in the chitin biosynthesis pathway.
Common Applications of Diflubenzuron
Diflubenzuron is used in various sectors for pest control due to its specific mode of action. In forestry, it manages destructive defoliators like gypsy moths and forest tent caterpillars, which can severely damage trees. It is also effective against other leaf-eating insect larvae in forest and ornamental plants.
In agriculture, diflubenzuron targets pests on crops such as citrus, cotton, and mushrooms. It controls pests like boll weevils, various caterpillars, and leaf miners that infest fruit trees, vegetables, and cereal grains. Application methods include aerial spraying, hydraulic sprayers, or irrigation systems.
Diflubenzuron also finds application in public health and livestock management. It is used as a larvicide to control mosquito populations in standing water bodies and drainage systems, as well as flies and gnats around animal shelters and waste areas. For livestock, it can be incorporated into animal feed as a “feed-through” product to control fly larvae developing in manure.
Environmental and Health Considerations
Diflubenzuron exhibits low toxicity to vertebrates, including birds, mammals, and fish, because these organisms do not produce chitin. Studies show it is practically non-toxic to birds like bobwhite quail and mallard ducks. Similarly, it has low toxicity to various fish species, such as bluegill sunfish and rainbow trout.
The compound is also considered non-toxic to bees, which are beneficial insects. However, it is highly toxic to freshwater aquatic invertebrates, including crustaceans, negatively affecting their reproduction, growth, and survival. This toxicity extends to marine and estuarine mollusks and invertebrates.
In terms of environmental fate, diflubenzuron is relatively non-persistent in soil, with a short half-life. Biodegradation by soil microbes is its primary dissipation route. While generally stable to hydrolysis and photolysis, its persistence on leaf surfaces can be longer.
Human exposure to diflubenzuron is considered low, with studies showing low acute oral, dermal, and inhalation toxicity. The Environmental Protection Agency (EPA) classifies it as Toxicity Category III, indicating slight toxicity. The EPA regulates its use, requiring all products to be registered and to bear hazard statements warning about potential adverse effects to aquatic organisms. The Agency conducts comprehensive ecological and human health risk assessments to ensure its use does not pose unreasonable risks.