Measurements of the Hansen solubility parameters of mites and cockroaches to improve pest control applications

Various pests, such as cockroaches and mites, can negatively affect agriculture and human health. Many pesticides have been developed to control these pests. The surfaces of pests are hydrophobic, so an insecticide in an aqueous solution will be repelled by the surface of a pest and therefore will not be effective. Adding a spreading agent (e.g., a surfactant) will improve the ability of a pesticide solution to wet pest surfaces and therefore improve the ability of the active ingredient to permeate and kill pests. Efficiently killing insects requires the insecticidal component to have an affinity for the pest surface. This affinity was assessed here using the Hansen solubility parameter, which is a quantitative measure of the affinity between two substances. We determined HSPs of mites and cockroaches using Hansen solubility sphere method. The HSPs of mites were δ(d) = 16.4 (MPa)(1/2), δ(p) = 2.6 (MPa)(1/2), and δ(h) = 4.7 (MPa)(1/2). The one HSPs of cockroaches were δ(d) = 15.5 (MPa)(1/2), δ(p) = 20.4 (MPa)(1/2), δ(h) = 20.2 (MPa)(1/2), and others were δ(d) = 17.6 (MPa)(1/2), δ(p) = 2.8 (MPa)(1/2), and δ(h) = 3.8 (MPa)(1/2). The HSPs of cockroaches showed two values of hydrophobicity and hydrophilicity. Finally, we proposed new derived guidelines for using Hansen solubility parameters in research into pest control agents.