A probability model of vector behavior: Effects of DDT repellency, irritancy, and toxicity in malaria control

A probability model of how DDT residues may function within a malaria contr ol program is described. A step-wise organization of endophagic behaviors c ulminates in a vector acquiring a human blood meal inside the house. Differ ent vector behaviors are described, epidemiologically defined, temporally s equenced, and quantified with field data. Components of vector behavior and the repellent, irritant, and toxic actions of insecticide residues are the n assembled into a probability model. The sequence of host-seeking behavior s is used to partition the total impact of sprayed walls according to the t hree chemical actions. Quantitatively, the combined effect of repellency an d irritancy exert the dominant actions of DDT residues in reducing man-vect or contact inside of houses. These relationships are demonstrated with publ ished and unpublished data for two separate populations of Anopheles darlin gi, for Anopheles gambiae and Anopheles funestus in Tanzania, and Anopheles punctulatus in New Guinea.