CAN PESTICIDE FORMULATIONS SIGNIFICANTLY INFLUENCE PEST BEHAVIOR - THE CASE OF TETRANYCHUS-URTICAE AND DICOFOL

Pesticide formulations profoundly influenced the encounter of pest wit h pesticide. In four differently formulated treatments of identical di cofol concentration, total time spent on treated areas of a checkerboa rd residue immediately following treatment varied dramatically from 13 .3% on Modified Formulation residues to 42.1% on 50 Wettable Powder re sidues. With 24 h old checkerboard residues, total time spent on treat ed areas varied from a low of 30.1% with Modified Formulation residues to a high of 45.1% with Emulsifiable Concentrate residues. Different formulations exhibited dramatically different decay of repellency over a 24 h period. The greatest loss of repellency was found on Modified Formulation residues, although this formulation was still the most rep ellent at 24 h. Observations were made of three behavior patterns with both 0 h and 24 h old residues of four formulations of dicofol. Our r esults indicate that the constituents of some pesticide formulations m ay elicit behavior that greatly reduces pest encounter with pesticide. To study this phenomenon it is necessary to observe pest behavior wit h discontinuous residues.