Insecticide Resistance in Seven Orlando House Fly Colonies

Abstract

House fly (Musca domestica L.) colonies were exposed to various insecticides in studies of the development of resistance. The No.1 colony, in which experimental development of resistance to DDT was first demonstrated, is in the 270th generation and is maintained in cages coated with DDT; resistance is indicated to be greater than 500-fold. Selection in the LDD colony, now in the 164th generation, is maintained by constant exposure to treated panels. The colony shows to-fold resistance to lindane, immunity to dieldrin, and 60- to 100-fold resistance to DDT. The C colony, exposed to 0.02% Dipterex in the diet, showed about 10-fold resistance when collected and developed no additional resistance in 98 generations of selection. The Bayer 21/199 colony developed greater than 90-fold resistance to this insecticide in .50 generations, the Grothe colony showed 52-fold resistance to malathion when collected and 100-fold resistance after 20 generations, the Tropical D colony showed 34-fold resistance to Diazinon when collected and 18-fold resistance after 20 generations, and the Tropical P colony showed greater than 18-fold resistance to parathion when collected and no increase in resistance after 20 generations; selection in these colonies was made with contact sprays.