18 



Insect growth regulators (IGR's) 



The first juvenile hormone was extracted from the abdomen of a 

 male cecropia moth over 20 years ago (Williams, 1956). Researchers have 

 since been trying to develop compounds showing juvenile hormone activity 

 for use as pesticides that would be specific for limited species of 

 target insects but would not be detrimental to the environment (Novak, 

 1375). House flies were sensitive to the early IGR's (Herzog and Monroe, 

 1972) as were mosquitoes (Spielman and Williams, 1966). Several books 

 are available giving the history, chemistry and mode of action of IGR ! s 

 (Novak, 1975; Gilbert, 1976; Menn and Beroza, 1972), and the types of 

 compounds exhibiting juvenile activity on insects (Slama, 1971). 

 Methoprene 



Methoprene, or ZR-515, has been widely tested for the control of 

 mosquitoes, house flies, and other diptera. Treatment residuals are 

 rapidly degraded by sunlight and the half life is only 2 to 2k hours 

 depending on the type of formulation (Schaefer and Dupras, 1373) - 

 Methoprene does not leach out of treated media into the environment 

 (Wright and Jones, 1976) and is not active against nontarget insects 

 in bovine fecal pats (Pickens and Miller, 1975). 



As a feed additive, methoprene gave significant fly control when 

 fed to cows at 2.5 mg/kg (Miller and Uebel , 1967). Breeden et al. ( 1 968) 

 fed methoprene to chickens in 86.9% technical and 1% encapsulated formu- 

 lations. The technical formulation at 50 and 100 ppm gave good fly 

 control 3 days and 1 day post-treatment respectively. The encapsulated 

 formulation at 5 and 10 ppm gave good control 8 and 2 days post-treatment 

 respectively. Adams et al. (1976) fed methoprene to hens for ^-2 days at 



