Sustained-release bolus for horn fly (Diptera: Muscidae) control: effects of methoprene and diflubenzuron on some nontarget species

Dung from cattle treated with sustained-release boluses containing either methoprene or diflubenzuron was bioassayed biweekly for 27 wk with the horn fly, Haematobia irritans (L.); two species of dung-burying beetles, Onthophagus gazella (F.) and Sisyphus rubrus Paschalidis; and two species of dung-inhabiting predators, Philonthus flavolimbatus Erichson and P. longicornis Clark. When reared on dung from a steer treated with the methoprene bolus, emergence of adult born flies was reduced 37.5-99.49% during the first 25 wk and 8.3% at 27 wk when compared with emergence of horn flies reared on untreated dung. Adult born fly emergence, when reared on dung from a steer that received the diflubenzuron bolus treatment, was reduced 82.9-100% over a 21-wk period, but there was no reduction at 27 wk. Emergence of adult 0. gazella and S. rubrus from brood balls made with dung from a steer treated with a diflubenzuron bolus was reduced for 7 wk after treatment. Dung from the methoprene-treated animal had no apparent effect on the reproduction of either dung beetle species. There was no apparent effect on P. flavolimbatus and P. longicornis when reared on dung from steers treated with either methoprene or diflubenzuron.