Control of Spodoptera spp. using ULV formulations of the acylurea insect growth regulator, flufenoxuron: Field studies with Spodoptera exempta and effect of toxicant concentration on contact activity

Abstract

AbstractField trials in Kenya showed that an ultra‐low‐volume (ULV) application of flufenoxuron (25 g a.i. litre−1; 1–0 litre ha−1) gave consistently good control of late‐instar larvae (L4‐L6) of the armyworm, Spodoptera exempta Walk. Flufenoxuron gave equivalent or greater control of S. exempta than did cypermethrin (24 g a.i. litre−1; 1–0 litre ha−1) from 96 h after ULV application. While initial (24–48 h) levels of larval mortality were greater with cypermethrin, many larvae treated with flufenoxuron showed signs of incomplete moulting after 48–72 h and would have been unable to feed normally. Laboratory spray bioassays with L3 Spodoptera littoralis suggested that the ULV formulation of flufenoxuron was most active at 25 g a.i. litre−1 when compared with higher (50 g) or lower (6.25 and 12.5 g a.i. litre−1) rates. Topical application studies with ULV formulations containing [14C]flufenoxuron showed that the accumulation of pesticide by L3 S. exempta over 1–4 h was consistently greater in larvae treated with 25 g than with 12.5 g flufenoxuron litre−1 and while initially lower, accumulation of pesticide appeared to be greater in larvae treated with 25 g than with 50 g flufenoxuron litre−1 after 2–4 h. The potential of ULV formulations of flufenoxuron for control of S. exempta is discussed.