Application rate trials with a nuclear polyhedrosis virus to control Spodoptera littoralis (Boisd.) on cotton in Egypt

Abstract A locally produced wettable powder formulation of a nuclear polyhedrosis virus (NPV) was applied to cotton in Egypt to control the Egyptian cotton leafworm, Spodoptera littoralis . The virus was sprayed at three different applications rates, 5 × 10 11 , 1 × 10 12 and 5 × 10 12 polyhedral inclusion bodies (p.i.b.) ha −1 , using a knapsack sprayer fitted with a cotton tailboom. The level of control, reflected by crop damage levels, was compared with the traditional method of controlling leafworm, the hand collection of egg masses. Control with the NPV was shown to be dose dependent and an application rate of 1 × 10 12 p.i.b. ha −1 resulted in a level of control equivalent to the hand collection of egg masses. This represented a five-fold reduction in the virus dose previously used.