Management of Spodoptera frugiperda J.E. Smith Using Recycled Virus Inoculum from Larvae Treated with Baculovirus under Field Conditions

SIMPLE SUMMARY: Maize is the staple food in Sub-Saharan Africa and a source of livelihood for millions of smallholder farmers. Constraints in production, which include pest damage, lead to loss of production and hunger. Since its arrival in Kenya in 2016, fall armyworm (FAW) has caused huge destruction. Chemical control is the preferred choice by farmers despite its negative effects. Baculoviruses offer a sustainable alternative to pesticides. However, their cost and special storage requirements make them unattractive to smallholder farmers, especially where repeat applications are required. The potential to use recycled virus inoculum from FAW larvae treated with a commercial baculovirus product has not been documented. This study evaluated the efficacy of recycled virus inoculum from larvae treated with Littovir, a commercial product, under laboratory and field conditions. Under laboratory conditions, the recycled virus inoculum caused varying mortality in different FAW instars, with the highest mortality recorded in the 1(st)–3(rd) instars. Under field conditions, the recycled virus inoculum produced maize yield comparable to that of commercial insecticides but similar to that of the control. This study has highlighted the potential of recycled virus inoculum from larvae treated with a commercial product. This approach offers affordable means of controlling FAW since farmers only need to purchase the commercial product once and can use recycled virus inoculum from treated larvae for repeat applications. ABSTRACT: Fall armyworm (FAW) is a major pest of maize and causes huge losses. Chemical pesticides are the commonly used control strategy among farmers. The efficacy of baculoviruses against FAW has been proven; however, farmers may not be able to afford the products. The use of farmer-produced baculovirus mixtures could provide an opportunity for a nature-based solution for FAW at a low cost. This study evaluated the potential of recycled virus inoculum from FAW larvae treated with a commercial baculovirus (Littovir) for the management of FAW under laboratory and field conditions. In the laboratory, the virus from 25, 50, 75 and 100 FAW larvae caused variable mortality among FAW instars. The highest mortality (45%) among 1(st)–3(rd) instars was caused by Littovir followed by recycled virus inoculum from 100 FAW larvae (36%). Under field conditions, even though recycled virus inoculum did not offer adequate protection against FAW damage, the maize yield was comparable to that of commercial insecticide-treated plots and similar to that of control plots. This study has shown the potential use of recycled virus inoculum from infected larvae for the management of FAW. This would offer the farmers a sustainable and affordable option for the management of FAW as it would require the farmers to purchase the commercial baculovirus once and collect larvae from treated plots for repeat applications.