Effect of Rabbit urine on Larval Behaviour, Egg Hatchability, Pupal Emergence and Oviposition Preference of the Fall Armyworm (Spodoptera Frugiperda J.E. Smith)

Abstract

The fall armyworm (FAW) (Spodoptera frugiperda) is a major cereal pest threatening food security in Africa. African smallholder farmers apply various indigenous pest management practices including the application of rabbit urine; however, there is no scientific evidence on its efficacy and mode of action. We evaluated the effect of rabbit urine on FAW 1st (neonates), 2nd and 3rd instar larvae. Larvae were exposed to rabbit urine treated and untreated maize leaves (control). Larval settlement, larval survival, pupal emergence, adult oviposition preference and egg hatchability were evaluated. More FAW larvae (55.5–73.0%) oriented on the untreated leaves compared to those (25.5–41.5%) that oriented on the rabbit urine-treated leaves. Rabbit urine caused 66, 69 and 72% reduction of damage caused by neonates, 2nd instars and 3rd instars, respectively, after 24 hours of exposure. Rabbit urine significantly reduced survival of FAW and had lethal time (LT50) of 5.0, 7.0 and 8.7 days and lethal dose (LD50) of 49, 94, and 55% for neonates, 2nd instars and 3rd instars, respectively. Additionally, egg hatchability and pupal emergence were reduced by 55.0% and 13.3%, respectively. When provided a choice, FAW female moth laid more eggs on rabbit urine treated plants (647 ± 153 eggs) than untreated plants (72 ± 64 eggs). This study confirms farmers’ assertions that the application of rabbit urine can manage FAW and, therefore, can be integrated into the FAW IPM package in Africa. Additional studies on the chemistry of rabbit urine, behavioural response and cost implication might be required for scaling up.