Empirical Assessment of the Role of Natural Enemies in Suppressing Helicoverpa armigera Populations in Tomato Farms Across Kaduna State, North West Nigeria

Helicoverpa armigera is among the most polyphagous and economically damaging lepidopteran pests globally, causing severe losses in tomato and other crops across Nigeria. Biological control through native parasitoids and predators represents a sustainable management option, but the extent to which natural enemies suppress H. armigera under Nigerian farm conditions has not been empirically quantified. This study empirically assesses parasitism rates and predator activity levels on H. armigera in tomato farms across three agroecological zones of Kaduna State over two growing seasons. Larvae will be systematically collected from 60 farms and reared to determine parasitism rates. Emerged parasitoids will be identified to species. Field predation will be estimated using sentinel egg and larval cards. Exclusion cage experiments on 12 farms will partition the yield protection attributable to natural enemies from that of other mortality sources. Generalized linear modeling will identify farm management predictors (pesticide intensity, crop diversity) that explain variance in natural enemy activity. This study generates the first empirical natural enemy suppression estimates for H. armigera in North West Nigeria, directly informing conservation biological control recommendations. Keywords: Helicoverpa armigera, natural enemies, parasitism rates, tomato, Kaduna State