Spatial Distribution and Oviposition Traits of Spodoptera eridania (Lepidoptera: Noctuidae) on Potato Plants Mediated by Chlorfenapyr

Spodoptera eridania (Cramer, 1792) is increasingly reported from potato (Solanum tuberosum L., Solanaceae) in the Brazilian Cerrado, where infestations can cause substantial yield losses. Insecticides may alter the behavioral ecology of agricultural pests. The adaptability of S. eridania mediated by insecticides, especially regarding oviposition behavior, remains poorly understood. This study aimed to evaluate the spatial distribution and oviposition traits of S. eridania on potato plants under chlorfenapyr spraying. Egg masses were collected weekly, day after planting (DAP), totaling 322 collections up to the 91st DAP. Evaluations included the vertical plant strata (upper, middle and lower thirds), leaf surface (adaxial vs. abaxial), and density of scales covering egg masses (high, low, or absent). Results showed that nearly 90% of egg masses were deposited in the upper and middle thirds of the plants. Insecticide spraying modulated oviposition behavior because females preferred the middle third in treated plants, whereas oviposition predominated in the upper third of untreated plants. Moreover, under chlorfenapyr, 93.0 ± 1.2% of egg masses were placed on the abaxial surface. These findings highlight the role of insecticide-mediated behavioral shifts in shaping host-pest interactions and provide relevant insights for integrated pest management of S. eridania in potato field systems.