Abstract:

To clarify whether Spodoptera frugiperda poses a threat to fruit and vegetable production in China, a comparative analysis of the feeding selectivity of 3rd-5th instar larvae of S. frugiperda on maize, sweet potato, tomato, and dongzao jujube leaves was conducted by leaf disc method. The feeding preferences of primary larvae initially domesticated on sweet potato and tomato leaves until they developed to the 3rd-5th instar larvae stages were examined. We assessed their selectivity for the initial food used for domestication and three other foods, compared feeding selectivity between various plant parts. The feeding preferences of S. frugiperda across all instar stages were as follows: maize (43.23%-61.82%)> sweet potato (20.37%-25.62%)> tomato (10.91%-24.3%)> dongzao jujube (5.45%-9.26%). Notably, after being domesticated on sweet potato and tomato leaves to 5th instar larvae, S. frugiperda exhibited heightened selectivity for the food they were initially domesticated on compared to maize. In contrast, although 3rd and 4th instar larvae retained a strong preference for maize leaves, they also demonstrated a substantial increase in selection rates for the food initially used for domestication. This increase ranged from 16.42-24.11 percentage points for sweet potato and 18.07-20.89 percentage points for tomato, compared to uncultivated larvae. Furthermore, the feeding selectivity analysis for different plant parts revealed that younger larvae displayed a preference for new leaves and corn whiskers of maize, whereas older larvae exhibited a preference for old leaves and male panicles. Concerning plant parts, younger larvae favoured plant stalks, whereas older larvae showed a preference for plant leaves. Our findings indicate that although S. frugiperda larvae exhibit lower feeding selectivity for sweet potato, tomato and dongzao jujube compared to maize, they still pose a potential threat to the production of these crops after domestication or under environmental stress. Notably, distinct variations in feeding choices for different parts of the plant were observed among younger and older larvae.

Key words: Spodoptera frugiperda, feeding preference, domestication feeding, environmental stress