Influence of Pistia Stratiotes Plant Quality on the Growth and Development of the Biological Control Agent Spodoptera Pectinicornis

摘要

Performance of the specialist herbivore Spodoptera pectinicornis (Hampson) (Lepidoptera: Noctuidae) was studied when fed the floating aquatic plant waterlettuce Pistia stratiotes L. (Araceae). Plants were either collected from six populations in south Florida or from plants grown with low or high fertilizer levels. Consumption of leaves with increasing toughness resulted in increased larval mortality to more than 80 percent; most mortality occurred during the first instar. Larvae fed low nitrogen leaves required up to twice the time and typically an extra instar to complete development. Larvae compensated for low nitrogen leaves by increasing fresh weight consumption threefold. Despite these dietary challenges, the biomass gained by the larvae was similar regardless of the quality of leaves consumed. These results are useful in understanding the adaptations and limitations of specialist herbivores to low nutrient foods. Additionally, they assisted in the selection of suitable release sites for this weed biological control agent. Finally, they improved mass rearing techniques for augmentative releases of this biological control species.