Effect of four host plants on the life history and nutritional indices of Spodoptera Littoralis

Abstract

The Egyptian cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) is a pervasive and highly polyphagous insect pest. As S. littoralis has developed resistance to major classes of conventional insecticides and the use of these insecticides has caused negative impacts on the ecosystems, it is necessary to search for eco-friendly, cost-effective, and sustainable agents to control. This can be achieved by identifying the preferred host plant. The present study aimed at evaluating the impacts of four host plants– castor bean, tomato, potato, and cucumber on the various life-history traits and nutritional indices of S. littoralis. The concentrations of nitrogen, potassium, and phosphorous in the tested host plants were quantified. Newly hatched larvae were divided into four groups. Each group was fed only on one type of the four tested host plants until pre-pupal stage. Then, the life-history traits and nutritional indices were determined. Larvae fed on castor bean showed the highest adult emergence, weight of full-grown larvae, number of eggs per female, and egg-hatch percent, food consumption, relative growth rate, and food utilization efficiencies. Whereas, larvae fed on cucumber showed the lowest egg-hatch percent, food consumption, relative growth rate, and food utilization efficiencies. There was a positive correlation between nitrogen and phosphorous concentrations in the tested host plants and larval weight, with the highest concentrations in castor bean. Castor bean was the most preferred host plant.