Is the biotic potential, expressed as life-history features and nutritional indices, of generalized herbivore insects a function of host plants? — Spodoptera littoralis as a case study

Abstract

Abstract The present study aimed at evaluating the impacts of castor bean, tomato, potato, and cucumber leaves on the various components of biological fitness and food consumption and utilization of S. littoralis. The levels of nitrogen, potassium, and phosphorous in the tested host plants were quantified. Feeding larvae on the tested host plants did not affect larval or pupal duration. Whereas, weight of full-grown larvae, adult emergence, and egg-hatch were significantly affected, with the highest and lowest values in case of feeding on castor bean and cucumber leaves, respectively. The highest and lowest number of eggs deposited per female were attained on castor bean and tomato leaves, respectively. Adult male and female longevity was the highest on potato and on castor bean leaves, respectively. Nutritional indices were dependent on the host plant, metamorphed instar, and age within instar, with the most profound change in case of 6th -instar larvae (last instar). Castor bean was the most nutritive host plant as it contained the highest levels of nitrogen and potassium. In contrast, tomato was the least nutritive one as it contained the lowest concentrations of nitrogen, phosphorous, and potassium. It appears that castor bean was the most suitable host plant, whereas tomato was the least suitable one. The findings obtained herein may help in understanding the biology of S. littoralis, leading to a better strategy to its control. Future studies should focus on testing a wider range of host plant species.