Mathematical modeling of weight gain in immature stages of spodoptera littoralis (boisduval, 1833) (lepidoptera: Noctuidae) reared on different foods

Abstract

2-s2.0-85099640952Spodoptera littoralis is a model insect in many entomological studies and an important pest species in agricultural production. There are many studies to understand the life cycle of this pest and to control thereof. This study aimed to determine effects of different foods on weight gain of S. littoralis larvae and whether the log-normal function applied onto the daily weights of these larvae was appropriate or not. For this purpose, penultimate instar larvae were fed on potato, lettuce and synthetic diet. Based on the results, larval weight gain was increased until the 5th day on the lettuce- and diet-fed larvae groups. The most weight-gaining larvae were the lettuce-fed larvae (400.20 mg) and the mean weight of the lettuce-fed larvae reached up to 885.13 mg. These larvae were followed by the potato-fed larvae (287.43 mg) from the point of weight gain and the mean weight of these larvae reached up to 776.43 mg. Maximum weight gain of the diet-fed larvae was 257.33 mg and the weight thereof reached up to 694.83 mg. Besides, the log-normal distribution model gave a satisfactory fit for daily weights of S. littoralis larvae. On the other hand, the numbers of eggs laid by the female adults obtained from the larvae reared in different foods were no statistically different. Consequently, it is concluded that log-normal distribution model can be applied to evaluate the daily weight of this pest in larval period and lettuce can be used as a food source for mass cultivation of this pest in the laboratory. © PS