Comparative study of different artificial diets on the biology of beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae)

Abstract

The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera; Noctuidae), is an important polyphagous insect pest of many vegetable and field crops in most parts of the world. Aimed at studies on insect manage methods including sterile insect technique (SIT), it is necessary to continuously maintain laboratory colonies of insect species on an artificial diet. The current study aimed to evaluate the effects of different protein-based diets (soybean chunks, chickpea, kidney bean, mung bean, pinto bean, white bean, lentil and corn) on the biology and growth indices of S. exigua. For this purpose, different artificial diets were prepared and larvae were reared on these diets. The larval survival, larval period, pupation, pupal weight, pupal period, adult emergence, adult longevity, fecundity, fertility and life span were calculated accordingly. The larval survival rates were lowest on lentil, pinto bean and corn diets (P < 0.01) and pupation did not occur on these diets. Based on the results, among the other five artificial diets, all the highest studied parameters, the developmental and reproduction values and growth indices, were recorded on soybean chunks and chickpea diets (P < 0.01). The larval survival, pupation rates, larval growth index and fitness index have been further optimized when these two protein-based ingredients were mixed together (50:50). Consequently, soybean chunks and chickpea are introduced as the best dry ground protein ingredients in the beet armyworm artificial diet.