Title:
Comparative studies of semi-artificial diets on the biology and the bionomics of the European corn borer, Ostrinia nubilalis Hübner (Or.: Lepidoptera, Fam. : Pyralidae).

Abstract:
Comparative studies of two semi-artificial diets (S.A.1 and S.A.2) as well as a natural corn diet were studied on the biology and bionomics of the European corn borer, Ostrinia nubilalis under laboratory conditions. The insect was successfully mass reared for ten successive generations at the conditions of 27 +/- 2 degrees C, 60-80% R.H. in addition of photoperiod of 6:18 (L: D) for larvae and 12:12 (L: D) for the other stages, respectively. Along ten successive generations, there were no significant differences between the larval periods for both artificial diets. The S.A.1 induced the shortest larval period (22.5 days) compared to the artificial diet S.A.2 (24 days) and the natural diet (25 days). Meanwhile, the rearing larvae on the natural diet revealed means of pre-pupal and pupal periods of 2 and 8 days which decreased to 2 and 6.5 days in both artificial diets (S.A.1 and S.A.2), respectively. However, the pupal weight and length were insignificantly increased in S.A.1 (121.7 g and 1.7 cm) than that in the natural diet (115.5 g and 1.8 cm) and were in the artificial diet S.A.2 (101.2 g and 1.7 cm), respectively. Moth longevity (pre-oviposition, oviposition and post-oviposition periods), was affected to a certain extent by the larval diets. The maximal moth longevity was recorded (15 days) for larva reared on the natural diets. On the other hand, the shortest period was observed (10.5 days) for the moth longevity in S.A.1. The artificial diet S.A.2 showed the moth longevity (13 days). The longest oviposition period was recorded (10 days) in the natural diet, while it was only (6.5 days) in the artificial diet S.A.1 compared with (8 days) in the artificial diet S.A.2. The number of the deposited eggs/female throughout the 10 successive generations was (400) in the natural diet, while the artificial diet S.A.1 revealed the least number (304.4) versus (358.2) in the artificial diet S.A.2. On the other hand, the number of hatched eggs/female were (320) in the natural diet, versus (310.9 and 256.5) in the artificial diet S.A.2 and S.A.1, consequently. The highest mean of hatchability percent was 86.93% resulted in the artificial diet S.A.2 compared to. 83.92% in the artificial diet S.A.1 and 80% in the natural diet. It was observed that the shortest total generation period found (41.5) days in the artificial diet S.A.1 while it was (50 and 45.5)days in the natural diet and the artificial diet S.A.2, consequently. The results declared that the artificial diet S.A.1 is a suitable artificial diet as it is considered mass rearing of the European corn borer, Ostrinia nubilalis Hub.