New Technology
For Optimizing Production
of Spodoptera
littoralis Nuclear
Polyhedrosis Virus
[70]
Bekehit1, H.K.M.; Amal1, M.
Mabrouk and F. Abo El-Abbas2
This study was carried out to optimize S. littoralis rearing for strengthen the productivity of it’s nuclear polyhedrosis virus. Results indicated that the feeding rate of larvae increased with increasing the age of larvae up to the 11th day post-feeding in the different tested diets, then the feeding rate of larvae decreased sharply for the 6th instar larvae. More food consumption was found in the larvae fed on tetracycline diet followed by tetracycline + formaldehyde, formaldehyde and control ones, respectively. In comparison with control diet, increase the percentage of food consumption for the larvae fed on tetracycline + formaldehyde diet ranged between 14.07 and 33.49%, while it ranged between 3.59 – 40.29% and 2.51 – 22.34% for the larvae fed on tetracycline and formaldehyde ones, respectively. Meanwhile, the larvae fed on the diet mixed with tetracycline alone/ or in the presence of formaldehyde gained higher weight (gram/larva) than that fed on both formaldehyde mixed and control diet. In comparison with Shorey and Hole diet, percentage of increase in larval weight increased and ranged between 10.73 – 43 % in tetracycline + formaldehyde diet, while it ranged between 11.84-44 and 4.85-22% in tetracycline and formaldehyde diets, respectively. There was a decrease in weight of the larvae fed on formaldehyde diet which ranged between 3.05 – 8.44% through the period from the 7th to 9th day. Addition of both tetracycline and formaldehyde separately or mixed are an important additives to prevent dissemination of pathogens , but formaldehyde must not be added to food used in the production of virus because it’s effect on nucleic acids. Disease incubation period to death decreased with increasing the tested concentration. There were slight variability in the response of 3rd instar larvae to NPV between the two tested diets after application. The LT50 values in the larvae fed on bean diet were 6.88, 6.01, 5.49 and 4.03 days at the concentrations of 1.47x105, 1.47x106, 1.47x107 and 1.47x108 PIB/gram diet, respectively. While The LT50 values in the larvae fed on bean diet were 6.71, 6.04, 5.50 and 4.91 days at the same concentrations mentioned above, respectively.