Laboratory and field evaluation of the nuclear polyhedrosis virus of Spodoptera litura (Fab.) (Lepidoptera:Noctuidae)
1987
Ebora, R.V.
Nuclear Polyhedrosis Virus (NPV) of Spodoptera litura exposed to direct sunlight reduced its virulence. The shade provided by the sweet potato leaves on NPV applied on their undersides prevented the total inactivation of the virus. The thermal inactivation point of NPV was 90 degrees Celsius and virulence started to decline at 50 degrees Celsius. Feed consumption of diseased and healthy larvae was not significantly different. Diseased larvae consumed an average of 5780.4 plus or minus 3640.8 mm to the eighth power mulberry leaves while healthy larvae consumed 6062.7 plus or minus 2152.6 sq. mm. NPV can be more effective in reducing leaf damage if used at high dosage or against early instars. The NPV isolate was specific to S. litura and failed to infect several other insect species when given at high dosage. Sprayed NPV caused infection of cutworm field populations on peanut during the wet and dry seasons. Infected larvae were noted 4 days after treatment while virus killed larvae were observed on the 8th day. The disease spread to the untreated plots. NPV controlled cutworm larval populations comparable to that of Azodrin 202R (Monocrotophos) and Thuricide HP (Bacillus thuringiensis). In terms of yield, no significant differences between treatments were noted. NPV from crude extract and those from heavily diseased larvae were successfully transmitted by pricking a diseased larvae with micropin and then to 2nd instar larvae of S. litura. Lower degree of transmission was noted when 4th instar larvae were infected due to the inherent resistance of older larvae to the disease. Significantly lower transmission was also obtained when mildly diseased larvae were used as donors due to the lower concentration of NPV present in the larval tissues and hemolymph.
Показать больше [+] Меньше [-]Ключевые слова АГРОВОК
Библиографическая информация
Эту запись предоставил University of the Philippines at Los Baños